"Our everyday world, plainly moulded by subatomic forces, also owes its existence to our universe's well tuned expansion rate, the processes of galaxy formation, the forging of carbon and oxygen in ancient stars, and so forth. A few basic physical laws set the 'rules'; our emergence from a simple Big Bang was sensitive to six 'cosmic numbers'. Had these number not been 'well tuned', the gradual unfolding of layer upon layer of complexity would have been quenched. Are there an infinity of other universes that are 'badly tuned', and therefore sterile? Is our entire universe an 'oasis' in a multiverse? Or should we seek other reasons for the providential values of our six numbers?"
Martin Rees
Martin Rees: Just Six Numbers
There are a small number of key physical constants that had they been slightly different would have led to our Universe developing very differently.
Figures of speech
Perhaps appropriately for a book that is about 'just six numbers' I wish to examine some of the figurative (see what I did there?) language used by an author in seeking to explain some abstract scientific ideas for a popular readership.
I have written quite a lot in this blog about the kinds of metaphorical and other figurative language used by teachers and other science communicators when trying to explain science, and here I want, in particular, to make a point about context: about the context in which such language is used,
"A technique that chemistry teachers share with teachers of other disciplines, as well as other communicators (such as journalists, but, indeed, people in general) is to draw comparisons with (what are assumed) familiar ideas, experiences and phenomena, simply by using language. This can be in the form of metaphors, similes and analogies…and these can sometimes be anthropomorphic in nature – that is, to put something (such as the 'behaviour' of a molecule) in terms of human feelings, thoughts and experiences.
Although, later, I make a distinction between metaphors, similes, and analogies – in practice, it is not always straightforward to distinguish between them. For example, our judgement about which category some comparison belongs in may change depending upon whether we consider a specific statement by itself, or examine it in the wider context in which it occurs. That is, material of relevance that is not explicit in the statement may be being assumed by the communicator as it has been previously referenced or alluded to, as part of the wider text or dialogue."
Taber, 2024
In a science classroom, that context might include earlier topics presented in the curriculum; some reading that was set ('homework') as preparation for class; what the teacher said last lesson; or something learners have just been asked to try out or to observe. In a text, such as an extract from a popular science book (as in the example above from 'Just Six Numbers'), the context that is provided is the rest of the text, and especially the part of the text preceding that extract – as this is the part an author can reasonable claim you 'should' have already read (though readers are of course free to engage with a book as they wish).
That is, 'should' does not here imply an imperative, but rather the author's reasonable defence that if you choose to read the text out of order, or just dip in, then the author cannot be considered to be responsible for anything you may have missed that is needed to make good sense of what is presented later in the book. Any teacher who has pointed out to a student claiming not to follow in class that they 'might have understood better if they had not missed the previous lesson' can appreciate this logic.
Interrogating the text
So, bearing in mind I have not reproduced the whole of Prof. Rees's book, but just an extract out of context, I would like readers to consider the extract at the start of this posting, and to ask themselves:
what does this mean?
how do I know what it means?
what would it be reasonable to expect a 'typical' general reader (one with an interest in the topic, but not being a science specialist) to make of the extract?
what terms or phrases in this extract can be considered to be used figuratively here (that is to not here strictly mean what those words, strictly, mean?)
I noticed this extract was rich in figurative language, such as metaphors with teir 'hidden' meanings. And then I re-read it, and further noticed I had actually read-through some of the metaphorswithout initially noticing them – so it was actually even richer in such language than I had first realised.Often we do not notice the metaphors and similes used in texts, but rather simply automatically make sense of them as part of the text. 1 Usually we read a text for meaning (semantics) rather than choice of vocabulary, and we 'automatically' (preconsciously) analyse the text in terms of pragmatics – that is what a term is likely to mean in this specific context:
I am going to the bank to cash this cheque
I am going to the bank to dangle my feet in the river
I am going to the bank to see if we have any AB negative
Language is fluid (so to speak)
The extract from Rees's book presents a range of terms which need to be interpreted to identify what they mean within this particular context. Now I do not intend this as a criticism: I think two relevant general principles here are that:
It is the nature of natural language (e.g., here English – 'other natural languages are available') to be somewhat fluid (so to speak), with many words and phrases being open to somewhat flexible use across a range of meanings: so it is generally the case that words, phrases, sentences, paragraphs, etc., take their specific meanings within a text from the wider textual context.
And indeed, in everyday situations, also the broader shared context. If someone is shouting out 'Fire!' this may mean something quite different in the context of a quiet accounts department in a tall office block than in the context of a Fascist's state's execution of a political prisoner – or indeed at an Arthur Brown concert.
When musician Arthur Brown performed his song 'Fire', and sang loudly 'Fire!', he did not intend his audience to leave the venue. (Though given his stage headgear, which sometimes malfunctioned, a careful risk assessment might have suggested that course of action.)
It is in the nature of unfamiliar abstract science concepts that they will not make good sense to learners (/readers/listeners) who cannot relate them to something already familiar. So science teaching (and science communication more generally) is often about making the unfamiliar familiar by showing how this unfamiliar idea is a bit like something you already understand and are comfortable with. This unfamiliar thing is not the same as that familiar thing (and differences will need to be addressed), but there is a similarity which can be used as a starting point for making the unfamiliar familiar.2
Using figurative language to explain science is therefore not a bad thing – although there can be poor examples which do not help or only confuse as well as very productive examples that support learning (and this may be relative to individuals, as each learner brings their unique set of 'interpretive resources' to make sense of learning). And indeed, sometimes, it may be a necessary teaching tactic if the gist of an abstract idea is to be effectively communicated. My discussion of examples in this blog then is certainly not intended to mock or deter this technique, but rather to highlight something of the complexity of using figures of speech in explaining science.
Let's start at the end…
The extract I present above is from the end of the book, as Prof. Rees concludes by summing up what he has been setting out to readers. This is then (most of) the very final paragraph in the text, so it is quite reasonable for Rees to assume that a reader getting to this point will have the context of having (in effect) read the book.
If you have not read the book, then perhaps that extract above may be too dense with ideas and figures of speech for you to fully appreciate it. But that depends: if you are a cosmologist or astronomer or physics teacher, then it is quite likely that you are sufficiently familiar with the ideas being communicated (and indeed some of the metaphorical language being used) to find the extract unproblematic. As always, each person brings their own unique set of interpretive resources to make sense of a text.
But, as an example, I am going to deconstruct the text to highlight some of the 'interpretation' involved in understanding it. Now, there are references made in the extract to scientific ideas which had been discussed earlier in the book, such as that of a multiverse, the Big Bang, and the expansion of the Universe. But my focus is on the non-technical figurative terms, or at least those that are likely seem non-technical to the general reader. 3
Tuning up the Universe
The terms well tuned (and in the marked form, 'well tuned') and 'badly tuned' are applied to the Universe. This notion has been well developed earlier in the preceding text. Tuning is originally a term used in relation to musical instruments that is figuratively used in other contexts. One might tighten the tension in a guitar string so it plays at the right frequency to give the required musical note.
Engines are also said to be tuned. Presumably this was originally used metaphorically, and because the process was done 'by ear' – by listening to the engine 'note'. Language develops over time so that engine tuning has become an accepted term and is no longer metaphorical. However, clearly there is something of a stretch (so to speak) to extend the notion of tuning to a universe. 4
Being well tuned (or badly tuned) is anthropomorphic or teleological. That is, there is nothing intrinsically right or wrong about a universe having particular qualities. But for a universe to have been suitable for us to appear it needs certain properties – a well tuned universe is one that has particular qualities that are seen (by someone) as desirable. Being well tuned might then imply developing in accord with some sense of purpose. (Again these ideas had been addressed earlier in the text by Rees for anyone reading the whole book.) 5
Moulding and forging
To mould means to shape something, perhaps (as with clay) by manipulation or (as with cooling molten metal) by pouring in a pre-shaped mould. The term is widely used metaphorically, and here the term is extended to the effects of subatomic forces.
Forging is a term relating to metal working, where a blacksmith (for example) uses a forge as a hot environment to shape (and sometimes harden and temper) metals. The forge is (in human terms) very hot – although the forging is itself achieved by hammering the metal once it is hot enough to be sufficiently malleable. The term is again commonly used metaphorically – perhaps a famous example was a much quoted speech by UK Prime Minister Harold Wilson who referred to how his government was
"…re-stating our Socialism in terms of the scientific revolution…. Britain that is going to be forged in the white heat of this revolution…"
The processes by which heavier atomic nuclei (i.e., anything heavier than helium nuclei in this context) are produced are nuclear process that only occur under what we would consider extreme conditions such as in the cores of suns (often considered 'nuclear furnaces') or during supernovae explosions or other events that irradiate material in space with highly energetic radiation. There is no forging as such, but the conditions may be seen as akin to those in a forge – e.g., unusually hot. If using 'forging' metaphorically to refer to the nucleosynthesis of elements, it is important to note that in the scientific context an important aspect of the original meaning does not transfer across: the blacksmith uses his forge to deliberately produce something, perhaps horseshoes, whereas there is no deliberate purpose or design to the nuclear changes going on in stars. 6
Unfolding the layers
The "gradual unfolding of layer upon layer of complexity" offers something of a mixed metaphor. We might argue that by definition it is only possible to unfold something that has previously been folded. But metaphorically we might see the opening of a flower, with its sepals and petals and pistil and stamens as being like a kind of unfolding – we can imagine these structures have been neatly folded away, though of course that never happened.
We might also say, metaphorically, that a story unfolds as new themes and characters and episodes are introduced (though here there is a sense that the author who planned the narrative has likely story-boarded this level of detail, and then (metaphorically) folded it away in the structure of the narrative.
The (metaphorical) unfolding referred to by Rees seems to be akin to that of a flower, in that as the Universe ages new structures appear through a developmental process just as the new organs appear on a plant when the flower develops. (Incidentally, astronomers tend to refer to the 'evolution' of the Universe although clearly there is no evolution in any sense parallel to that seen in organisms – through variation and natural selection. A better analogy would seem to be with the development of an individual living thing that passes through different stages of life.)
The layers of complexity are surely metaphorical, as it is only human cognition which finds it convenient to see them as layers. We can see the world in terms of a series of strata of increasing complexity with new phenomena emerging at the different 'levels': so perhaps sociology from psychology, which emerges from biology, chemistry, and ultimately physics.
We can consider structure in the Universe at 'levels' such as galactic clusters, galaxies, stellar clusters, solar systems…nuclei, quarks, etc. But in the Universe these do not occupy actual levels, rather this is an abstraction we impose to help analyse the complexity (we 'dig down' to the 'level' of molecules or nuclei or quarks or whatever). This is probably obvious to most readers as we are so used to imposing metaphorical layers on conceptual systems (but it might mystify a perfectly normal modern human who had not received a formal education 7).
Quenching
Quenching takes us back to the forge. I strongly remember metal work at school when I was eleven, and having to heat a piece of metal till it glowed a particular colour before plunging it into cold water to 'quench' it: to cool it rapidly. Having hardened the metal it was next 'tempered' by heating again before being thrust into sand to cool less rapidly. While I have forgotten much I did at that age at school, the sheer fear of using lathes, massive drills and blowtorches provided an emotional quality that seems to have 'forged' those memories. (But I do still have the screwdriver I made.)
One can also use water to quench a fire or one's thirst – so quenching is a process of removing. In Rees' text the metaphorical layers of complexity would not have occurred, and so could not have been metaphorically unfolded if the 'six numbers' had had very different values. Some minor shift in one or more of those numbers may have changed the timescale of universal development, so that some of the processes and structures in our Universe would not have had time to develop, or to have developed as much.
In either case it is only a potential which is 'quenched' as nothing that comes into being is removed, and there is no active quenching agent – it is more a (metaphorical) lack of formation of the combustible material than the action of some water to put out a fire.
Does this make for a poor metaphor? This is quite difficult to judge as words have aesthetic and other qualities (such as salience) as well as literal meanings, and a metaphor which seems less apt semantically may still have some impact on a learner/reader/listener and lead to engagement with the ideas being communicated. (And this will vary between individuals of course.) So the crux of the question of whether 'quench' is a good choice here is an empirical one: if it helps communicate Rees's intended meaning to (most of) his readers then it is effective: if instead it mainly mystifies or confuses or misleads them, then not so.
A desert of sterile universes?
If there are other universes which developed with different values of the key cosmic constants (constant, in any particular universe, that is) then in many of those universes there would be no galaxies and stars. And in some that did lead to galaxies and stars there would be no opportunities for life to evolve (if stars burned out rapidly, for example). And in some that gave opportunities for some kind of simple life, there would not be sufficient scope for the evolution of sentient beings capable of asking questions about other universes.
If sterile means unable to reproduce, then this is a metaphor which could be applied to any universe. 8 Sterile can also mean free from organisms (usually especially microorganisms) which could therefore seem as a non-figurative term when applied to some imaginable universes (which might include stars systems etc., but that are) incapable of supporting life.
If there is a multiverse – that is, if our Universe is one of many coexisting but completely non-communicating universes – where the different universes have widely different values of these cosmological constants, then likely most of them will not have developed with the complexity of ours, and so most would not support the evolution of life. Thus if we see the multiverse as a desert, then, metaphorically, a universe like ours would be an oasis – a small location where life can survive in the desert.
The metaphor requires us to step out of our Universe to take a view of the multiverse, and imagine a traveller moving across the desert and entering the oasis; when the 'oasis' is actually a self-contained world, not even hermetically sealed off (so to speak) from any other such worlds as it has no boundary with them, and there is no means of seeing out beyond the oasis. No traveller could move from one universe to another (so there would be no opportunity to look back in anger if they found the grass was not actually greener).
Is the universe like an oasis? (Image by AlexBishop from Pixabay)A galaxy – an island universe? (Image by Kyoung-Sik Choi from Pixabay)
Despite this, my own feeling is this metaphordoes communicate a meaning well, and it reminds me of a long-established metaphor where galaxies are seen as their own island universes in the ocean of space. 8 So again, I do not think we can judge the effectiveness of metaphor simply in terms of the technical aptness of that metaphor, but this does remind us that in interpreting a metaphor the reader or listener is selecting some, but not all, of the associations available for the term (and so of course may select different associations to those the author or speaker had in mind).
Coda: Texts may have their own dark matter
What this analysis is intended to do, is not to critique the specific figures of speech used here (which can only sensibly be evaluated by questioning a representative sample of readers who had finished the book to see how they made sense of the text), but rather to highlight just how many layers of complexity may be enfolded (so to speak) in forging even a short text, and so just how much interpretive work a reader needs to do in making sense of a text.
We think of scientific articles as being as explicit and precise as possible, and so rich in formal technical language; and this is appropriate as the intended readership can be expected to have mastered the relevant concepts and technical vocabulary necessary to make sense of such a text. But in explaining science to a non-expert audience (in teaching; in writing a popular science book) one has to mould an account to resonate with the audience members' available funds of interpretive resources. These resources may be rich and varied, but will be technically more limited.
So such texts can only be populated with the lower density of technical ideas and terminology that can either be assumed as common to the audience, or gradually introduced in the text. Technical terms therefore are widely interspersed among the 'space' of the text, with the meaning being held together by the use of figurative language such as metaphors with their 'hidden' (implicit) meanings. The work of making sense relies on a good understanding of the technical terms used, and a suitable interpretation of the supporting 'dark matter' of figures of speech.
Usually, most of this interpretive work is automatic – occurring outside the 'spotlight' of conscious awareness – but the reader still has to process the text to try and mould it into a reading that makes sense to them. A text needs to be well-tuned for its readers, or else that sense-making will be quenched, making the metaphors sterile. (So to speak.) Or worse? Perhaps being fertile grounds for unintended meanings to germinate.
This 'tuning' is always a challenge given that different readers will have different levels of background knowledge and other interpretive resources, and so may resonate across a wide range of different natural frequencies, so to speak. A well judged (tuned) book will at least largelyresonate with most of its readers regarding most of the metaphors used. Then they will likely not even notice these figures of speech, as interpretation will be automatic and the text will simply, subjectively, make sense. Somewhat like the dark matter thought to make up much of the mass of the Universe, these figures of speech hold the text together semantically without being conspicuous. Of course, sometimes the wrong feature of the metaphor may be adopted, so the reader's meaning may not perfectly match what the author intended.
There may be outliers, including perhaps some readers not well prepared to tackle the text (lacking essential background knowledge or reading level perhaps) who may find themselves in a metaphorical semantic dessert with just the odd oasis that seems fertile with meaning. (So to speak.) An author, unlike a teacher, does not have the opportunity to constantly check on how they are being understood and make adjustments, so this is an unavoidable feature of texts of this kind.
All an author can do is choose their metaphors carefully, bearing in mind their expected readership; and offer context by incrementally forging a kind of customised metaphorical lexicon across the text. 9 As Rees does in his book.
If you are intrigued by the extract discussed, and wish to know more, the full textual context (Rees, 1999) is available!
Sources cited:
Luria, A. R. (1976). Cognitive Development: Its cultural and social foundations. Harvard University Press.
Rees, Martin (1999) Just Six Numbers. The deep forces that shape the Universe. Weidenfeld & Nicolson. London.
1 By similes I mean those figures of speech which are marked by the author, for examples using inverted commas (speech marks) as in 'well tuned' as in "…not been 'well tuned', the gradual…", as well as metaphors such as well tuned in "our universe's well tuned expansion rate". Similes may also be marked by using like, as, in a sense, so to speak, etc.
Many examples of science similes are listed in 'Creative Comparisons: Making Science Familiar through Language. An illustrative catalogue of figurative comparisons and analogies for science concepts'. Free Download.
We usually 'read through' such figures of speech, but as I have become rather obsessed with the use of figurative language in science I tend to notice many of them, often reading a text both for the scientific meaning and also to see the way the author is explaining the science.
3 I make this distinction because sometimes terms which are originally used metaphorically, such as the 'death' of a star, come to be habitually used; and so in effect become technical terms within a scientific field, while still appearing to be metaphorical to a non-expert in that field. They become phantom metaphors (something a non-expert will assume is a figure of speech, although it is being used as if a technical term).
4 Traditionally the Universe referred to everything there is, but (following Rees in his text) we can both consider other potential universes that could perhaps have existed instead of ours, and also that there may be totally separate non-communicating alternatives beyond what we can observer as our Universe which potentially have quite different natural laws. In this usage 'our' Universe may be one element in a 'multiverse'.
5Anthropomorphism is when an inanimate object or non-sentient organism is spoken of as though it has human experience, desires and so forth. The atom needs another electron. The virus tries to hide in the tissue.
Many examples of anthropomorphism are listed in 'Creative comparisons: Making science familiar through language. An illustrative catalogue of figurative comparisons and analogies for science concepts'. Free Download.
Teleology is about having a purpose or goal. Much of the functioning of living things seems purposeful (we can suggestion functions to the heart or to the gene as though they are working towards some outcomes, rather than having evolved to be like they are by natural selection). The idea of a well tuned universe could imply some ultimate goal (e.g., to be suitable for life to evolve) which is only achieved when the cosmic numbers Rees discusses have the 'right' values.
6 I am not here excluding the possibility that there may be a creator who has deliberately set up the system, but science is only concerned with natural mechanisms, not ultimate causes. The star has no purpose or intention – it makes heavier elements simply because that is what happens to that material under those conditions.
7 Some of the habits of mind we take for granted are acquired through the culture. For example, people with a formal academic education tend to readily appreciate the form of syllogism and how it is used. But this is something we learn from culture:
fluency in using syllogism depends upon experience that is acquired through education;
people in some traditional cultures have not received the formal education that introduces, and offers experience of thinking with, syllogisms;
therefore people from such cultures will not tend to show fluency in using syllogism.
At least this was what the Russian psychologist Alexander Luria (1976) found when he did field work among traditional cultures just being introduced (indoctrinated?) into the collectivism of the Soviet Union.
8 Of course, as our Universe is by definition all we can directly know, it could only be speculation about whether a universe could in a sense reproduce. Such speculations exist. For example an expanding universe may slow, and contract, till eventually passing through a 'big crunch' back into a singularity – which some think could rebound into a new 'big bang', perhaps with a resetting of the laws and constants of nature. There is also speculation about the singularities at the 'heart' of black holes.
At one time the galaxy (that is, the milky way, our galaxy) was seen as synonymous with the Universe. The discovery that there was other galaxies at vast distances form our own led to seeing them as other universes: each galaxy an 'island' in the immensity of intergalactic space. Now it is commonly suggested there may be other universes (many with their own vast numbers of distinct galaxies) beside our own.
9 In teaching it is usually better to use simile so that the figurative nature of terms is marked (a 'well tuned' universe), unlike in a metaphor (a well tuned universe). One common textual feature is for a term to be introduced as a simile, perhaps by putting it in square quotes, or making it clear it is only 'like' the thing being discussed; but then moving to use the term metaphorically.
In one example I read of a part of a plant being described as like a boat, but then a few paragraphs later this was referred to as the boat without being marked as a simile. A reader has to recognise the term boat is still being used figuratively. This kind of metaphoricalcreep (or metaphorical encroachment perhaps?) could be problematic if a reader forgets a simile was being used, or only starts reading after if has been introduced and marked as being a comparison.
Of undead trees, silent genes and chaperone proteins
Keith S. Taber
These zombie metaphors become (like a neutron star) 'undead' as they pass from the expert's text to the novice's mind. They are phantom metaphors in the sense that they will manifest as 'living' metaphors to the uninitiated even though the expert user knows they have been put to death.
…the novice or non-specialist has no way of knowing what is the refined meaning and what is just semantic residue.
I have become a little obsessed with the figurative language used to explain science. Science often involves quite abstract ideas, which – by definition, being abstract – do not directly relate to familiar concrete objects and experiences. Learning theory suggests that to make good sense of new information, we need to relate it existing mental resources (existing knowledge and understanding; familiar experiences or images, and so forth).
This implies a paradox (indeed this is related to a traditional puzzle known as 'the learning paradox'):
we can only make sense of things we can relate to in terms of past experience
the science curriculum sets out a large number of abstract ideas that do not directly relate to the everyday experience of most people
We are all familiar with green plants, and may know from practical experience that they need light and moisture, but that direct everyday, phenomenal, experience is some way from the abstractconcept of photosynthesis. This point could be repeated regarding any number of other ideas met in science courses: magnetic hysteresis, p-orbitals, electron spin, genomes, metabolism, uniform electrical fields, electronegativity…
Now, perhaps any science teachers or scientists who read that passage may feel I am exaggerating – they can no doubt readily bring to mind images representing hysteresis and fields and genomes, and equations for photosynthesis with chemical formulae, and the values electron spin can take (±1/2, obviously). These things will be familiar and can be readily represented in 'working memory' (where we undertake deliberate thinking), so to be applied or mentipulated in various ways. But that is a result of the familiarity of expertise built up over a good deal of time. Sure, I can bring to mind a representation of a double bond or a methane molecule or the earth's magnetic field as easily as I can bring to mind an image of a table or a bus or a blackbird. This is useful for a science educator, but is also a potential barrier to putting oneself in the place of a novice learner.
A key is that "the science curriculum sets out a large number of abstract ideas that do not directly relate to the everyday experience of most people". And teachers, and other science communicators (such as journalists and science writers) can address this in two ways.
The best response, when possible, is to provide experiences (through demonstrations and practical activities) that motivate the concepts to be learnt. By motivate, I mean that this experience provides a recognised need for the explanations (as well as associated technical terminology) to make sense of the experiences. Practical work in science classes can be used in various ways, and rather than teach students about some theory, and then demonstrate it, it may be possible to offer experiences which raise questions and wonderment that will give the explanations 'epistemic relevance' (Taber, 2015). The learner will not just be learning about concept X because it is in a syllabus, but because they want to know why Y happened. Now that may seem idealistic – but most children start curious (perhaps before the routine nature of formal education somewhat dulls this) and it is something to aim for.
But of course some things are too slow, too fast, too big, or too small (or too dangerous or too expensive) to bring into the classroom. One cannot* teach the big bang by giving learners a direct experience which will lead to them asking questions that can be satisfactory answered by introducing the canonical scientific account. (* Perhaps I am wrong – if so, I would like to see ther lesson plan.)
Tools for making the unfamiliar familiar
So, the other approach to 'making the unfamiliar familiar' needs to be indirect, perhaps with videos and simulations and models which represent the inaccessible experiences – supported by (and where those tools are not available, through) a narrative where the teacher talks new entities into existence in a learner's 'mind (Lemke, 1990).
Important tools here are analogies where the learner is told that the unknown 'X' is in some ways a bit like the very familiar 'A'. There are a great many examples of analogies used in explaining science. Here are just a few:
Now analogies (like models more generally) are never perfect. X is like A in some ways, but in other ways X is not at all like A. (Otherwise, an X would be an A, and so no more familiar than what is being introduced.) This imperfect mapping does not matter because the use of analogy is not just (i) saying 'X' is in some ways a bit like 'A', as having established that anchor in the learner's prior experience, the teacher develops the comparison by exploring with the learners (ii) the ways in which the two things are alike and (iii) the ways they are not alike, and so starts to build up the learner's familiarity with the nature and properties of X.
carefully analyse the analogy in advance and be confident that the analogy, and, in particular, the features of the positive analogy that are useful for teaching, are indeed already familiar to learners in the class;
be explicit about the use of the analogy as a tool, a kind of model or device for generating conjectures to think about;
be very explicit about the structural features being mapped across, so it is very clear which features of the analogue are being drawn upon to introduce the target knowledge…
explore aspects of the negative analogy that could mislead learners (perhaps invite learners to consider other features of the analogue and suggest aspects that may or may not transfer);
consider the analogy as part of a scaffolding strategy – an interim support to be withdrawn as soon as it is no longer needed as learners are comfortable with the target concept."
A weaker technique than analogy is simile: simply pointing out that X is like A. This is clearly not going to do the work of an analogy, as when introducing a whole new theoretical concept, but has a role 'in passing' when pointing out some single feature or function.
Simile is widely used in communicating science. There are descriptive similes that tell us that something unfamiliar physically resembles something familiar ('lacework', 'bristle-like', 'like a boat') : this technique was widely used by naturalists in describing things they observed, such as novel species, and was especially valuable before the invention of photography. Contemporary science communicators also commonly make use of this technique with more abstract comparisons to functions and properties rather than just appearance:
Now metaphor is like simile, except that the comparison is implicit. That is, consider the difference between saying:
a mitochondrion is like the engine room of a cell; and
a mitochondrion is the engine room of a cell;
As in the simile, the user does not go on to explain how the mitochondria may be understood in this way (which would constitute an analogy) and so the audience is required to do some work (so similes should only be used in teaching when the teacher is confident meanings are obvious to the learners). But with the metaphor the audience has to first even recognise there is a comparison being made, as this is not explicit. After all,the following two propositions have parallel structures:
'a mitochondrion is the engine room of a cell'
'a headteacher is the professional leader of a school staff'
In one case identity is intended (a headteacher IS the professional leader of a school staff), but in the other case there is only a figurative identity: a mitochondrion is not an engine room (even if that could be the basis of an analogy that could be productively explored). So, I advise teachers to avoid metaphor in their explanations, and to always make it clear they are using a comparison. It may seem obvious that a tiny organelle is not (and cannot be) the same thing as the engine room in a ship; but why add to the learner's task in making sense of teaching by adding the need for an extra stage of interpretation that could be avoided?
Manifold metaphors
That said, metaphors are very common in science communication. Here are just a few examples of many I have collected.
Perhaps we should not be surprised at metaphors being so ubiquitous because metaphor is a core feature of language. They are so commonplace that we do not always consciously notice them, but can often simply read or listen straight past them. Even if we notice there is a metaphor in a text, where it is successful we immediately grasp the meaning and so it aids understanding rather than confounding it. I am hoping that my use of the metaphor 'anchor', above, worked that way. You may have spotted it was a metaphor – but I hope you did not have to stop reading and puzzle out what I meant by it in that context.
An anchor (Image by Tanya from Pixabay) but what has this got to do with meaningful learning?
In particular, language often develops by metaphor. So a term that is used initially as a metaphor, sometimes get taken up and repeated to such an extent that some decades later it is treated as a conventional meaning for a term and no longer considered a metaphor. Thus the language grows. So 'charge', in 'electrical charge', was initially a metaphor, an attempt to describe something new in terms of something already familiar (the charge that needed to be placed in a firearm ready for the next shot) but is not considered so now. Sometimes the 'new' meaning comes to exist alongside the original as a kind of homonym (as separate meanings – as with the word 'bank' when referring to a river bank and a financial institution), and sometimes the original meaning falls out of use (as few people use firearms today, and even fewer charge them with shot and gun powder before use).
So, terms that are at one time metaphorical can become 'literal' over time, and these are sometimes called deadmetaphors. They are also known as historical or frozenmetaphors. The latter term appeals (although it is a metaphor, of course! – words do not actually freeze) because it suggests a change of state that may take some time. That is, there are active metaphors, and frozen metaphors, and then some 'freezing metaphors' that are beginning to be widely understood directly without being understood as figurative, but where this transformation is not yet complete.
I am sure there are plenty of terms that are in common use in the language where, if people were asked, some, but not all, would recognise them as metaphorical (dyingmetaphors? freezingmetaphors?) – and where perhaps decade-on-decade repeat surveys would show some of these had died/frozen, while new metaphors were appearing, becoming widely used, and slowly starting to solidify.
At the risk of pushing an analogy too far, we might note that the state of a sample of a substance depends on the conditions (there are no ice sheets over the Caribbean islands), so if we extend this freezing metaphor, might we find metaphors that have frozen in some environments but are still fluid in other conditions?
Zombie metaphors?
Actually, I think this is likely very common in technical fields like the sciences. I have written here about some of the language used by astronomers when discussing the births, life-cycles and deaths of stars.
Clearly these terms were introduced metaphorically. But now they are treated as if technical terms – so, now, stars really do get born, and really do die because these terms now refer to what actually happens to stars, rather than just to processes that had some similarity to what happened to stars.
I think this is potentially problematic from an educational perspective, as the novice who reads a popular astronomy book or listens to a podcast or hears a news report where stars are said to be born, live out their long lives, and die, is unfamiliar with the astronomical processes labelled in this way, and can only understand these terms metaphorically by reference to how familiar living [sic, non-figuratively living] things are born, live, and die. A pet dog that dies is no longer around, but a large star that 'dies' in a supernova explosion may then live on as a neutron star – a bit like some phoenix that rises from the funeral ashes to be reborn.
Reincarnation? The Crab Nebula as seen by the Hubble Space Telescope (HST). The Nebula is a Supernova Nebula — One formed from a supernova which left a millisecond pulsar at its center. So was the explosion the death of as star – or was it just a transition to a new phase of the star's life cycle?
I am not suggesting that people will be generally confused about heavenly bodies being actually alive (even if for many centuries they were widely assumed to be so – many people seem to have thought stars and planets are living beings like humans), but because – for the experts 'born', 'live', 'die' are no longer metaphors – they may be are used without awareness of how a novice may struggle to fully appreciate their 'technical' implications.
So, in a sense, these metaphors become 'undead' (like the neutron star?) as they pass from the expert's text to the novice's mind. They are phantom metaphors in the sense that they will manifest as 'living' metaphors to the uninitiated even though the expert user knows they have (through habitual use) been put to death.
Not just out of this world…
I suspect that there are zombie metaphors in use not just in astronomy, but in many technical fields. This means that any of us who are reading 'out of specialism' are likely to mistake phantoms for live metaphors even when an author or speaker is using a term non-figuratively with a meaning that has long ago solidified in that specific discourse environment.
When a pure substance freezes it may exclude impurities. So, for example, a sample of sea water will start to freeze, and the ice forming will exclude the salts dissolved in the water (so the salt concentration in the remaining solution increases). When a metaphor freezes to become a technical term it retains the aspect of the comparison that were originally intended figuratively, but not other features that are not relevant – they get 'frozen out' so to speak. The expert has in mind the 'purified' meaning, and does not bring unintended associations to mind. But the non-specialist has no way of knowing what is the refined meaning and what is just semantic residue.
Figuring out erythrocytes…
Consider, for example, a textbook chapter entitled "Anemias, Red Cells, and the Essential Elements of Red Cell Homeostasis" (Benz, 2018). This chapter uses a range of figures of speech to help communicate technical ideas. Some of these can be glossed:
There are also a couple of places where phrasing might be seen to move beyond simple metaphor to anthropomorphism: that is, writing that seems to imply non-sentient entities have preferences and desires or act after conscious deliberation:
The chapter also refers to the proteins known as Ankyrin. This is a technical term of course. A review article relates that
"Ankyrin is a binding protein linking structural proteins of the cytoplasm to spectrin, a protein present in the membrane cytoskeleton in human erythrocytes that functions as an anchoring system to provide resistance to shear stress."
Caputi & Navarra, 2020
Indeed, ankyrin gets it's name from the Greek word for anchor. So ankyrin is not a metaphor, but derives its name metaphorically in relation to its perceived function.
Ribbon diagram of a fragment of the membrane-binding domain of human erythrocytic ankyrin (left-hand image, from Wikipedia commons), member of a class of proteins named after an anchor (right-hand image).
But I also noticed a number of other terms which manifested as metaphors, but which I do not think would be considered metaphors by specialists. In the field, they would be dead metaphors, but to a novice they might appear as phantoms, assumed to be meant metaphorically:
These can seem to be figures of speech, with the fluid quality of offering the reader the creative act of deciding which properties to transfer across from the metaphor/simile: but actually are all widely used terms in the field, and so actually have definite 'frozen' meanings. A vascular tree has branches (and twigs) but no leaves or fruits.
Perhaps there is not too much potential here to confuse readers (especially given the intended readership for this particular text would be professional / graduate), but it does reinforce the idea that communicating science is a challenge when not only, as is often noted, so much of the language of science texts is technical; but a lot of technical terms are dead metaphors: with frozen meanings that have the potential to melt back to life, and invite more fluid interpretations from learners.
Work cited:
Benz, Edward J. (2018) Anemias, red cells, and the essential elements of red cell homeostasis, in Edward J. Benz, Nancy Berliner, & Fred J. Schiffman, Anemia. Pathophysiology, Diagnosis, and Management, Cambridge University Press, 1-13.
Caputi, Achille Patrizio & Navarra, Pierluigi (2020) Beyond antibodies: ankyrins and DARPins. From basic research to drug approval. Current Opinion in Pharmacology, 51, April 2020, pp.93-101.
Lemke, Jay L. (1990) Talking Science: Language, Learning, and Values, Bloomsbury Academic.
Taber, K. S. (2015) Epistemic relevance and learning chemistry in an academic context. In I. Eilks & A. Hofstein (Eds.), Relevant Chemistry Education: From Theory to Practice (pp. 79-100). Sense Publishers. [Download chapter]
Making unfamiliar cultures familiar using scientific concepts
Keith S. Taber
Clifford Geertz may have been a social scientist, but he clearly thought that some abstract ideas about culture, society and politics were best explained using concepts and terminology from the natural sciences.
Clifford Geertz was a social scientist who referenced a goof deal of scientific vocabulary
I first came across the anthropologist Clifford Geertz when teaching research methods to graduate students. Geertz had popularised the notion of the importance of thick description, or rich description, in writing case studies. I acquired his book 'The Interpretation of Cultures' (a collection of his papers and essays) to read more about this. I found Geertz was an engaging and often entertaining author.
"Getting caught, or almost caught, in a vice raid is perhaps not a very generalisable recipe for achieving that mysterious necessity of anthropological field work, rapport, but for me it worked very well."
(From 'Deep play: notes on the Balinese cockfight')
Anthropology: A rather different kind of science – largely based on case studies.
Generalisation in natural science
Case studies are very important in social sciences, in a way that does not really get reflected in natural science.
It has long been recognised that in subjects such as chemistry and physics we can often generalise from a very modest number of specimens. So, any sample of pure water at atmospheric pressure will boil around 100˚C.1 All crystals of NaCl have the same cubic structure. All steel wires will stretch when loaded. And so on. Clearly scientists have not examined, say, all the NaCl crystals that have ever formed in the universe, and indeed have only actually ever examined a tiny fraction, in one local area (universally speaking), over a short time period (cosmologically, or even geologically, speaking) so such claims are actually generalisationssupported by theoretical assumptions. Our theories give us good reasons to think we understand how and why salt crystals form, and so how the same salt (e.g., NaCl) will always form the same type of crystal.2
Even in biology, where the key foci of interest, organisms, are immensely more complex than salt crystals or steel wires, generalisation is, despite Darwin 3, widespread:
"We might imagine a natural scientist, a logician, and a sceptical philosopher, visiting the local pond. The scientist might proclaim,
"see that frog there, if we were to dissect the poor creature, we would find it has a heart".
The logician might suggest that the scientist cannot be certain of this as she is basing her claim on an inductive process that is logically insecure. Certainly, every frog that has ever been examined sufficiently to determine its internal structure has been found to have a heart, but given that many frogs, indeed the vast majority, have never been specifically examined in this regard, it is not possible to know for certain that such a generalisation is valid. (The sceptic, is unable to arbitrate as he simply refuses to acknowledge that he knows there is a frog present, or indeed that he can be sure he is out walking with colleagues who are discussing one, rather than perhaps simply dreaming about the whole episode.)
…I imagine most readers are still siding with the scientist's claim. So, can we be confident this particular frog has a heart, without ourselves being heartless enough to cut it open to see?
Strictly, in an absolute sense, we cannot know for certain the entity identified as a frog has a heart. After all,
perhaps it is a visiting alien from another solar system that looks superficially like our frogs but has very different anatomy;
perhaps it is a mechanical automaton disguised as a frog, that is covertly collecting intelligence data for a foreign power;
perhaps it is a perfectly convincing holographic image of a 'late' frog that, since being imaged, was eaten by a predator;
perhaps other logically possible but barely feasible options come to mind?
But if it really is a living (Terran) frog, then we know enough about vertebrate evolution, anatomy and physiology, to be as near to certain it has a functioning heart as we could be certain of just about anything. 4
Generalisation in social science
Often, however, this type of generalisation simply does not work in social science contexts. If we find that a particular specimen of gorilla has seven cervical vertebrae then we can probably assume: so do other gorillas. But if we find that one school has 26 teachers, we clearly cannot assume this will apply to the next school we look at. Similarly, the examination results and truancy levels will vary greatly between schools. If we find one 14 year old learner thinks that plants only respire during the night time, then it is useful to keep this in mind when working with other students, but we cannot simply assume they will also think this.
The distinction here is not absolute, as clearly there are many things that vary between specimens of the same species, which is why many biological studies use large samples and statistics. In general [sic], generalisation gets more problematic as we shift from physical sciences through life sciences to social sciences. And this is partially why case study is so common within the social sciences.
The point is that the assumption that we can usually safely generalise from one NaCl crystal to another, but not from one biology teacher to another, is based on theoretical considerations that tell us why the shape (but not the mass or temperature) of a crystal transfers from one specimen of a substance to another, but why the teaching style or subject knowledge of one teacher depends on so many factors that it cannot be assumed to transfer to other teachers.
Drawing upon both a quotidian comparison and a scientific simile, Geertz warned against seeing "a remote locality as the world in a teacup or as the sociological equivalent of a cloud chamber".
A case study examines in depth one instance from among many instances of that kind: one teacher's teaching of entropy; one school's schemes of work for lower secondary science; one learner's understanding of photosynthesis; the examples, similes and analogies used in one textbook; …
Case studies look at a single instance (e.g., one school, one classroom, one lesson, one teaching episode) in great detail. Case studies are used when studying complex phenomena that are embedded in their context and so have to be studied in situ. You can study a crystal in the lab. You can also study extract cells from an organism and look at them in a Petri dish – but those isolated cells in vitro will only tell you so much about how they normally function in vivo within the original tissue.
Similarly, if you move a teacher and her class out of their normal classroom embedded in a particular school in order to to study a lesson in a special teaching laboratory in a research institution set up with many cameras and microphones, you cannot assume you will see the lesson that would have taken place in the normal context. Case studies therefore need to be 'naturalisic' (carried out in their usual context) rather than involving deliberate researcher manipulation. Geertz rejected the description of the field research site as a natural laboratory, reasonably asking "what kind of laboratory is it where none of the parameters are manipulatable?"
When I worked in further education I recall an inspection where one colleague told us that the external inspector had found her way to her classroom late, after the lesson had already started, and so asked the teacher to start the lesson again. This would have enabled the inspector to see the teacher and class act out the start of the lesson, but clearly she could not observe an authentic teaching episode in those circumstances.
Case study is clearly a sensible strategy when he have a particular interest in the specific case (why do this teacher's students gets such amazing examination results?; why does this school have virtually zero truancy rates?), but is of itself a very limited way of learning about the general situation. We learn about the general by a dual track (and often iterative) process where we use both surveys to find out about typicality, and case studies to understand processes and to identify the questions it is useful to include in surveys.
If case studies are to be useful, they need to offer a detailed account (that 'thick description') of the case, including its context: so to understand something about an observed lesson it may be useful to know about the teacher's experience and qualifications; about the school demographic statistics and ethos; about the curriculum being followed, and other policies in place; and so forth.
As one example, to understand why a science teacher does not challenge a student's clear misconceptions about natural selection (is the teacher not paying attention, or not motivated, or herself ignorant of the science?), it may sometimes be important to know something about the local community and and administrative practices. In the UK, a state school teacher (who is legally protected from arbitrary, capricious or disproportionate disciplinary action) is not going to get in trouble for explaining science that is prescribed in the curriculum, even if some parents do not like what is taught; but that may not be true in a very different context where the local population largely holds fundamentalist, anti-science, views, and can put direct pressure on school leaders to fire staff.
Beware of unjustified generalisation
This use of 'thick description' provides the context for a reader to better understand the case. However, no matter how detailed a case study is, and regardless of the insight it offers into that case, a single case by itself never provides the grounds for generalisation beyond the case. It can certainly offer useful hypotheses to be tested in other cases – but not safe conclusions!
Geertz was an anthropologist who knew that much field work involves specific researchers (with their idiosyncraticinterpretive resources – background knowledge, past experiences, perspectives, beliefs, etc. -and individual personalities and inter-personal skills) spending extended periods of time in very specific contexts – this village, that town, this monastery, that ministry… The investigators were not just meant to observe and record, but also to look to make sense of (and so interpret) the cultures they were immersed in – but this invites over-generalisation. Geertz warns his readers of this at one point,
"I want to do two things which are quintessentially anthropological: to discuss a curious case from a distant land; and to draw from that case some conclusions of fact and method more far-reaching than any such isolated example can possibly sustain."
(From: 'Politics past, politics present: some notes on the uses of anthropology in understanding the new states')
Using science to make the unfamiliar familiar
One of the features of Geertz's writings that I found interesting was his use of scientific notions. Often on this site I have referred to the role of the teacher in 'making the unfamiliar familiar' and suggested that science communicators (such as teachers, but also journalists, authors of popular science books and so forth) seek to make abstract scientific ideas familiar for their audience by comparing them with something assumed to already be very familiar. As when Geertz suggests that the 'human brain resembles the cabbage'. I have also argued that whilst this may be a very powerful initial teaching move, it needs to be just a first step, or learners are sometimes left with new misconceptions of the science.
For a science teacher, the scientific idea is thetarget knowledge to be introduced, and a comparison with something familiar is sought which offers a useful analogue. I list myriad examples on this site – some being science teachers' stock comparisons, some being more original and creative, and indeed some which are perhaps quite obscure. Here are just a few examples:
But this can be flipped when the audience has a strong science knowledge, and so a scientific phenomenon or notion can be used to introduce something less familiar. (As one example, the limited capacity of working memory and the idea of 'chunking' may be introduced by comparison with different triglycerides: see How fat is your memory? A chemical analogy for working memory. But this is only useful if the audience already knows about the basic structure of triglycerides.)
Geertz may have been a social scientist, but he clearly assumed some abstract ideas about culture, society and politics were best explained using concepts and terminology from the natural sciences. So, for example, he made the argument for case study approaches in research,
"The notion that unless a cultural phenomenon is empirically universal it cannot reflect anything about the nature of man is about as logical as the notion that because sickle-cell anaemia is, fortunately, not universal, it cannot tell us anything about human genetic processes. It is not whether phenomena are empirically common that it is critical in science – else why should Becquerel have been so interested in the peculiar behaviour of uranium? – but whether they can be made to reveal the enduring natural processes that underlie them. Seeing heaven in a grain of sand 5 is not a trick that only poets can accomplish."
(From: 'The impact of the concept of culture on the concept of man')
Geertz was also aware of another failing that I have seen many novice (and some experienced) researchers fall into. In education, as in anthropology, we often rely on research participants as informants, but we have to be careful not to confuse what they tell us with direct observations:
'the teacher is careful to involve all learners in the class in answering questions and classroom discussion' (when it should be: the teacher reports that he is careful to involve all learners in the class in answering questions and classroom discussion )
'the learner was very good at using mathematics in physics lessons' (when it should be: the learner thought that she very good at using mathematics in physics lessons.
'the school had a highly qualified, and select group of teachers who were all enthusiastic subject experts' (or so the headteacher told me).
If such slips seem rather amateur affairs, it is not uncommon to see participant ratings mis-described: so a statements like '58% of the teachers were highly confident in using the internet in the classroom' may be based on participants responding to a scale item on a questionnaire (asking 'How confident are you…') where 58% of respondents selected the 'highly confident' rating.
So, actually '58% of the teachers rated themselves as highly confident in using the internet in the classroom'. For these two things to be equivalent we have to ourselves be 'highly confident' in a number of regards – some more likely than others. Here are some that come to mind:
the teachers took the questionnaire seriously, and did not just tick boxes arbitrarily to complete the activity quickly (I am sure none of us have ever done that 😎);
the teachers read the question carefully, and ticked the box associated with their genuine rating (i.e., did not tick the wrong box by mistake, perhaps misaligning response boxes for a different item);
the teachers understood and shared the researcher's intended meaning of the item (e.g., researcher and responder mean the same thing by 'confidence in using the internet in the classroom');
the teachers had a stable level of confidence such that a rating reflected more than their feeling at that moment in time (perhaps after an especially successful, or fraught, lesson);
a teacher's assessment of confidence clearly fitted with one of the available response options (here, highly confident – perhaps the only options presented to be selected from were 'highly competent'; 'neither professionally competent nor incompetent'; 'completely hopeless');
the teachers were open and honest about their responses (so, not influenced by how the researcher might perceive them, or who else might gain access to the data and for what purpose);
the teacher was a good judge of their own level of confidence (and does not come from a cultural context where it would be shameful to boast, or where exaggeration is expected).
As scientists we tend to come to rely on instrumentation even though it is fallible. We may report distances and temperatures and so forth without feeling we need to add a caveat such as "according to the thermometer" each time. 6 But instrumentation in social science tends to be subject to more complications. Geertz realised that in his field there was commonly the equivalent of writing that '58% of the teachers were highly confident in using the internet in the classroom' when the data only told us '58% of the teachers rated themselves as highly confident in using the internet in the classroom':
"In finished anthropological writings, including those collected here, this fact – that what we call our data are really our own constructions of other people's construction of what they and their compatriots are up to – is obscured because most of what we need to comprehend a particular vent, ritual, custom, idea, or whatever is insinuated as background information before the thing itself is is directly examined."
(From 'Thick description: toward an interpretative theory of culture.')
Some scientific comparisons
In discussing a teknonymous system of reference – where someone who had been named Joe at birth but who is now the father of Bert, is commonly known as 'Father of Bert' rather than Joe; at least until Bert and Bertha bring forth Susie (and take on new names themselves accordingly), at which point Joe/Father of Bert is then henceforth referred to as 'Grandfather of Susie' – Geertz suggests what "looks like a celebration of a temporal process is in fact a celebration of the maintenance of what, borrowing a term from physics, Grgory Batesaon has aptly called 'steady state'." This is best seen as a simile, as the figurative use of the term 'steady state' is clearly marked (both by the 'scare quotes' and the acknowledgement of the borrowing of the term).
Many of Geertz's figures of speech are metaphors where the comparison being used is not explicitly marked (so the state capital 'was' the nucleus). Another 'doubly marked' simile (by scare quotes and the phrase 'so to speak') concerned the idea of a centre of gravity:
"The two betting systems, though formally incongruent, are not really contradictory to one another, but are part of a single larger system, in which the centre bet is, so to speak, the 'centre of gravity', drawing , the larger it is the more so, the outside bets toward the short-odds end of the scale."
(From 'Deep play: notes on the Balinese cockfight')
Among the examples of Geertz using scientific concepts as the 'familiar' to introduce ideas to his readers that I spotted were:
Not all of these examples seemed to be entirely coherent, or strictly aligned with the technical concept. Geertz was using the ideas as figures of speech, relying on the way a general readership might understand them. Although, in some of these cases I wonder how familiar his readership might be with the scientific idea. We can only 'make the unfamiliar familiar' by comparing what is currently unfamiliar with what is – already – familiar.
Making the unfamiliar familiar, by using something else unfamiliar?
My general argument on this site has been that if the comparison being referred to is not already familiar to an audience, then it cannot help explain the target concept – unless the unfamiliar comparison is first itself explained; which would seem to make it self-defeating as a teaching move.
However, while I think this is generally true, I can see possible exceptions.
One scenario might be where the target idea is seen as so abstract, that the teacher or author feels it is worth first introducing, and explaining, a more concrete or visualisable comparison as a potential stepping stone to the target concept.
Another scenario might be where the teacher or author has a comparison which is considered especially memorable (perhaps controversial or risque, or a vivid or bizarre image), and so again thinks the indirect route to the target concept may be effective (or, at least, entertaining).
There might also be an argument, at least with some audiences, that because using a comparison makes the (engaged) reader process the comparison it aids understanding and later recall even when it needs to be explained before it will work as a comparison.
So, for example, typical readers of anthropology reports may know little about the neural organisation of cephalopods, but when being told that "the octopus, whose tentacles are in large part separately integrated, neurally quite poorly connected with one another and with what in the octopus passes for a brain … nonetheless manages…to get around…", perhaps this elicits reflection on how being an octopus must be such a different experience to being human, such that the reader pauses for thought, and then (while imagining the octopus moving around without a"smoothly coordinated synergy of parts" but rather "by disjointed movements of this part, then that") pays particular attention to how this offers a "appropriate image [for] cultural organisation".
These are tentacled, sorry, tentative suggestions, and I would imagine they all sometimes apply – but empirical evidence is needed to test out their range of effectiveness. Perhaps this kind of work has been done (I do not recall seeing any studies) but, if not, it should perhaps be part of a research programme exploring the effectiveness of such devices (similes, metaphors, analogies, etc.) in relation to their dimensions and characteristics, modes of presentation, and particular kinds of audiences (Taber, 2025).
Some of Geertz's references could certainly be seen as fitting the wider zeitgeist – references to DNA with its double helix may be seen to tap into a common cultural motif:
"So far as culture patterns, that is, systems or complexes of symbols, are concerned…that they are extrinsic sources of information. By 'extrinsic', I mean only that – unlike genes for example – they lie outside the boundaries of the individual organism …By 'source of information', I mean only that – like genes – they provide a blueprint of template in terms of which processes external to themselves can be given a definite form. As the order of bases in a strand of DNA forms a coded program, a set of instructions, or a recipe, for the synthesis of the structurally complex proteins which shape organic functioning, so culture patterns provide such programmes for the institution of the social and psychological processes which shape human behavior …this comparison of gene and symbol is more than a strained analogy …
"Symbol systems…are to the process of social life as a computer's program is to its operations, the genic helix to the development of the organism…
There is a sense in which a computer's program is an outcome of prior developments in the technology of computing, a particular helix of phylogenetic history…But …one can, in principle anyhow, write out the program, isolate the helix…"
(From 'Religion as a cultural system' and 'After the revolution: The fate of nationalism in the new states')
Geertz also goes beyond simply offering metaphors, as in this extract from an essay review of the classic structuralist anthropology text with a title normally rendered into English as 'The Savage Mind':
"That Lévi-Strauss should have been able to transmute the romantic passions of Tristes Tropiques into the hypermodern intellectualism of La Pense Sauvage is surely a startling achievement. But there remain the questions one cannot help but ask. Is this transmutation science or alchemy? Is the 'very simple transformation' which produced a general theory out of a persona disappointment real or a sleight of hand? Is it a genuine demolition of the walls which seem to separate mind from mind by showing that the walls are surface structures only, or is it an elaborately disguised evasion necessitated by a failure to breach them when they were directly encountered?"
(From 'The cerebral savage: on the work of Claude Lévi-Strauss')
It is worth noting here that whenever a work is translated from one language to another, there is an interpretive process, as many words do not have direct equivalents (covering precisely the same scope or range, with exactly the same nuances) in other languages. 'Savage' in English suggests (to me at least) aggression, and an association with violence. The French original 'sauvage' could be translated instead as 'wild' or 'untamed' which do not necessarily have the same negative associations. This is why when educational, and other social, research is reported in a language other than that in which data was collected, it is important for investigators to report this, and explain how the authenticity of translation was tested (Taber, 2018).
This device of an extended metaphor, where a comparison is not just mentioned at one point but threaded through a passage, can approach analogy – but without the explicit mapping of analogue-to-target expected in a formal teaching analogy. Here the idea of a property of meaning is compared with physical or chemical properties, but without the techniques the scientist has to identify and quantify such properties:
"And so we hear cultural integration spoken of as a harmony of meaning, cultural change as an instability of meaning, and cultural conflict as an incongruity of meaning, with the implication that the harmony, the instability, or the incongruity are properties of meaning itself, as, say, sweetness is a property of sugar or brittleness of glass.
Yet, when we try to treat these properties as we would sweetness or brittleness, they fail to behave, 'logically', in the expected way. When we look for the constituents of the harmony, the instability, or the incongruity, we are unable to find them resident in that of which they are presumably properties. One cannot run symbolic forms through some sort of cultural assay to discover their harmony content, their stability ratio, or their index of incongruity; one can only look and see if the forms in question are in fact coexisting, changing, or interfering with one another in some way or other, which is like tasting sugar to see if it is sweet or dropping a glass to see if it is brittle, not like investigating the chemical composition of sugar or the physical structure of glass."
"But, details aside, the point is that there swirl around the emerging governmental institutions of the new states, and the specialised politics they tend to support, a whole host of self-reinforcing whirlpools of primordial discontent, and that the parapolitical maelstrom is a great part an outcome – to continue the metaphor, a backwash – of that process of political development itself."
(From 'The integrative revolution: The primordial sentiments and civil politics in the new states')
Offering manifold comparisons
Sometimes Geertz offers several alternative comparisons for his readers: so, above, the genetic helix is offered in parallel with a computer program, a blueprint for building a bridge, the score of a musical performance, and a recipe for cake. Another example might be:
"The second law of thermodynamics, or
the principle of natural selection, or
the production of unconscious motivation, or
the organisation of the means of production
does not explain everything, not even everything human, but it still explains something; and our attention shifts to isolating just what that something is, to disentangle ourselves from a lot of pseudoscience to which, in the first flush of its celebrity, it has also given rise."
(From 'Thick description: toward an interpretative theory of culture')
There are several ways to explain use of this technique. One is that Geertz is sometimes not confident in his comparisons, so offers alternatives – if one does not 'hit home' with a reader, another might. Perhaps this is about diversity and personalisation – after all, each reader brings their own unique set of interpretive resources (based on their idiosyncratic array of knowledge and experience), so if you do not know about the physics or biology, perhaps you do know about the example from psychology, or economics.
Alternatively, I sometimes got a sense that Geertz was simply enjoying the writing process, and not wanting to censor the creative spark as ideas presented themselves to him. Of course, that is a personal interpretation based on my unique set of interpretive resources: I have also sometimes got the feeling that I am getting carried away with my writing – carried along by the 'flow' experience described by Mihaly Csikszentmihalyi – enjoying my own prose (which at least means that a minimum of one person does), and so possibly at risk of writing too much and consequently boring the reader. Reading Geertz gave me the feeling that he enjoyed the writing process, and that he crafted his writing with a concern for style as well as to communicate information.
From a pedagogic point of view, comparisons (similes, metaphors, analogies) are like models, always imperfect reflections of the target. Greetz suggested that not only was metaphor strictly wrong, but that it could be most effective when most wrong! In teaching it is important to highlight the positive and negative analogy (how this model is like a cell or a star or a molecule, and also how it is not), and that level of explication would be suitable for a textbook; but otherwise could (as well as disrupting style) come across as too didactic. By offering multiple comparisons, each of which are wrong in different ways, perhaps the common target feature can be highlighted?
"To put the matter this way is to engage in a bit of metaphoricalrefocusing of one's own, for it shifts the analysis of cultural forms form an endeavour in general parallel to
dissecting an organism,
diagnosing a symptom,
deciphering a code, or
ordering a system
– the dominant analogies in contemporary anthropology – to one in general parallel with penetrating a literary text."
(From 'Deep play: notes on the Balinese cockfight')
"The meanings that symbols, the material vehicles of thought, embody are often elusive, vague, fluctuating, and convoluted, but they are, in principle, as capable of being discovered through systematic investigation – especially if the people who perceive them will cooperate a little –
as the atomic weight of hydrogen or
the function of the adrenal glands."
(From 'Person, time, and conduct in Bali')
Even if this is not the case; we can expect that if the reader does mental work comparing across the multiple comparisons then this will have brought focal attention to the point being made as the reader passes through the passage of text. (Again, there is a useful theme here for any research programme on the use of figures of speech in science communication: how do readers or listeners process multiple comparisons of this kind, and does this figurative device lead to greater understanding?)
Cultural crystallisation
One recurring image in Geertz's writing is that of crystallisation.
"It is the crystallisation of a direct conflict between primordial and civil sentiments – this 'longing not to belong to any other group' – that gives to the problem variously called tribalism, parochialism, communalism, and so on, a more ominous and deeply threatening quality that most of the other, also very serious and intractable, problems the new states face…
"The actual foci around which such discontent tends to crystallise are various"
"In the one case where [a particular pattern of social organisation] might have crystallised, with the Ashanti in Ghana, the power of the central group seems to have, at least temporarily, been broken."
"The pattern that seems to be developing and perhaps crystallising, is one in which a comprehensive national party…comes almost to comprise the state…"
"…raises the spectre of separatism by superimposing a comprehensive political significance upon those antagonisms, and, particularly when the crystallising ethnic blocs outrun state boundaries…"
(From 'The integrative revolution: The primordial sentiments and civil politics in the new states')
Crystallisation occurs when existing parts (ions, molecules) that are in a fluid (in solution, in the molten state) come together into a unified whole as a result of interactions between the system and its surroundings (evaporation of solvent, thermal radiation). Some of these quoted examples might stand up to being developed as analogies (where features of the social phenomenon can be mapped onto features of the physical change), but when used metaphorically the requirement is simply that there is some sense of parallel.
An interesting question might be whether such metaphors are understood differently by subject experts (here, chemists or mineralogists for example) who may be (consciously or otherwise) looking to map a scientific model onto the author's accounts, rather than a general reader who may have a much less technical notion of 'crystallisation' but might find the reference triggers a strong image?
We might also ask if 'crystallisation' has become something of a dead metaphor: that is, has it been used as a metaphor (a comparison with the change of state) so widely that it has taken on a new general meaning (of little more than things coming together)?
Balanced and unbalanced (social) forces
Another motif that I noticed in Geertz's writing was talking about social/cultural 'forces' as if they were indeed analogous to physical forces. In the following example, the force metaphor is extended:
"In sum, nineteenth century Balinese politics can be seen as stretched taut between two opposing forces; the centripetal one of state ritual and the centrifugal one of state structure."
(From 'Politics past, politics present: some notes on the uses of anthropology in understanding the new states')
The following example also features (as opposed to crystallisation) dissolving,
"In Malaya one of the more effective binding forces that has, so far at least, held Chinese and Malays together in a single state despite the tremendous centrifugal tendencies the racial and cultural differences generates is the fear on the part of either group that should the Federation dissolve they may become a clearly submerged minority in some other political framework: the Malays through the turn of the Chinese to Singapore or China; the Chinese through the turn of the Malays to Indonesia."
(From 'The integrative revolution: The primordial sentiments and civil politics in the new states')
There seems to be another extendedmetaphor here as well, in that following dissolution, there is a danger of becoming submerged in the fluid. This quote also features the notion of 'centrifugal' force, which reappears elsewhere in Geertz's work (see below).
Canonical and alternative conceptions
I associate references to centrifugal force with the common alternative conception that orbiting bodies are subject to balancing forces – a centripetal force that pulls an orbiting body towards the centre, which is balanced or cancelled by a centrifugal force which pulls the object away from the centre. This (incorrect) notion is very common (read about 'Centrifugal force').
From a Newtonian perspective, orbital motion is accelerated motion, which requires a net force – if there was not a centripetal force, then the orbiting body would leave orbit (as, incredibly, happened to the moon in the sci-fi series 'Space: 1999' 7) and move off along a straight line. So, circular motion requires an unbalanced force (at least if we ignore the way mass effects the geometry of space 8).
Martin Landau and Barbara Bain – in 'Space: 1999' (created by Gerry and Sylvia Anderson, produced by ITC Entertainment)
I wondered whether the quote above would be interpreted differently according to a person's level of scientific literacy. Two possible readings are:
"…one of the more effective binding forces…has…held Chinese and Malays together in a single state despite the tremendous centrifugal tendencies…" because the binding forces were stronger than the centrifugal force.
"…one of the more effective binding forces…has…held Chinese and Malays together in a single state despite the tremendous centrifugal tendencies…" because the binding forces balance the centrifugal force.
The implication in the quote is that there is a steady state (if you will pardon the pun), so there must be an equilibrium of forces (that is, option 2). But, this is an area where learners will commonly have alternative conceptions: for example suggesting that gravity must be larger than the reaction force with the floor, or else they would float away; or that in a solid structure the attractive forces between molecules must be greater than the repulsive forces to hold the structure together.
"When [English A level students in a Further Education College] were shown diagrams of stable systems (objects stationary on the ground, or on a table) they did not always recognise that there was an equilibrium of forces acting. Rather, several of the students took the view that the downward force due to gravity was the larger, or only force acting. Two alternative notions were uncovered. One view was that no upward force was needed, as the object was supported instead, or simply that the object could not fall any lower as the ground was in the way. The other view was the downward force had to be greater to hold the object down: if the forces had been balanced there would have been nothing stopping the object from floating away."
Geertz was writing about society, and using the notion of forces metaphorically, but we know that when a learner is led to activate something in memory this reinforces that prior learning. For someone holding this common misconception for static equilibrium (as being due to a larger maintaining force overcoming some smaller force) then reading Geertz's account is likely to lead to:
interpreting the social example in terms of the misconception: binding forces are larger so they hold the state together;
thus rehearsing and reinforcing the prior (mis)understanding of forces!
That is, even though the topic is cultural not physical, and even though Geertz may well have held a perfectly canonical understanding of the physics, his metaphorical language has the potential to reinforce a scientific misconception!
This is not a particular criticism of Geertz: whenever a learner comes across an example that fits their prior conceptions, they are likely to activate that prior knowledge, and so reinforce the prior learning. This is helpful if they have learnt the principles as intended, but can reinforcemisconceptions as well as canonical ideas. References to a scientific phenomenon or principle that assume, and so do not make explicit, the scientific ideas, always risk reinforcing existing misconceptions. (The teacher therefore tends to reiterate the core scientific message each time a previously taught principle is referenced in class – what might be called a 'drip-feed' tactic!)
Geertz seemed to be quite keen on the 'centrifugal' reference:
"It is the Alliance…where the strong centrifugal tendencies, as intense as perhaps any state…"
"the integrative power of a generally mid-eastern urban civilisation against the centrifugal tendencies of tribal particularism".
In the following extract, Geertz has two opposed centrifugal influences:
"Yet out of all this low cunning has come not only the most democratic state in the Arab world [Lebanon], but the most prosperous; and one that has in addition been able to – with one spectacular exception – to maintain its equilibrium under intense centrifugal pressures from two of the most radially opposed extrastate primordial yearnings extant: that of the Christians, especially the Maronites, to be part of Europe, and that of the Moslems especially the Sunnis, to be part of pan-Arabia."
(From 'The integrative revolution: The primordial sentiments and civil politics in the new states')
A cursory reading might be that as these two opposed forces balance there is an equilibrium between them – but the scientist would realise this must be read as there being a strong enough cohesive force to hold the centre together against the combined effect of these forces – think perhaps of the famous Magdeburg hemispheres where two teams of forces were unable to pull apart two hemispheres with a vacuum between them (so that the pressure of air pushing on the outside spheres applied sufficient force to balance the maximum pull the horses could manage).
Engraving showing Otto von Guericke's 'Magdeburg hemispheres' experiment (Source: https://commons.wikimedia.org/wiki/File:Magdeburg.jpg)
Again, the metaphor might well lead a reader to apply, and so reinforce, their notions of forces acting – whether these notions match the canonical science account or not.
Some other scientific references.
Among the other scientific concepts I noticed referenced were
"A cockfight is …not vertebrate enough to be called a group…"
"…the intense stillness that falls with instant suddenness, rather as someone had turned off the current…"
"…that is like saying that as a perfectly aseptic environment is impossible, one might as well conduct surgery in a sewer."
"there has almost universally arisen around the developing struggle for governmental power as such a broad penumbra of primordial strife."
Sharing scientific and cultural resources
The very way that language evolves means that words change, or acquire new, meanings, and also shift between domains. If scientific terms are used enough figuratively, metaphorically, as part of non-scientific contexts then in time they will acquire new accepted non-technical meanings. We see this shift from metaphorical to widely accepted meanings in the establishment of idioms which must sometimes be quite mystifying to those not familiar with them, like non-native language speakers (Taber, 2025): understanding an idiom is not rocket science to the initiated, but the language learner might feel they've missed the boat or are having their leg pulled – and, if already struggling with the language, may consider them the last straw.
Indeed, there is a scholarly equivalent. So, I suspect many natural scientists may not know what a Procrustean bed is, or the significance of finding yourself between Scylla and Charybdis ("I'll have a chocolate and strawberry Scylla in a cone, and a bottle of 1990 Charybdis please"?), but such references are common in academic writing in some fields.
But scientists are in no position to complain when technical terms drift into figurative use in everyday language. After all, scientists are not above borrowing everyday terms metaphorically, and then through repeated use treating them as if technical terms. Certainly (as I describe in detail elsewhere, 'The passing of stars: Birth, death, and afterlife in the universe'), references to the 'births' and 'deaths' of stars are now used as formal technical terms in astronomy; but this is nothing new, for 'charge', as in electrical charge, was borrowed from the charge used in early firearms; and quarks originated in James Joyce – and calling them 'up', 'down', 'truth'/'top', 'beauty'/'bottom' and their qualities as 'strangeness' and 'charm' gave new meanings to terms taken from common usage. And having been sequestered by physics, they have then been borrowed back into popular culture again by the likes of Hawkwind and Florence and the Machine. 9
So, I have no criticisms of Geertz in using scientific terms figuratively in his writings about culture- even if sometimes those uses seem a little forced; and even if inevitably (simply because this is how human memory works) when such terms are used without definition or explication they may actually activate and reinforcealternative conceptions in those who already hold misconceptions of the science. A communicator has to draw upon the resources they have available, and which they hope will resonate (sic) with their audience in order to bring about the challenging task of sharing ideas between minds.
I read Geertz to find out a little more about his area of (social) science, but ended up reflecting especially upon how he used the language of natural science and how this might be understood by non-scientists. It has been suggested there is no privileged meaning to a text, as each reader brings their own personal reading. I do not entirely agree, at least with regard to non-fiction. There is certainly no meaning in the text itself (it is just the representation of the author's ideas and needs to be interpreted) but there is an intended meaning that the author hopes to communicate, and which the author seeks to privilege by using all the rhetorical tools available in the hope that readers will understand the texts much as intended. As every teacher likely knows: that is not an automatic or easy task.
Sources:
Change, H. (2004) Inventing Temperature: Measurement and Scientific Progress. Oxford University Press.
Clifford Geertz (2000) After the revolution: The fate of nationalism in the new states (first published 1971), in The Interpretation of Cultures. Selected Essays (2nd Edition). New York. Basic Books, pp.234-254
Clifford Geertz (2000) Deep play: notes on the Balinese cockfight (first published 1972), in The Interpretation of Cultures. Selected Essays (2nd Edition). New York. Basic Books.
Clifford Geertz (2000) Person, time, and conduct in Bali (first published 1966), in The Interpretation of Cultures. Selected Essays (2nd Edition). New York. Basic Books, pp.360-411.
Clifford Geertz (2000) Politics past, politics present: some notes on the uses of anthropology in understanding the new states (first published 1967), in The Interpretation of Cultures. Selected Essays (2nd Edition). New York. Basic Books.
Clifford Geertz (2000) Religion as a cultural system (first published 1966), in The Interpretation of Cultures. Selected Essays. 2nd Edition. New York. Basic Books, pp.87-125.
Clifford Geertz (2000) The cerebral savage: on the work of Claude Lévi-Strauss (first published 1967), in The Interpretation of Cultures. Selected Essays (2nd Edition). New York. Basic Books, pp.345-359.
Clifford Geertz (2000) The impact of the concept of culture on the concept of man (first published 1966), in The Interpretation of Cultures. Selected Essays. 2nd Edition. New York. Basic Books, pp.33-54.
Clifford Geertz (2000) The integrative revolution: The primordial sentiments and civil politics in the new states (first published 1963), in The Interpretation of Cultures. Selected Essays (2nd Edition). New York. Basic Books, pp.255-310
Clifford Geertz (2000) Thick description: toward an interpretative theory of culture, in The Interpretation of Cultures. Selected Essays. 2nd Edition (1973), pp.3-30.
1 We often say exactly 100˚C, but in practice factors such as the container used do make measurable differences – (Chang, 2004) – that we generally ignore.
2 Life is not always so simple. Sulphur, for example, forms different crystal structures at different temperatures; and many metals also undergo 'phase transitions' between structures at different temperatures. But we think our theories can also explain this, so we can generalise about, say, the shape of all sulphur crystals formed below 96˚C.
3 That is, before Darwin it was widely believed that species represented clear cut types of beings where in principle clear demarcation lines could be established between different natural kinds. We now understand that even if at any one time this is approximately true (see the figure), taking a broader perspective informed by Darwin's work we find different types of organisms blend into each other and there is no absolute boundary around one species distinguishing it from others. See, for example, 'Can ancestors be illegitimate?'
The scientific perspective on the evolution of living things considers 'deep time' whereas the everyday experience of learners is limited to a 'snapshot' of the species alive at one geological moment (from Taber, 2017).
4 This is a tricky area for the science educator. Scientists should always be open to alternative explanations, and even the overthrow of long accepted ideas. But sometimes the evidence is so overwhelming that for all practical purposes we assume we have certain knowledge. There are alternative explanations for the vast evidence for evolution (e.g., an omnipotent creator who wants to mislead us) but these seem so unfeasible and convoluted that we would be foolish to take them too seriously.
When it comes to climate change, we can never be absolutely sure the effects we are seeing are due to the anthropogenic actions we believe to be damaging, but the case is so strong, and the consequences of not changing our behaviours so serious, that no reasonable person should suggest delaying remedial action. This would be like someone playing 'Russian roulette' with a revolver with only one empty chamber. They cannot be sure they would shoot themselves, so why not go ahead and pull the trigger?
Similar arguments relate to the Apollo moon landings. One can imagine a highly convoluted ongoing global conspiracy to fake the landings with all the diverse evidence – but this requires accepting a large number of incredibly infeasible propositions. (Read: 'The moon is a long way off and it is impossible to get there'.)
5 The radical poet (and engraver and visionary) William Blake:
"To see a world in a grain of sand
And a heaven in a wild flower,
Hold infinity in the palm of your hand
And eternity in an hour."
6 Even in the natural sciences, this depends upon how we think about the instrument used. If the instrument and technique are considered basic and simple and relivable, and 'standard' for the job in hand (part of the 'disciplinary matrix' of an established research field), we may not bother adding 'as measured with the metre rule' or 'according to the calibrated markings on the measuring cylinder' and then describe how we used the rule or cylinder. However, if a technique or instrument is new, or considered problematic, or known to be open to large errors in some contexts, we would be expected to give details.
7 Supposedly, according to the premise of 'Space: 1999', by 1999 the people of earth had amassed a vast stockpile of nuclear waste which was stored on one location on the moon. Even more supposedly, this was meant to have exploded with sufficient force to eject the moon from earth orbit and indeed the solar system, but without the moon actually losing its structural integrity. Just as unlikely, the space through which the moon moved was so dense with other planetary systems that the humans stranded on the moon at the time of the accident were able to engage in regular interplanetary adventures. Despite the fact that
"Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
Douglas Adams
and that generally interstellar distances are vast, the projectile moon moved fast enough to quickly reach new alien civilizations but slowly enough to allow some interaction before passing by. (It was just entertainment. Extremely long sequences of episodes where the moon just moved through very tenuous gas and the odd dust cloud, and incrementally approaches some far star, may have been much more realistic, but would not have made for exciting television.)
Actors Martin Landau and Barbara Bain (seen in the publicity shot for 'Space: 1999' reproduced above) were a married couple who starred in 'Space: 1999', having previously appeared together in the classic series 'Mission: Impossible' – which also featured one Leonard Nimoy (see below) who also famously later ventured into space as Mr Spock.
The 'Mission: Impossible' team. "No Jim, not impossible captain, just very challenging."
8 From the perspective of general relativity, an orbiting body is simply following a geodesic in the curved space around a massive body, so gravitational force might be seen as an epiphenomenon: fictitious – a bit like centrifugal force.
9
"Copernicus had those Renaissance ladies Crazy about his telescope And Galileo had a name that made his Reputation higher than his hopes Did none of these astronomers discover While they were staring out into the dark That what a lady looks for in her lover Is charm, strangeness and quark"
From the lyrics of 'Quark, strangeness and charm' (Dave Brock, Robert Newton Calvert)
"The static of your arms, it is the catalyst Oh the chemical it burns, there is nothing but this It's the purest element, but it's so volatile An equation heaven sent, a drug for angels Strangeness and Charm"
From the lyrics of 'Strangeness and Charm' (Florence Welch Paul Epworth)
(Possibly) the first in an occasional series to test the imagination of science teachers and other science communicators.
Those who explain science (such as teachers, scientists themselves, journalists) often seek to 'make the unfamiliar familiar' by suggesting that the novel scientific concept is in some ways like something else – something it is assumed will already be familiar with the audience.
Can you match the science and the comparison?
In the table below I have selected ten examples of comparisons for science concepts (from those reported on this website) – but I have separated the scientific ideas from the comparisons (and then presented both lists alphabetically).
The challenge is to see if you can identify which comparison was used in discussing which scienceconcept:
Can you work out which comparisons were used in explaining the different science concepts?
Of course, it is very unfair of me to present these comparisons stripped of any context – but that is what makes it a challenge.
[All of these examples are featured somewhere on the site, so if you give up (or wish to 'cheat') you could use the 'Search the website' box. If you admit defeat, the answers are at at the bottom of the post.]
A fun activity – with a serious point
I hope some readers may find this a fun activity for a tea break in the prep. room or as a way to relax for those now finally on Summer break. However, I think such comparison invite closer attention.
Devices such as analogies and similes are invaluable in getting across abstract unfamiliar ideas. However, choosing them is itself a challenge as the comparison has to be familiar to the learner/listener/reader or it cannot be helpful (in which case it may be demotivating as it adds an additional burden to what the person does not know!) Moreover, the learner/listener/reader needs to appreciate which aspect of the comparison is being highlighted as relevant. (In an analogy this should be mapped out – but in metaphors and similes it is left implicit).
There is also a danger that these devices – so useful for introducing scientific ideas – outstay their welcome (so to speak). An author of a popular science book may only be concerned with the reader having the (subjective) impression of understanding, feeling 'oh yes, that makes sense'; but the science teacher aims for objective understanding (that would be creditable on examination), and intends the analogy or simile to be a temporary 'scaffold' toward understanding which will not be needed once the scientific concept has been learnt and consolidated. Yet, sometimes, learners do not move beyond the comparison – seeing its meaning as literally accurate (much as learners may not appreciate that many scientific models are not intended to be realistic and complete accounts).
Science communicators – scientists, teachers, science writers and the like – are also often knowledgeable about a wide range of topics and cultural references – but these may not always be shared by some of their target learners/listeners/readers. (This may be particularly true when a source is being used in another part of the world to where it was created, or perhaps when a scientist's work is read many decades after being composed.)
These are also highly intelligent people who may have strong powers of imagination – so sometimes they may form creative connections which others may find obscure and idiosyncratic!
I was recently listening to a podcast of an episode of a science magazine programme which included two items of astronomy news, one about a supernovae, the next about a quasar. I often find little snippets in such programmes that I think work making a note of (quite a few of the analogies, metaphors and similes – and anthropomorphisms – reported on this site come from such sources). Here, I went back and listened to the items again, and decided the discussions were rich enough in interesting points to be worth taking time to transcribe them in full. The science itself was fascinating, but I also thought the discourse was interesting from the perspective of communicating abstract science. 1
I have appended my transcriptions below for anyone who is interested – or you can go and listen to the podcast (episode 'Largest ever COVID safety study' of the BBC World Service's Science in Action).
Space, as Douglas Adams famously noted, is big. And it is not easy for humans to fully appreciate the scales involved – even of say, the distance to the moon, or the mass of Jupiter, let alone beyond 'our' solar system, and even 'our' galaxy. Perhaps that is why public communication of space science is often so rich with metaphor and other comparisons?
When is a star no longer a star (or, does it become a different star?)
One of the issues raised by both items is what we mean by a star. When we see the night sky there are myriad visible sources of light, and these were traditionally all called stars. Telescopes revealed a good many more, and radio telescopes other sources that could not detected visually. We usually think of the planets as being something other than stars, but even that is somewhat arbitrary – the planets have also been seen as a subset of the stars – the planetary or wandering stars, as opposed to the 'fixed' stars.
At one time it was commonly thought the fixed stars were actually fixed into some kind of crystalline sphere. We now know they are not fixed at all, as the whole universe is populated with objects influenced by gravity and in motion. But on the scale of a human lifetime, the fixed stars tend to appear pretty stationary in relation to one another, because of the vast distances involved – even if they are actually moving rather fast in human terms.
Wikipedia (a generally, but not always, reliable source) suggests "a star is a luminous spheroid of plasma held together by self-gravity" – so by that definition the planets no longer count as stars. What about Supernova 1987A (SN 1987A) or quasar J0529-4351?
"This image, taken with Hubble's Wide Field and Planetary Camera 2in 1995, shows the orange-red rings surrounding Supernova 1987A in the Large Magellanic Cloud. The glowing debris of the supernova explosion, which occurred in February 1987, is at the centre of the inner ring. The small white square indicates the location of the STIS aperture used for the new far-ultraviolet observation. [George Sonneborn (Goddard Space Flight Center), Jason Pun (NOAO), the STIS Instrument Definition Team, and NASA/ESA]" [Perhaps the supernova explosion did not actually occur in February 1987]
Supernova 1987A is so-called because it was the first supernova detected in 1987 (and I am old enough to remember the news of this at the time). Stars remain in a more-or-less stable state (that is, their size, temperature, mass are changing, but, in proportional terms, only very, very slowly2) for many millions of years because of a balance of forces – the extremely high pressures at the centre work against the tendency of gravity to bring all the matter closer together. (Imagine a football supported by a constant jet of water fired vertically upwards.) The high pressures inside a star relate to a very high temperature, and that temperature is maintained despite the hot star radiating (infra-red, visible, ultraviolet…) into space 3 because of the heating effect of the nuclear reactions. There can be a sequence of nuclear fusion reactions that occur under different conditions, but the starting point and longest-lasting phase involves hydrogen being fused into helium.
The key point is that when the reactants ('fuel') for one process have all (or nearly all) been reacted, then a subsequent reaction (fusing the product of a previous phase) becomes more dominant. Each specific reaction releases a particular amount of energy at a particular rate (just as with different exothermic chemical reactions), so the star's equilibrium has to shift as the rate of energy production changes the conditions near the centre. Just as you cannot run a petrol engine on diesel without making some adjustments, the characteristics of the star change with shifts along the sequence of nuclear reactions at its core.
These changes can be quite dramatic. It is thought that in the future the Earth's Sun will expand to be as large as the Earth's orbit – but that is in the distant future: not for billions of years yet.
Going nova
Massive stars can reach a point when the rate of energy conversion drops so suddenly (on a stellar scale) that there is a kind of collapse, followed by a kind of explosive recoil, that ejects much material out into space, whilst leaving a core of condensed nuclear matter – a neutron star. For even more massive stars, not even nuclear material is stable, as there is sufficient gravity to even collapse nuclear matter, and a black hole forms.
It was such an explosion that was bright enough to be seen as a 'nova' (new star) from Earth. Astronomers have since been waiting to find evidence of what was left behind at the location of the explosion – a neutron star, or a black hole. But of course, although we use the term 'nova', it was not actually a new star, just a star that was so far away, indeed in another galaxy, that it was not noticeable – until it exploded.
Dr. Olivia Jones (from the UK Astronomy Technology Centre at The Royal Observatory, Edinburgh) explained that neutron stars form from
"…really massive stars like Supernova 1987A or what it was beforehand, about 20 times the mass of a Sun…
So, what was SN 1987A before it went supernova? It was already a star – moreover, astronomers observing the Supernova were studying
…how it evolves in real time, which in astronomy terms is extremely rare, just tracing the evolution of the death of a star…
So, it was a star; and it died, or is dying. (This is a kind of metaphor, but one that has become adopted into common usage – this way of astronomers talking of stars as having births, lives, careers, deaths, has been discussed here before: 'The passing of stars: Birth, death, and afterlife in the universe.') What once was the star, is now (i) a core located where the star was – and (ii) a vast amount of ejected material now "about 20 light years across" – so spread over a much larger volume than our entire solar system. The core is now a "neutron star [which] will start to cool down, gradually and gradually and fade away".
So, SN 1987A was less a star, than an event: the collapse of a star and its immediate aftermath. The neutron star at is core is only part of what is left from that event (perhaps like a skeleton left by a deceased animal?) Moreover, if we accept Wikipedia's definition then the neutron star is not actually a star at all, as instead of being plasma (ionised gas – 'a phase of matter produced when material is too hot to exist as, what to us seems, 'normal' gas) it comprises of material that is so condensed that it does not even contain normal atoms, just in effect a vast number of atomic nuclei fused into one single object – a star-scale atomic nucleus. So, one could say that SN 1987A was no so much a star, as the trace evidence of a star that no longer existed.
And SN 1987A is not alone in presenting identity problems to astronomers. J0529-4351 is now recognised as being possibly the brightest object in the sky (that is, if we viewed them all from the same distance to give a fair comparison) but until recently it was considered a fairly unimpressive star. As doctoral researcher Samuel Lai (Research School of Astronomy and Astrophysics, Australian National University) pointed out,
this one was mis-characterised as a star, I mean it just looks like one fairly insignificant point, just like all the other ones, right, and so we never picked it up as quasar before
But now it is recognised to only appear insignificant because it is so far away – and it is not just another star. It has been 'promoted' to quasar status. That does not mean the star has changed – only our understanding of it.
But is it a star at all? The term quasar means 'quasi–stellar object', that is something that appears much like a star. But, if J0529-435 is a quasar, then it consists of a black hole, into which material is being attracted by gravity in a process that is so energetic that the material being accreted is heated and radiates an enormous amount of energy before it slips from view over the black hole's event horizon. That material is not a luminous spheroid of plasma held together by self-gravity either.
This video from the European Southern Observatory (ESO) gives an impression of just how far away (and so how difficult to detect) the brightest object in the galaxy actually is.
These 'ontological' questions (how we classify objects of different kinds) interest me, but for those who think this kind of issue is a bit esoteric, there was a great deal more to think about in these item.
"A long time ago, in a galaxy far, far away"
For one thing, it was not, as presenter Roland Pease suggested, strictly the 37th anniversary of the SN 1987A – at least not in the sense that the precursor star went supernovae 37 years ago. SN 1987A is about 170 000 light years away. The event, the explosion, actually occurred something like 170 000 years before it could be detected here. So, saying it is the 37th anniversary (rather than, perhaps, the 170 037th anniversary4) is a very anthropocentric, or, at least, geocentric take on things.
Then again, listeners are told that the supernova was in "the Large Magellanic Cloud just outside the Milky Way galaxy" – this is a reasonable description for someone taking an overview of the galaxies, but there is probably something like 90,000 light-years between what can be considered the edges of our Milky Way galaxy and this 'close by' one. So, this is a bit like suggesting Birmingham is 'just outside' London – an evaluation which might make more sense to someone travelling from Wallaroo rather than someone from Wolverhampton.
It is all a matter of scale. Given that the light from J0529-4351 takes about twelve billion years to reach us, ninety thousand light years is indeed, by comparison, just outside our own galaxy.
But the numbers here are simply staggering. Imagine something the size of a neutron star (whether we think it really is a star or not) that listeners were informed is "rotating…around 700 times a second". I do not think we can actually imagine that (rather than conceptualise it) even for an object the size of a pin – because our senses have not evolved to engage with something spinning that fast. Similarly, material moving around a black hole at tens of thousands of kilometres per second is also beyond what is ready visualisation. Again, we may understand, conceptually, that "the neutron star is over a million degrees Celsius" but this is just another very big number way that is outside any direct human experience.
Comparisons of scale
Thus the use of analogies and other comparisons to get across something of the immense magnitudes involved:
"If you think of our Sun as a tennis ball in size, the star that formed [SN] 87A was about as big as the London Eye."
"A teaspoon of this material, of a neutron star, weighs about as much as Everest"
the black home at the centre of the quasar acquires an entire Sun worth of mass every single day
the black hole at the centre of the quasar acquires the equivalent of about four earths, every single second
the quasar is about five hundred trillion times brighter than the Sun, or equivalent to about five hundred trillion suns
Often in explaining science, everyday objects (fridges, buses – see 'Quotidian comparisons') are used for comparisons of size or mass – but here we have to shift up to a mountain. The references to 'every single day' and 'every single second' include redundancy: that is, no meaning is lost by just saying 'every day' and 'every second' but the inclusion of 'single' acts a kind of rhetorical decoration giving greater emphasis.
Figurative language
Formal scientific reports are expected to be technical, and the figurative language common in most everyday discourse is, generally, avoided – but communication of science in teaching and to the public in journalism often uses devices such as metaphor and simile to make description and explanations seem more familiar, and encourage engagement.
Of course, it is sometimes a matter of opinion whether a term is being used figuratively (as we each have our own personal nuances for the meanings of words). Would we really expect to see a 'signature' of a pulsar? Not if we mean the term literally, a sign made by had to confirm identify, but like 'fingerprint' the term is something of a dead metaphor in that we now readily expect to find so-called 'signatures' and 'fingerprints' in spectra and D.N.A. samples and many other contexts that have no direct hand involvement.
Perhaps, more tellingly, language may seem so fitting that it is not perceived as figurative. To describe a supernova as an 'evolving fireball' seems very apt, although I would pedantically argue that this is strictly a metaphor as there is no fire in the usual chemical sense. Here are some other examples I noticed:
"we have been searching for that Holy Grail: has a neutron star formed or has a black hole been left behind"
"the quasar is not located in some kind of galactic desert"
there is a "storm, round the black hole"
"the galaxies are funnelling their material into their supermassive black hole"
"extraordinarily hot nuclear ember"
"a dense dead spinning cinder"
"the ultimate toaster"
Clearly no astronomer expects to find the Holy Grail in a distant galaxy in another part of the Universe (and, indeed, I recently read it is in a Museum in Ireland), but clearly this is a common idiom to mean something being widely and enthusiastically sought.5
A quasar does exist in a galactic desert, at least if we take 'desert' literately as it is clearly much too hot for any rain to fall there, but the figurative meaning is clear enough. The gravitational field of the black hole causes material to fall into it – so although the location, at the centre of a galaxy (not a coincidence, of course), means there is much material around, I was not sure how the galaxy was actively 'funnelling' material. This seems a bit light suggesting spilt tea is being actively thrown to the floor by the cup.
A hot ember or cinder may be left by a fire that has burned out, and one at over a million degrees Celsius might indeed 'toast' anything that was in its vicinity. So, J0529-4351 may indeed be the ultimate toaster, but not in the sense that it is a desirable addition to elite wedding lists.
Anthropomorphism
Anthropomorphism is a particular kind of metaphor that describes non-human entities as if they had the motivations, experiences, drives, etc., of people. The references to dying stars at least suggest animism (that the stars are in some sense alive – something that was once commonly believed 6), but there are other examples (that something is 'lurking' in the supernova remnant) that seem to discuss stellar entities as if they are deliberate agents like us. In particular, a black hole acquiring matter (purely due to its intense gravitational field) was described as feeding:
quasars are basically supermassive black holes just swallowing up all the stars and rubbish around
a quasar is feeding from the accretion disc
a monstrous black hole gobbling up anything within reach
just sat [sic] there, gobbling up everything around it
it has to have been feeding for a very, very long time
it will eat about four of those earths, every single second
in a particularly nutritious galaxy
a quasar that has been declared the hungriest object in the universe
The notion of a black hole feeding on surrounding material seems apt (perhaps, again, because the metaphor is widely used, and so familiar). But there seems a lot more 'negative analogy' than 'positive analogy: that is the ways in which (i) a black hole acquires matter, and (ii) an organism feeds, surely have more points of difference than similarity?
For advanced animals like mammals, birds, fish, snails and the like, feeding is a complex behaviour that usually involves active searching for suitable food, whereas the black hole does not need to go anywhere.
The animal has specialist mouth-parts and a digestive system that allows it to break apart foodstuff. The black-hole just tears all materials apart indiscriminately:"it's just getting chopped up, heated up, shredded".
The organism processes the foodstuff to release specific materials (catabolism) and then processes these is very specific ways to support is highly complex structure and functioning, including the building up of more complex materials (anabolism). The black hole is just a sink for stuff.
The organism takes in foodstuffs to maintain equilibrium, and sometimes to grow in very specific, highly organised ways. The black hole just gets more massive.
A black hole surely has more in keeping with an avalanche or the collapse a tall building than feeding?
One person's garbage…?
Another feature of the discourse that I found intriguing was the relative values implicitly assigned to different material found in distant space. There is a sense with SN 1987A that, after the explosion, the neutron star in some sense deserves to be considered the real remnant of the star, whilst the other material has somehow lost status by being ejected and dispersed. Perhaps that makes sense given that the neutron star remains a coherent body, and is presumably (if the explosion was symmetrical) located much where the former star was.
But I wonder if calling the ejected material – which is what comprises the basis of "an absolutely stunning supernova [which is] beautiful" – as 'debris' and 'outer debris"? Why is this material seen as the rubbish – could we not instead see the neutron star as the debris being the inert residue left behind when the rest of the star explored in a magnificent display? (I am not suggesting either should be considered 'debris', just playing Devil's advocate.)
Perhaps the reference to being able to "isolate the core where the explosion was from the rest of the debris" suggests all that is left is debris of a star, which seems fairer; but the whole history of the universe, as we understand it, involves sequences of matter changing forms quite drastically, and why should we value one or some of these successive phases as being the real product of cosmic evolution (stars?) and other phases as just rubbish? This is certainly suggested by the reference to "supermassive black holes in the middle of a galaxy … swallowing up all the stars and rubbish".
Let's hear it for the little guys
Roland Pease's analogy to "the muck at the bottom of your sinkgoing down into the blender" might also suggest a tendency to view some astronomical structures and phenomenon as intrinsically higher status (the blender/black hole) than others (clouds of dust, or gas or plasma – the muck). Of course, I am sympathetic to the quest to better understand "these guys"(intense quasars already formed early in the universe), but as objectively minded scientists we should be looking out for the little guys (and gals) as well.
Appendix A: "the star hidden in the heart of [the] only supernova visible from Earth"
"If you are listening to this live on Thursday, then you're listening to the 37th anniversary of the supernova 1987A, the best view astronomers have had of an exploding star in centuries, certainly during the modern telescope era. So much astrophysics to be learned.
All the indications were, back then, that amidst all the flash and glory, the dying star should have given birth to a neutron star, a dense dead spinning cinder, that would be emitting radio pulses. So, we waited, and waited…and waited, and still there's no pulsing radio signal.
But images collected by the James Webb telescope in its first weeks of operation, peering deep into the ejecta thrown out by the explosion suggest there is something powerful lurking beneath. Olivia Jones is a James Webb Space Telescope Fellow at Edinburgh University and she helped in the analysis."
"87A is an absolutely stunning supernova , it's beautiful, and the fact that you could see it when it first exploded with the naked eye is unprecedented for such an object in another galaxy like this.
We have been able to see how it evolves in real time, which in astronomy terms is extremely rare, just tracing the evolution of the death of a star. It's very exciting."
"I mean the main point is the bit which we see when the star initially explodes , we see all the hot stuff which is being thrown out into space, and then you've got this sort of evolving fireball which has been easiest to see so far."
"Yes, what see initially is the actual explosion of the star itself right in the centre. What happens now is then we had a period of ten years when you couldn't actually see very much in the centre. You needed these new telescopes like Webb and JWST to see the mechanics of the explosion and then, key to this is what was left behind, and we have been searching for that Holy Grail: has a neutron star formed or has a black hole been left behind at the centre of this explosion. And we've not seen anything for a very long time."
"And this neutron star, so this is the bit where the middle of the original star which at the ends of its life is mostly made of iron, just gets sort of crushed under it's own weight and under the force of the explosion to turn itself entirely into this sort of ball of neutron matter."
"Yeah, it's the very, very core of the star. So the star like the Sun, right in the centre is a very dense core, but really massive stars like Supernova 1987A or what it was beforehand, about 20 times the mass of a Sun.
If you think of our Sun as a tennis ball in size, the star that formed 87A was about as big as the London Eye. So it's a very massive star. The pressure and density right in the centre of that star is phenomenal. So, it creates this really, really, compact core. A teaspoon of this material, of a neutron star, weighs about as much as Everest. So, it's a very, a very dense, very heavy, core that is left behind."
"These were the things which were first detected in the 1960s, because they have magnetic fields and they rotate, they spin very fast and they cause radio pulsations and they're called pulsars. so When the supernova first went off I know lots of radio astronomers were hoping to see those radio pulsations from the middle of this supernova remnant."
"Yes. So, we know really massive stars will form a black hole in the centre, 30, 40, 50 solar masses will form a black hole when it dies. Something around 20 solar masses you'd expect to form a neutron star, and so you'd expect to see these signatures, like you said, in the radiowaves or in optical light of this really fastly rotating – by fastly rotating it can be around 700 times a second – but you would expect to see that signature or some detection of that. But even with all these telescopes – with the radio telescopes, X-ray observatories, Hubble – we've not seen that signature, before and so we are wondering, has a black hole been formed? We've seen neutrinos, so we thought the neutron star had formed, but we've not had that evidence before now."
"So, as I understand it, what your research is doing is showing that there's some unexplained source of heat in the middle of the debris that's been thrown out, and that's what your associating which what ought to be a neutron star in the middle, is that roughly speaking the idea?"
"So, the wonderful thing thing about the Webb telescope, you can see at high resolution both the ring, the outer debris of the star, and right at the very centre where the explosion was, but it's not just images we take, so it's not just taking a photograph, we also have this fantastic instrument or two instruments, called spectrographs, which can break down light into their individual elements, so very small wavelengths of light, it's like if you want to see the blue wavelength or the red wavelength, but in very narrow bands."
"And people may have done this at school when they threw some salt into a Bunsen burner and saw the colours, it's that kind of analysis?"
"Yes. And so what we see where the star was and where it exploded was argon and sulphur, and we know that these needed an awful lot of energy, to create these, and I mean a lot, of energy. And the only thing that can be doings this, we compared to many different kinds of scenarios, is a neutron star."
"So this is basically an extraordinarily hot nuclear ember, that's sort of sitting in the middle."
"Yes, right in the middle and you can see this, cause Supernova 1987A is about 20 light years across, in total, and we can isolate the core where the explosion was from the rest of the debris in this nearby galaxy, which I think is fantastic."
"Do you know how hot the surface of this star is and is it just sort of the intense heat, X-ray heat I imagine, that's coming off, that's causing all this radiation that you're seeing."
"I hope you are ready for a very big number."
"Go on."
"The neutron star is over a million degrees Celsius."
"And so, that's just radiating heat, is it, from, I mean this is like the ultimate toaster?"
"Yes, so what eventually will happen over the lifetime of the universe is this neutron star will start to cool down, gradually and gradually and fade away. But that'll be many, many billions of years from now.
What we currently have now is one of the hottest things you can imagine, in a very small location, heating up all its surroundings. I would not want to be anywhere nearby there."
Roland Pease interviewingDr. Olivia Jones (Edinburgh University)
Appendix B: "possibly the brightest object in our universe"
"Now 1987A was, briefly, very bright. Southern hemisphere astronomy enthusiasts could easily spot it in the Large Magellanic Cloud just outside [sic] the Milky Way galaxy. But it was nothing like as bright as JO529-4351 [J0529-4351], try memorising that, its a quasar twelve or so billion light years away that has been declared the brightest object in the universe and the hungriest. At first sight, it's an anonymous, unremarkable spot of light of trillions on [sic] an astronomical photo. But, if you are an astronomer who knows how to interpret the light, as Samual Lai does, you will find this is a monstrous black hole gobbling up anything within reach. Close to the edge of all that we can see."
"So this quasar is a record breaking ultra-luminous object, in fact it is the most luminous object that we know of in the universe. Its light has travelled twelve billion years to reach us, so it's incredibly far object, but it's so intrinsically luminous that it appears bright in the sky."
"And as I understand it, you identified this as being a very distant and bright object pretty recently though you have gone back through the catalogues and its was this insignificant speck for quite a long time."
"Yes, indeed. In fact we were working on a survey of bright quasars, so we looked at about 80% of the sky using large data sets from space satellites. Throughout our large data sets, this one was mis-characterised as a star, I mean it just looks like one fairly insignificant point, just like all the other ones, right, and so we never picked it up as quasar before. Nowadays we are in the era of extremely astronomical, pardon the pun, data sets where in order to really filter thorough them we have these classification algorithms that we use. So, we have the computer, look at the data set, and try to learn what we are looking at, and pick out between stars and quasars."
"Now, is it also interesting, they were discovered about sixty years ago, the first quasars. These are basically supermassive black holes in the middle of a galaxy that's just swallowing up all the stars and rubbish just around it, and that's the bit that for you is quite interesting in this instance?"
"Yes, exactly, and the quasar owes its luminosity to the rate at which it is feeding from this accretion disc, this material that's swirling around, like a storm, with the black hole being the eye of the storm."
"I mean, I think of it as being a bit like the muck at the bottom of your sink going down into the blender at the bottom, it's just getting chopped up, heated up, shredded, and, I mean what sort of temperatures are you talking about? What, You know, what kind of energy are you talking about being produced in this system?"
"Yes ,so the temperatures in the accretion disc easily go up to tens of thousands of degrees, but talking about brightness, the other way that we like to measure this is in terms of the luminosity of the Sun, which gives you are sense of scale. So, this quasar is about five hundred trillion times brighter than the Sun, or equivalent to about five hundred trillion suns."
"And it's been doing this sort of constantly, or for really for a long time, I mean it's just sat there, gobbling up everything around it?"
"Yeah, I mean the mass of the quasar is about 17 billion solar masses, so in order to reach that mass it has to have been feeding for a very, very long time. We work it out to be about one solar mass per day, so that's an entire Sun worth of mass every single day. Or if you like to translate that to more human terms, if you take the Earth and everybody that's on it, and you add up all of that mass together, it will eat about four of those earths, every single second."
"I suppose what I find gob-smacking about this is (a) the forces, the gravitational forces presumably involved in sweeping up that amount of material, but (b) it must be an incredibly busy place – it can't be doing this in some kind of galactic desert."
"Yes, indeed, I mean these quasars, these super-massive black holes are parts of their galaxies, right, they're always in the nuclear regions of their host galaxies, and in some way the galaxies are funnelling their material into their supermassive black hole."
"But this one must be presumably a particularly, I don't know, nutritious galaxy, I guess. It is so far away, you can't make out those kinds of details."
"We can however make out that some of that material moving around, inside the storm, round the black hole, their dynamics are such that their velocities reach up to tens of thousands of kilometres per second."
"Why are you looking for then? Is it because you just want to break records – I'm sure it's not. Or is it, that you can see these things a long way away? Is it, it tells you about the history of galaxies?"
"I mean we can learn a lot about the universe's evolution by looking at the light from the quasars. And in fact, the quasar light it tells you a lot about not just the environment that the quasar resides in, but also in anything the quasar light passes through. So, you can think of this, lights from the quasar, as a very distant beacon that illuminates information about everything and anything in between us and the quasar."
"I mean the thing that I find striking is, if I've read the numbers right, this thing is so far away that the universe was about a billion years old. I mean I suppose what I'm wondering is how did a black hole becomes so massive so early in the universe?"
"Ah see, I love this question because you are reaching to the frontier of our current understanding, this is science going as we speak. We are running into an issue now that some of these black holes are so massive that there's not enough time in the universe, at the time that we observe them to be at, in order for them to have grown to such masses as they are seen to be. We have various hypotheses for how these things have formed, but at the moment we observe it in its current state, and we have to work backwards and look into the even older universe to try to figure out how these guys came to be."
Roland Pease interviewingDr. Samuel Lai (Australian National University)
Notes
1 Having been a science teacher, I find myself listening to, or reading, science items in the media at two levels
I am interested in the science itself (of course)
I am also intrigued by how the science is presented for the audience
So, I find myself paying attention to simplifications, and metaphors, and other features of the way the science is communicated.
Teachers will be familiar with this. Curriculum selects some parts of science and omits other parts (and there is always a debate to be had about wither the right choices are made about what to include, and what to omit). However, it is rare for the selected science itself to be presented in 'raw' form in education. The primary science literature is written by specialists for other specialists, and to a large extent by researchers for other researchers in the same field – and is generally totally unsuitable for a general audience.
Curriculum science is therefore an especially designed representation of the science intended to be accessible to learners at a particular stage in their education. Acids for twelve years olds or natural selection for fifteen year olds cannot be as complex, nuanced and subtle as the current state of the topic as presented in the primary literature. (And not just because of the level f presentation suitable for learners, but also because in any live field, the work at the cutting edge will by definition be inconsistent across studies as this is just where the experts are still trying to make the best sense of the available evidence.)
The teacher then designs presentations and sequences of learning activities to engage particular classes of learners, for often teaching models and analogies and the like are needed as stepping stones, or temporary supports, even to master the simplified curriculum models set out as target knowledge. Class teaching is challenging as every learner arrives with a unique nexus of background knowledge, alternative conceptions, relevant experiences, interests, vocabulary, and so forth. Every class is a mixed ability class – to some extent. The teacher has to differentiate within a basic class plan to try and support everyone.
I often think about this when I listen to or read science journalism or popular science books. At least the teacher usually knows that all the students are roughly the same age, and have followed more-or-less the same curriculum up to that point. Science communicators working with the public know very little about their audience. Presumably they are interested enough in the topic or science more generally to be engaging with the work: but likely of a very diverse age, educational level, background knowledge: the keen ten year old to the post-doctoral researcher; the retired engineer to the autistic child with an intense fascination in every detail of dinosaurs…
I often find myself questioning some of the simplifications and comparisons used on science reports in the media – but I do not underestimate the challenge of reporting on the latest findings in some specialist area of science in an 'academically honest' way (to borrow a term from Jerome Bruner) in a three minute radio slot or 500 words in a magazine. So, in that spirit, I was fascinated by the way in which the latest research into Supernova 1987A and J0529-4351 was communicated, at least as much as the science itself.
2 That is, the flux of material emitted by our Sun, for example, is quite significant in human terms, but is minute compared to its total mass. Our sun has cooled considerably in the past few billions of years, but that's long time for it to change! (The Earth's atmosphere has also changed over the same time scale, which has compensated.)
3 Some very basic physics (Isaac Newton's law of cooling) tells us that objects radiate energy at a rate according to their temperature. Stars are (very large and) very hot so radiate energy at a high rate. An object will also be absorbing radiation – but the 'bath' of radiation it experiences depends on the temperature of its surroundings. A hot cup of coffee will cool as it is radiating faster than it is absorbing energy, because it is hotter than its surroundings. Eventually it will be as cool as the surroundings and will reach a dynamic equilibrium where it radiates and absorbs at the same rate. (Take the cooled cup of coffee into the sauna and it will actually get warmer. But do check health and safety rules first to see if this is allowed.)
The reference to how
"what eventually will happen over the lifetime of the universe is this neutron star will start to cool down, gradually and gradually and fade away. But that'll be many, many billions of years from now"
should be understood to mean that the cooling process STARTED as soon as there was no internal source of heating (form nuclear reactions or gravitational collapse) to maintain the high temperature; although the process will CONTINUE over a long period.
4 That weak attempt at humour is a variant on the story of the museum visitors who asked the attendant how old some ancient artefacts were. Surprised at the precision of the reply of "20 012 " years, they asked how the artefacts could be dated so precisely. "Well", the attended explained, "I was told they were twenty thousand years old when I started, and I've worked here for twelve years."
Many physics teachers will not find this funny at all, as it is not at all unusual for parallel mistakes to be made by students. (And not just students: a popular science book suggested that material in meteors can be heated in the atmosphere to temperatures of up to – a rather precise – 36 032 degrees! (See 'conceptions of precision').
5 The Holy Grail being the cup that Jesus is supposed to have used at the last supper to share wine with his disciples before he was arrested and crucified. Legend suggests it was also used to collect some of his blood after his execution – and that it was later brought to England (of all places) by Joseph of Arimathea, and taken to Glastonbury. The Knights of King Arthur's Round Table quested to find the Grail. It was seen as a kind of ultimate Holy Relic.
6 Greek and Roman cultures associated the planets (which for them included the Sun and Moon) with specific Gods. Many constellations were said to be living beings that have been placed in the heavens after time on earth. Personification of these bodies by referring to them in gendered ways ('he', 'she') still sometimes occurs.
In his cosmogony, Plato had the stars given a kind of soul. Whereas Aristlotle's notion of soul can be understood as being something that emerges from the complexity of organisation (in organisms), Plato did imply something more supernatural.
Does the medieval notion of the human body as a microcosm of the wider Cosmos – in which is played out an eternal battle between good and evil – still influence our thinking?
Keith S. Taberwants to tell you a story
Are you sitting comfortably?
Good, then I will begin.
Once upon a time there was an evil microbe. The evil microbe wanted to harm a human being called Catherine, and found ways for his vast army of troops to enter Catherine's body and damage her tissues. Luckily, unbeknown to the evil microbe, Catherine was prepared to deal with invaders – she had a well-organised defence force staffed by a variety of large battalions, including some units of specialist troops equipped with the latest anti-microbe weapons. There were many skirmishes, and then a series of fierce battles in various strategic locations – and some of these battles raged for days and days, with heavy losses on both sides. No prisoners were taken alive. Many of Catherine's troops died, but knowing they had sacrificed themselves for the higher cause of her well-being. But, in the end, all of the evil microbe's remaining troops were repelled and the war was won by the plucky defenders. There was much rejoicing among the victorious army. The defence ministry made good records of the campaign to be referred to in case of any future invasions, and the surviving soldiers would long tell their stories of ferocious battles and the bravery of their fallen comrades in defeating the wicked intruders. Catherine recovered her health, and lived happily ever after.
There is a myth, indeed, perhaps even a fairy story, that is commonly told about microbial disease and immunity. Disease micro-organisms are 'invaders' and immune cells are 'defenders' and they engage in something akin to warfare. This is figurative language, but has become so commonly used in science discourse that we might be excused for forgetting this is just a stylistic feature of science communication – and so slip into habitually thinking in the terms that disease actually is a war between invading microbes and the patient's immune system.
Immunity is often presented through a narrative based around a fight between opposed sentient agents. (Images by Clker-Free-Vector-Images and OpenClipart-Vectors from Pixabay.)
Actually this is an analogy: the immune response to infection is in some waysanalogous to a war (but as with any analogy, only in some ways, not others). As long as we keep in mind this is an analogy, then it can be a useful trope for talking and thinking about infectious disease. But, if we lose sight of this and treat such descriptions as scientific accounts, then there is a danger: the myth undermines core biological principles, such that the analogy only works if we treat biological entities in ways that are contrary to a basic commitment of modern science.
In this article I am going to discuss a particular, extensive, use of the disease-as-war myth in a popular science book (Carver, 2017), and consider both the value, and risks, of adopting such a biological fairy-tale.
Your immune system comprises a vast army of brave and selfless soldiers seeking to protect you from intruders looking to do you harm: an immune response is a microcosm of the universal fight between good and evil?
A myth is a story that has broad cultural currency and offers meaning to a social group, usually involving supernatural entities (demons, superhuman heroes, figures with powerful magic), but which is not literally true.
Carver's account of the immune system
I recently read 'Immune: How your body defends and protects you' (henceforth, 'Immune') by Catherine Carver. Now this is clearly a book that falls in the genre 'popular science'. That is, it has been written for a general audience, and is not meant as a book for experts, or a textbook to support formal study. The publishers, Bloomsbury, appropriately describe Carver as a 'seasoned science communicator'. (Appropriately, as metaphorical dining features strongly in the book as well.)
Carver uses a lot of contractions ("aren't", "couldn't", "doesn't", "don't", "isn't", "it's", "there's", "they're", "we've", "what's", "who'd", "wouldn't", "you'd") to make her writing seem informal, and she seems to make a special effort to use metaphor and simile and to offer readers vivid scenes they can visualise. She offers memorable, and often humorous, images to readers. A few examples offer an impression of this:
"…the skin cells…migrate through the four layers of the epidermis, changing their appearance like tiny chameleons…"
"Parietal cells dotted around the surface of the stomach are equipped with proton pumps, which are like tiny merry-go-rounds for ions."
"a process called 'opsonisation' make consuming the bacterial more appealing to neutrophils, much like sprinkling tiny chocolate chips on a bacterial cookie."
"The Kupffer cells hang around like spiders on the walls of the blood vessels…"
In places I wondered if sometimes Carver pushed this too far, and the figurative comparisons might start to obscure the underlying core text…
"…the neutrophil…defines cool. It's the James Dean of the immune system; it lives fast, dies young and looks good in sunglasses."
Carver, 2017, p.7
"The magnificence of the placenta is that it's like the most efficient fast-food joint in the world combined with a communications platform that makes social media seem like a blind carrier pigeon, and a security system so sophisticated that James Bond would sell his own granny to the Russians just to get to play with it for five minutes."
Carver, 2017, p.113
When meeting phrases such as these I found myself thinking about the metaphors rather than what they represented. My over-literal (okay, pedantic) mind was struggling somewhat to make sense of a neutrophil in (albeit, metaphoric) sunglasses, and I was not really sure that James Bond would ever sell out to the Russians (treachery being one of the few major character faults he does not seem to be afflicted by) or be too bothered about playing with a security system (his key drives seem focused elsewhere)…
…but then this is a book about a very complex subject being presented for an audience that could not be assumed to have anything beyond the most general vague prior knowledge of the immune system. As any teacher knows, the learner's prior knowledge is critical in their making sense of teaching, and so offering a technically correct account in formal language would be pointless if the learner (or, here, reader) is not equipped to engage at that level.
'Immune' is a fascinating and entertaining read, and covers so much detailed ground that I suspect many people reading this book would would not have stuck with something drier that avoided a heavy use of figurative language. Even though I am (as a former school science teacher *) probably not in the core intended audience for the book, I still found it very informative – with much I had not come across before. Carver is a natural sciences graduate from Cambridge, and a medical doctor, so she is well placed to write about this topic.
Catherine Carver's account of the immune system is written to engage a popular readership and draws heavily on the disease-as-war analogy.
My intention here is not to offer a detailed review or critique of the book, but to explore its use of metaphors, and especially the common disease-as-war theme (Carver draws on this extensively as a main organising theme for the book, so it offers an excellent exemplar of this trope) – and discuss the role of the figurative language in science communication, and its potential for subtly misleading readers about some basic scientific notions.
The analogy
The central analogy of 'Immune' is clear in an early passage, where Carver tells us about the neutrophil,
"…this cell can capture bubonic plague in a web of its own DNA, spew out enzymes to digest anthrax and die in a kamikaze blaze of microbe-massacring glory. The neutrophil is a key soldier in an eternal war between our bodies and the legions of bacteria, viruses, fungi and parasites that surround us. From having sex to cleaning the kitchen sink, everything we do exposes us to millions of potential invaders. Yet we are safe. Most of the time these invaders' attempts are thwarted. This is because the human body is like an exceedingly well-fortified castle, defended by billions of soldiers. Some live for less than a day, others remember battles for years, but all are essential for protecting us. This is the hidden army that we all have inside of us…"
Carver, 2017, p.7
Phew – there is already a lot going on there. In terms of the war analogy:
We are in a perpetual war with (certain types) of microbes and other organisms
The enemy is legion (i.e., has vast armies)
These enemies will invade us
The body is like a well-protected fort
We have a vast army to defend us
There will be battles between forces from the two sides
Some of our soldiers carry out suicide (kamikaze) missions
Our defenders will massacre microbes
We (usually) win the battles – our defences keep us safe
Some of these specific examples can be considered as metaphors or similes in they own right when they stand alone, but collectively they fit under an all-encompassing analogy of disease-as-war.
But this is just an opening salvo, so to speak. Reading on, one finds many more references to the 'war' (see Boxes 1 and 2 below).
The 'combatants' and their features are described in such terms as army, arsenals, assassins, band of rebels, booby-traps, border guards, border patrol force, commanders, defenders, fighting force, grand high inquisitors, hardened survivor, invaders, lines of defence, muscled henchman, ninjas, soldiers, terminators, trigger-happy, warriors, and weapons.
Disease and immune processes and related events are described in terms such as alliance, armoury, assassination campaign, assault, assault courses, attack, battlefield, bashing, battles, boot camp, border control, calling upsoldiers, chemical warfare, cloaking device, craft bespoke weaponry, decimated, dirty bomb, disables docking stations, double-pronged attack, exploding, expose to a severe threat,fight back, fighting on fronts, friendly fire, go on the rampage, hand grenades, heat-seeking missiles, hold the fort, hostile welcome, instant assault , kamikaze, killer payload, massacring, patrolling forces, pulling a pin on a grenade, R & R [military slang for 'rest and recuperation'], reinforcing, security fence, self-destruct, shore updefences, slaughters/slaughtering, smoke signals, standing down, suicidal missions, Swiss army knife, taking on a vast army on its home turf, throwing dynamite, time bomb, toxic cloud, training camp, training ground, trip the self-destruct switch, Trojan horse, victories, war, and wipe out the invader.
Microbes and cells as agents
A feature of the analogue is that war is something undertaken by armies of soldiers, that are considered as having some level of agency. The solder is issued with orders, but carries them out by autonomous decision-making informed by training as well as by conscience (a soldier should refuse to obey an illegal order, such as to deliberately kill civilians or enemy combatants who have surrendered). Soldiers know why they are fighting, and usually buy into at least the immediate objectives of the current engagement (objectives which generally offer a more favourable outcome for them than for the enemy soldiers). A soldier, then, has objectives to be achieved working towards a shared overall aim; purposes that (are considered to) justify the actions taken; and indeed takes deliberate actions intended to bring out preferred outcomes. Sometimes soldiers may make choices they know increase risks to themselves if they consider this is justified for the higher 'good'. These are moral judgements and actions in the sense of being informed by ethical values.
An extensive range of terminology related to conflict is used to describe aspects of disease and the immune response to infection. (Image sources: iXimus [virus], OpenClipart-Vectors [cell], Tumisu [solders in 'Raising the Flag on Iwo Jima'-like poses], from Pixabay.)
Now, I would argue that none of this applies to either disease organisms nor components of a human immune system. Neither a bacterium nor an immune cell know they are in a war; neither have personal, individual or shared, objectives; and neither make deliberate choices about actions to take in the hope they will lead to particular outcomes. No cell knowingly puts itself at risk because it feels a sacrifice is justified for the benefit of its 'comrades' or the organism it is part of.
So, all of this might be considered part of what is called the 'negative analogy', that is, where the analogy breaks down because the target system (disease processes and immune responses) no longer maps onto the analogue (a war). Perhaps this should be very obvious to anyone reading about the immune system? At least, perhaps scientists might assume this would be very obvious to anyone reading about the immune system?
Now, if we are considering the comparison that an immune response is something like a nation's defence forces defending its borders against invaders, we could simply note that this is just a comparisonbut one where the armies of each side are like complex robotic automatons pre-programmed to carry out certain actions when detecting certain indicators: rather than being like actual soldiers who can think for themselves, and have strategic goals, and can rationally choose actions intended to bring about desired outcomes and avoid undesired ones. (A recent television advertising campaign video looking to recruit for the British Army made an explicit claim that the modern, high-tech, Army could not make do with robots, and needed real autonomous people on the battlefield.)
However, an account that relies too heavily on the analogy might be in danger of adopting language which is highly suggestive that these armies of microbes and immune cells are indeed like human soldiers. I think Carver's book offers a good deal of such language. Some of this language has already been cited.
Immune cells do not commit kamikaze
Consider a neutrophil that might die in a kamikaze blaze of microbe-massacring glory. Kamikaze refers to the actions of Japanese pilots who flew their planes into enemy warships because they believed that, although they would surely die and their planes be lost, this could ensure severe damage to a more valuable enemy resource – where the loss of their own lives was justified by allowing them to remain at the plane's controls until the collision to seek to do maximum damage. Whatever we think of war in general, or the Kamikazi tactics in particular, the use of this term alludes to complex, deliberate, human behaviour.
Immune cells do not carry out massacres
And the use of the term massacre is also loaded. It does not simply mean to kill, or even to kill extensively. For example, the Jallianwala Bagh massacre, or Amritsar massacre, is called a massacre because (British) soldiers with guns deliberately fired at, with intent to kill or seriously injure, a crowd of unarmed Indians who were in their own country, peacefully protesting about British imperial policies. The British commanders acted to ensure the protesters could not easily escape the location before ordering soldiers to fire, and shooting continued despite the crowd trying to flee and escape the gunfire. Less people died in the Peterloo Massacre (1819) but it is historically noteworthy because it represented British troops deliberately attacking British demonstrators seeking political reform, not in some far away 'corner of Empire', but in Manchester.
Amritsar occurred a little over a century ago (before modern, post-Nurenmberg, notions of the legality of military action and the responsibility of soldiers to not always follow orders blindly), but there are plenty of more recent examples where the term 'massacre' is used, such as the violent clearing of protesters in Tiananmen Square in 1989 and the Bogside 'Bloody Sunday' massacre in 1972 (referenced in the title of the U2 song, 'Sunday Bloody Sunday'). In these examples there is seen to be an unnecessary and excessive use of force against people who are not equipped to fight back, and who are not shown mercy when they wish to avoid or leave the confrontation.
'Monument in Memory of Chinese from Tiananmen in Wrocław, Poland' commemorating the massacre of 4th June 1989 when (at least) hundreds were killed in Beijing after sections of the People's Liberation Army were ordered to clear protesters from public places (Masur, Public domain, via Wikimedia Commons)
The term massacre loses its meaning without this sense of being an excessively immoral act – and surely can only apply to an action carried out by 'moral agents' – agents who deliberately act when they should be aware the action cannot be morally justified, and where they can reasonably see the likely outcomes. (Of course, it is more complicated that this, in particular as a soldier has orders as well as a conscience – but that only makes the automatic responses of immune cells towards pathogens even less deserving of being called a massacre.)
The term moral agent does not mean someone who necessarily behaves morally, but rather someone who is able to behave morally (or immorally) because they can make informed judgements about what is right and wrong – they can consider the likely consequence of their actions in terms of a system of values. An occupied building that collapses does harm to people, but cannot be held morally responsible for its 'behaviour' in the way a concentration camp guard or a sniper can be. A fox that takes a farmer's chickens has no conception of farming, or livestock, or ownership, or of the chickens as sentient beings that will experience the episode from a different perspective, but just acts instinctively to access food. Microbes and cells are like the building or the fox, not the guard or the sniper, in this respect.
Moreover, in the analogue, the massacred are also moral agents: human beings, with families, and aspirations for their futures, and the potential for making unique contributions to society… I am not convinced that bacteria or microbes are the kinds of entities that can be massacred.
Anthropomorphic references
Carver then writes about the immune system, or its various components, as well as various microbes and other pathogenic organisms, as though they are sentient, deliberative agents acting in the world with purposes. After all, wars are a purely human phenomenon.1 Wars involve people: people with human desires, motives, feelings, emotions, cunning, bravery (or not), aims and motivations.
Anthropomorphism is describing non-human entities as if they are people. Anthropomorphism is a common trope in science teaching (and science communication) but learners may come to adopt anthropomorphic explanations (e.g., the atom wants…) as if they are scientific accounts (Taber & Watts, 1996).
Bacteria, body cells and the like are not these kinds of entities, but can be described figuratively as though they are. Consider how,
"Some bacteria are wise to this and use iron depletion as an indicator that they are inside an animal. Other bacteria have developed their own powerful iron-binding molecules called 'siderophores' which are designed to snatch the iron from the jaws of lactoferrin. Perhaps an even smarter strategy is just to opt out of the iron wars altogether…
…tear lipocalin, whose neat structure includes a pocket for binding a multitude of molecules. This clever pocket allows tear lipocalin to bind the bacterial siderophores…neutralising the bacterium's ability to steal iron from us…"
Carver, 2017, pp.20-21
Of course, bacteria are only 'wise' metaphorically, and they only 'develop' and 'design' molecules metaphorically, and they only adopt 'smarter strategies' or can 'opt out' of activities metaphorically – and as long as the reader appreciates this is all figurative language it is unproblematic. But, when faced with multiple, and sometimes extended, passages seeming to imply wise and clever bacteria developing tools and strategies, could the reader lose sight of this (and, if so, does that matter?)
If bacteria are not really clever, nor are pockets (or 'pockets' – surely this is a metaphor, as actual pockets are designed features not evolved ones). Stealing is the deliberate taking of something one knows is owned by someone else. Bacteria may acquire iron from us, but (like the fox) they do not stealas they have no notion of ownership and property rights, nor indeed, I suggest, any awareness that those environments from which they acquire the iron are considered by them[our]selves as 'us'.
That is, there is an asymmetrical relationship here: humans may be aware of the bacteria we interact with (although this has been so only very recently in historical terms) but it would be stretching credibility to think the bacteria have any awareness – even assuming they have ANY awareness in the way we usually use the term – of us as discrete organisms. So, the sense in which they "use iron depletion as an indicator that they are inside an animal" cannot encompass a deliberate use of an indicator, nor any inference they are inside an animal. There is simply a purely automatic, evolved, process that responds to environmental cues.
I have referred in other articles posted here to examples of such anthropromorphic language in public discourse being presented apparently in the form of explanations: e.g.,
My focus here is Catherine Carver's book, but it is worth bearing in mind that even respectable scientific journals sometimes publish work describing viruses in such terms as 'smart', 'nasty', 'sneaky' – and, especially it seems, 'clever' (see 'So who's not a clever little virus then?'). So, Carver is by no means an outlier or maverick in using these devices.
'Immune' is embellished throughout with this kind of language – language that suggests that parasites, microbes, body cells, or sometimes even molecules:
act as agents that are aware of their roles and/or purposes;
do things deliberately to meet objectives;
have preferences and tastes.
The problem is, that although this is all metaphorical, as humans we readily interpret information in terms of our own experiences, so a scientific reading of a figurative text may requires us to consciously interrogate the metaphors and re-interpret the language. Historians of chemistry will be well aware of the challenge from trying to make sense of alchemical texts which were often deliberately obscured by describing substances and processes in metaphoric language (such as when the green lion covers the Sun). Science communicators who adopt extensive metaphors would do well to keep in mind that they can obscure as well as clarify.
For example, Carver writes:
"…the key to a game of hide and seek is elementary: pick the best hiding place. In the human body, the best places to hide are those where the seekers (the immune system) find it hard to travel. This makes the brain a very smart place for a parasite to hide."
Carver, 2017, p.132
'There is a strong narrative here ("the eternal game of hide and seek [parasites] play with us")- most of us are familiar with the childhood game of hide and seek, and we can readily imagine microbes or parasites hiding out from the immune cells seeking them. This makes sense, because of course, natural selection has led to an immune system that has components which are distributed through the body in such a way that they are likely to encounter any disease vectors present – as this increases fitness for the creature with such a system – and natural selection has also led to the selection of such vectors that tend to lodge in places less accessible to the immune cells – as this increase fitness of the organism that we2 consider a disease organism. Thus evolution has often been described, metaphorically, as an arms race.
But this is not really a game(which implies deliberate play – parasites can not know they are playing a game); and the disease vectors do not have any conception of hiding places, and so do not pick where to go accordingly, or using any other criterion; the immune cells are not knowingly seeking anything, and do not experience it being harder to get to some places than others (they are just less likely to end up in some places for purely naturalistic reasons).
So, a parasite that ends up in the brain certainly may be less accessible to the immune system, but is not deliberately hiding there – and so is no more 'smart' to end up there than boulders that congregate at the bottom of a mountainside because they think it is a good place to avoid being sent rolling by gravity (and perhaps having decided it would be too difficult to ascend to the top of the mountain).4
It is not difficult to de-construct a text in the way I have done above for the hide-and-seek comparison- if a reader thinks this is useful, and consequently continually pauses to do so. Yet, one of the strengths of a narrative is that it drives the reader forward through a compelling account, drawing on familiar schemata (e.g., hide and seek; dining; setting up home…) that the reader readily brings to mind to scaffold meaning-making.
Another familiar (to humans) schema is choosing from available options:
"…the neutrophil's killer skills come to the fore…It only has to ask one question: which super skills should be deployed for the problem at hand?"
Carver, 2017, p.27
So, it seems this type of immune cell has 'skills', and can pose itself (and answer) the question of which skills will be most useful in particular circumstances (perhaps just like a commando trained to deal with unexpected scenarios that may arise on a mission into enemy-held territory?) Again, of course, this is all figurative, but I wonder just how aware most readers are of this as they read.
Carver's account of Kupffer cells makes them seem sentient,
"The Kupffer cells hang around like spiders on the walls of the blood vessels waiting to catch any red blood cells which have passed their best before date (typically 120 days). Once caught, the red blood cell is consumed whole by the Klupffer cell, which sets about dismantling the haemoglobin inside its tasty morsel."
Carver, 2017, p.27
Kupffer cells surely do not 'hang around' or 'wait' in anything more than a metaphorical sense. If 'catching' old red blood cells is a harmless metaphor, describing them as tasty morsels suggests something about the Kupffer cells (they have appetites that discriminate tastes – more on that theme below) that makes them much more like people than cells.
Another striking passage suggests,
"Some signals are proactive, for example when cells periscope from their surface a receptor called ULBP (UL16-binding protein). Any NK cell that finds itselfshaking hands with a ULBP receptor knows it has found a stressed-out cell. The same is true if the NK cell extends its receptors to the cell only to find it omits parts of the secret-handshakeexpected from a normal cell. Normal, healthy cells display a range of receptors on their surface which tell the world 'I'm one of us, everything is good'. Touching these receptors placates NK cells, inhibiting their killer ways. Stressed, infected cells display fewer of these normal receptors on their surface and in the absence of their calming presence the trigger-happy NK cells attack."
Carver, 2017, p.27
That cells can 'attack' pathogens is surely now a dead metaphor and part of the accepted lexicon of the topic. But cells are clearly only figuratively telling the world everything is good – as 'telling' surely refers to a deliberate act. The hand-shaking, including the Masonic secret variety (n.b., a secret implies an epistemic agent capable of of knowing the secret), is clearly meant metaphorically – the cell does not 'know' what the handshake means, at least in the way we know things.
If the notion of a cell being stressed is also a dead metaphor (that is 'stressed' is effectively a technical term here {"the concept of stress has profitably been been exported from physics to psychology and sociology" Bunge, 2017/1998}), a stressed-out cell seems more human – perhaps so much so that we might be subtly persuaded that the cell can actually be placated and calmed? The point is not that some figurative language is used: rather, the onslaught (oops, it is contagious) of figurative language gives the reader little time to reflect on how to understand the constant barrage of metaphors…
"…it takes a bit of time for the B cells to craft a specific antibody in large quantities. However the newly minted anti-pollen antibodies are causing mischief even if we can't see evidence of it yet. They travel round the body and latch on to immune cells called masts anywhere they can find them. This process means the person is now 'sensitised' to the pollen and the primed mast cells lie in wait throughout the body…"
Carver, 2017, pp.183-184
…so, collectively the language can be insidious – cells can 'craft' antibodies (in effect, complex molecules) which can cause mischief, and find mast cells which lie in waitfor their prey.
Sometimes the metaphors seemed to stretch even figurative meaning. A dying cell will apparently 'set its affairs in order'. In humans terms, this usually relates to someone ensuring financial papers are up to date and sorted so that the executors will be able to readily manage the estate: but I was not entirely sure what this metaphor was intended to imply in the case of a cell.
Animistic language
Even a simple statement such as "First the neutrophil flattens itself"(p.28) whilst not implying a conscious process makes the neutrophil the active agent rather than a complex entity subject to internal mechanisms beyond its deliberate control. 3
So, why write
"Finally, the cell contracts itself tightly before exploding like a party popper that releases deadly NETs [neutrophil extracellular traps] instead of streamers."
Carver, 2017, p.27
rather than just "…the cell contracts tightly…"? I suspect because this offers a strong narrative (one of active moral agents engaged in an existential face-off) that is more compelling for readers.
Neutrophils are said to 'gush' and to 'race', but sometimes to be slowed down to a 'roll' when they can be brought to a stop ("stopping them in their tracks" if rolling beings have tracks?). But on other occasions they 'crawl'. Surely crawling is a rather specific means of locomotion normally associated with particular anatomy. Typically, babies crawl (but so might soldiers when under fire in a combat zone?)
There are many other examples of phrases that can be read as anthropomorphic, or at least animistic, and the overall effect is surely insidious on the naive reader. I do not mean 'naive' here to be condescending: I refer to any reader who is not so informed about the subject matter sufficiently to already understand disease and immunity as natural processes, that occur purely through physical and chemical causes and effects, and that have through evolution become part of the patterns of activity in organisms embedded in their ecological surroundings. A process such as infection or an immune response may look clever, and strategic, and carefully planned, but even when very complex, is automatic and takes place without any forethought, intentions, emotional charge or conscious awareness on the part of the microbes and body cells involved.
There are plenty of other examples in 'Immune' of phrasing that I think can easily be read as referring to agents that have some awareness of their roles/aims/preferences, and act accordingly. And by 'can easily be read', I suspect for many lay readers (i.e., the target readership) this means this will be their 'natural' (default) way of interpreting the text.
So (see Box 3 , below), microbes, cells, molecules and parasites variously are in relationships, boast, can beckon and be beckoned, can be crafty, can be egalitarian, can be guilty, can be ready to do things, can be spurred on, can be told things, can be treacherous, can be unaware (which implies, sometimes they are aware), can dance choreographed, can deserve blame, can find things appealing, can have plans, can mind their own business, can pay attention, can spot things, can take an interest, can wheedle (persuade), congregate, craft things, dare to do things, do things unwittingly, find things, get encouraged, go on quests, gush, have aims, have friends, have goals, have jobs, have roles, have skills, have strategies, have talents, have techniques, insinuate themselves, know things, like things, look at things, look out for things, play, outwit, race, seek things, smuggle things, toy with us, and try to do things.
Microbes moving in
One specific recurring anthropomorphic feature of Carver's descriptions of the various pathogens and the harmless microbes which are found on and in us, is related to finding somewhere to live – to setting up a home. Again, this is clearly metaphorical, a microbe may end up being located somewhere in the body, but has no notion, or feeling, of being at home. Yet the schema of home – finding a home, setting up home, being at home, feeling at home – is both familiar and, likely, emotionally charged, and so supports a narrative that fits with our life-experiences.
A squatter among pathogen society? Images by Peter H (photograph) and Clker-Free-Vector-Images (superimposed virus) from Pixabay
Viruses and bacteria are compared in terms of their travel habits (in relation to which, "The human hookworm…[has] got quite an unpleasant commute to work…"),
"…viruses are the squatters of pathogen society. Unlike bacteria, which tend to carry their own internal baggage for all their disease-making needs, viruses pack light. They hold only the genes they need to gain illegal entry to our cells and then instruct our cells' machinery to achieve the virus's aims. The cell provides a very happy home for the virus, and also gives it cover from the immune system."
Carver, 2017, p.35
These pathogens apparently form a society (where there is a distinction between what is and what is not legal 5) and individually have needs and aims. A virus not only lives in a home, but can be happy there. Again, such language does have a sensible meaning (if we stop to reflect on just what the metaphors can sensibly mean), but it is a metaphorical meaning and so should not be taken literally.
"…the human microbiota is the collective name for the 100 trillion micro-organisms that have made us their real estate. From the tip of your tongue to the skin you sit on, they have set up home in every intimate nook and cranny of our body…The prime real estate for these microbes, the Manhattan or Mayfair equivalent inside you and me, is the large intestine or colon. If you had a Lonely Planet or Rough Guide to your gut, the colon would have an entry something like this: 'The colon is a must-see multi-cultural melting-pot, where up to one thousand species of bacteria mingle and dine together every second of every day. In this truly 24/7 subterranean city, Enterococcirub shoulders with Clostridia; Bacteroides luxuriate in their oxygen-depleted surroundings and Bifidobacteria banquet on a sumptuous all-you-can-eat poo buffet. It's the microbe's place to see, and be seen'. ….[antibiotic's] potential to kill off vast swathes of the normal gut flora. This creates an open-plan living space for a hardy bacterium called Clostridium difficile. This so-called superbug (also known as C. diff) is able to survive the initial antibiotic onslaught and then rapidly multiplies in its newly vacated palace."
Carver, 2017, p.76-78
This metaphor is reflected in a number of contexts in Immune. So, the account includes (see Box 4, below) break ins, camps, communities, homes, lounging, palaces, penthouses, playgrounds, preferred places to live, real estate, residents, shops, squatters, suburban cul-de-sacs, and tenants .
What is for dinner?
The extracts presented above also demonstrate another recurring notion, that microbes and body cells experience 'eating' much like we do ('tasty morsel', 'dine together', 'banquet…buffet'). There are many other such illusions in 'Immune'.
We could explain human eating preferences and habits in purely mechanistic terms of chemistry, physics and biology – but most of us would think this would miss an important level of analysis (as if what people can tell us about what they think and feel about their favourite foods and their eating habits is irrelevant to their food consumption) and would be very reductive. Yet, when considering a single cell, such as a Kupffer cell, surely a mechanistic account in terms of chemistry, physics and biology is not reductionist, but exhaustive. Anything more is (as Einstein suggested about the aether) superfluous.
One favoured dining location is the skin:
"The Demodexdine on sebum (the waxy secretion we make to help waterproof our skin), as well as occasionally munching on our skin cells and even some unlucky commensal bacteria like Propionibacterium acnes…like many of us, P. acnes is a lipophile, which is to say it adores consuming fat. The sebum on our skin is like a layer of buttery, greasy goodness that has P. acnessmacking its lips. However, when P. acnes turns up to dine it has some seriously bad table manners, which can include dribbling chemicals all over our faces…[non-human] animal sebum lacks the triglyceride fats that P. acnes [2 ital] loves to picnic on." p.82
Carver, 2017, pp.81-82
It is hopefully redundant, by this point, for me to point out that Propionibacterium acnes does not adore anything – neither preferred foodstuffs nor picnics – but has simply evolved to have a nutritional 'regime' that matches its habitat. Whilst this extract immediately offers a multi-course menu of metaphors, it is supplemented by a series of other semantic snacks. So 'Immune' also includes references to buffet carts, chocolate chips, cookies, devouring, easy meals, gobbling up, making food appetising, making food tastier, munching, a penchant for parma ham and rare steak, soft-boiled eggs, tasty treats and yummy desserts.
Can you have too much of a metaphorical good thing?
I am glad I bought 'Immune'. I enjoyed reading it, and learnt from it. But perhaps a more pertinent question is whether I would recommend it to a non-scientist* interested in learning something about immunity and the immune system. Probably, yes, but with reservations.
Is this because I am some kind of scientific purist (as well as a self-acknowledged pedant)? I would argue not: if only because I am well aware that my own understanding of many scientific topics is shallow and rests upon over-simplifications, and in some cases depends upon descriptive accounts of what strictly need to be appreciated in formal mathematical terms. I do not occupy sufficiently high ground to mock the novice learner's need for images and figures of speech to make sense of unfamiliar scientific ideas. As a teacher (and author) I draw on figurative language to help make the unfamiliar become familiar and the abstract seem concrete. But, as I pointed out above, figurative language can sometimes help reveal (to help make the unfamiliar, familiar); but can also sometimes obscure, a scientific account.
I have here before made a distinction between the general public making sense of science communication in subjective and objective terms. Objective understanding might be considered acquiring a creditable account (that would get good marks in an examination, for example). But perhaps that is an unfair test of a popular science book: perhaps a subjective making-sense, where the reader's curiosity is satisfied – because 'yes, I see, that makes sense to me' – is more pertinent. Carver has not written 'Immune' as a text book, and if readers come away thinking they have a much better grasp of the immune system (and I suspect most 'naive' readers certainly would think that) then it is a successful popular science book.
My reservation here is that we know many learners find it difficult to appreciate that cornerstone of modern biology, natural selection (e.g., Taber, 2017), and instead understand the living world in much more teleological terms – that biological processes meet ends – occur to achieve aims – and do so through structures which have been designed with certain functions in mind.
So, microbes, parasites, cells, and antibodies, which are described as though they are sentient and deliberate actors – indeed moral agents seeking strategic goals, and often being influenced by their personal aesthetic tastes – may help immunity seem to make sense, but perhaps by reinforcing misunderstandings of key foundational principles of biology.
In this, Catherine Carver is just one representative of a widespread tendency to describe the living world in such figurative terms. Indeed, I might suggest that Carver's framing of the immune system as a defence force facing hostile invaders makes 'Immune' a main-stream, conventional, text in that it reflects language widely used in public science discourse, and sometimes even found in technical articles in the primary literature.
A myth is a story that has broad cultural currency and offers meaning to a social group, usually involving supernatural entities (demons, superhuman heroes, figures with powerful magic – perhaps microbial aesthetes and sentient cells?), but which is not literally true. e.g., Your immune system comprises a vast army of brave and selfless soldiers seeking to protect you from intruders looking to do you harm: an immune response is a microcosm of the universal fight between good and evil?
My question, then, is not whether Carver was ill-advised to write 'Immune' in the way she has, but whether it is time to more generally reconsider the widespread use of the mythical 'war' analogy in talking about immunity and disease.
Notes
1 Even if, for example, some interactions between groups of ants from different nests {e.g., see 'Ant colony raids a rival nest | Natural World – Empire of the Desert Ants – BBC'} look just as violent as anything from human history, their 'battles' are surely not planned as part of some deliberate ongoing campaign of hostilities.
2 The bacteria infecting us, if they could conceptualise the situation (which they cannot), would have no more reason to consider themselves a disease, than humans who 'infected' an orchard and consumed all the fruit would consider themselves a disease. Microbes are not evil for damaging us, they are just being microbes.
3 If my rock analogy seems silly, it is because we immediately realise that rocks are just not the kind of entities that behave deliberately in the world. The same is true of microbes and body cells -they are just not the kind of entities that behave deliberately in the world, and as long as this is recognised such metaphorical language is harmless. But I am not sure that is so immediately obvious to readers in these cases.
4 Such an issue can arise with descriptions about people as well. If I want to share a joke with a friend I may wink. If a fly comes close to my eye I may blink. Potentially these two actions may seem indistinguishable to an observer. However, the first is a voluntary action, but in the second case the 'I' that blinks is not me the conscious entity that ascribes itself self-hood, but an autonomous and involuntary subsystem! In a sense a person winks, but has blinking done to her.
5 If entry to our cells was 'illegal' in the sense of being contrary to natural laws/laws of nature, it would not occur.
* A note on being a scientist. Any research scientists reading this might scoff at my characterisation of the readers of popular science books as being non-scientists with the implied suggestion that I, by comparison, should count as a scientist. I have never undertaken research in the natural sciences, and, although I have published in research journals, my work in science education would be considered as social science – which in the Anglophile world does not usually count as being considered 'science' per se. However, in the UK, the Science Council recognises science educators as professional scientists. Learned societies such as the Royal Society of Chemistry and the Institute of Physics will admit teachers of these subjects as professional members, and even Fellows once their contributions are considered sufficient. This potentially allows registration as a Chartered Scientist. Of course, the science teacher does not engage in the frontiers of a scientific research field in the way a research scientist does, however the science teacher requires not only a much broader knowledge of science, but also a specialist professional expertise that enables the teacher to interrogate and process scientific knowledge into a form suitable for teaching. This acknowledges the highly specialised nature of teaching as an expert professional activity which goes far beyond the notion of teaching as a craft that can be readily picked up (as sometimes suggested by politicians).
Work cited
Bunge, M. (2017/1998). Philosophy of Science. Volume 1: From problem to theory. Routledge. (1967)
Carver, C. (2017). Immune. How your body defends and protects you. Bloomsbury Sigma.
"neutrophil is a key soldier" "the human body is like an exceedingly well-fortified castle, defended by billions of soldiers" "…the incredible arsenal that lives within us…" "the hidden army" "…our adaptive assassins, our T and B cells" "The innate system is the first line of defence…" skin: "…an exquisite barrier that keeps unwanted invaders out." "…your airways are exceedingly well booby-trapped passages lined with goblet cells, which secrete a fine later of mucus to trap dirt and bacteria." "Initially it was seen as a simple soldier with a basic skills set …Now we know it is a crafty assassin with a murderous array of killing techniques." "…ninja skill of neutrophils…", "ninja neutrophils" "macrophages are stationed at strategic sites…what an important outpost the liver is for the immune system" "NK cells [have] killer ways" "trigger-happy NK cells" "Ever neat assassins, NK cells" "vicious immune cells" compared to "a pack of really hungry Rottweilers" interleukins are "pro-inflammatory little fire-starters" "neutrophils, macrophages and other immune system soldiers" "T cells…activate their invader-destroying skills." "…a weapon with a name worthy of a Bond villain's invention: the Membrane Attack Complex" "miniature mercenaries" "a system whose raise d'etre is to destroy foreign invaders" "everything we do exposes us to millions of potential invaders." "…all invaders need an entry point…" "these tiny sneaks [e.g., E. coli]" "the dark-arts of pus-producing bacteria…" Neisseria meningitidis: "this particular invader" "foreign invaders" "an aggressive border patrol" 'Tregs are the prefects of the immune system…" "…the parasite larva has more in common with a time bomb…" "T cells…are the grand high inquisitors of the immune system, spotting and destroying infected cells and even cancer…these assassins" "imagining you have to make a Mr Potato Head army, and you know that the more variety in your vegetable warriors the better" "this process is about …making a mutant army." "they form a fighting force that rivals Marvel Comic's Fantasic Four" "each antibody molecule released as a single soldier" "The pancreas … acts as the commander-in-chief when its comes to controlling blood sugar levels." "our tiny but deadly defenders" "cells in the spleen with a specialised killer-skill" "wears a mask that conceals its killer features from its would-be assassins" "the microbiological mass murderers…the serial killers" "PA [protective antigen] is the muscled henchman" "the murderous cast of immune cells and messengers…this awe-inspiring army" "a microscopic army, capable of seeking out and destroying bacteria" "the terminators are targeted killers" "weaponised E. coli
Box 1: References to the immune system and its components as a defence force
"a kamikaze blaze of microbe-massacringglory" "an eternal war between our bodies and the legions of bacteria, viruses, fungi and parasites that surround us" "these invaders' attempts are thwarted" "battles" "all my innate defences would essentially hold the fort and in many instances this first line would be enough to wipe out the invader before the adaptive system gets a chance to craft bespoke weaponry." "the tears we shed [are] a form of chemical warfare." "…allowing the neutrophils to migrate through the blood vessel and into the battlefield of the tissue beyond" "the cell contracts itself tightly before exploding" "their friendly fire contributed to the death of the victim." "spewing microbe-dissolving chemicals into the surround tissue. This allows the neutrophil to damage many microbes at once, a bit like fishing by throwing dynamite into the water." "NK [natural killer] cells target the microbes that have made it inside our cells." "NK cells attack" "…the initial hole-poking assault…" "all part of the NK cell's plan to kill the cell." "…they trip the cell's self-destruct switch" "expose a cell to a severe, but not quite lethal threat…transform the cell into a hardened survivor" immune cells have an "ability to go on the rampage" "call up … immune system soldiers to mount a response" "leukaemia … has decimated a type of white blood cells called T cells" "it behaves like a Trojan horse [as in the siege of the City of Troy]" "telling our soldier cells to kick back and take some R & R" "the smoke signals of infection" "…like a showing of tiny hand grenades on the surrounding cells." "the donor cells would be vastly outnumbered and it would be like a band of rebels taking on a vast army on its home turf" "the recipient's own immune system is in a weakened state and unable to fight back" "…the antibodies …are therefore able to give a hostile welcome to alpha-gal-wearing malaria parasites." "…our gut bacteria effectively provide a training ground for the immune system – a boot camp led by billions of bacteria which teaches us to develop an arsenal of antibodies to tackle common foreign invader fingerprints…" "fighting on certain fronts" "edgy alliance" "shore up the intestinal defences by reinforcing the tight junctions which link the gut cells together" "our gut's security fence" "a self-cell that should be defended, not attacked" "this mouse-shaped Trojan horse" "the scanning eyes of the immune system" "a form of border control, policing" "…the bacteria-bashing brilliance…" "…the IgA effectively blocks and disables the invaders' docking stations…" "B cells and their multi-class antibody armoury have the ability to launch a tailored assassination campaign against almost anything" "the exquisitely tailored assassination of bacteria, viruses and anything else that dares enter the body" "One of the seminal victories in our war on bugs" "Some bacteria have a sugar-based cloaking device" "…tripped by the pollen attaching to the IgE-primed mast cells and, like pulling a pin on a grenade, causing them to unleash their allergy-inducing chemicals." "The almost instant assault of the immediate phase reaction occurs within minutes as the dirty bomb-like explosion of the mast cell fill the local area with a variety of rapidly acting chemicals." "..the battle against infectious diseases." "teaching the patrolling forces of the immune system to stand down if the cell they're interrogating is a healthy cell that belong to the body. It's a bit like a border patrol force wandering through the body and checking passports" "like a training camp for the newly created border guards". "ordering those that react incorrectly to self-destruct" "These bacteria have a sugar-based polysaccharide outer shell, which acts like a cloaking device" "the [oncolytic] viruses have a Swiss army knifeselection of killer techniques" "This approach slaughters these foot soldiers of our immune system…" "they [macrophages] have picked up a time bomb" "antibodies that act like heat-seeking missiles" "Kadcyla …has a double-pronged attack." "we are setting up easy antibiotic assault courses all over the place" "His suicidal minions were engineered to seek out a pneumonia-causing bacterium by the name of Pseudomonas aeruginosa and explode in its presence releasing a toxic cloud of a Pseudomonas-slaughtering chemical called pyocin." "it could secrete its killer payload" "stimulate the little terminators to produce and release their chemical warfare."
Box 2: References to disease and immune processes as war and violent activity
"The macrophage's … job as a first responder…" " osteoclasts and osteoblasts" are "Carver refers to "the bony equivalent of yin and yang…osteoblasts are the builders in this relationship" (said to be "toiling") …osteoclast, whose role is the constant gardener of our bones" "…a white blood cell called the regulatory T cell, or 'Treg' to its friends…" "…this biological barcode lets the T cell know that it's looking at a self-cell …" "…the ball of cells that makes up the new embryo finishes bumbling along the fallopian tube and finds a spot in the uterus to burrow into…" "By using this mouse-shaped Trojan horse the parasite gets itself delivered directly into the cat's gut, which is where Toxoplasma likes to get it on for the sexual reproduction stage of its lifecycle." "It's as if the trypanosome has a bag of hats that it can whip out and use to play dressing-up to outwit the immune system." "proteins… help smuggle the ApoL1 into the parasite" "Some parasites have a partner in crime…" "the chosen strategy of the roundworm Wuchereria bancrofti…uses a bacterium to help cloak itself from the immune system." "the work of a master of disguise…precisely what Wuchereria bancrofti is." "…its bacterial side-kick" "parasites that act as puppet masters for our white blood cells and direct our immune response down a losing strategy" "parasites with sartorial skills that craft themselves a human suit made from scavenged proteins" "parasites toy with us" "B cells have one last technique" "Chemical messengers beckon these B cells" "what AID [activation induced deaminase] seeks to mess with" "Each class [of antibody] has its own modus operandi for attacking microbes" "in terms of skills, IgG can activate the complement cascade" "…one of its [IgA] key killer skills is to block any wannabe invaders from making their way inside us." "the helper T cell and the cytotoxic T cell, which take different approaches to achieve the same aim: the exquisitely tailored assassination of bacteria, viruses and anything else that dares enter the body." "B cells, cytoxic T cells and macrophages in their quest to kill invaders" "T cells interact with their quarry" "add a frisson of encouragement to the T cell, spurring it on to activation." "the brutally egalitarian smallpox" "Polio is another virus that knows all about image problems." "the guilty allergen" "IgE and mast cells are to blame for this severe reaction [anaphylaxis]" "…The T regulatory cells identify and suppress immune cells with an unhealthy interest in normal cells." "the skills of a type of virus well versed in the dark arts of integrating into human DNA" "The spleen is a multi-talented organ" "to get rid of the crafty, cloaked bacteria" "Even once cells are able to grow despite the chemical melting pot they're stewing in telling them to cease and desist…" "It is believed that tumour cells bobbing about in the bloodstream try to evade the immune system by coating themselves in platelets…" "the cancer's ability to adorn itself" "They [oncolytic viruses] work by …drawing the attention of the immune system" "when the replicating virus is finally ready to pop its little incubator open" "…anthrax, which lurks in the alveoli awaiting its cellular carriage: our macrophages…" "The macrophages are doing what they ought … Completely unaware that they have picked up a time bomb…" "the microbial thwarting talents of interferons" "…your mAbs will do the legwork for you, incessantly scouring the body for their target destination like tiny, demented postal workers without a good union." "One of the tumour techniques is to give any enquiring T cells a 'these aren't the cells you're looking for' handshake that sends them on their way in a deactivated state, unaware they have let the cancer cells off the hook. Checkpoint inhibitor mAbs bind to the T cell and prevent the deactivating handshake from happening. This leaves the T cell alert and able to recognise and destroy the cancer cells." "A third neutrophil strategy…" "all part of the NK cell's plan to kill the cell." "…a majestic dance of immune cells and messengers, carefully choreographed…" "So my immune system's bag of tricks might not currently include a smallpox solution, but if I were to contract the disease my adaptive immune response would try its hardest to create one to kill the virus before it killed me." "Thus earwax can catch, kill and kick out the multitude of microbes that wheedle their way into out ears…" "Up to 200 million neutrophils gush out of our bone marrow and into the blood stream every day. They race around the blood on the look-out for evidence of infection." "a process called 'opsonisation' make consuming the bacterial more appealing to neutrophils" "the same siren call of inflammation and infection that beckoned the neutrophils." "…a set of varied and diverse circumstances can prompt multiple macrophages to congregate together and, like a massive Transformer, self-assemble into one magnificent giant cell boasting multiple nuclei." "The cell responds to the initial hole-poking assault by trying to repair itself…At the same time that it pulls in the perforin holes, the cell unwittingly pulls in a family of protein-eating granzymes…" "the gigantosome is more than just a pinched-off hole-riddled piece of membrane; its creation was all part of the NK cell's plan to kill the cell." caspases in cells "play an epic game of tag" Arachidonic acid: "Normally it just minds its own business" "The interferon molecule insinuates itself into the local area" "The chemokines …their ability to beckon a colourful array of cells to a particular location…they can call up neutrophils, macrophages and other immune system soldiers to mount a response to injury and infection…" "chemicals that can tell these cells where to go and what to do. These crafty chemicals…" "…the triad of goals of the complement system…" "It's the T cell's job to spot infected or abnormal cells." "Microbes aren't easy bedfellows" "…the 'lean' microbes won out over the 'obese' ones." "IgD is the most enigmatic of all the immunoglobins" "the parasite larva …treacherous"
Box 3: Examples of phrasing which might suggest that microbes, cells, etc., are sentient actors with human motivations
"Bifidobacterium infantis, a normal resident of the healthy infant gut" "trillions of microbes that make us their home" "…a much more diverse community of inner residents…" "Entamoeba … just happened to prefer to live in a multicultural colon." "…the mouth had the least stable community, like the microbial equivalent of transient squatters, while the vagina was the quiet suburban cul-de-sac of the map, with a fairly fixed mix of residents." "that's where they [Mycobacteria] set up home" "Neisseria meningitidis "sets up shop inside our cells…it breaks in…" "…Heliocobacter pylori (a.k.a H. pylori), a bacterium that makes its home in the sticky mucus that lines the stomach. While the mucus gives H. pylori some protection from the gastric acid, it also employed a bit of clever chemistry to make its home a touch more comfortable." Dracunculus medinensis will "seek out a mate, turning the abdominal wall into their sexual playground." "…plenty of creepy crawlies have been known to to call the human brain home, lounging among our delicate little grey cells…" the tapeworm Spirometra erinaceieuropaei : "…this particular tenant ensconced in their grey matter." "the worm…wriggled up through his body to reach its cranial penthouse where it could enjoy the luxury of a very special hiding spot." "There are flatworms, roundworms hookworms, whipworms, fleas and ticks, lice and amoeba. They're all queuing up to get a room at the palace of parasites" Clostridium tetani "can often set up camp in soil", "About 75 million people worldwide are thought to carry the dwarf tapeworm in their small intestine, where it lives a fairly innocuous life and causes its host few if any symptoms." "Though it may not seem like it, our nostrils are prime real estate and rival bacteria fight each other for resources, a fight which includes chemical warfare." "…we'll meet the creepy critters that like to call us home and the ways our immune system tries to show them the door."
Box 4: Microbes and cells described as the kind of entities which look for and set up homes.
"an all-you-can-eat oligosaccharide buffet for B. infantis [Bifidobacterium infantis]" "…complement's ability to make these bacteria seem tastier to our macrophages…" "Mycobacteria… actually want to be gobbled up by our macrophages…" "sprinkling C3b on the surface of bacteria makes them much more appetising to microbe-munching cells" macrophages 'devour' the remains of dead cells "…Salmonella, which likes a soft-boiled egg, and Toxoplasma gondii, which shares my penchant for parma ham and rare steak." Dracunculus medinensis "looks like an easy meal for a peckish water flea. Sadly for the water flea the parasite larva has more in common with a time bomb than a tasty snack ever should, and the treacherous morsel spends the next 14 days inside the flea…" "…flagging a microbe as munchable for macrophages…" "IgG …can mark targets as munchable. Thus any bacterium, virus or parasite coated in IgG finds itself the yummiest dessert on the buffet cart and every hungry macrophage rushes to get itself a tasty treat." "…from our brain to our bones, we are riddled with munching macrophages…" opsonisation: "much like sprinkling tiny chocolate chips on a bacterial cookie" "Demodex dine on sebum…as well as occasionally munching on our skin cells" "P. acnes is a lipophile, which is to say it adores consuming fat. The sebum on our skin is like a layer of buttery, greasy goodness that has P. acnes smacking its lips." "when "P. acnes turns up to dine it has some seriously bad table manners" " P. acnes loves to picnic."
Box 5: References to the culinary preferences and habits of entities such as microbes and immune cells
A reflection on the pedagogy in Andrew Scott's 'Vital Principles'
Keith S. Taber
Andrew Scott's introduction to the chemistry of the cell is populated by a diverse cast of characters, including ballot machines, beads; blind engineers and blind-folded art-seekers; builders and breaker's yards; cars, freight vehicles and boats; Christmas shoppers, dancers; gatecrashers (despite gatekeepers) and their hosts; invaders, jack-in-the-boxes, legal summonses, light bulbs, mixing bowls, maelstroms, music tapes, office blocks; oceans, seas, rivers, streams, floods and pools; skeletons and their bones, split personalities, springs; sorting offices and postal systems; turnstiles, the water cycle, water wheels, ropes, pulleys and pumps; work benches and work stations; and weeding and seaweed forests.
Scott, A. (1988). Vital Principles. The molecular mechanisms of life. Basil Blackwell.
The task of the popular science writer
This piece is not a formal review of, what is, now, hardly a recent title 1, but a reflection on an example of a science book aimed at – not a specific level of student, but – a more general audience. The author of a 'popular science book' has both a key advantage over the author of many science textbooks, and a challenge. The advantage is being able to define your own topic – deciding what you wish to cover and in how much detail. By contrast, a textbook author, certainly at a level related to formal national examination courses, has to 'cover' the specified material. 2
However the textbook author has the advantage of being able to rely on a fairly well defined model of the expected background of the readership. 3 Students taking 'A level' physics (for example) will be expected to have already covered a certain range of material at a known level through science teaching at school ('G.C.S.E. level') and to have also demonstrated a high level of competence against the school maths curriculum. This is important because human learning is incremental, and interpretive, and so iterative: we can only take in a certain amount of new material at any time, and we make sense of it in terms of our pool of existing interpretative resources (past learning and experiences, etc.) 4
The teacher or textbook author designs their presentation of material based on a mental model of the interpretive resources (e.g., prerequisite learning, familiar cultural referents that may be useful in making analogies or similes, etc.) available to, and likely to be activated in the mind of, the learner when engaging with the presentation.
So, the science teacher works with a model of the thinking of the students, so as to pitch material in manageable learning quanta, that should relate to the prior learning. The teacher's mental model can never be perfect, and consequently teaching-learning often fails (so the good teacher becomes a 'learning doctor' diagnosing where things have gone wrong). However, at least the teacher has a solid starting point, when teaching 11 year olds, or 15 year olds, or new undergraduates, or whatever.
The textbook author shares this, but the popular science author has a potential readership of all ages and nationalities and levels of background in the subject. Presumably the reader has some level of interest in the topic (always helpful to support engagement) but beyond that…
Now the role of the science communicator – be they research scientist with a general audience, teacher, lecturer, textbook author, journalist, documentary producer, or popular scienceauthor – is to make what is currently unfamiliar to the learner into something familiar. The teacher needs to make sure the learners both have the prerequisite background for new teaching and appreciate how the new material relates to and builds upon it. Even then, they will often rely on other techniques to make the unfamiliar familiar – such as offfering analogies and similes, anthropomorphism, narratives, models, and so forth.
As the popular science writer does not know about the background knowledge and understanding of her readers, and, indeed, this is likely to be extremely varied across the readership, she has to reply more on these pedagogic tactics. Or rather, a subset of these ways of making the unfamiliar familiar (as the teacher can use gestures, and computer animations, and physical models; and even get the class to role-play, say, electrons moving through a circuit, or proteins binding to enzymes). Thus, popular science books abound with analogies, similes, metaphors and the like – offering links between abstract scientific concepts, and what (the author anticipates) are phenomena or ideas familiar to readers from everyday life. In this regard, Andrew Scott does not disappoint.
Andrew Scott
Scott's website tells us he has a B.Sc. in biochemistry from Edinburgh, and a Ph.D. from Cambridge in chemistry, and that he has produced "science journalism published by academic publishers, newspapers, magazines and websites", and he is an "author of books translated into many languages". I have not read his other books (yet), but thought that Vital Principlesdid a good job of covering a great deal of complex material – basically biochemistry. It was fairly introductory (so I doubt much could be considered outdated) but nonetheless tackled a challenging and complex topic for someone coming to the book with limited background.
I had a few quibbles with some specific points made – mainly relating to the treatment of underpinning physics and chemistry 5 – but generally enjoyed the text and thinking about the various comparisons the author made in order to help make the unfamiliar familiar to his readership.
Metaphors for molecular mechanisms
Andrew Scott's introduction to the chemistry of the cell is populated by a diverse cast of characters, including ballot machines, beads; blind engineers and blind-folded art-seekers; builders and breaker's yards; cars, freight vehicles and boats; Christmas shoppers, dancers; gatecrashers (despite gatekeepers) and their hosts; invaders, jack-in-the-boxes, legal summonses, light bulbs, mixing bowls, maelstroms, music tapes, office blocks; oceans, seas, rivers, streams, floods and pools; skeletons and their bones, split personalities, springs; sorting offices and postal systems; turnstiles, the water cycle, water wheels, ropes, pulleys and pumps; work benches and work stations; and weeding and seaweed forests.
A wide range of metaphors are found in the book. Some are so ubiquitous in popular science discourse that it may be objected they are not really metaphors at all. So, do "… 'chloroplasts'…trap the energy of sunlight…"? This is a simplification of course (and Scott does go into some detail of the process), but does photosynthesis actually 'trap' the energy of sunlight? That is, is this just a simplification, or is it a figurative use of language? Scott is well aware that energy is not a concept it is easy to fully appreciate,
"Energy is really an idea invented by mankind, rather than some definite thing…
energy can be thought of as some sort of 'force resistance' or 'antiforce' able to counteract the pushes or pulls of the fundamental forces."
pp.25-26
But considerable ingenuity has been used in making the biochemistry of the cell familiar through metaphor:
lipids "have split personalities" (and they have 'heads' and 'tails' of course)
proteins can "float around within a sea of lipid"
proteins are "the molecular workers"
the inside of cells can be a "seething 'metabolite pool' – amaelstrom of molecules"; "a swirling sea of chemical activity…the seething sea of metabolism" (so, some appealing alliteration, as well, here 6);
the molecules of the cell cytosol are "dancing"
"...small compressed springs of ATP, can be used to jack up the chemistry of the cell…"
"…thermal motion turns much of the chemical microworld into a molecular mixing bowl."
"The membranes of living cells…form a boundary to all cells, and they cordon off specific regions within a cell into distinct organelles."
"Some of these gatecrashers within other cells would then have slowly evolved into the mitochondria and chloroplasts of present-day life..."
"the 'Ca2+ channels' to open up, this causes Ca2+ ions to flood into the cell …"
"the 'ribosomes' … are the chemical automatons…"
The figurative flavour of the author's language is established early in the book,
"In a feat of stunning self-regulating choreography, billions of atoms, molecules and ions become a part of the frantic dance we call life. Each revolution of our planet in its stellar spotlight raises a little bit of the dust of earth into the dance of life, while a little bit of the life crumbles back into dust."
p.1
Phew – there is quite a lot going on there. Life is a dance, moreover a frantic dance, of molecular level particles: but not some random dance (though it relies on molecular motion that is said to be a random dance, p.42), rather one that is choreographed, indeed, self-choreographed. Life has agency. It is a dance that is in some sense powered by the revolution of the earth (abound its axis? around its star?) which somehow involves the cycling of dust into, and back out, of life – dust to dust. The reference to a stellar spotlight seems at odds with the Sun as symmetrically radiating in all directions out into the cosmos – the earth moves through that radiation field, but could not escape it by changing orbit. Perhaps this image is meant to refer to how the daily rotation of the earth brings its surface into, and out of, illumination.
So, there is not a spotlight in any literal, sense (the reference to "the central high energy furnace", p.39, is perhaps a more accurate metaphor), but the 'stellar spotlight' is a metaphor that offers a sense of changing illumination.
Similarly, the choreographed dance is metaphorical. Obviously molecules do not dance (a deliberate form of expression), but this gives an impression of the molecular movement within living things. That movement is not choreographed in the sense of something designed by a creator. But something has led to the apparently chaotic movements of billions of molecules and ions, of different kinds, giving rise to highly organised complex entities (organisms) emerging from all this activity. Perhaps we should think of one of those overblown, heavily populated, dance sequences in Hollywood films of the mid 20th century (e.g., as lampooned in Mel Brook's Oscar winning 'The Directors')?
So, in Vital Principles, Scott seeks to make the abstract and complex ideas of science seem familiar through metaphors that can offer a feel for the basic ideas of biochemistry. The use of metaphor in science teaching and other forms of science communication is a well established technique.
Later in the book a reader will find that the metaphoricalchoreographer is natural selection, and natural selection is just the tautological selection of what can best reproduce itself in the environment in which it exists,
"…the brute and blind force of natural selection can be relied upon to weed out the harmful mutations and nurture the beneficial ones. We must always remember, however, that the criterion by which natural selection judges mutations as harmful or beneficial is simply the effect of the mutations on an organism's ability to pass its genetic information on to future generations."
p.182
So, natural selection is a force which is brute and blind (more metaphors) and is able to either weed out (yes, another metaphor) or nurture. That is an interesting choice of term given the popular (but misleadingly over-simplistic) contrast often made in everyday discourse between 'nature' (in the sense of genetics) and 'nurture' (in the sense of environmental conditions). Although natural selection is 'blind', it is said to be able to make judgements.
Form and function in biology
Here we enter one of the major issues in teaching about biology: at one level, that of a naturalistic explanation 7, there is no purpose in life: and anatomical structures, biochemical processes, even instinctive behaviours, have no purpose – they just are; and because they were components of complexes of features that were replicated, they have survived (and have 'survival value').
Yet, it seems so obvious that legs are for walking, eyes are for seeing, and the heart's function is to pump blood around the body. A purist would deny each of these (strictly these suggestions are teleological) and replace each simple statement with a formally worded paragraph completely excluding any reference to, or hint at, purpose.
So, although it seems quite natural to write
"…hormones… are released from one cell to influence the activity of other cells;
…neurotransmitters…are released from nerve cells to transmit a nerve impulse…"
pp.120-121
we might ask: is this misleading?
One could argue that in this area of science we are working with a model which is founded on the theory of natural selection and which posits the evolved features of anatomy, physiology, biochemistry,etc., that increase fitness areanalogous to designed and purposeful features that support the project of the continuation of life.
Something that scientists are very quick to deny (that organisms have been designed with purposes in mind) is nevertheless the basis of a useful analogy (i.e., we can consider the organism as if a kind of designed system that has coordinated component parts that each have roles in maintaining the 'living' status of the overall system). We then get the economy of language where
hormones and neurotransmitters are released for 'this' purpose, to carry out 'that' function;
being selected (!) over
more abstract and complex descriptions of how certain patterns of activity are retained because they are indirectly selected for along with the wider system they are embedded in.
Do scientists sometimes forget they are working with a model or analogy here? I expect so. Do learners appreciate that the 'functions' of organs and molecules in the living thing are only figurative in this sense? Perhaps, sometimes, but – surely -more often, not; and this probably both contributes to, and is encouraged by, the known learning demand of appreciating the "blind [nature of the] force of natural selection".
Scott refers to proteins having a particular task (language which suggests purpose and perhaps design) whilst being clear he is only referring to the outcomes of physical interactions,
"A protein folds up into a conformation which is determined by its amino acid sequence, and which presents to the environment around it a chemical surface which allows the protein to perform its particular chemical task; and the folding and the performance of the task (and, indeed, the creation of the protein in the first place) all proceed automatically governed only by physical laws and forces of nature – particularly the electromagnetic force."
pp.54-55
In practice, biologists and medical scientists – and indeed the rest of us – find it much more convenient to understand organisms in terms of form and function. That is fine if you always keep in mind that natural selection only judges mutations metaphorically. Natural selection is not the kind of entity which can make a judgement, but it is a process that we can conceptualise as if it makes judgements.
This is a difficult balancing act:
"Nature is a blind but a supremely effective engineer. Through the agency of undirected mutation she continually adjusts the structure and the mechanisms of the living things on earth."
p.182
Nature is here treated as if a person: she is an engineer tinkering with her mechanisms. Personification of nature is a long-standing trope, once common among philosophers and not always eschewed by scientists in their writings (e.g., Nicolaus Copernicus, Henri Poincaré, Michael Faraday, even Albert Einstein have personified Nature) – and she is always female.
But usually a competent engineer tinkers according to a plan, or at least with a purpose in mind, whereas nature's tinkering is here described as 'undirected' – it is like she arbitrarily changes the size of a gear or modifies the steam pressure in a cylinder or changes the number of wheels on the locomotive, and then tinkers some more with those that stay on the tracks and manage to keep moving.
Personification (by referring to her, she, etc.) is not needed to imply entities have some human traits. Indeed, a very common pedagogic technique used when explaining science, anthropomorphism, is to use a kind of metaphorical language which treats inanimate objects or non-human beings as if they are people – as if they can feel, and think, and plan, and desire; and so forth.
"Once an enzyme had met and captured the required starting materials …"
"Some [non-protein metabolites] act as 'coenzymes', which becomes bound to enzymes and help them to perform their catalytic tasks."
"Cells, which had previously been aggressively independent individualists, discovered the advantages of communal life."
"…descendants of cells which took up residence within other cells and then became so dependent on their hosts, and also so useful to them, that neither hosts nor gatecrashers could afford to live apart."
So, for example, plants are living beings, but do not have a central nervous system and do not experience and reflect on life as people do: so, they do not wish for things,
"…the oxidation of sugars, is also performed by plants when they wish to convert some of their energy stores (largely held in the form of complex carbohydrates) back into ATP."
p.144
Again, such phrasing offers economy of language. Plants do not wish, but any technically correct statement would likely be more complicated and so, arguably, more difficult to appreciate.
Dead metaphors
A key issue in discussing metaphors is that in many cases different readers are likely to disagree over whether a term is indeed being used figuratively or literally. Language is fluid (metaphorically speaking), and a major way language grows is where the need for new terms (to denote newly invented artefacts or newly discovered phenomena) is satisfied by offering an existing term as a metaphor. Often, in time the metaphor becomes adopted as standard usage – so, no longer a metaphor. These examples are sometimes called dead metaphors (or clichéd metaphors). So, for example, at some point, many decades ago, astronomers started to talk of the 'life cycle' of stars which have a moment of 'birth' and eventual 'death'. These metaphors have become so established they are now treated as formal terms in the language of the discipline, regularly used in academic papers as well as more general discourse (see 'The passing of stars: Birth, death, and afterlife in the universe').
So, when Scott writes of "how some micro-organism, say a virus, invades the body…"(p.109) it is very likely most readers will not notice 'invade' as being a metaphor, as this usage is widely used and so probably familiar. The (former?) metaphor is extended to describe selective immune components "binding to foreign invaders [that] can act as a very effective means of defence against disease." These terms are very widely used in discussing infections: though of course there are substantive differences, as well as similarities, with when a country defends itself against actual foreign invaders.
I suspect that considering the lipid bilayer to be "a stable sandwich of two layers of lipid molecules" (p.115) is for many, a dead metaphor. The reference to a DNA double-helix leading to"two daughter double-helices" reflects how atomic nuclei and cells are said to give rise to 'daughters' on fission: again terminology that has become standard in the field.
Sharing a psuedo-explanation for covalent bonding
One phrase that seems to have become a dead metaphor is the notion of electrons being 'shared' in molecules, which "…are formed when their constituent atoms come together to leave at least some of their electrons shared between them" (pp.28-29). Whilst this seems harmless as a description of the structure, it is also used as an explanation of the bonding:
"'hydrogen molecules and water molecules (and all other molecules) are held together by virtue of the fact that electrons are shared between the individual atoms involved, a similarity recognised by saying that in such cases the atoms are held together by 'covalent' bonds.
p.29
But we might ask: How does 'sharing' a pair of electrons explain the molecule being 'held together'? Perhaps a couple with a strained relationship might be held together by sharing a house; or two schools in a confederation by sharing a playing field; or two scuba divers might be held together if the breathing equipment of one had failed so that they only had one functioning oxygen cylinder shared between them?
In these examples, there is of course a sense of ownership involved. Atoms do not 'own' 'their' electrons: the only bonds are electromagnetic; not legal or moral. This may seem so obvious it does not deserve noting: but some learners do come to think that the electrons are owned by specific atoms, and therefore can be given, borrowed, stolen, and so forth, but should ultimately return to their 'own' atom! So, if we acknowledge that there is no ownership of electrons, then what does it even mean for atoms to 'share' them?
So, why would two atoms, each with an electron, become bound by pooling these resources? (Would sharing two houses keep our couple with a strained relationship together; or just offer them a ready way to separate?) The metaphor does not seem to help us understand, but the notion of a covalent bond as a shared electron pair is so well-established that the description commonly slips into an explanation without the explainer noticing it is only a pseudo-explanation (a statement that has the form of an explanation but does not explain anything, e.g., "a covalent bond holds two atoms together because they share a paired of electrons").
Elsewhere in the book Scott does explain (if still anthropomorphically) that viable reactions occur because:
"In the new configuration, in other words, the electromagnetic forces of attraction and repulsion between all the electrons and nuclei involved might be more fully satisfied, or less 'strained' than they were before the reaction took place."
p.36
How are metaphors interpreted?
The question that always comes to my mind when I see metaphorical language used in science communication, is how is this understood by the audience? Where I am reading about science that I basically understand reasonably well (and I was a science teacher for many years, so I suspect I cannot be seen a typical reader of such a book) I do reflect on the metaphors and what they are meant to convey. But that means I am often using the familiar science to think about the metaphor, whereas the purpose of the metaphor is to help someone who does not already know the science get a take on it. This leads me to two questions:
to what extent does the metaphor give the reader a sense of understanding the science?
to what extent does the metaphor support the reader in acquiring an understanding that matches the scientific account?
These are genuine questions about the (subjective and objective) effectiveness of such devices for making the science familiar. There is an interesting potential research programme there.
Shifting to similes
The difference between metaphors and similes is how they are phrased. Both make a comparison between what is being explained/discussed and something assumed to be more familiar. A metaphor describes the target notion as being the comparison (nature is an engineer), but the listener/reader is expected to realise this is meant figuratively, as a comparison. A simile makes the comparison explicit. The comparison is marked – often by the use of 'as' or 'like' as when physicist Max Planck suggested that the law of conservation of energy was "like a sacred commandment".
So, when Scott refers to how proteins "act as freight vehicles transporting various chemicals around the body", and "as chemical messages which are sent from one cell to another" (p.10), these are similes.
Springs are used as similes for the interactions between molecules or ions in solids or the bonds within molecules
"…even in solids the constituent molecules and atoms and ions are constantly jostling against one another and often vibrating internally like tiny sub-microscopic springs. All chemical bonds behave a bit like tiny springs, constantly being stretched and compressed as the chemicals they are part of are jostled about by the motion of the other chemicals all around them."
p.39
[Actually the bonds in molecules or crystals are behaving like springs because of the inherent energy of the molecule or lattice: the 'jostling' can transfer energy between molecules/ions and 'springs' so that the patterns of "being stretched and compressed" change, but it is always there. The average amount of 'jostling' depends on the temperature of the material. 5]
In the way the word is usually used in English, jostling is actually due to the deliberate actions of agents – pushing through a crowd for example, so strictly jostling here can be seen as an anthropomorphicmetaphor, but the intended meanings seems very clear – so, I suspect many readers will not even have noticed this was another use of figurative language.
One way of marking phrases meant as similes is putting then in inverted commas, so-called scare-quotes, as in
"A rather simple chemical 'cap', for example, is added to the start of the RNA, while a long 'tail' consisting of many copies of the nucleotide A is added to its end…The most significant modifications to the precursor, however, involve the removal of specific portions from the interior [sic] of the RNA molecule, and the joining together of the remaining portions into mature mRNA… This 'splicing' process …"
p.79
Here we have something akin to a cap, and something akin to a tail. As noted above, a difficulty in labelling terms as metaphors or similes is that language is not static, but constantly changing. In science we often see terms borrowed metaphorically from everyday life to label a technical process as being somewhat like something familiar – only for the term to become adopted within the field as a technical term. The adopted terms become literal, with a related, but somewhat different – and usually more precise – meaning in scientific discourse. (This can be the basis of one class of learning impediments as students may not realise the familiar term has specials affordances or restrictions in its technical context.)
Here 'splicing' is marked as a simile – there is a process seen as somewhat similar to how, for example, radio programmes and musical recordings used to be edited by the cutting and resequencing strips of magnetic tape. Yet gene splicing is now widely accepted as a literal use of splicing, rather than being considered figurative. [I suspect a young person who was told about, for example, the Beatles experiments with tape splicing might guess the term is used because the process is like gene splicing!]
The following quote marks a number of similes by placing them within inverted commas:
"The interior of the cell is criss-crossed by a network of structural proteins which is known as the cytoskeleton. The long protein 'bones' of this skeleton are formed by the spontaneous aggregation of many individual globular protein molecules…
Cells use many strong chemical 'pillars' and 'beams' and 'glues' and 'cements', both inside them, to hold the internal structure of cells together, and outside of them, to hold different cells together; but the electromagnetic force is the fundamental 'glue' upon which they all depend."
pp.995-6
Again the phrasing here suggests something being deliberately undertaken towards some end by an active agent (teleology): the cell uses these construction materials for a purpose.
There are various other similes offered – some marked with inverted commas, some with explicit references to being comparisons ('kind of', 'act as', 'sort of', etc.)
"…amino acids comprise the chemical 'alphabet' from which the story of protein-based life (i.e., all life on earth) is constructed"
"the endoplasmic reticulum is a kind ofmolecular 'sorting office'…"
endosomes and lysomes "form a kind of intracellular digestive system and 'breaker's yard'."
"The proteins which perform these feats are not gates, but 'pumps'..."
"Proteins could be described asthe molecular workers which actually construct and maintain all cells…"
"…proteins are the molecular 'labourers' of life, while genes are the molecular 'manuals' which store the information needed to make new generations of protein labourers…"
"Membrane proteins often float around within a sea of lipid (although they can also be 'held at anchor' in the one spot if required)"
"A ribosome travels down its attached mRNA, a bit like a bead running down a thread (or sometimes likea thread being pulled through a bead)..."
"…the 'ribosomes' – molecular 'work-benches' composed of protein and RNA…"
Nucleic acids "act as genetic moulds"
"the high energy structure of ATP really is very similar to the high energy state of a compressed spring"
"Some vital non-protein metabolites act as a sort of 'energy currency'…"
Advancing to analogies
Metaphors and similes point out a comparison, without detailing the nature and limits of that comparison. A key feature of an analogy is there is a 'structural mapping': that is that two systems can be represented as having analogous structural features. In practice, the use of analogy goes beyond suggesting there is a comparison, to specifying, at least to some degree, how the analogymaps onto the target.
Scott employs a number of analogies for readers. He develops the static image of the cell skeleton (met above) with its 'bones', 'pillars' and 'beams' into a dynamic scenario:
"Structural proteins are often referred to as the molecular scaffolding of life, and the analogy is quite apt since so many structural proteins are long fibres or rods; but we think of scaffolding as a static, unchanging, framework. Imagine, however, a structure built of scaffolding in which some of the scaffolding rods were able to slide past one another and then hold the whole framework in new positions."
p.96
Many good metaphors/similes may be based upon comparisons of this type, but they do not become analogies until this is set out, rather than being left to the listener/reader to deduce. For this reason, analogies are better tools to use in teaching than similes as they do not rely on the learners inferring (guessing?) what the points of comparison are intended to be. 8
So, Scott offers the simile of molecules released as 'messengers', but then locates this in the analogy of the postal system, before using another analogy to specify the kind of message being communicated,
"Cells achieve such chemical communication in various ways, but the most vital way is by releasing chemical 'messenger' molecules (the biological equivalent of the postal system, if you like analogies), and many of these messengers are either proteins, or small fragments of proteins." … "A biological messenger molecular is more like a legal summons than a friendly note or some junk mail advertisement – it commands the target cell to react in a precise way to the arrival of the message."
pp.102-103
In the following analogy the mapping is very clear:
"One gene occupies one region of a chromosome containing many genes, much like one song occupies one region of a music tape containing many songs overall."
p.7
Song on music tape is to gene on chromosome
For an analogy to be explicit the mapping between target and analogue must be clear, as here, where Scott spells out how workstations on a production line map onto enzymes,
"The production line analogy is a very good one. The individual 'work stations' are the enzymes, and at these molecular work stations various chemical components are brought together and fashioned into some new component of product. The product of one enzyme can then pass down the line, to become the substrate of the next enzyme, and so on until the pathway is complete."
p.147
Some analogies offer a fairly basic mapping between relatively simple systems:
"If there is lots of A around in the cell, for example, then the rate at which A tends to meet up with enzyme EAB will obviously increase (just as an increase in the number of people you happen to know entering a fairground will increase the chances of you meeting up with someone you know)."
p.150
fairground
cell
people at a fairground
molecules in the cytosol
you at the fairground
a specific enzyme in the cytosol
people entering the fairground that know you personally
molecules of a type that binds to the specific enzyme
chance of you meeting someone you know
rate of collision between enzyme and the specific molecules it binds to
Scott compares a nerve cell, the activity of each of which is influenced by a large number of 'input' signals, to a ballot counting machine,
"…most nerve cells receive inputs, in the form of neurotransmitters, from many different cells, so the 'decision' about whether or not the cell should fire depends on the net effect of all the different inputs, some of which will be excitatory, and some inhibitory, with the pattern of input perhaps varying all the time.
So any single nerve cells acts like an [sic] tiny automatic ballot machine, assessing the number of 'yes' and 'no' votes entering it at any one time and either firing or not firing depending on which type of vote predominates at any one time.
…Nerve cells receive electrochemical signals from other cells, and each signal represents a 'yes' or a 'no' vote in an election to determine whether the cell should fire."
pp.166-8
Turnstiles in Alewife station, image from Wikimedia Commons (GNU Free Documentation License)
Scott uses the image of a turnstile, a device that blocks entry unless triggered by a coin or ticket, and which automatically locks once a person has passed through, as a familiar analogue for an ion channel into a cell. The mapping is not spelt out in detail, but should be clear to anyone familiar with turnstiles of this kind,
"When it is sitting in a polarised membrane, this protein is in a conformational state in which it is unable to allow any ions to pass through the cell. When the membrane around it becomes depolarised, however, the protein undergoes a conformational change which causes it briefly to form a channel through which Na+ ions can pass. The channel only remains open for a short time, however, since the conformational upheaval [sic] of the protein continues until it adopts a new conformation in which the passage of Na+ ions is once again blocked. The overall effect of this conformational change is a bit like the operation of a turnstile – it moves from one conformation which prevents anything from passing, into a new conformation which also prevents anything from passing, but in the process of changing from one conformation to another there is a brief period during which a channel allowing passage through is opened up."
p.163
An analogy between a sodium ion channel in a membrane, and a turnstile of the kind sometimes used to give entry to a sporting ground or transport system.
Whether there is an absolute distinction between metaphors/similes and analogies in practice can be debated. So, for example, Scott goes beyond simply suggesting that the nanoscale of molecules is like a mixing bowl, but does not offer a simple mapping between systems,
"Thermal motion turns much of the chemical microworld into a 'molecular mixing bowl' … So the solution of the cytosol acts as an all pervading chemical sea in which many of the chemicals of life are mixed together by random thermal motion as if in a molecular mixing bowl."
p.40
We could see the ocean as a simile (marked by 'acts as an') and the mixing bowl as another (marked by the scare quotes, and then 'as if in a') – but there is a partial mapping with a macroscopic mixing bowl: we are told (i) what is mixed, and (ii) the agent that mixes at the molecular scale, but it is assumed that we already know these should map to (i) the ingredients of a dish being mixed by (ii) a cook.
In places, then, Scott seems to rely on his readers to map features of analogies themselves. For example, in the following (where "The chaos of a large department store on Christmas Eve, or during the January sales, is a reasonable analogy [for the cell, as] there is order and logic within a scene of frantic and often seemingly chaotic activity"), the general point about scale was well made, but (for this reader, at least) the precise mapping remained obscure,
"The frantic chaos of chemistry proceeds too fast and too remotely for us to follow it without great difficulty. We are in the position of airborne observers who see trainloads of shoppers flowing into the city on Christmas Eve morning, and trainloads of the same shoppers laden with purchases flowing back to the suburbs in the evening. From the air we can see the overall effect of suburban shoppers 'reacting' with the shops full of goods, but we remain unaware of the hidden random chaos which allows the reaction to proceed!
p.44
Perhaps other readers immediately see this, but I am not sure what the shoppers are: molecules? but then they are unchanged by reactions? As they flow together into and out of the city (cell?) they could be ions in a nerve cell, but then what are the purchases they carry away (and have they paid for them in energy)? What are the trains? (ion channels? ribosomes?) What are the shops (mitochondria)? Perhaps I am trying to over-interpret an image that is not meant to be specific – but elsewhere Scott seems to have designed his analogies carefully to have specific mappings.
A reference to "a cofactor called 'heme' which actually acts as the chemical vessel on which the oxygen is carried"seems, by itself to be a metaphor, but when read in the context of text that precedes it, seems part of a more developed analogy:
"The most obvious system of bulk transport in the human body is the blood, which flows through our arteries, capillaries and veins like a 'river of life', bringing chemical raw materials (oxygen, water and food) to every cell of the body, and taking waste products away. Within this bulk system, however, the actual job of transporting specific substances is sometimes performed by small 'freighters' such as individual blood cells and even individual protein molecules."
p.98
The precise form of transport acting as an analogue shifts when the discussion shifts from the transport process itself to what I might refer to as the loading and unloading of the 'freighter',
"So the binding of one oxygen molecule to one subunit of an empty [sic] haemoglobin complex greatly encourages the binding of oxygen to the other three available sites. This makes the multi-subunit haemoglobin complex a bit like a four-seater car in which the first person into the carunlocks the door for another three passengers. The crucial step in loading the car is getting the first person in, after which the first person helps all the others to climb aboard.
An opposite effect occurs when loaded haemoglobin reaches a tissue in need of oxygen: the loss of one oxygen molecule from one subunit causes a conformational change in the complex which allows the other three oxygen molecules to be off-loaded much more readily. A suitable analogy to this would be an unstable four-man boat, since, if one man jumps overboard, he may rock the boat sufficiently to make the other three fall out!"
pp.100-101
Why is a child like an office block?
Child is to zygote as office building is to light bulb? (Images from Pixabay)
Scott compares the development of the child from a single cell with a self-assembling office block,
"When a human egg cell begins to divide and create a newborn child it achieves an enlargement equivalent to a lightbulb giving rise to a massive office block 250 metres high; which then, over the next 15 years or so, stretches and widens to an astounding 1,000 metres in height and nearly 250 metres across. In the 'office block' that is you all the plumbing, heating, lighting, telecommunication and ventilation systems were assembled automatically and work together smoothly to sustain a bewildering diversity of very different 'suites' and 'offices'.
p.4
Scott later revisits his office analogy, though now the building is not the growing organism, but just a single cell (one of the 'offices' from the earlier analogy?),
"Cells are not stable and unchanging structures like office blocks. Instead, most parts of a cell are in a state of continual demolition and renewal, known as 'metabolic turnover'. Imagine an office block in which a large team of builders is constantly moving through, knocking down existing walls and using the bricks to build up new ones; ripping apart the furniture and then reassembling it into new forms; peeling off wallpaper, then using it as the raw material to produce new paper which is then put back up again; and all the time some new materials are arriving through the door, to assist in the continual rebuilding, while some of the older materials are constantly being discarded out of the windows. The living cells is in a very similar siltation, with teams of enzymes constantly ripping down the structure of the cell while other teams of enzymes build it up.
… Life in the office block imagined earlier might sometimes be a little difficult and chaotic, but at least when change was required it could be brought about quickly, since the necessary tradesmen and supplies would always be on hand; and any mistakes made during the building process could always quickly be put right. Metabolic turnover bestows similar advantages on the living cell."
pp.118-119
The reference to 'teams' of enzymes is another subtle anthropomorphicmetaphor. Those in a team are conscious of team membership and coordinate their activities towards a common goal – or at least that is the ideal. Enzymes may seem to be working together, but that is a just a slant we put on processes. Presumably the two sets of teams of enzymes (a catabolic set and an anabolic set) map onto the large team of builders – albeit the enzymes seem to be organised into more specialised working teams than the builders.
Some of Scott's prose, then, combines different ways of making the science familiar, as when he tells the reader
"Water, in other words, is the solvent of life, meaning that it is the liquid which permeates into all the nooks and crannies of the cell and in which all the chemical reactions of life take place. There are various small regions of the cell from which water is excluded, especially within the interior of some large molecules; but the chemistry of life largely proceeds in an ocean of water. It is not a clear ocean – thousands of different types of chemical are dissolved in it, and it is criss-crossed by a dense tangle of giant molecules which form 'fibres' or 'cables' or 'scaffolding' throughout the cell. Swimming through the cell 'cytosol' (the internal 'fluid' of the cell) would be like struggling through a dense underwater forest of seaweed, or through a thick paste or jelly, rather than darting though clear ocean."
p.6
On the molecular level, the water inside of a cell is "an ocean" (a metaphor), which can access the "nooks and crannies of the cell" (a metaphor). The ocean is interrupted by "giant molecules which form 'fibres' or 'cables' or 'scaffolding'…" These terms seem to be used as similes, marked by the use of inverted commas, although Scott also uses this convention to introduce new terms – 'cytosol' is not a simile. Presumably 'fluid' (marked by inverted commas) is being used as a simile as the cytosol is not a pure liquid, but a complex solution.
[The quote implies that "It is not a clear ocean – [as/because] thousands of different types of chemical are dissolved in it", but dissolved solutes would not stop a solution being clear: the actual ocean is very salty, with many different types of ions dissolved in it, but can be clear. Lack of transparency would be due to material suspended, but not actually dissolved, in the water.]
If this is a metaphorical ocean, it is an ocean that would be difficult to swim in, as the tangle of giant molecules is analogous to "a dense underwater forest of seaweed" so it would be like swimming trough "a thick paste or jelly".
The water cycle of life
Perhaps the pièce de résistance in terms of an analogy adopted in the book was the use of a comparison between metabolism and the water cycle,
"I have drawn an analogy between the creation of living things containing many high energy chemicals (i.e. those in which the electromagnetic force is resisted much more than it could be), and the raising water vapour from the sea into the sky. We can continue with this analogy as we look deeper into the energetics of the living cell."
pp.126-127
Scott does indeed develop the analogy, as can be seen from the quotations parsed into the table below:
"…thermodynamic law determines that the energy of the sun must disperse out to the earth and raise the energy level of the things that are found there.
The raw materials of life are some of the things that are found there, and the energy from the sun raises these raw materials up into the higher energy levels associated with organised life,
just as
it raises water up into the sky and deposits some of it in tidy little mountain pools."
the creation of living things containing many high energy chemicals…
and
the raising water vapour from the sea into the sky."
⧟
"The raising of water to the skies is not an isolated and irreversible event, but part of a cycle in which the water eventually loses the energy gained from the sun and returns to the earth as rain, only to absorb some more energy and be lifted up once more, and so on…
Similarly, of course,
the creation of a living being such as yourself is not an isolated and irreversible event, but is part of a cycle of life and death, of growth and decay…"
⧟
"If we look inside the chemical mechanisms of the living cell we find that they can harness the energy available in the environment, most of which ultimately comes from the sun,
in a manner similar to
the [person] who has built a water wheel, a pump, a reservoir and many secondary wheels used to power many different tasks…."
⧟
"In living things
the roles of
the water-wheels and pumps
are played by
various systems of proteins and membranes,
whilst
the the most common immediate energy reservoir is a chemical known as 'adenosine triphosphate' (ATP). ATP is the cell's
equivalent of
water stored in a high level reservoir or a tank
because
it takes an energy input to make it, while energy is given out when it breaks apart into ADP and phosphate."
⧟
"The considerable resistance to the electromagnetic force embodied in the structure of ATP imposes a strain on the ATP molecule.
It is like
the compressed spring of a jack-in-the-box just waiting to be released;
and when it is released in some appropriate chemical reaction, then the energy level of the molecule falls as it splits up into ADP and phosphate.
Just as the force of water falling from a high gravitational energy level to a lower one can be harnessed to make various energy-requiring processes proceed,
so
the force of an ATP molecule falling from a high chemical energy level to a lower one can be harnessed to make a wide variety of energy-requiring chemical reactions proceed…"
Whether this should be seen as one extended analogy, or more strictly as several, somewhat distinct but related, comparisons is moot, as becomes clear when trying to map out the different features. My best attempt involved some duplication and ambiguity. (Hint to all designers of teaching analogies – map them out as parallel concept maps to help you visualise and keep track of the points being made.)
An analogy (or set of analogies) between biological/biochemical and physical systems
Visualisation – mental simulation
Teaching analogies usually link to what is expected to be (for the members of the audience) a familiar situation, experience, or phenomenon. Readers will be familiar with an office block, or swimming in water.
However, it is also possible for the science communicator to set up an analogy based on a scenario which is unlikely to be familiar, but which can be readily imagined by the reader.
"To appreciate the power of random motion to bring about seemingly purposeful change, imagine a room full of blindfolded people all instructed to walk about at random 'bouncing' off the walls and one another. Imagine also that they have been told to stop moving only when they bump into a small picture hanging from a wall. Finally, suppose that all the pictures are hung in a second room, linked to the room full of people by a narrow open doorway…"
p.40
Few if any readers will have been familiar with this scenario, but the components – groups of people in rooms, blindfolding, adjoining rooms, pictures hung on walls – are all familiar and there is nothing inherently problematic about the scenario even it does not seem very likely. So, here the reader has to build up the analogy from a number of familiar but distinct images.
So, we might consider this a kind of 'gedankenexperiment' or thought experiment – the reader is prompted to consider what would happen if…(and then to transfer what would happen to the target system at the molecular scale). Perhaps some readers immediately 'see' (intuit) what happens in this situation, but otherwise they can 'run' a mental simulation to find out – a technique scientists themselves have used (if probably not regarding blindfolded people in picture galleries).
Analogies only reflect some aspects of the target being compared. The features that map unproblematically are known as the positive analogy, but there is usually a negative analogy as well: features that do not match, and so which would be misleading if carried across. Realistically, the negative analogy will usually have more content than the positive analogy, although much of the negative analogy will be so obviously irrelevant that it is unlikely to confuse anyone.
So, for example, in the analogy the blindfolded people will be wearing clothes, may exchange apologies (or curses) on bumping into each other, and will likely end up bruised – and human nature being what it is, some may cheat by sneaking a look past the edge of the blindfold – but no reader is likely to think these are features that transfer across to the target! Perhaps, however, a reader might wonder if the molecules, like the blindfolded people, are drawing on a source of energy to keep up the activity, and would tire eventually?
There are some other potentially more problematic aspects of the negative analogy. In the thought experiment, the people have been given instructions about what to do, and when to stop, and are acting deliberately. These features do not transfer across, but a reader might not realise this, and could therefore understand the analogy anthropomorphically. It is in situations like this where the teacher can seek feedback on how the analogy is being interpreted (that is, use informal formative assessment), but an author of a book loses control once the manuscript is completed.
Molecular mechanisms made familiar?
There is nothing unusual in Scott's use of metaphor, simile and analogy in seeking to help readers understand abstract scientific ideas. This is an approach common to a good deal of science communication, within and beyond formal teaching. Vital Principles offers many examples, but such devices are common in books seeking to explain science.
I did raise two questions about these techniques above. How do we know if these comparisons are effective in communicating the science? To find out, we would need to talk to readers and question them about their interpretations of the text.
In formal science teaching the focus of such research would likely be the extent to which the presentation supported a learner in acquiring a canonical understanding of the science.
However, as I suggested above, if such research concerned popular science books, we might ask whether the purpose of such books is to teach science or satisfy reader interest. Thus, above, I distinguished an objective and a subjective aspect. If a reader selected a book purely for interest, and is satisfied by what they have read – it made sense to them, and satisfied their curiosity – then does it matter if they may have not understood canonically?
When I read such texts, I wonder about both how a general readership responds to the comparisons offered by authors to make the unfamiliar familiar, and what sense the readers come away with of the science. I guess to some extent popular science authors at least get some level of feedback on the former question – if readers come back for their other titles, then they must be doing something right.
I thought Scott showed a good deal of ingenuity and craft in setting out an account of a challenging and complex area of science – but I would love to know how his different readers interpreted some of his comparisons.
Work cited:
Scott, A. (1988). Vital Principles. The molecular mechanisms of life. Basil Blackwell.
1 I have picked up a good many 'popular science books' over the years, but quite a few of them got put on the shelves till I had time to engage with them in any depth. Other things usually got in the way – lesson/lecture preparation being the most demanding imperative for soaking up time over my 'working' life. Retirement has finally allowed me to start going through the shelves…
2 In the English context, perhaps elsewhere, the textbook is now also often expected to not only cover the right content, but follow the examination board's line on the level of treatment, even to the degree of what is acceptable phrasing. Indeed, there are now textbooks associated with the different exam board syllabuses for the 'same' qualification (e.g., A level Chemistry). This seems very unhealthy, and come the revolution…
3 The model I am referring to here is the mental model in the teacher's mind of the learner or reader – the background knowledge they have available, their existing level of understanding, the sophistication of their thinking, the range of everyday references they are familiar with which might be useful in making comparisons, their concentration span for dealing with new material or complex language …
If we think of teaching-learning as a system, many system failure (failures of students to understand teaching as intended) can be considered to be due to a mismatch – the teacher's mental model is inaccurate in ways that leads to non-optimal choices in presenting material (Taber, 2001 [Download article]).
5 There was little in the book I really would have argued with. However, there were a few questionable statements:
"Yet this apparent miracle is completed thousands of times each day throughout the world [in humans], and similar miracles create all manner of simpler creatures, from elephants and birds and flies to bacteria and flowers and mighty oaks."
p.5
This statement seemed to reflect the long-lasting notion of nature as a 'great chain of being' with humans (in the middle of the chain, below a vast range of angelic forms, but) top of the natural world. Bacteria are simpler than humans, I would acknowledge; but I am less sure about flies; even less sure about birds; and question considering trees and other flowering plants, or elephants, as (biologically) simpler than us. This seems an anthropocentric (human-centred), rather than a scientific, take.
"…the periodic table… lists the 92 naturally occurring atoms (plus a few man-made ones) which are the basic raw materials of chemistry…"
p.19
There are clearly more than 92 naturally occurring atoms in the universe. I believe we think there are 90 naturally occurring elements. That is 90 "naturally occurring [kinds of, in the specific sense of proton number] atoms".
Similarly, "a 'compound' is any chemical [sic] composed of two or more atoms chemically bonded together" (pp.29-30) would imply that H2, C60, N2, O2, F2, P4, S8, Cl2, etc are all compounds (when these are elements, not compounds).
Another slightly questionable suggestion was that
"…electrons appear to surround the atomic nucleus, but in a way that allows them to dart to and fro in a seemingly chaotic manner within a particular region of space."
p.21
The notion of electrons darting back and forth does not really reflect the scientific model, but the orbital/quantum model of the atom is subtle and difficult to explain, and was not needed at the level of the description being presented.
A more obvious error was that
"…'heat' is just a measure of the kinetic energy with which particles of matter are moving…"
p.26
In physics, the temperature of a material is considered to reflect the average kinetic energy of the particles (e.g., molecules). But heat is a distinct concept from temperature. Heat is the energy transferred between samples of matter, due to a difference in temperature. So, when Scott writes
"We all know that heat energy moves inevitably from hot places to cold places, and that it will never spontaneously move in the opposite direction."
p.32
this could be seen as a tautology: like saying that imports always come into the county rather than leave – because of how imports are defined.
Although heat and temperature are related concepts, confusing or conflating them is a common alternative conception found among students. Confusing heat with temperature is like confusing a payment into your bank account with the account balance.
Moreover, Scott uses the wrong term when writes,
"[The molecules of?] Chemicals come into contact with one another because they are all constantly moving with the energy we call heat."
p.191
This internal energy that substances have due to the inherent motion of their particles is not heat – it is present even when there is a perfectly uniform temperature throughout a sample (and so no heating going on).
Scott tells readers that "Another name for … a voltage difference is a 'potential difference'…" (p.162) but the term voltage (not voltage difference) normally refers to a potential difference, p.d.. (So, the term voltage difference implies a difference between potential differences, not a difference in potential. If you had one battery with a p.d. across its terminals of 6.0V, and another with a p.d. across its terminals of 4.5V, you could say the 'voltage difference' between the batteries was 1.5V.)
A common alternative conception which Scott seems to share, or at least is happy to reinforce, is the 'fairy tale'* of how ionic bonding results from the transfer of an electron from a metal atom to a neutral non-metal atom,
"When sodium atoms react with chlorine atoms electrons are actually transferred from one atom to the other (see figure [which shows electron transfer from one atom to another]). One electron which is relatively loosely held by a sodium atom can move over to become attached to a chlorine atom."
p.30
This describes a chemically very unlikely scenario (neither sodium nor chlorine are found in the atomic state under normal conditions on earth), and if a sodium atom were to somehow collide with a chlorine atom, the process Scott describes would be thermodynamically non-viable – it requires too much energy to remove even the outermost 'relatively loosely held' electron from the neutral sodium atom. Perhaps this is why in the school laboratory NaCl tends to be prepared from solutions that already contain the sodium ions [NaOH(aq)] and the chloride ions [HCl(aq)].
It is hard to be too critical of Scott here, as this account is found in many chemistry text books (and I have even seen it expected in public examinations) although from a scientific point of view, it is a nonsense. That many learners come to think that ionic bonding is due to (or even, 'is') a process of electron transfer is surely a pedagogic learning impediment (Taber, 1994) – a false idea that is commonly taught in school chemistry.
7 Many scientists will believe there is a purpose underpinning the evolution of life on earth, and will see creation as the unfolding of a supernatural plan. (Some others will vehemently reject this. Others still will be agnostic.) However, natural science is concerned with providing natural explanations of the world in terms of natural mechanisms. Even if a scientist thinks things are the way they are because that is God's will, that would be inadmissible as a scientific argument, as it does not explain how things came about through natural processes.
8 Teaching, or for that matter writing a science book, is informed by the teacher's/author's mental model of how the reader/listener will make sense of the text (see above). How they actually make sense of the text depends on the interpretive resources they have available, and bring to mind, and it is common for learners/readers not to interpret texts in the way intended – often they either do not make sense of the information, or make a different sense to that intended. A teacher who is a 'learning doctor' can seek to diagnose and treat these 'teaching-learning system failures' when they inevitably occur, but teachers can avoid a good many potential problems by being as explicit as possible and not relying on learners to spontaneously make intended associations with prior learning or cultural referents.
As suggested above, authors have an even more challenging task as their readerships may have a diverse range of prior knowledge and other available interpretive resources (e.g., a popular television programme or pop star in one country may be unknown to readers from another); and the author cannot check they have been understood as intended, in the way a teacher usually can.
…to the best of my knowledge, there is absolutely no reason to suspect that Prof. Theodorescu falsified his academic credentials…
The following text is an extract from a podcast item reporting recently published research into bladder cancer:
"The Y-negative cells cause an immune evasive environment in the tumour, and that, if you will, paralyses, the T cells, and exhausts them, makes them tired and ineffective, and this prevents the Y-negative tumour from being rejected, therefore allowing it to grow much better."
"Exhausted T cells have lost their ability to kill cancer cells, and have lots of proteins on their surface known as checkpoints, which put the brakes on immune responses.
But this exhausting environment made by the tumours could actually be their undoing"
"What they also did, inadvertently I'm sure, is made themselves a lot more vulnerable to one of the most useful and prevalent therapeutics in cancer today, which is immune checkpoint inhibitors."
"Immune checkpoint inhibitors are a class of drugs that block those checkpoint proteins that sit on the surface of T cells, effectively taking the brakes off immune responses, causing T cells to become more aggressive."
Dan Theodorescu & Nick Petrić Howe speaking on the Nature Podcast
Prof. Dan Theodorescu MD, PhD, is the Director of the Samuel Oschin Comprehensive Cancer Institute at Cedars-Sinai, Professor of Surgery, Pathology and Laboratory Medicine; and corresponding author on the paper (Abdel-Hafiz et al., 2023) published in Nature, and discussed in the podcast.
Nick Petrić Howe, Senior Multimedia Editor at Nature Research, was the journalist presenting the item on the podcast.
Communicating science
Scientific research is communicated to other specialist scientists through research reports which reflect a particular genre of writing, and are written with specialist researchers in the same field as the main target readership. Such reports are usually of a quite technical nature, and (appropriately) assume that readers will have a high level of prior understanding of concepts in the field and the technical language used. Such tropes as simile and analogy certainly can sometimes feature, but generally figurative language is kept to a minimum.
Communication to a wider audience of people with a general interest in science needs to adopt a different register. As I have noted on this site before, this is quite challenging as a general public audience is likely to be very diverse in terms of its level of knowledge and understanding of background to any scientific research. Perhaps that is why as a former teacher (and so a science communicator that could make reasonably informed assumptions about the background of my audience in any particular lesson) I find the language of this type of science dissemination fascinating.
The study discussed in the podcast reported on a line of research exploring the genomics of bladder cancer, and in particular how tumours that develop from cells that have deficiencies in the Y chromosome seem to have particular characteristics.
Put simply, tumours of this kind were likely to be inherently more damaging to the patient, although also likely to be more responsive to an existing class of medicines. (At this stage the work has largely relied on in vitro studies and 'animal models' (mice) so the implications for actual human cancer patients are reasonable, but speculative.)
The language used
The short extract of the dialogue I have transcribed above seems quite 'dense' in interesting language when de-constructed:
Y-negative cells – a new technical term?
The extract starts with reference to Y-negative cells. Earlier in the item it had been explained that some cells have no Y chromosome, or an incomplete Y chromosome. (For someone to understand this information, they would need to have some background knowledge relating to what chromosomes are, and why they are important in cells. 1 ) The term Y-negative cell therefore, given that context, refers to a cell which lacks the usual Y chromosome. 2 If such a cell turns cancerous it will give rise to a tumour which is Y-negative (as all the tumour cells are formed from the division of that cancerous cell). The published report notes "Loss of the Y chromosome (LOY) is observed in multiple cancer types, including 10-40% of bladder cancers" (Abdel-Hafiz et al., 2023), an observation which motivates the area of research.
An immune evasive environment?
The word 'evasion' appears in the title of the paper. To evade something means to avoid it, which might suggest a sense of deliberation. Immune evasion is a recognised issue, as in cancers "interactions between the immune system and the tumour occur through complex events that usually eventually climax either in successful tumour eradication or immune evasion by the tumour" (Vinay et al., 2015): that is, either the immune system destroys the cancer, or the cancer is able to grow due to some mechanism(s) that prevent the immune system killing the tumour cells. The 'immune evasive environment' then refers to the environment of the tumour's cells in a context where aspects of the normal immune mechanisms are inoperative or restricted.
Paralysed, exhausted and tired T cells
T cells are one of the classes of cell that make up the immune system, and the item was suggesting that with 'LOY' the T cells are unable to function in the way they normally do when interacting with cancer cells that have an intact Y chromosome. ('LOY' is the acronym for a process, viz., "loss of the Y chromosome", but once defined can be used in a way that reifies LOY as if it refers to an object. 3 In "…with 'LOY'…", I am treating LOY as a medically diagnosable condition.)
Are the T cells paralysed? That normally means not able to move, which is not the case here. So 'paralysed' seems to be used as a metaphor, a way of 'making the unfamiliar familiar' for a non specialist audience. A large part of the task of a science teacher is to make the unfamiliar [become] familiar to learners.
Actually, I would better class this specific use as a simile rather than a metaphor:
"The Y-negative cells cause an immune evasive environment in the tumour, and that, if you will, paralyses, the T cells"
A simile in poetic language normally refers to something being 'like' or 'as' something else, as when the star Betelgeuse was said to be "like an imbalanced washing machine tub" or a laser was described as being used as a "kind of spark plug". Here, Prof. Theodorescu marks the term 'paralyses' with 'if you will' in a similar way to how when selection theory has been said to be "like a Tibetan prayer-wheel…" the word 'like' marks that this is noting a similarity, not an identity (selection theory is not suggested to be a prayer-wheel, but rather to be in some way like one).
The T cells were said to be as if paralysed, but they were also exhausted and tired. Yet, again, 'exhausted' does not seem to be meant literally. The T cell has not used up its supply of something (energy, or anything else), so this is another metaphor. 'Tired' can be seen as synonymous to exhausted, except usually 'tired' refers to a subjective experience. The T cells are not sentient and presumably do not feel tired – so, this is another metaphor; indeed an anthropomorphicmetaphor, as it refers to the cells as though they have subjective experience like a person.
Hey, you immune cells – are you feeling tired? How about taking a break, and doing some stretching exercises and a little yoga?
Images from Pixabay
Anthropomorphism is a common trope in science discourse, especially in biological contexts. It can sometimes help communication of abstract material to present scientific phenomena in a narrative that relates to human subjective experience – perhaps referring to disease 'evading' the immune system – but consequently often gets adopted into in students' pseudo-explanations (e.g., the reaction happened because the atom wanted another electron, the gas expands because the molecules wanted more space). 4
Yet the term 'exhausted' also appears in the published research report ("Ylow bladder cancers contained a higher proportion of exhausted and progenitor exhausted CD8+ T cells..."). So, this is a term that is being adopted into the terminology of the research field. A paper from 2019 set out to define what this means: "'T cell exhaustion' is a broad term that has been used to describe the response of T cells to chronic antigen stimulation, first in the setting of chronic viral infection but more recently in response to tumours" (Blank, et al., 2019). Another study notes that
"It is now clear that T cells are not necessarily physically deleted under conditions of antigen persistence but can instead become functionally inept and incapable of elaborating the usual array of effector activities typically associated with robust, protective, effector and memory T-cell populations."
Yi, Cox, & Zajac, 2010
It is not unusual for terms that seem to be initially used metaphorically, to become adopted in a scientific field as technical terms (such as the 'birth' and 'death' of stars in astronomy). Indeed, inept seem to me a term that is normally applied to people who have agency and can learn skills, but lack skill in an area where the are active. The field of oncology seems to have adopted the notion of ineptitude, to label some T cells as 'inept'.
Unlike in human hereditary, where we would not assume a child can directly inherit a lack of skill in some area of activity from its parents (there is no gene for playing chess, or spraying cars, or heart surgery, or balancing account books), at the cellular level it is possible to have "inept T-cell lineages" (Fredholm et al, 2018). If one is going to anthropomorphise cells, then perhaps 'inept' is an unfair descriptor for structural changes that modify functionality, and can be passed on to 'daughter' cells: should these cells be considered to have a disability rather than be inept? For that matter, an exhausted T-cell seems to have more in common with a metamorphosed caterpillar than an exhausted marathon runner.
Rejection – a dead metaphor?
'Rejection' is a technical terms used in medical science for when the immune system 'attacks' something that it 'identifies' as not self: be that a tumour or a transplanted tissue. Note that here terms such as 'attacks' and 'identifies' are really also anthropomorphicmetaphors to label complex processes and mechanisms that we gloss in human terms.
What actually happens is in effect some chemistry – there is nothing deliberate about what the cancer cells or the immune cells are doing. Tumours that grow quickly are described as 'aggressive' ("…causing T cells to become more aggressive") another term that might be understood as an anthropomorphicmetaphor, as aggression normally refers to an attitude adopted. The tumour cells are just cells that grow and divide: they have no attitude nor intentions, and do not deliberately harm their host or even deliberately divide to grow the cancer.
When the term 'rejection' was first suggested for use in these contexts it will have been a metaphor itself, a word transplanted [sic] from one context where it was widely used to another novel context. However, the 'transplant took' (rather than being 'rejected'!) and came to be accepted as having a new biological meaning. Such a term is sometimes called a dead metaphor (or a clichéd metaphor) as it has lost its metaphorical status, and become a technical term. Tumours are now literally rejected. And T cells do now become exhausted (and inept). And tumours can now be aggressive.
Within the specialist field, such words now have nuanced technical meanings, related to, but subtly different from, their source words' usage in general language. Experts know that – but lay people may not always realise. Strictly, the words aggressive in 'an aggressive drunk' and 'an aggressive tumour' are homonyms.
Seated checkpoints: quo vardis, friend or foe?
The same is the case with 'checkpoints'. Referring to proteins on the immune cell surface that interact with proteins on tumour cells, the label 'checkpoints' will have been a metaphorical transplant of an existing term (as in border checkpoints, where it is checked that someone's papers are in order for entry to a country); but, now, this is accepted usage.
T cells are able to destroy other cells. However, they have proteins on their surfaces which can bind to proteins on other cells, and when these are bound the T cells do not destroy the other cells. (Do these proteins really "sit on the surface of T cells" – or is sitting an action only available to organisms with certain types of anatomic features – such as buttocks and jointed legs perhaps? So, this is another metaphor, but one that conveys meaning so readily that most listeners will not have noticed it. 6 )
So, immune cells have evolved because they 'protect' the organism from 'foreign' cells, and the checkpoints have evolved because they prevent the immune cells destroying cells from the same individual organism. 5 This works to the extent that the binding of the checkpoints is specific. Tumour cells (which are derived from the individual) can sometimes bind, and so the T cells may be ineffective in destroying them. Immune checkpoint inhibitors can interfere with the mechanism by which tumour cells act on the T cells as 'self' cells – something sometimes referred to as a checkpoint 'blockade' (yet another metaphor) – something represented in the following image:
Figure entitled "Immune checkpoint blockade for T-cell activation" (note the 'exhausted' T cells) (Fig. 2, from Darvin, et al., 2018. Open access under http://creativecommons.org/licenses/by/4.0/). [There is an interesting mix of iconic (cell shapes) and symbolic (e.g., lightning strikes?) signs in the figure.]
The extract of dialogue quoted above suggests that the checkpoints "put the brakes on immune responses". There are of course no actual brakes, so this is again metaphorical. However, we might consider 'putting the brakes' on as having become an Englishidiom, that is, the term is now widely understood as applying to any situation where a process is brought to a stop, regardless of whether or not there are actual brakes involved. A raise in bank interest rates might be said to be intended to put the brakes on inflation. (Indeed, as my O level economics teacher at North Romford Comp. habitually explained managing the economy in terms of driving a car – which of course we were all too young to legally have experienced – he may well have actually said this.)
Can tumours behave advertently?
At one point Prof. Theodorescu, suggested that "what [the tumours] also did, inadvertently I'm sure, is made themselves a lot more vulnerable to one of the most useful and prevalent therapeutics in cancer today". I am also sure that this effect was inadvertent. Otherwise, the tumour acted advertently, which would mean it behaved deliberately with this outcome in mind.
It clearly would not seem to be in a tumour's interest to make itself more susceptible to therapeutics, but then agents do sometimes behave in ways that seem irrational to others – for example, because of bravado. So, I do not rule out apparently self-destructive behaviour from being deliberate (as I drafted this piece, the news broadcast reports on an apparent coup attempt in Russia, suggesting that a few tens of thousands of men are looking to take over a nation of over 140 million that had been paying them to fight in the illegal invasion of Ukraine). Rather, my reason for being sure this not deliberate, is that I do not think that a tumour is the kind of entity that can behave advertently. 7
So, I do not disagree with Prof. Theodorescu, but I do think that stating that, in this case, the behaviour was inadvertent seems to imply that that a tumour can in some circumstances act deliberately (i.e., anthropomorphism, again). I am sure that was not the intention, but it seems, inadvertently I'm sure, to reflect the tactic of conspicuously stating someone is not guilty of some act as a means of starting a contrary rumour.
So, I would like to make it absolutely clear, without any sense of ambiguity, that, certainly to the very best of my knowledge, there is absolutely no reason to suspect that Prof. Theodorescu falsified his academic credentials using red crayons and recycled cereal packets.
Work cited:
Abdel-Hafiz, H.A., Schafer, J.M., Chen, X. et al. Y chromosome loss in cancer drives growth by evasion of adaptive immunity. Nature (2023). https://doi.org/10.1038/s41586-023-06234-x
Blank, C. U., Haining, W. N., Held, W., Hogan, P. G., Kallies, A., Lugli, E., . . . Zehn, D. (2019). Defining 'T cell exhaustion'. Nature Reviews Immunology, 19(11), 665-674. https://doi.org/10.1038/s41577-019-0221-9
Darvin, P., Toor, S. M., Sasidharan Nair, V., & Elkord, E. (2018). Immune checkpoint inhibitors: recent progress and potential biomarkers. Experimental & Molecular Medicine, 50(12), 1-11. https://doi.org/10.1038/s12276-018-0191-1
Fredholm , S., Willerslev-Olsen, A., Met, O., Kubat, L., Gluud, M., Mathiasen, S. L., . . . Ødum, N. (2018). SATB1 in Malignant T Cells. Journal of Investigative Dermatology, 138(8), 1805-1815. https://doi.org/https://doi.org/10.1016/j.jid.2018.03.1526
Vinay, D. S., Ryan, E. P., Pawelec, G., Talib, W. H., Stagg, J., Elkord, E., . . . Kwon, B. S. (2015). Immune evasion in cancer: Mechanistic basis and therapeutic strategies. Seminars in Cancer Biology, 35, S185-S198. https://doi.org/https://doi.org/10.1016/j.semcancer.2015.03.004
1 Any communication of science will inevitably have to assume some background. In teaching, we can use conceptual analysis to break down any topic and identify pre-requisite prior knowledge that will be needed before introducing new information. Science education builds up understanding slowly over many years, 'building on' what learners have already been taught. Anyone asked to give an account or explanation to a general audience has to make an informed judgement of where it is reasonable to start.
2 It might seem that the cells of females are 'Y-negative' as these do not usually contain Y chromosomes. However, from the context (the discussion of loss of, or incomplete, Y-chromosomes) the term is being used to refer to cells with no Y chromosomes that derived ultimately (by imperfect copying) from a cell which did have a Y chromosome. That is, this is a feature of tumours in men.
Although women do not (usually) have Y chromosomes, it is sometimes suggested that the man's Y chromosome can be considered an incomplete X chromosome, so in a sense all men might be considered as incomplete, imperfect women, as some readers might have long suspected.
3 This is not meant as some kind of criticism, but rather an observation on one of the affordances of language in use. It is very useful for the scientist to package up an idea (here, the loss of the Y chromosome from a cell's set of nuclear chromosomes) in a new term or acronym, which can then be put to work as a neologism, thus simplifying sentence structure. The reader then needs to decode this new term in various contexts. That is perfectly reasonable within the genre of research reports (as this only adds minimally to the interpretative load of a specialist reader who is likely to have strong enough background to have capacity to readily make sense of the new term in various contexts). So, in the published paper (Abdel-Hafiz, 2023), we find, inter alia,
"…LOY correlates with…"
"…naturally occurringLOY mutant bladder cancer cells…"
"In ageing men, LOYhas been associated with many adverse health consequences."
"…cancer cells withLOY…"
"…mouse tumours withLOY…"
"…human bladder cancer specimens withLOY…"
"…LOY is present early in disease progression…"
"…the lack of Y chromosome gene expression in the MB49 sublines was due toLOY"
"…the important role of these two genes in conferring the LOY phenotype…"
"…patients withLOY had a reduced overall survival following surgery…"
"…tumours withLOY grew more aggressively…"
"…the mechanism of LOY-driven tumour evasion…"
There is even a case of LOY being taken as a sufficiently familiar to be compounded into a further acronym, 'MADLOY':
"we used TCGA DNA sequencing data and mosaic alteration detection for LOY (MADLOY) to detect LOY".
4 Unfortunately, thinking anthropomorphically about viruses, cells, molecules, etc., can become a habit of mind. Students may come to see such anthropomorphisms as having the status of genuine scientific explanations (that they can use in exams, for example). Therefore, care is needed with using anthropomorphism in science teaching (Taber & Watts, 1996).
'checkpoints' is a recently deceased metaphor, with its new meaning only familiar in the technical language community of oncologists and cognate specialists, whereas
'sits' is a long dead metaphor as its broader meaning is likely to be understood widely within the natural language community of English speakers.
6 My use of 'because' is not to be read in a teleological sense as
immune cells have evolved in order to protect the organism from 'foreign' cells
the checkpoints have evolved in order to prevent the immune cells destroying cells form the same individual organism
Rather in the sense of the reason something has evolved is because it has a property that offers an advantage, and so was selected for:
immune cells have evolved because they were selected for because they protect the organism from 'foreign' cells
the checkpoints have evolved because they were selected for because they prevent the immune cells destroying cells from the same individual organism
7 I am making an 'ontological judgement'. I might say I am doing ontology. In my teaching of graduate students I found some were wary of terms like ontology and epistemology, but actually I would argue that we all 'do ontology' every time we make a judgement about the kind of entity something is (and we do epistemology every time we make a judgement about the likely truth value of some claim).
If you judge that fairies are imaginary or that dinosaurs are extinct, I suggest that you are doing ontology. For that matter, if you judge that fairies and dinosaurs are alive and well, and live at the bottom of your garden, then you are also doing ontology – if perhaps not so well.
It seems a bloated star dimmed because it sneezed, and spewed out a burp.
'Pardon me!' (Image by Angeles Balaguer from Pixabay)
I was intrigued to notice a reference in Chemistry World to a 'stellar burp'.
"…the dimming of the red giant Betelgeuse that was observed in 2019…was later attributed to a 'stellar burp' emitting gas and dust which condensed and then obscured light from the star"
Motion, 2022
The author, Alice Motion, quoted astrophysics doctoral candidate and science communicator Kirsten Banks commenting that
"In recorded history…It's the first time we've ever seen this happen, a star going through a bit of a burp"
although she went on to suggest that the Boorong people (an indigenous culture from an area of the Australian state Victoria) had long ago noticed a phenomena that became recorded in their oral traditions 1, which
"was actually the star Eta Carinae which went through a stellar burp, just like Betelgeuse did"
Clearly a star cannot burp in the way a person can, so I took this to be a metaphor, and wondered if this was a metaphor used in the original scientific report.
A clump and a veil
The original report (Montargès, et al, 2021) was from Nature, one of the most prestigious science research journals. It did not seem to have any mention of belching. This article reported that,
"From November 2019 to March 2020, Betelgeuse – the second-closest red supergiant to Earth (roughly 220 parsecs, or 724 light years, away) – experienced a historic dimming of its visible brightness…an event referred to as Betelgeuse's Great Dimming….Observations and modelling support a scenario in which a dust clump formed recently in the vicinity of the star, owing to a local temperature decrease in a cool patch that appeared on the photosphere."
Montargès, et al., 2012, p.365
So, the focus seemed to be not on any burping but a 'clump' of material partially obscuring the star. That material may well have arisen from the star. The paper in nature suggests that Betelgeuse may loose material through two mechanisms: both by a "smooth homogeneous radial outflow that consists mainly of gas", that is a steady and continuous process; but also "an episodic localised ejection of gas clumps where conditions are favourable for efficient dust formation while still close to the photosphere" – that is the occasional, irregular, 'burp' of material, that then condenses near the star. But the word used was not 'burp', but 'eject'.
A fleeting veil
Interestingly the title of the article referred to "A dusty veil shading Betelgeuse". The 'veil' (another metaphor) only seemed to occur in the title. There is an understandable temptation, even in scholarly work, to seek a title which catches attention – perhaps simplifying, alliterating (e.g., '…mediating mental models of metals…') or seeking a strong image ('…a dusty veil shading…'). In this case, the paper authors clearly thought the metaphor did not need to be explained, and that readers would understand how it linked to the paper content without any explicit commentary.
Word
Frequency in Nature article
clump(s)
25 (excluding reference list)
eject(ed, etc.)
4
veil
1 (in title only)
burp
0
blob
0
There's no burping in Nature
The European Southern Observatory released a press release (sorry, a 'science release') about the work entitled 'Mystery of Betelgeuse's dip in brightness solved', that explained
"In their new study, published today in Nature, the team revealed that the mysterious dimming was caused by a dusty veil shading the star, which in turn was the result of a drop in temperature on Betelgeuse's stellar surface.
Betelgeuse's surface regularly changes as giant bubbles of gas move, shrink and swell within the star. The team concludes that some time before the Great Dimming, the star ejected a large gas bubble that moved away from it. When a patch of the surface cooled down shortly after, that temperature decrease was enough for the gas to condense into solid dust.
'We have directly witnessed the formation of so-called stardust,' says Montargès, whose study provides evidence that dust formation can occur very quickly and close to a star's surface. 'The dust expelled from cool evolved stars, such as the ejection we've just witnessed, could go on to become the building blocks of terrestrial planets and life', adds Emily Cannon, from KU Leuven, who was also involved in the study."
So, again, references to ejection and a veil – but no burping.
Delayed burping
Despite this, the terminology of the star burping, seems to have been widely taken up in secondary sources, such as the article in Chemistry World
A New Scientist report suggested "Giant gas burp made Betelgeuse go dim" (Crane, 2021). On the website arsTECHNICA, Jennifer Ouellette wrote that "a cold spot and a stellar burp led to strange dimming of Betelgeuse".
On the newsite Gizmodo, George Dvorsky wrote a piece entitled "A dusty burp could explain mysterious dimming of supergiant star Betelgeuse". Whilst the term burp was only used in the title, Dvorsky was not shy of making other corporeal references,
"a gigantic dust cloud, which formed after hot, dense gases spewed out from the dying star. Viewed from Earth, this blanket of dust shielded the star's surface, making it appear dimmer from our perspective, according to the research, led by Andrea Dupree from the Centre for Astrophysics at Harvard & Smithsonian.
A red supergiant star, Betelgeuse is nearing the end of its life. It's poised to go supernova soon, by cosmological standards, though we can't be certain as to exactly when. So bloated is this ageing star that its diameter now measures 1.234 million kilometers, which means that if you placed Betelgeuse at the centre of our solar system, it would extend all the way to Jupiter's orbit."
The New York Times published an article (June 17, 2021) entitled "Betelgeuse Merely Burped, Astronomers Conclude", where author Dennis Overbye began his piece:
Overbye also reports the work from the Nature paper
"We have directly witnessed the formation of so-called stardust," Miguel Montargès, an astrophysicist at the Paris Observatory, said in a statement issued by the European Southern Observatory. He and Emily Cannon of Catholic University Leuven, in Belgium, were the leaders of an international team that studied Betelgeuse during the Great Dimming with the European Southern Observatory's Very Large Telescope on Cerro Paranal, in Chile.
Parts of the star, they found, were only one-tenth as bright as normal and markedly cooler than the rest of the surface, enabling the expelled blob to cool and condense into stardust. They reported their results on Wednesday in Nature."
So, instead of the clumps referred to in the Nature article as ejected, we now have an expelled blob (neither word appears in the nature article itself). Overbye also explains how this study followed up on earlier observations of the star
"Their new results would seem to bolster findings reported a year ago by Andrea Dupree of the Harvard-Smithsonian Center for Astrophysics and her colleagues, who detected an upwelling of material on Betelgeuse in the summer of 2019.
'We saw the material moving out through the chromosphere in the south in September to November 2019,', Dr. Dupree wrote in an email. She referred to the expulsion as 'a sneeze.'
'…material moving out through the chromosphere in the south…': Hubble space telescope images of Betelgeuse (Source: NASA) 2
Bodily functions and stellar processes
I remain unsure why, if the event was originally considered a sneeze, it became transformed into a burp. However the use of such descriptions is not so unusual. Metaphor is a common tool in science communication to help 'make the unfamiliar familiar' by describing something abstract or out-of-the-ordinary in more familiar terms.
Here, the body [sic] of the scientific report keeps to technical language although a metaphor (the dust cloud as a veil) is considered suitable for the title. It is only when the science communication shifts from the primary literature (intended for the science community) into more popular media aimed at a wider audience that the physical processes occurring in a star became described in terms of our bodily functions. So, in this case, it seems a bloated star dimmed because it sneezed, and spewed out a burp.
Coda
The astute reader may have also noticed that the New York Times article referred to Betelgeuse as an "ageing star" that is "nearing the end of its life": terms that imply a star is a living, and mortal, being. This might seem to be journalistic license, but the NASA website from which the sequence of Betelgeuse images above are taken also refers to the star as ageing (as well as being 'petulant' and 'injured').2NASA employs scientifically qualified people, but its public websites are intended for a broad, general audience, perhaps explaining the anthropomorphic references.
Crane, L. (2021). Giant gas burp made Betelgeuse go dim. New Scientist, 250(3340), 22. doi:10.1016/S0262-4079(21)01094-0
Hamacher, D. W., & Frew, D. J. (2010). An aboriginal Australian record of the great eruption of Eta Carinae. Journal of Astronomical History and Heritage, 13(3), 220-234.
Montargès, M., Cannon, E., Lagadec, E., de Koter, A., Kervella, P., Sanchez-Bermudez, J., . . . Danchi, W. (2021). A dusty veil shading Betelgeuse during its Great Dimming. Nature, 594(7863), 365-368. doi:10.1038/s41586-021-03546-8
1 William Edward Stanbridge (1816-1894) was an Englishman who moved to Australia in 1841. He asked Boorong informants about their astronomy, and recorded their accounts. He presented a report to the Philosophical Institute of Victoria in 1857 and published two papers (Hamacher & Frew, 2010). The website Australian Indigenous Astronomy explains that
"The larger star of [of the binary system] Eta Car is unstable and undergoes occasional violent outbursts, where it sheds material from its outer shells, making it exceptionally bright. During the 1840s, Eta Car went through such an outburst where it shed 20 solar masses of its outer shell and became the second brightest star in the night sky, after Sirius, before fading from view a few years later. This event, commonly called a "supernova-impostor" event, has been deemed the "Great Eruption of Eta Carinae". The remnant of this explosion is evident by the Homunculus Nebulae [see figure above – nebulae are anything that appears cloud-like to astronomical observation]. This identification shows that the Boorong had noted the sudden brightness of this star and incorporated it into their oral traditions."
A paper in the Journal of Astronomical History and Heritage concludes that
"the Boorong people observed 𝜂 Carinae in the nineteenth century, which we identify using Stanbridge's description of its position in Robur Carolinum, its colour and brightness, its designation (966 Lac, implying it is associated with the Carina Nebula), and the relationship between stellar brightness and positions of characters in Boorong oral traditions. In other words, the nineteenth century outburst of 𝜂 Carinae was recognised by the Boorong and incorporated into their oral traditions"
This seems rather anthropomorphic – petulance and struggle are surely concepts that refer to sentient deliberate actors in the world, not massive hot balls of gas. However, anthropomorphic narratives are often used to make scientific ideas accessible.
The recovery (from 'injury') is described in terms of two similes,
"The star's interior convection cells, which drive the regular pulsation may be sloshing around like an imbalanced washing machine tub, Dupree suggests. … spectra imply that the outer layers may be back to normal, but the surface is still bouncing like a plate of gelatin dessert [jelly] as the photosphere rebuilds itself."
What can either wander door to door, or rush to respond; and when it arrives might touch, sniff, nip, rear up, stroke, seal, or kill?
Keith S. Taber
a science teacher would need to be more circumspect in throwing some of these metaphors out there, without then doing some work to transition from them to more technical, literal, and canonical accounts
BBC Radio 4's 'Start the week' programme is not a science programme, but tends to invite in guests (often authors of some kind) each week according to some common theme. This week there was a science theme and the episode was titled 'Building the Body, Opening the Heart', and was fascinating. It also offers something of a case study in how science gets communicated in the media.
Sian Harding is Professor of Cardiac Pharmacology at the National Heart and Lung Institute, Imperial College London, and Director of the Imperial Cardiac Regenerative Medicine Centre
As a science educator I listen to science programmes both to enhance and update my own science knowledge and understanding, but also to hear how experts present scientific ideas when communicating to a general audience. Although neither science popularisation nor the work of scientists in communicating to the public is entirely the same as formal teaching (for example,
are usually much more diverse than found in classrooms, and
are free to leave at any point they lose interest or get a better offer),
they are, like teachers, seeking to inform and explain science.
Science communicators, whether professional journalists or scientists popularising their work, face similar challenges to science teachers in getting across often complex and abstract ideas; and, like them, need to make the unfamiliar familiar. Science teachers are taught about how they need to connect new material with the learners' prior knowledge and experiences if it is to make sense to the students. But successful broadcasters and popularisers also know they need to do this, using such tactics as simplification, modelling, metaphor and simile, analogy, teleology, anthropomorphism and narrative.
Perhaps one of the the biggest differences between science teaching and science communication in the media is the ultimate criterion of success. For science teachers this is (sadly) usually, primarily at least, whether students have understood the material, and will later recall it, sufficiently to demonstrate target knowledgein exams. The teacher may prefer to focus on whether students enjoy science, or develop good attitudes to science, or will consider working in science: but, even so, they are usually held to account for students' performance levels in high-stakes tests.
Science journalists and popularisers do not need to worry about that. Rather, they have to be sufficiently engaging for the audience to feel they are learning something of interest and understanding it. Of course, teachers certainly need to be engaging as well, but they cannot compromise what is taught, and how it is understood, in order to entertain.
With that in mind, I was fascinated at the range of ways the panel of guests communicated the science in this radio show. Much of the programme had a focus on cells – and these were described in a variety of ways.
Talking about cells
Dr Rutherford introduced cells as
"the basic building blocks of life on earth"; and observed that he had
"spent much of my life staring down microscopes at these funny, sort of mundane, unremarkable, gloopy balloons"; before suggesting that cells were
"actually really these incredible cities buzzing with activity".
Dr. Mukherjee noted that
"they're fantastical living machines" [where a cell is the] "smallest unit of life…and these units were built, as it were, part upon part like you would build a Lego kit"
Listeners were told how Robert Hooke named 'cells' after observing cork under the microscope because the material looked like a series of small rooms (like the cells where monks slept in monasteries). Hooke (1665) reported,
"I took a good clear piece of Cork, and with a Pen-knife sharpen'd as keen as a Razor, I cut a piece of it off, and…cut off from the former smooth surface an exceeding thin piece of it, and…I could exceeding plainly perceive it to be all perforated and porous, much like a Honey-comb, but that the pores of it were not regular; yet it was not unlike a Honey-comb in these particulars
…these pores, or cells, were not very deep, but consisted of a great many little Boxes, separated out of one continued long pore, by certain Diaphragms, as is visible by the Figure B, which represents a sight of those pores split the long-ways.
"In my book I sort of board the cell as though it's a spacecraft, you will see that it's in fact organised into rooms and there are byways and channels and of course all of these organelles which allow it to work."
We were told that "the cell has its own skeleton", and that the organelles included the mitochondria and nuclei ,
"[mitochondria] are the energy producing organelles, they make energy in most cells, our cells for instance, in human cells. In human cells there's a nucleus, which stores DNA, which is where all the genetic information is stored."
A cell that secretes antibodies which are like harpoons or missiles that it sends out to kill a pathogen?
(Images by by envandrare and OpenClipart-Vectors from Pixabay)
Immune cells
Rutherford moved the conversation onto the immune system, prompting 'Sid' that "There's a lovely phrase you use to describe T cells, which is door to door wanderers that can detect even the whiff of an invader". Dr. Mukherjee distinguished between the cells of the innate immune system,
"Those are usually the first responder cells. In humans they would be macrophages, and neutrophils and monocytes among them. These cells usually rush to the site of an injury, or an infection, and they try to kill the pathogen, or seal up the pathogen…"
and the cells of the adaptive system, such as B cells and T cells,
"The B cell is a cell that eventually becomes a plasma cell which secretes antibodies. Antibodies, they are like harpoons or missiles which the cell sends out to kill a pathogen…
[A T cell] goes around sniffing other cells, basically touching them and trying to find out whether they have been altered in some way, particularly if they are carrying inside them a virus or any other kind of pathogen, and if it finds this pathogen or a virus in your body, it is going to go and kill that virus or pathogen"
A cell that goes around sniffing other cells, touching them? 1 (Images by allinonemovie and OpenClipart-Vectors from Pixabay)
Cells of the heart
Another topic was the work of Professor Harding on the heart. She informed listeners that heart cells did not get replaced very quickly, so that typically when a person dies half of their heart cells had been there since birth! (That was something I had not realised. It is believed that this is related to how heart cells need to pulse in synchrony so that the whole organ functions as an effective pumping device – making long lasting cells that seldom need replacing more important than in many other tissues.)
At least, this relates to the cardiomyocytes – the cells that pulse when the heart beats (a pulse that can now be observed in single cells in vitro). Professor Harding described how in the heart tissue there are also other 'supporting' cells, such as "resident macrophages" (immune cells) as well as other cells moving around the cardiomyocytes. She describe her observations of the cells in Petri dishes,
"When you look at them in the dish it's incredible to see them interact. I've got a… video [of] cardiomyocytes in a dish. The cardiomyocytes pretty much just stay there and beat and don't do anything very much, and I had this on time lapse, and you could see cells moving around them. And so, in one case, the cell (I think it was a fibroblast, it looked like a fibroblast), it came and it palpated at the cardiomyocyte, and it nipped off bits of it, it sampled bits of the cardiomyocyte, and it just stroked it all the way round, and then it was, it seemed to like it a lot.
[In] another dish I had the same sort of cardiomyocyte, a very similar cell came in, it went up to the cardiomyocyte, it touched it, and as soon as it touched it, I can only describe it as it reared up and it had, little blobs appeared all over its surface, and it rushed off, literally rushed off, although it was time lapse so it was two minutes over 24 hours, so, it literally rushed off, so what had it found, why did one like it and the other one didn't?"
Making the unfamiliar, familiar
The snippets from the broadcast that I have reported above demonstrate a wide range of ways that the unfamiliar is made familiar by describing it in terms that a listener can relate to through their existing prior knowledge and experience. In these various examples the listener is left to carry across from the analogue features of the familiar (the city, the Lego bricks, human interactions, etc.) those that parallel features of the target concept – the cell. So, for example, the listener is assumed to appreciate that cells, unlike Lego bricks, are not built up through rigid, raised lumps that fit precisely in depressions on the next brick/cell. 2
Analogies with the familiar
Hooke's original label of the cell was based on a kind of analogy – an attempt to compare what we has seeing with something familiar: "pores, or cells…a great many little Boxes". He used the familiar simile of the honeycomb (something directly familiar to many more people in the seventeenth century when food was not subject to large-scale industrialised processing and packaging).
Other analogies, metaphors and similes abound. Cells are visually like "gloopy balloons", but functionally are "building blocks" (strictly a metaphor, albeit one that is used so often it has become treated as though a literal description) which can be conceptualised as being put together "like you would build a Lego kit" (a simile) although they are neither fixed, discrete blocks of a single material, nor organised by some external builder. They can be considered conceptually as the"smallest unit of life"(though philosophers argue about such descriptions and what counts as an individual in living systems).
The machine description ("fantastical living machines") reflects one metaphor very common in early modern science and cells as "incredible cities" is also a metaphor. Whether cells are literally machines is a matter of how we extend or limit our definition of machines: cells are certainly not actually cities, however, and calling them such is a way of drawing attention to the level of activity within each (often, apparently from observation, quite static) cell. B cells secrete antibodies, which the listener is old are like (a simile) harpoons or missiles – weapons.
Skeletons of the dead
Whether "the cell has its own skeleton" is a literal or metaphorical statement is arguable. It surely would have originally been a metaphoric description – there are structures in the cell which can be considered analogous to the skeleton of an organism. If such a metaphor is used widely enough, in time the term's scope expands to include its new use – and it becomes (what is called, metaphorically) a 'dead metaphor'.
Telling stories about cells
A narrative is used to help a listener imagine the cell at the scale of "a spacecraft". This is "organised into rooms and there are byways and channels" offering an analogy for the complex internal structure of a cell. Most people have never actually boarded a spacecraft, but they are ubiquitous in television and movie fiction, so a listener can certainly imagine what this might be like.
Endoplastic reticulum? (Still from Star Trek: The Motion Picture, Paramount Pictures, 1979)
Oversimplification?
The discussion of organelles illustrates how simplifications have to be made when introducing complex material. This always brings with it dangers of oversimplification that may impede further learning, or even encourage the development of alternative conceptions. So, the nucleus does not, strictly, 'store' "all the genetic information" in a cell (mitochondria carry their own genes for example).
More seriously, perhaps, mitochondria do not "make energy". 'More seriously' as the principle of conservation of energy is one of the most basic tenets of modern science and is considered a very strong candidate for a universal law. Children are often taught in school that energy cannot be created or destroyed. Science communication which is contrary to this basic curriculum science could confuse learners – or indeed members of the public seeking to understand debates about energy policy and sustainability.
Anthropomorphising cells
Cells are not only compared to inanimate entities like balloons, building bricks, cities and spaceships. They are also described in ways that make them seem like sentient agents – agents that have experiences, and conscious intentions, just as people do. So, some immune cells are metaphorical 'first responders' and just as emergency services workers they "rush to the site" of an incident. To rush is not just to move quickly, buy to deliberately do so. (By contrast, Paul McAuley refers to "innocent" amoeboid cells that collectively form into the plasmodium of a slime mould spending most of their lives"bumbling around by themselves" before they "get together". ) The immune cells act deliberately – they "try" to kill. Other immune cells "send out" metaphorical 'missiles' "to kill a pathogen". Again this language suggests deliberate action (i.e., to send out) and purpose.
That is, what is described is not just some evolved process, but something teleological: there is a purpose to sending out antibodies – it is a deliberate act with an aim in mind. This type of language is very common in biology – even referring to the 'function' of the heart or kidney or a reflex arc could be considered as misinterpreting the outcome of evolutionary developments. (The heart pumps blood through the vascular system, but referring to a function could suggest some sense of deliberate design.)
Not all cells are equal
I wonder how many readers noticed the reference above to 'supporting' cells in the heart. Professor Harding had said
"When you look inside the [heart] tissue there are many other cells [than cardiomyocytes] that are in there, supporting it, there are resident macrophages, I think we still don't know really what they are doing in there"
Why should some heart cells be seen as more important and others less so? Presumably because 'the function' of a heart is to beat, to pump, so clearly the cells that pulse are the stars, and the other cells that may be necessary but are not obviously pulsing just a supporting cast. (So, cardiomyocytes are considered heart cells, but macrophages in the same tissue are only cells that are found in the heart, "residents" – to use an analogy of my own, like migrants that have not been offered citizenship!)3
That is, there is a danger here that this way of thinking could bias research foci leading researchers to ignore something that may ultimately prove important. This is not fanciful, as it has happened before, in the case of the brain:
"Glial cells, consisting of microglia, astrocytes, and oligodendrocyte lineage cells as their major components, constitute a large fraction of the mammalian brain. Originally considered as purely non-functional glue for neurons, decades of research have highlighted the importance as well as further functions of glial cells."
Jäkel and Dimou, 2017
The lives of cells
Narrative is used again in relation to the immune cells: an infection is presented as a kind of emergency event which is addressed by special (human like) workers who protect the body by repelling or neutralising invaders. "Sniffing" is surely an anthropomorphicmetaphor, as cells do not actually sniff (they may detect diffusing substances, but do not actively inhale them). Even "touching" is surely an anthropomorphism. When we say two objects are 'touching' we mean they are in contact, as we touch things by contact. But touching is sensing, not simply adjacency.
If that seems to be stretching my argument too far, to refer to immune cells "trying to find out…" is to use language suggesting an epistemic agent that can not only behave deliberately, but which is able to acquire knowledge. A cell can only "find" an infectious agent if it is (i.e., deliberately) looking for something. These metaphors are very effective in building up a narrative for the listener. Such a narrative adopts familiar 'schemata', recognisable patterns – the listener is aware of emergency workers speeding to the scene of an incident and trying to put out a fire or seeking to diagnose a medical issue. By fitting new information into a pattern that is familiar to the audience, technical and abstract ideas are not only made easier to understand, but more likely to be recalled later.
Again, an anthropomorphic narrative is used to describe interactions between heart cells. So, a fibroblast that "palpates at" a cardiomyocyte seems to be displaying deliberate behaviour: if "nipping" might be heard as some kind of automatic action – "sampling" and "stroking" surely seem to be deliberate behaviour. A cell that "came in, it went up [to another]" seems to be acting deliberately. "Rearing up" certainly brings to mind a sentient being, like a dog or a horse. Did the cell actually 'rear up'? It clearly gave that impression to Professor Harding – that was the best way, indeed the "only" way, she had to communicate what she saw.
Again we have cells "rushing" around. Or do we? The cell that had reared up, "rushed off". Actually, it appeared to "rush" when the highly magnified footage was played at 720 times the speed of the actual events. Despite acknowledging this extreme acceleration of the activity, the impression was so strong that Professor Harding felt justified in claiming the cell "literally rushed off, although it was time lapse so it was two minutes over 24 hours, so, it literally rushed off…". Whatever it did, that looked like rushing with the distortion of time-lapse viewing, it certainly did not literally rush anywhere.
But the narrative helps motivate a very interesting question, which is why the two superficially similar cells 'behaved' ('reacted', 'responded' – it is actually difficult to find completely neutral language) so differently when in contact with a cardiomyocyte. In more anthropomorphic terms: what had these cells "found, why did one like it and the other one didn't?"
Literally speaking?
Metaphorical language is ubiquitous as we have to build all our abstract ideas (and science has plenty of those) in terms of what we can experience and make sense of. This is an iterative process. We start with what is immediately available in experience, extend metaphorically to form new concepts, and in time, once those have "settled in" and "taken root" and "firmed up" (so to speak!) they can then be themselves borrowed as the foundation for new concepts. This is true both in how the individual learns (according to constructivism) and how humanity has developed culture and extended language.
So, should science communicators (whether scientists themselves, journalists or teachers) try to limit themselves to literal language?
Even if this were possible, it would put aside some of our strongest tools for 'making the unfamiliar familiar' (to broadcast audiences, to the public, to learners in formal education). However these devices also bring risks that the initial presentations (with their simplifications and metaphors and analogies and anthropomorphic narratives…) not only engage listeners but can also come to be understood as the scientific account. That is is not an imagined risk is shown by the vast numbers of learners who think atoms want to fill their shells with octets of electrons, and so act accordingly – and think this because they believe it is what they have been taught.
Does it matter if listeners think the simplification, the analogy, the metaphor, the humanising story,… is the scientific account? Perhaps usually not in the case of the audience listening to a radio show or watching a documentary out of interest.
In education it does matter, as often learners are often expected to progress beyond these introductory accounts in their thinking, and teachers' models and metaphors and stories are only meant as a starting point in building up a formal understanding. The teacher has to first establish some kind of anchor point in the students' existing understandings and experiences, but then mould this towards the target knowledge set out in the curriculum (which is often a simplified account of canonical knowledge) before the metaphor or image or story becomes firmed-up in the learners' minds as 'the' scientific account.
'Building the Body, Opening the Heart' was a good listen, and a very informative and entertaining episode that covered a lot of ideas. It certainly included some good comparisons that science teachers might borrow. But I think in a formal educational context a science teacher would need to be more circumspect in throwing some of these metaphors out there, without then doing some work to transition from them to more technical, literal, and canonical accounts.
Jäkel S and Dimou L (2017) Glial Cells and Their Function in the Adult Brain: A Journey through the History of Their Ablation. Frontiers in Cellullar Neuroscience, 11:24. doi: 10.3389/fncel.2017.00024
1 The right hand image portrays a mine, a weapon that is used at sea to damage and destroy (surface or submarine) boats. The mine is also triggered by contact ('touch').
2 That is, in an analogy there are positive and negative aspects: there are ways in which the analogue IS like the target, and ways in which the analogue is NOT like the target. Using an analogy in communication relies on the right features being mapped from the familiar analogue to the unfamiliar target being introduced. In teaching it is important to be explicit about this, or inappropriate transfers may be made: e.g., the atom is a tiny solar system so it is held together by gravity (Taber, 2013).
3 It may be a pure coincidence in relation to the choice of term 'resident' here, but in medicine 'residents' have not yet fully qualified as specialist physicians or surgeons, and so are on placement and/or under supervision, rather than having permanent status in a hospital faculty.
NASA might be said to be engaged in looking for other Gaias beyond our Gaia, as Dr Milam explained to another Gaia.
This post is somewhat poignant as something I heard on a radio podcast reminded me how science has recently lost one of its great characters, as well as an example of that most rare thing in today's science – the independent scientist.
I was listening to the BBC's Inside Science pod-cast episode 'Deep Space and the Deep Sea – 40 years of the International Whaling Moratorium' where the presenter – somewhat ironically, in view of the connection I was making, Gaia Vince – was talking to Dr Stefanie Milam of Nasa's Goddard Space Flight Centre about how the recently launched James Webb Space Telescope could help scientists look for signs of life on other planets.
"spectra…give us all the information that we really need to understand a given environment. And that's one of the amazing parts about the James Webb space telescope. So, what we have access to with the wavelengths that the James Webb space telescope actually operates at, is that we have the fingerprint pattern of given molecules, things like water, carbon monoxide, carbon dioxide, all these things that we find in our own atmosphere, and so by using the infrared wavelengths we can look for these key ingredients in atmospheres around other planets or even, actually, objects in our own solar system, and that tells us a little bit about what is going on as far as the dynamics of that planet, whether or not its has got geological activity, or maybe even something as crazy as biology."
Dr Stefanie Milam, interviewed for 'Inside Science'
"Webb has captured the first clear evidence of carbon dioxide (CO2) in the atmosphere of a planet outside of our solar system!" (Hot Gas Giant Exoplanet WASP-39 b Transit Light Curve, NIRSpec Bright Object Time-Series Spectroscopy.) Image: NASA, ESA, CSA, and L. Hustak (STScI). Released under 2.0 Generic (CC BY 2.0) License – Some rights reserved by James Webb Space Telescope
Do molecules have fingerprints
Fingerprints have long been used in forensic work to identify criminals (and sometimes their victims) because our fingerprints are pretty unique. Even 'identical' twins do not have identical fingerprints (thought I suspect that fact rather undermines some crime fiction plots). But, to have fingerprints one surely has to have fingers. A palm print requires a palm, and a footprint, a foot. So, can molecules, not known for their manual dexterity, have fingerprints?
Well, it is not exactly by coincidence (as the James Webb space telescope has had a lot of media attention) that I very recently posted here, in the context of new observations of the early Universe, that
"Spectroscopic analysis allows us to compare the pattern of redshifted spectral lines due to the presence of elements absorbing or emitting radiation, with the position of those lines as they are found without any shift. Each element has its own pattern of lines – providing a metaphorical fingerprint.
In chemistry, elements and compounds have unique patterns of energy transitions which can be identified through spectroscopy. So, we have 'metaphorical fingerprints'. To describe a spectrum as a chemical substance's (or entity's, such as an ion's) fingerprint is to use a metaphor. It is not actually a fingerprint – there are no fingers to leave prints – but this figure of speech gets across an idea though an implicit comparison with something already familiar. *1 That is, it is a way of making the unfamiliar familiar(which might be seen as a description of teaching!)
Dead metaphors
But perhaps this has become a 'dead metaphor' so that now chemicals do have fingerprints? One of the main ways that language develops is by words changing their meanings over time as metaphors become so commonly used they case to be metaphorical.
For example, I understand the term electrical charge is a dead metaphor. When electrical charge was first being explored and was still unfamiliar, the term 'charge' was adopted by comparison with the charging of a canon or the charge of shot used in a shotgun. The shot charge refers to the weight of shot included in a cartridge. Today, most people would not know that, whilst being very familiar with the idea of electrical charge. But when the term electrical charge was first used most people knew about charging guns.
So, initially, electrical 'charge' was a metaphor to refer to the amount of 'electricity' – which made use of a familiar comparison. Now it is a dead metaphor, and 'electrical charge' is now considered a technical tern in its own right.
Another example might be electron spin: electrons do not spin in the familiar sense, but really do (now) have spin as the term has been extended to apply to quanticles with inherent angular momentum by analogy with more familiar macroscopic objects that have angular momentum when they are physically rotating. So, we might say that when the term was first used, it was a metaphor, but no longer. (That is, physicists have expanded the range of convenience of the term spin.)
Perhaps, similarly, fingerprint is now so commonly used to mean a unique identifier in a wide range of contexts, that it should no longer be considered a metaphor. I am not sure if that is so, yet, but perhaps it will be in, say, a century's time – and the term will be broadly used without people even noticing that many things have acquired fingerprints without having fingers. (A spectrum will then actually be a chemical substance's or entity's fingerprint.) After all, many words we now commonly use contain fossils of their origins without us noticing. That is, metaphorical fossils, of course. *2
James Lovelock, R.I.P.
The reason I found this news item somewhat poignant was that I was listening to it just a matter of weeks after the death (at age 103) of the scientist Jim Lovelock. *3 Lovelock invented the device which was able to demonstrate the ubiquity of chlorofluorocarbons (CFCs) in the atmosphere. These substances were very commonly used as refrigerants and aerosol propellants as they were very stable, and being un-reactive (so non-toxic) were considered safe.
But this very stability allowed them to remain in and spread through the atmosphere for a very long time until they were broken down in the stratosphere by ultraviolet radiation to give radicals that reacted with the ozone that is so protective of living organisms. Free radical reactions can occur as chain reactions as when a radical interacts with a molecule it leads to a new molecule, plus a new radical which can often take part in a further interaction with another molecule: so, each CFC molecule could lead to the destruction of many ozone molecules. CFCs have now been banned for most purposes to protect the ozone 'layer', and so us.
Life is chemistry out of balance
But another of Lovelock's achievements came when working for NASA to develop means to search for life elsewhere in the universe. As part of the Mariner missions, NASA wanted Lovelock to design apparatus that could be sent to other worlds and search for life (and I think he did help do that), but Lovelock pointed out that one could tell if a planet had life by a spectroscopic analysis.
Any alien species analysing light passing through earth's atmosphere would see its composition was far from chemical equilibrium due to the ongoing activity of its biota. (If life were to cease on earth today, the oxygen content of the atmosphere would very quickly fall from 21% to virtually none at all as oxygen reacts with rocks and other materials.) If the composition of an atmosphere seemed to be in chemical equilibrium, then it was unlikely there was life. However, if there were high concentrations of gases that should react together or with the surface, then something, likely life, must be actively maintaining that combination of gases in the atmosphere.
"Living systems maintain themselves in a state of relatively low entropy at the expense of their nonliving environments. We may assume that this general property is common to all life in the solar system. On this assumption, evidence of a large chemical free energy gradient between surface matter and the atmosphere in contact with it is evidence of life. Furthermore, any planetary biota which interacts with its atmosphere will drive that atmosphere to a state of disequilibrium which, if recognized, would also constitute direct evidence of life, provided the extent of the disequilibrium is significantly greater than abiological processes would permit. It is shown that the existence of life on Earth can be inferred from knowledge of the major and trace components of the atmosphere, even in the absence of any knowledge of the nature or extent of the dominant life forms. Knowledge of the composition of the Martian atmosphere may similarly reveal the presence of life there."
Dian R. Hitchcock and James E. Lovelock – from Lovelock's website (originally published in Icarus: International Journal of the Solar System in 1967)
The story was that NASA did not really want to be told they did not need to send missions with spacecraft to other words such as Mars to look for life, rather that they only had to point a telescope and analyse the spectrum of radiation. Ironically, perhaps, then, that is exactly what they are now doing with planets around other star systems where it is not feasible (not now, perhaps not ever) to send missions.
Gaia and Gaia
But Lovelock became best known for his development and championing of the Gaia theory. According to Gaia (the theory, not the journalist), the development of life on earth has shaped the environment (and not just exploited pre-existing niches) and developed as a huge integrated and interacting system (the biota, but also the seas, the atmosphere, freshwater, the soil,…) such that large scale changes in one part of the system have knock-on effect elsewhere. *4
So, Gaia can be understood not as the whole earth as a planet, or just the biota as the collective life in terms of organisms, but rather as the dynamic system of life of earth and the environment it interacts with. In a sense (and it is important to see this is meant as an analogy, a thinking tool) Gaia is like some supra-organism. Just as snail has a shell that it has produced for its self, Gaia has shaped the biosphere where the biota lives. *4
The system has built in feedback cycles to protect it from perturbations (not by chance, or due to some mysterious power, but due to natural selection) but if it is subject to a large enough input it would shift to a new (and perhaps very different) equilibrium state. *5 This certainly happened when oxygen releasing organisms evolved: the earth today is inhospitable to the organisms that lived here before that event (some survived to leave descendants, but only in places away from the high oxygen concentrations, such as in lower lays of mud beneath the sea), and most organisms alive today would die very quickly in the previous conditions.
It would be nice to think that Gaia, the science journalist that is, was named after the Gaia theory – but Lovelock only started publishing about his Gaia hypothesis about the time that Gaia was born.*6 So, probably not. Gaia is a traditional girl's name, and was the name of the Greek goddess who personified the earth (which is why the name was adopted by Lovelock).
Still, it was poignant to hear a NASA scientist referring to the current value of a method first pointed out by Lovelock when advising NASA in the 1970s and informed by his early thinking about the Gaia hypothesis. NASA might be said to now be engaged in looking for other Gaias on worlds outside our own solar system, as Dr Milam explained to – another – Gaia here on earth.
Notes:
*1 It is an implicit comparison, because the listener/reader is left to appreciate that it is meant as a figure of speech: unlike in a simile ('a spectrum is like a fingerprint') where the comparison is made explicit .
*2 For some years I had a pager (common before mobile phones) – a small electronic device which could receive a text message, so that my wife could contact me in an emergency if I was out visiting schools by phoning a message to be conveyed by a radio signal. If I had been asked why it was called a pager, I would have assumed that each message of text was considered to comprise a 'page'.
However, a few weeks ago I watched an old 'screwball comedy' being shown on television: 'My favourite wife' (or 'My favorite [sic] wife' in US release).
(On the very day that Cary Grant remarries after having his first wife, long missing after being lost at sea, declared legally dead, wife number one reappears having been rescued from a desert island. That this is a very unlikely scenario was played upon when the film was remade in colour, as 'Move Over Darling', with Doris Day and James Garner. The returned first wife, pretending to be a nurse, asks the new wife if she is not afraid the original wife would reappear, as happened in that movie; eliciting the response: 'Movies. When do movies ever reflect real life?')
Some of the action takes place in the honeymoon hotel where groom has disappeared from the suite (these are wealthy people!) having been tracked down by his first wife. The new wife asks the hotel to page him – and this is how that worked with pre-electronic technology:
Paging Mr Arden: Still from 'My Favorite Wife'
*3 So, although I knew Lovelock had died (July 26th), he was still alive at the time of the original broadcast (July 14th). In part, my tardiness comes from the publicly funded BBC's decisions to no longer make available downloads of some of its programmes for iPods and similar devices immediately after broadcast. (This downgrading of the BBC's service to the public seems to be to persuade people to use its own streaming service.)
*4 The Gaia theory developed by Lovelock and Lyn Margulis includes ideas that were discussed by Vladimir Vernadsky almost a century ago. Although Vernadsky's work was well known in scientific circles in the Soviet Union, it did not become known to scientists in Western Europe till much later. Vernadsky used the term 'biosphere' to refer to those 'layers' of the earth (lower atmosphere to outer crust) where life existed.
*5 A perturbation such as as extensive deforestation perhaps, or certainly increasing the atmospheric concentrations of 'greenhouse' gases beyond a certain point.
*6 Described as a hypothesis originally, it has been extensibility developed and would seem to now qualify as a theory (a "consistent, comprehensive, coherent and extensively evidenced explanation of aspects of the natural world") today.
Faster-than-light electrons race from a sitting start and are baked to give off light brighter than millions of suns that can be used to image tiny massage balls: A case of science communication
Keith S. Taber
(The pedantic science teacher)
Ockham's razor
Ockham's razor (also known as Occam's razor) is a principle that is sometimes applied as a heuristic in science, suggesting that explanations should not be unnecessarily complicated. Faced with a straightforward explanation, and an alternative convoluted explanation, then all other things being equal we should prefer the former – not simply accept it, but to treat is as the preferred hypothesis to test out first.
Ockham's Razor is also an ABC radio show offering "a soap box for all things scientific, with short talks about research, industry and policy from people with something thoughtful to say about science". The show used to offer recorded essays (akin to the format of BBC's A Point of View), but now tends to record short live talks.
I've just listened to an episode called The 'science donut' – in fact I listened several time as I thought it was fascinating – as in a few minutes there was much to attend to.
I approached the episode as someone with an interest in science, of course, but also as an educator with an ear to the ways in which we communicate science in teaching. Teachers do not simply present sequences of information about science, but engage pedagogy (i.e., strategies and techniques to support learning). Other science communicators (whether journalists, or scientists themselves directly addressing the public) use many of the same techniques. Teaching conceptual material (such as science principles, theories, models…) can be seen as making the unfamiliar familiar, and the constructivist perspective on how learning occurs suggests this is supported by showing the learner how that which is currently still unfamiliar, is in some way like something familiar, something they already have some knowledge/experience of.
Science communicators may not be trained as teachers, so may sometimes be using these techniques in a less considered or even less deliberate manner. That is, people use analogy, metaphor, simile, and so forth, as a normal part of everyday talk to such an extent that these tropes may be generated automatically, in effect, implicitly. When we are regularly talking about an area of expertise we almost do not have to think through what we are going to say. 1
Science communicators also often have much less information about their audience than teachers: a radio programme/podcast, for example, can be accessed by people of a wide range of background knowledge and levels of formal qualifications.
One thing teachers often learn to do very early in their careers is to slow down the rate of introducing new information, and focus instead on a limited number of key points they most want to get across. Sometimes science in the media is very dense in the frequency of information presented or the background knowledge being drawn upon. (See, for example, 'Genes on steroids? The high density of science communication'.)
A beamline scientist
Dr Emily Finch, who gave this particular radio talk, is a beamline scientist at the Australian Synchrotron. Her talk began by recalling how her family visited the Synchrotron facility on an open day, and how she later went on to work there.
She then gave an outline of the functioning of the synchrotron and some examples of its applications. Along the way there were analogies, metaphors, anthropomorphism, and dubiously fast electrons.
The creation of the god particle
To introduce the work of the particle accelerator, Dr Finch reminded her audience of the research to detect the Higgs boson.
"Do you remember about 10 years ago scientists were trying to make the Higgs boson particle? I see some nods. They sometimes call it the God particle and they had a theory it existed, but they had not been able to prove it yet. So, they decided to smash together two beams of protons to try to make it using the CERN large hadron collider in Switzerland…You might remember that they did make a Higgs boson particle".
This is a very brief summary of a major research project that involved hundreds of scientists and engineers from a great many countries working over years. But this abbreviation is understandable as this was not Dr Finch's focus, but rather an attempt to link her actual focus, the Australian Synchrotron, to something most people will already know something about.
However, aspects of this summary account may have potential to encourage the development of, or reinforce an existing, common alternative conception shared by many learners. This is regarding the status of theories.
In science, theories are 'consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world', yet students often understand theories to be nothing more than just ideas, hunches, guesses – conjectures at best (Taber, Billingsley, Riga & Newdick, 2015). In a very naive take on the nature of science, a scientist comes up with an idea ('theory') which is tested, and is either 'proved' or rejected.
This simplistic take is wrong in two regards – something does not become an established scientific theory until it is supported by a good deal of evidence; and scientific ideas are not simply proved or disproved by testing, but rather become better supported or less credible in the light of the interpretation of data. Strictly scientific ideas are never finally proved to become certain knowledge, but rather remain as theories. 2
In everyday discourse, people will say 'I have a theory' to mean no more that 'I have a suggestion'. A pedantic scientist or science teacher might be temped to respond: "no you don't, not yet,"
This is sometimes not the impression given by media accounts – presumably because headlines such as 'research leads to scientist becoming slightly more confident in theory' do not have the same impact as 'cure found', 'discovery made, or 'theory proved'.
The message that could be taken away here is that scientists had the idea that Higgs boson existed, but they had not been able to prove it till they were able to make one. But the CERN scientists did not have a Higgs boson to show the press, only the data from highly engineered detectors, analysed through highly complex modelling. Yet that analysis suggested they had recorded signals that closely matched what they expected to see when a short lived Higgs decayed allowing them to conclude that it was very likely one had been formed in the experiment. The theory motivating their experiment was strongly supported – but not 'proved' in an absolute sense.
The doughnut
Dr Finch explained that
"we do have one of these particle accelerators here in Australia, and it's called the Australian Synchrotron, or as it is affectionately known the science donut
…our synchrotron is a little different from the large hadron collider in a couple of main ways. So, first, we just have the one beam instead of two. And second, our beam is made of electrons instead of protons. You remember electrons, right, they are those tiny little negatively charged particles and they sit in the shells around the atom, the centre of the atom."
One expects that members of the audience would be able to respond to this description and (due to previous exposure to such representations) picture images of atoms with electrons in shells. 'Shells' is of course a kind of metaphor here, even if one which with continual use has become a so-called 'dead metaphor'. Metaphor is a common technique used by teachers and other communicators to help make the unfamiliar familiar. In some simplistic models of atomic structure, electrons are considered to be arranged in shells (the K shell, the L shell, etc.), and a simple notation for electronic configuration based on these shells is still often used (e.g., Na as 2.8.1).
However, this common way of talking about shells has the potential to mislead learners. Students can, and sometimes do, develop the alternative conception that atoms have actual physical shells of some kind, into which the electrons are located. The shells scientists refer to are abstractions, but may be misinterpreted as material entities, as actual shells. The use of anthropomorphic language, that is that the electrons "sit in the shells", whilst helping to make the abstract ideas familiar and so perhaps comfortable, can reinforce this. After all, it is difficult to sit in empty space without support.
The subatomic grand prix?
Dr Finch offers her audience an analogy for the synchrotron: the electrons "are zipping around. I like to think of it kind of like a racetrack." Analogy is another common technique used by teachers and other communicators to help make the unfamiliar familiar.
Dr Finch refers to the popularity of the Australian Formula 1 (F1) Grand Prix that takes place in Melbourne, and points out
"Now what these race enthusiasts don't know is that just a bit further out of the city we have a race track that is operating six days a week that is arguably far more impressive.
That's right, it is the science donut. The difference is that instead of having F1s doing about 300 km an hour, we have electrons zipping around at the speed of light. That's about 300 thousand km per second.
There is an interesting slippage – perhaps a deliberate rhetoric flourish – from the synchrotron being "kind of like a racetrack" (a simile) to being "a race track" (a metaphor). Although racing electrons lacks a key attraction of an F1 race (different drivers of various nationalities driving different cars built by competing teams presented in different livery – whereas who cares which of myriad indistinguishable electrons would win a race?) that does not undermine the impact of the mental imagery encouraged by this analogy.
This can be understood as an analogy rather than just a simile or metaphor as Dr Finch maps out the comparison:
[Many in the audience would have known that the Melbourne Grand Prix takes place on a 'street circuit' that is only set up for racing one weekend each year.]
racing electrons
racing 'F1s' (i.e., Grand Prix cars)
at the speed of light
at about 300 km an hour
An analogy between the Australian Synchrotron and the Melbourne Grand Prix circuit
So, here is an attempt to show how science has something just like the popular race track, but perhaps even more impressive – generating speeds orders of magnitude greater than even Lewis Hamilton could drive.
They seem to like their F1 comparisons at the Australian Synchrotron. I found another ABC programme ('The Science Show') where Nobel Laureate "Brian Schmidt explains, the synchrotron is not being used to its best capability",
"the analogy here is that we invested in a $200 million Ferrari and decided that we wouldn't take it out of first gear and do anything other than drive it around the block. So it seems a little bit of a waste"
Brian Schmidt (Professor of Astronomy, and Vice Chancellor, at Australian National University)
A Ferrari being taken for a spin around the block in Melbourne (Image by Lee Chandler from Pixabay )
How fast?
But did Dr Finch suggest there that the electrons were travelling at the speed of light? Surely not? Was that a slip of the tongue?
"So, we bake our electrons fresh in-house using an electron gun. So, this works like an old cathode ray tube that we used to have in old TVs. So, we have this bit of tungsten metal and we heat it up and when it gets red hot it shoots out electrons into a vacuum. We then speed up the electrons, and once they leave the electron gun they are already travelling at about half the speed of light. We then speed them up even more, and after twelve metres, they are already going at the speed of light….
And it is at this speed that we shoot them off into a big ring called the booster ring, where we boost their energy. Once their energy is high enough we shoot them out again into another outer ring called the storage ring."
So, no, the claim is that the electrons are accelerated to the speed of light within twelve metres, and then have their energy boosted even more.
But this is contrary to current physics. According to the currently accepted theories, and specifically the special theory of relativity, only entities which have zero rest mass, such as photons, can move at the speed of light.
Electrons have a tiny mass by everyday standards (about 0.000 000 000 000 000 000 000 000 001 g), but they are still 'massive' particles (i.e., particles with mass) and it would take infinite energy to accelerate a single tiny electron to the speed of light. So, given our current best understanding, this claim cannot be right.
I looked to see what was reported on the website of the synchrotron itself.
The electron beam travels just under the speed of light – about 299,792 kilometres a second.
Strictly the electrons do not travel at the speed of light but very nearly the speed of light.
The speed of light in a vacuum is believed to be 299 792 458 ms-1 (to the nearest metre per second), but often in science we are working to limited precision, so this may be rounded to 2.998 ms-1 for many purposes. Indeed, sometimes 3 x 108 ms-1 is good enough for so-called 'back of the envelope' calculations. So, in a sense, Dr Finch was making a similar approximation.
But this is one approximation that a science teacher might want to avoid, as electrons travelling at the speed of light may be approximately correct, but is also thought to be physically impossible. That is, although the difference in magnitude between
(i) the maximum electron speeds achieved in the synchrotron, and
(ii) the speed of light,
might be a tiny proportional difference – conceptually the distinction is massive in terms of modern physics. (I imagine Dr Finch is aware of all this, but perhaps her background in geology does not make this seem as important as it might appear to a physics teacher.)
Dr Finch does not explicitly say that the electrons ever go faster than the speed of light (unlike the defence lawyer in a murder trial who claimed nervous impulses travel faster than the speed of light) but I wonder how typical school age learners would interpret "they are already going at the speed of light….And it is at this speed that we shoot them off into a big ring called the booster ring, where we boost their energy". I assume that refers to maintaining their high speeds to compensate for energy transfers from the beam: but only because I think Dr Finch cannot mean accelerating them beyond the speed of light. 3
The big doughnut
After the reference to how "we bake our electrons fresh in-house", Dr Finch explains
And so it is these two rings, these inner and outer rings, that give the synchrotron its nick name, the science donut. Just like two rings of delicious baked electron goodness…
So, just to give you an idea of scale here, this outer ring, the storage ring, is about forty one metres across, so it's a big donut."
So, there is something of an extended metaphor here. The doughnut is so-called because of its shape, but this doughnut (a bakery product) is used to 'bake' electrons.
If audience members were to actively reflect on and seek to analyse this metaphor then they might notice an incongruity, perhaps a mixed metaphor, as the synchrotron seems to shift from being that which is baked (a doughnut) to that doing the baking (baking the electrons). Perhaps the electrons are the dough, but, if so, they need to go into the oven.
But, of course, humans implicitly process language in real time, and poetic language tends to be understood intuitively without needing reflection. So, a trope such as this may 'work' to get across the flavour (sorry) of an idea, even if under close analysis (by our pedantic science teacher again) the metaphor appears only half-baked.
Perverting the electrons
Dr Finch continued
"Now the electrons like to travel in straight lines, so to get them to go round the rings we have to bend them using magnets. So, we defect the electrons around the corners [sic] using electromagnetic fields from the magnets, and once we do this the electrons give off a light, called synchrotron light…
Now electrons are not sentient and do not have preferences in the way that someone might prefer to go on a family trip to the local synchrotron rather than a Formula 1 race. Electrons do not like to go in straight lines. They fit with Newton's first law – the law of inertia. An electron that is moving ('travelling') will move ('travel') in a straight line unless there is net force to pervert it. 4
If we describe this as electrons 'liking' to travel in straight lines it would be just as true to say electrons 'like' to travel at a constant speed. Language that assigns human feelings and motives and thoughts to inanimate objects is described as anthropomorphic. Anthropomorphism is a common way of making the unfamiliar familiar, and it is often used in relation to molecules, electrons, atoms and so forth. Sadly, when learners pick up this kind of language, they do not always appreciate that it is just meant metaphorically!
Whether the radiation is 'captured' is a moot point, as it no longer exists once it has been detected. But what caught my attention here was the claim that the synchrotron radiation was brighter than a million suns. Not because I necessarily thought this bold claim was 'wrong', but rather I did not understand what it meant.
The statement seems sensible at first hearing, and clearly it means qualitatively that the radiation is very intense. But what did the quantitative comparison actually mean? I turned again to the synchrotron webpage. I did not find an answer there, but on the site of a UK accelerator I found
"These fast-moving electrons produce very bright light, called synchrotron light. This very intense light, predominantly in the X-ray region, is millions of times brighter than light produced from conventional sources and 10 billion times brighter than the sun."
Sunlight spreads out and its intensity drops according to an inverse square law. Move twice as far away from a sun, and the radiation intensity drops to a quarter of what it was when you were closer. Move to ten times as far away from the sun than before, and the intensity is 1% of what it was up close.
The synchrotron 'light' is being shaped into a beam "like a LASER". A LASER produces a highly collimated beam – that is, the light does not (significantly) spread out. This is why football hooligans choose LASER pointers rather than conventional torches to intimidate players from a safe distance in the crowd.
Comparing light with like
This is why I do not understand how the comparison works, as the brightness of a sun depends how close you are too it – a point previously discussed here in relation to NASA's Parker solar probe (NASA puts its hand in the oven). If I look out at the night sky on a clear moonlight night then surely I am exposed to light from more "than a million suns" but most of them are so far away I cannot even make them out. Indeed there are faint 'nebulae' I can hardly perceive that are actually galaxies shining with the brightness of billions of suns. 5 If that is the comparison, then I am not especially impressed by something being "brighter than a million suns".
How bright is the sun? it depends which planet you are observing from. (Images by AD_Images and Gerd Altmann from Pixabay)
We are told not to look directly at the sun as it can damage our eyes. But a hypothetical resident of Neptune or Uranus could presumably safely stare at the sun (just as we can safely stare at much brighter stars than our sun because they are so far away). So we need to ask :"brighter than a million suns", as observed from how far away?
How bright is the sun? That depends on viewing conditions (Image by UteHeineSch from Pixabay)
Even if referring to our Sun as seen from the earth, the brightness varies according to its apparent altitude in the sky. So, "brighter than a million suns" needs to be specified further – as perhaps "more than a million times brighter than the sun as seen at midday from the equator on a cloudless day"? Of course, again, only the pedantic science teacher is thinking about this: everyone knows well enough what being brighter than a million suns implies. It is pretty intense radiation.
Applying the technology
Dr Finch went on to discuss a couple of applications of the synchrotron. One related to identifying pigments in art masterpieces. The other was quite timely in that it related to investigating the infectious agent in COVID.
"Now by now you have probably seen an image of the COVID virus – it looks like a ball with some spikes on it. Actually it kind of looks like those massage balls that your physio makes you buy when you turn thirty and need to to ease all your physical ailments that you suddenly have."
Coronavirus particles and massage balls…or is it… (Images by Ulrike Leone and Daniel Roberts from Pixabay)
Again there is an attempt to make the unfamiliar familiar. These microscopic virus particles are a bit like something familiar from everyday life. Such comparisons are useful where the everyday object is already familiar.
By now I've seen plenty of images of the coronavirus responsible for COVID, although I do not have a physiotherapist (perhaps this is a cultural difference – Australians being so sporty?) So, I found myself using this comparison in reverse – imagining that the "massage balls that your physio makes you buy" must be like larger versions of coronavirus particles. Having looked up what these massage balls (a.k.a. hedgehog balls it seems) look like, I can appreciate the similarity. Whether the manufacturers of massage balls will appreciate their products being compared to enormous coronavirus particles is, perhaps, another matter.
Work cited:
Taber, K. S., Billingsley, B., Riga, F., & Newdick, H. (2015). English secondary students' thinking about the status of scientific theories: consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world – or just 'an idea someone has'. The Curriculum Journal, 1-34. doi: 10.1080/09585176.2015.1043926
Notes:
1 At least, depending how we understand 'thinking'. Clearly there are cognitive processes at work even when we continue a conversation 'on auto pilot' (to employ a metaphor) whilst consciously focusing on something else. Only a tiny amount of our cognitive processing (thinking?) occurs within conscousness where we reflect and deliberate (i.e., explicit thinking?) We might label the rest as 'implicit thinking', but this processing varies greatly in its closeness to deliberation – and some aspects (for example, word recognition when listening to speech; identifying the face of someone we see) might seem to not deserve the label 'thinking'?
2 Of course the evidence for some ideas becomes so overwhelming that in principle we treat some theories as certain knowledge, but in principle they remain provisional knowledge. And the history of science tells us that sometimes even the most well-established ideas (e.g., Newtonian physics as an absolutely precise description of dynamics; mass and energy as distinct and discrete) may need revision in time.
3 Since I began drafting this article, the webpage for the podcast has been updated with a correction: "in this talk Dr Finch says electrons in the synchrotron are accelerated to the speed of light. They actually go just under that speed – 99.99998% of it to be exact."
4 Perversion in the sense of the distortion of an original course
5 The term nebulae is today reserved for clouds of dust and gas seen in the night sky in different parts of our galaxy. Nebulae are less distinct than stars. Many of what were originally identified as nebulae are now considered to be other galaxies immense distances away from our own.
