A well-known Palestinian proverb reminds us that we do not fatten the cow simply by repeatedly weighing it. But, sadly, teachers and others working in education commonly get so fixated on assessment that it seems to become an end in itself.
Images by Clker-Free-Vector-Images from PixabayOpenClipart-Vectors and Deedster from Pixabay
A research study using P-O-E
I was reading a report of a study that adopted the predict-observe-explain, P-O-E, technique as a means to elicit "high school students' conceptions about acids and bases" (Kala, Yaman & Ayas, 2013, p.555). As the name suggests, P-O-E asks learners to make a prediction before observing some phenomenon, and then to explain their observations (something that can be specially valuable when the predictions are based on strongly held intuitions which are contrary to what actually happens).
Kala and colleagues begin the introduction to their paper by stating that
"In any teaching or learning approach enlightened by constructivism, it is important to infer the students' ideas of what is already known"
Kala, Yaman & Ayas, 2013, p.555
Constructivism?
Constructivism is a perspective on learning that is informed by research into how people learn and a great many studies into student thinking and learning in science. A key point is how a learner's current knowledge and understanding influences how they make sense of teaching and what they go on to learn. Research shows it is very common for students to have 'alternative conceptions' of science topics, and often these conceptions either survive teaching or distort how it is understood.
The key point is that teachers who teach the science without regard to student thinking will often find that students retain their alternative ways of thinking, so constructivist teaching is teaching that takes into account and responds to the ideas about science topics that students bring to class.
If teachers are to take into account, engage with, and try to reshape, learners ideas about science topics, then they need to know what those ideas are. Now there is a vast literature reporting alternative conceptions in a wide range of science topics, spread across thousands or research reports – but no teacher could possibly find time to study them all. There are books which discuss many examples and highlight some of the most common alternative conceptions (including one of my own, Taber, 2014)
However, in any class studying some particular topic there will nearly always be a spread of different alternative conceptions across the students – including some so idiosyncratic that they have never been reported in any literature. So, although reading about common misconceptions is certainly useful to prime teachers for what to look out for, teachers need to undertake diagnostic assessment to find out about the thinking of their own particular students.
There are many resources available to support teachers in diagnostic assessment, and some activities (such as using concept cartoons) that are especially useful at revealing student thinking.
Diagnostic assessment, assessment to inform teaching, is carried out at the start of a topic, before the teaching, to allow teachers to judge the learners' starting points and any alternative conceptions ('misconceptions') they may have. It can therefore be considered aligned to formative assessment ('assessment for learning') which is carried out as part of the learning process, rather than summative assessment (assessment of leaning) which is used after studying to check, score, grade and certify learning.
P-O-E as a learning activity…
P-O-E can best support learning in topics where it is known learners tend to have strongly held, but unhelpful, intuitions. The predict stage elicits students' expectations – which, when contrary to the scientific account, can be confounded by the observe step. The 'cognitive conflict' generated by seeing something unexpected (made more salient by having been asked to make a formal prediction) is thought to help students concentrate on that actual phenomena, and to provide 'epistemic relevance' (Taber, 2015).
Epistemic relevance refers to the idea that students are learning about things they are actually curious about, whereas for many students following a conventional science course must be experienced as being presented with the answers to a seemingly never-ending series questions that had never occurred to them in the first place.
Students are asked to provide an explanation for what they have observed which requires deeper engagement than just recording an observation. Developing explanations is a core scientific practice (and one which is needed before another core scientific practice – testing explanations – is possible).
To be most effective, P-O-E is carried out in small groups, as this encourages the sharing, challenging and justifying of ideas: the kind of dialogic activity thought to be powerful in supporting learners in developing their thinking, as well as practicing their skills in scientific argumentation. As part of dialogic teaching such an open-forum for learners' ideas is not an end in itself, but a preparatory stage for the teacher to marshal the different contributions and develop a convincing argument for how the best account of the phenomenon is the scientific account reflected in the curriculum.
Constructivist teaching is informed by learners' ideas, and therefore relies on their elicitation, but that elicitation is never the end in itself but is a precursor to a customised presentation of the canonical account.
Group work also has another function – if the activity is intended to support diagnostic assessment, then the teacher can move around the room listening in to the various discussions and so collecting valuable information on what students think and understand. When assessment is intended to inform teaching it does not need to be about students completing tests and teachers marking them – a key principle of formative assessment is that it occurs as a natural part of the teaching process. It can be based on productive learning activities, and does not need marks or grades – indeed as the point is to help students move on in their thinking, any kind of formal grading whilst learning is in progress would be inappropriate as well as a misuse of teacher time.
Probing students' understandings about acid-base chemistry
The constructivist model of learning applies to us all: students, teachers, professors, researchers. Given what I have written above about P-O-E, about diagnostic assessment, and dialogic approaches to learning, I approached Kala and colleagues' paper with expectations about how they would have carried out their project.
These authors do report that they were able to diagnose aspects of student thinking about acids and bases, and found some learning difficulties and alternative conceptions,
"it was observed that eight of the 27 students had the idea that the "pH of strong acids is the lowest every time," while two of the 27 students had the idea that "strong acids have a high pH." Furthermore, four of the 27 students wrote the idea that the "substance is strong to the extent to which it is burning," while one of the 27 students mentioned the idea that "different acids which have equal concentration have equal pH."
Kala, Yaman & Ayas, 2013, pp.562-3
The key feature seems to be that, as reported in previous research, students conflate acid concentration and acid strength (when it is possible to have a high concentration solution of a weak acid or a very dilute solution of a strong acid).
Yet some aspects of this study seemed out of alignment with the use of P-O-E.
The best research style?
One feature was the adoption of a positivistic approach to the analysis,
Although there has been no reported analyzing procedure for the POE, in this study, a different [sic] analyzing approach was offered taking into account students' level of understanding… Data gathered from the written responses to the POE tasks were analyzed and divided into six groups. In this context, while students' prediction were divided into two categories as being correct or wrong, reasons for predictions were divided into three categories as being correct, partially correct, or wrong.
Kala, Yaman & Ayas, 2013, pp.560
Group
Prediction
Reasons
❀
correct
correct
❁
correct
partially correct
✯
correct
wrong
✿
wrong
correct
❂
wrong
partially correct
✤
wrong
wrong
"the written responses to the POE tasks were analyzed and divided into six groups"
There is nothing inherently wrong with doing this, but it aligns the research with an approach that seems at odds with the thinking behind constructivist studies that are intended to interpret a learner's thinking in its own terms, rather than simply compare it with some standard. (I have explored this issue in some detail in a comparison of two research studies into students' conceptions of forces – see Taber, 2013, pp.58-66.)
In terms of research methodology we might say it seem to be conceptualised within the 'wrong' paradigm for this kind of work. It seems positivist (assuming data can be unambiguously fitted into clear categories), nomothetic (tied to 'norms' and canonical answers) and confirmatory (testing thinking as matching model responses or not), rather than interpretivist (seeking to understand student thinking in its own terms rather than just classifying it as right or wrong), idiographic (acknowledging that every learner's thinking is to some extent unique to them) and discovery (exploring nuances and sophistication, rather than simply deciding if something is acceptable or not).
The approach used seemed more suitable for investigating something in the science laboratory, than the complex, interactive, contextualised, and ongoing life of classroom teaching. Kala and colleagues describe their methodology as case study,
"The present study used a case study because it enables the giving of permission to make a searching investigation of an event, a fact, a situation, and an individual or a group…"
Kala, Yaman & Ayas, 2013, pp.558
A case study?
Case study is a naturalistc methodology (rather than involving an intervention, such as an experiment), and is idiographic, reflecting the value of studying the individual case. The case is one from among many instances of its kind (one lesson, one school, one examination paper, etc.), and is considered as a somewhat self contained entity yet one that is embedded in a context in which it is to some extent entangled (for example, what happens in a particular lesson is inevitably somewhat influenced by
the earlier sequence of lessons that teacher taught that class {the history of that teacher with that class},
the lessons the teacher and student came from immediately before this focal lesson,
Although a lesson can be understood as a bounded case (taking place in a particular room over a particular period of time involving a specified group of people) it cannot be isolated from the embedding context.
Case study – study of one instance from among many
As case study is idiographic, and does not attempt to offer direct generalisation to other situations beyond that case, a case study should be reported with 'thick description' so a reader has a good mental image of the case (and can think about what makes it special – and so what makes it similar to, or different from, other instances the reader may be interested in). But that is lacking in Kala and colleagues' study, as they only tell readers,
"The sample in the present study consisted of 27 high school students who were enrolled in the science and mathematics track in an Anatolian high school in Trabzon, Turkey. The selected sample first studied the acid and base subject in the middle school (grades 6 – 8) in the eighth year. Later, the acid and base topic was studied in high school. The present study was implemented, based on the sample that completed the normal instruction on the acid and base topic."
Kala, Yaman & Ayas, 2013, pp.558-559
The reference to a sample can be understood as something of a 'reveal' of their natural sympathies – 'sample' is the language of positivist studies that assume a suitably chosen sample reflects a wider population of interest. In case study, a single case is selected and described rather than a population sampled. A reader is left to rather guess what population being sampled here, and indeed precisely what the 'case' is.
Clearly, Kala and colleagues elicited some useful information that could inform teaching, but I sensed that their approach would not have made optimal use of a learning activity (P-O-E) that can give insight into the richness, and, sometimes, subtlety of different students' ideas.
Individual work
Even more surprising was the researchers' choice to ask students to work individually without group discussion.
"The treatment was carried out individually with the sample by using worksheets."
Kala, Yaman & Ayas, 2013, p.559
This is a choice which would surely have compromised the potential of the teaching approach to allow learners to explore, and reveal, their thinking?
I wondered why the researchers had made this choice. As they were undertaking research, perhaps they thought it was a better way to collect data that they could readily analyse – but that seems to be choosing limited data that can be easily characterised over the richer data that engagement in dialogue would surely reveal?
Assessment habits
All became clear near the end of the study when, in the final paragraph, the reader is told,
"In the present study, the data collection instruments were used as an assessment method because the study was done at the end of the instruction/ [sic] on the acid and base topics."
Kala, Yaman & Ayas, 2013, p.571
So, it appears that the P-O-E activity, which is an effective way of generating the kind of rich but complex data that helps a teacher hone their teaching for a particular group, was being adopted, instead, as means of a summative assessment. This is presumably why the analysis focused on the degree of match to the canonical science, rather than engaging in interpreting the different ways of thinking in the class. Again presumably, this is why the highly valuable group aspect of the approach was dropped in favour of individual working – summative assessment needs to not only grade against norms, but do this on the basis of each individual's unaided work.
An activity which offers great potential for formative assessment (as it is a learning activity as well as a way of exploring student thinking); and that offers an authentic reflection of scientific practice (where ideas are presented, challenged, justified, and developed in response to criticism); and that is generally enjoyed by students because it is interactive and the predictions are 'low stakes' making for a fun learning session, was here re-purposed to be a means of assessing individual students once their study of a topic was completed.
Kala and colleagues certainly did identify some learning difficulties and alternative conceptions this way, and this allowed them to evaluate student learning. But I cannot help thinking an opportunity was lost here to explore how P-O-E can be used in a formative assessment mode to inform teaching:
Yes, I agree that "in any teaching or learning approach enlightened by constructivism, it is important to infer the students' ideas of what is already known", but the point of that is to inform the teaching and so support student learning. What were Kala and colleagues going to do with their inferences about students ideas when they used the technique as "an assessment method … at the end of the instruction".
As the Palestinian adage goes, you do not fatten up the cow by weighing it, just as you do not facilitate learning simply by testing students. To mix my farmyard allusions, this seems to be a study of closing the barn door after the horse has already bolted.
Work cited
Kala, N., Yaman, F., & Ayas, A. (2013). The effectiveness of predict-observe-explain technique in probing students' understanding about acid-base chemistry: a case for the concepts of pH, pOH, and strength. International Journal of Science and Mathematics Education, 11(3), 555-574. https://doi.org/10.1007/s10763-012-9354-z
"…I am older than I once was And younger than I'll be But that's not unusual No, it isn't strange After changes upon changes We are more or less the same After changes we are more or less the same…"
From the lyrics of 'The Boxer' (Simon and Garfunkel song) by Paul Simon
In a recent post I discussed the treatment of Newtonian forces in a book (Thomson, 2005) about the history of natural theology (a movement which sought to study the natural world as kind of religious observance – seeking to glorify God by the study of His works) and its relationship to the development of evolutionary theory.
The book was written by a prestigious scientist, who had held Professorships at both Yale in the US and at Oxford. Yet the book contained some erroneous physics – 'howlers' of the kind that are sometimes called 'schoolboy errors' (as presumably most schoolgirls would be careful not to make them?)
My point is not to imply that this is a poor read – the book has much to commend it, and I certainly thought it was worth my time. I found it an informative read, and I have no reason to assume that the author's scholarship in examining the historical sources was was not of the highest level – even if his understanding of some school physics seemed questionable. I think this highlights two features of science:
Science is so vast that research scientists setting out to write 'popular' science books for a general readership risk venturing into areas outside their specialist knowledge – areas where they may lack expertise 1
Some common alternative conceptions ('misconceptions') are so insidious that we confidently feel we understand the science we have been taught whilst continuing to operate with intuitions at odds with the science.
Out of specialism
In relation to the first point, I previously highlighted a reference to "Einstein's relativity theory" being part of quantum physics, and later in the book I found another example of a non-physicist confusing two ideas that may seem similar to the non-specialist but which to a physicist should not be confused:
"In the 1930s, Arthur Holmes worked out the geology of the mechanism [underpinning plate tectonics] and the fact that the earth's inner heat (like that of the sun) comes from atomic fission." p.190
Thomson, 2005: 190
The earth contains a good deal of radioactive material which, through atomic fission, heats up the earth from within. This activity has contributed to the, initially hot, earth cooling much more slowly than had once been assumed – most notably according to modelling undertaken by Thomson's namesake, Lord Kelvin.2 Kelvin did not know about nuclear fission.
But the sun is heated by a completely different kind of nuclear reaction: fusion. The immense amount of energy 'released' during this process enables stars to burn for billions of years without running out of hydrogen fuel.3
Lord Kelvin did not know about that either, leading to him suggesting
"…on the whole most probable that the sun has not illuminated the earth for 100,000,000 years, and almost certain that he has not done so for 500,000,000 years"
Thomson, 1862
Kelvin suggested this was 'almost' but not 'absolutely' certain – a good scientist should always keep an open mind to the possibility of having missed something (take note, BBC's Nick Robinson).
We now think the sun has been 'illuminating' for about 4 600 000 000 years, almost ten times as long as Kelvin's upper limit. It may seem strange that a serious scientist should refer to the sun as 'he', but this kind of personification was once common in scientific writings.
The first atomic weapons were based on fission processes of the kind used in nuclear power stations.
Hydrogen bombs are much more devastating still, making use of fusion as occurs deep in the sun.
(Image by Gerd Altmann from Pixabay)
A non-scientist may feel this conflation of fission and fusion is a minor technical detail. But it is a very significant practical distinction.
For one thing the atomic bombs that were used to devastate Hiroshima and Nagasaki were fission devices. The next generation of atomic weapons, the 'hydrogen bombs' were very much more powerful – to the extent that they used a fission device as a kind of detonator to set off the main bomb! It is these weapons, fusion weapons, which mimic the processes at the centre of stars such as the sun.
…The rusty wire that holds the cork that keeps the anger in Gives way and suddenly it's day again The sun is in the east Even though the day is done Two suns in the sunset, hmph Could be the human race is run…
From the lyrics of 'Two suns in the sunset' (Pink Floyd song) by Roger Waters
In terms of peaceful technologies, fission-based nuclear power stations, whilst not using fossil fuels, have been a major concern because of the highly radioactive waste which will remain a high health risk for many thousands of years, and because of the dangers of radiation leaks – very real risks as shown by the Three Mile Island (USA) and Windscale (England) accidents, and much more seriously at Fukushima (Japan) and, most infamously, Chernobyl (then USSR, now Ukraine). There are also serious health and human rights issues dogging the mining of uranium ore, which is, of course, a declining resource.
For decades scientists have been trying to develop, as an alternative, nuclear fusion based power generation which would be a source of much cleaner and sustainable power supplies. This has proved very challenging because the conditions under which fusion takes place are so much more extreme. Critically, no material can hold the plasma at the extreme temperatures, so it has to be magnetically suspended well away from the containment vessel 'walls'.
The tenacious nature of some misconceptions
My second point, the insidious nature of some common alternative conceptions, is a challenge for science teachers as simply giving clear, accurate presentations with good examples may not be enough to bring about change in well-established and perhaps intuitive ways of thinking, even when students study hard and think they have learnt what has been taught.
I suggested this was reflected in Prof. Thomson's text (Keith, that is, not Sir William) in his use of references to Newton's ideas about force and motion. Prof. Thomson was not as a biologist therefore seeking to avoid referring to physics, but rather actively engaging with Newton's notions of inertia and the action of forces to make his points. Yet, also, seemingly misusing Newtonian mechanics because of a flawed understanding. Likely, as with many students, Prof. Thomson's intuitive physics was so strong that although he had studied Newton's laws, and can state them, when he came to apply them his own 'common-sense' conceptions of force and motion insidiously prevailed.
The point is not that Prof. Thomson has got the physics wrong (as research suggests most people do!) but that he was confident enough in his understanding to highlight Newtonian physics in his writing and, in effect, seek to teach his readers about it.
Newton's laws
What are commonly known as 'Newton' three laws of motion' can be glossed simply as:
N1: When no force is acting, an object does not change its motion: if stationary, it remains stationary; if moving, it carries on moving at the same speed in the same direction.
Indeed, this is also true if forces are acting, but they cancel because they are balanced, i.e.,
N1': When no net (overall, resultant) force is acting, an object does not change its motion: if stationary, it remains stationary; if moving, it carries on moving at the same speed in the same direction.
N2: When a net force is acting on a body it changes its motion in a way determined by the magnitude and direction of the force. (The change in velocity takes place in the direction of the force, and at a rate depending on the magnitude of the force).
So, if the force acts along the direction of motion, then the speed will change but not direction; but if the force acts in any other direction it will lead to a change in direction.
Strictly, the law relates to the 'rate of change of momentum' but assuming the mass of the body is fixed, we can think in terms of changes of velocity. 4
N3: Forces are interactions between two bodies/objects (that attract or repel each other): the same size force acts on both. (This is sometimes unfortunately phrased as 'every action having an equal and opposite reaction') 5.
These (perhaps) seem relatively simple, but there are complications in applying them. Very simply, the first law,when applied to moving bodies does not seem to fit our experience (moving bodies often seem to come to a stop by themselves – due to forces that we do not always notice).
The second law relates an applied force to a process of change, but it is very easy to instead think of the applied force directly leading to an outcome. That is people often equate the change in direction with the final direction. The change occurs in the direction of the force: that does not mean the final direction is the direction of the force.
The third law is commonly misapplied by assuming that if 'forces come in pairs' these will be balanced and cancel out. But they cannot cancel out because they are acting on the two bodies. (If your friend hits you in the eye after one too many pedantic complaints about her science writing you cannot avoid a black eye simply by hitting her back just as hard!)
A N3 force 'pair' does not balance out!
Often objects are in equilibrium because the forces acting on them are balanced. But they are never in equilibrium just because a force on them is also acting on another body! An apple hangs from a tree because the branch pulls it up the same amount as its weight pulls it down: these are two separate forces, each of which is also acting on the other body involved (the branch, and the earth, respectively).
"Any trajectory other than a straight line must be the result of multiple forces acting together."
"the concept of 'a balance of forces' keeping the moon circling the earth and the earth in orbit around the sun…
"a Newtonian balance of forces… rocks: gradually worn down by erosion, washed into the seas, accumulating as sediments, raised up as new dry land, only to be eroded again"
The first two statements are simply wrong according to conventional physics. Curved paths are often the result of a single force acting. The earth and moon orbit because they are both the subject of unbalanced forces.
Those two statements are contrary to N1 and N2.
The third statement seemed to suggest that a balance of forces was somehow considered to bring about changes. The suggestion appeared to be that a cycle of changes might be due to a balance of forces. But I acknowledged that "this reference to Hutton's ideas seems to preview a more detailed treatment of the new geology in a later chapter in the book (that I have not yet reached), so perhaps as I read on I will find a clearer explanation of what is meant by these changes being based on a theory of balance of forces".
Now I have finished the book, I wanted to address this.
A sort of balance
Prof. Thomson discusses developing ideas in geology about how the surface of the earth came to have its observed form. Today we are familiar with modern ideas about the structure of the earth, and continental drift, and most people have seen this represented in various ways.
Image by Venita Oberholster from PixabayImage by Clker-Free-Vector-Images from PixabayOriginal images by by Michel Müller from Pixabay
However, it was once widely assumed that the earth's surface was fairly static , but had been shaped by violent events in the distant past – a view sometimes called 'catastrophism'. One much referenced catastrophe was the flood associated with the biblical character Noah (of Ark fame) that was sometimes considered to have been world-wide deluge. (Those who considered this were aware that this required a source of water beyond normal rainfall – such as perhaps vast reservoirs of water escaping from underground).
The idea that the earth was continually changing, and that forces that acted continuously over vast periods of time could slowly (much too slowly for us to notice) lead to the formation of, for example, mountain ranges seemed less feasible.
Yet we now understand how the tectonic plates float on a more fluid layer of material and how these plates slowly collide or separate with the formation of new crust where they move apart. Vast forces are at work and change is constant, but there are cyclic processes such that ultimately nothing much changes.
Well, nothing much changes on a broad perspective. Locally of course, changes may be substantial: land may become submerged, or islands appear from the sea; mountains or great valleys may appear – albeit very, very slowly. But crust that is subsumed in one place will be balanced by crust formed elsewhere. And – just as walking from one side of a small boat to another will lead to one side rising out of the water, whilst the opposite side sinks deeper into the water – as land is raised in one place it will sink elsewhere.
This is the kind of model that scientists started to develop, and which Prof. Thomson discusses.
"[Dr John Woodward (1665-1728) produced] "an ingenious theory, parts of it quite modern, parts simply seventeenth century sophistry within a Newtonianmetaphor. Woodward's earth, post deluge, is stable, but not in fact unchanging. This is possible because it is in a sort of balance – a dynamic balance between opposing forces."
Thomson, 2005: 156
Plus ça change, plus c'est la même chose
James Hutton (1726 – 1797) was one of the champions of this 'uniformitarianism',
"Hutton's earth is in a constant state of flux due to processes acting over millions of years as mountains are eroded by rain and frost. In turn, the steady raising up of mountains, balances their steady reduction through erosion.
…for Hutton the evidence of the rocks demonstrated a cyclic history powered by Newtonian steady-state dynamics: the more it changed, the more it stayed the same." p.181
Thomson, 2005: 181
The more it changed, the more it stayed the same: plus ça change, plus c'est la même chose. This, of course, is an idiom that has found resonance with many commentators on the social, as well as the physical, world,
"…A change, it had to come We knew it all along We were liberated from the fold, that's all And the world looks just the same And history ain't changed 'Cause the banners, they all flown in the last war … There's nothing in the street Looks any different to me And the slogans are effaced, by-the-bye And the parting on the left Is now parting on the right And the beards have all grown longer overnight…"
From the lyrics of 'Won't get fooled again' (The Who song), by Pete Townsend
Steady states
So, there are vast forces acting, but the net effect is a planet which stays substantially the same over long periods of time. Which might be considered analogous to a body which is subject to very large forces, but in such a configuration that they cancel.
Where Prof. Thomson is in danger of misleading his reader is in confusing a static equilibrium and a macroscopic overall steady state that is the result of many compensating disturbances. This is an important difference when we consider energy and not just the forces acting.
A steady state can be maintained by nothing happening, or by several things happening which effectively compensate.
If we consider a very heavy mass sitting on a very study table, then the mass has a large weight, but does not fall because the table exerts a balancing upward reaction force. Although large forces are acting, nothing happens. In physics terms, no work is done. 6
Now consider a sealed cylinder, perfectly insulted and shielded from its surroundings, containing some water, air and too much salt to fully dissolve. It would reach a stead state where the
the mass of undissolved salt is constant
the height of the solution in the tube is constant
On a macroscopic level, nothing then happens – it is all pretty boring (especially as if the cylinder was perfectly insulated we would not be able to monitor it anyway!)
Actually, all the time,
salt is dissolving
salt is precipitating
gases from the air are dissolving in the solution
gases are leaving the solution
water is evaporating into the air
water vapour is condensing
But the rates of 1 and 2 are the same; the rates of 3 and 4 are the same; and the rates of 5 and 6 are the same. In terms of molecules and ions, there is a lot of activity – but in overall terms, nothing changes: we have a steady state, due to the dynamic equilibria between dissolving and precipitating; between dissolving and degassing; and between evaporation and condensation.
This activity is possible because of the inherent energy of the particles. In the various interactions between these particles a molecule is slowed here, an ion is released from electrical bonds – and so. But no energy transfer takes placeto or from the system, it is only constantly redistributed among the ensemble of particles. No work is done.
Cycling is hard work
But macroscopic stable states maintained by cyclic processes are not like that. A key difference is that in the geological cycles there are significant frictional effects. In our sealed cylinder, the processes will continue indefinitely as the energy of the system is constant. In the geological systems, change is only maintained because there is source of power – the sun drives the water cycle, radioactive decay in effect drives the rock cycle.
Work is done in forming new crust under the sea between two plates. More work is done pushing one plate beneath another at a plate boundary. It does not matter if the compensating changes were produced by identical magnitude forces pushing in opposite directions – these are not balanced forces in the sense of cancelling out (they act on different masses of material) – if they had been, nothing would have happened.
You cannot move tectonic plates around without doing a great deal of work – just as you cannot cycle effortlessly by using a circular track that brings you back to where you started, even though when cycling in one direction the ground was pushing you one way, and on the way back the ground was pushing you in the opposite direction! (Your tyres pushed on the track, and as Newton's third law suggests, it pushed back on the tyres in the opposite direction – but those equal forces did not cancel as they were acting on different things: or you would not have moved.)
Perhaps Prof. Thomson understands this, but his language is certainly likely to mislead readers:
"Hooke realised that there was a balance of forces: while the geological strata were being formed and mountains were raised up, at the same time the land was constantly being eroded…"
"the concept of 'a balance of forces' keeping the moon circling the earth and the earth in orbit around the sun"
"any trajectory other than a straight line must be the result of multiple forces acting together"
which suggests a genuine confusion about how forces act.
One of these mistakes is that planetary orbits (which require a net {unbalanced} force), are due to 'opposing forces',
"…Paley's tortured dancing on the heads of all these metaphysical pins is pre-shadowing of modern ecological thinking and a metaphysical extension of Hooke and Newton's explanation of planetary orbits in terms of opposing forces, or Woodward's theory of matter, or Hutton's geology – it is the living world as a dynamic system of force and counterforce, of checks and balances." p.242
Thomson, 2005: 242 (my emphasis)
The other was that a single force cannot lead to a curved path,
"…the philosophical concept of reduction, namely that any complex system can be reduced to the operation of simple causes. Thus the parabolic trajectory of a projectile is the product of two straight-line forces acting on each other [sic];…" p.264
Thomson, 2005: 264 (my emphasis)
Forces are interactions between bodies, they are abstractions and do not act on each other. The parabolic path is due to a single constant force acting on a body that is already moving (but not in the direction of the applied force). It can be seen as the result of the combination of a force (acting according to N2) and the body's existing inertia (i.e., N1). Prof. Thomson seems to be thinking of the motion itself as corresponding to a force, where Newton suggested that it is only a change of motion that corresponds to a force.
However, whilst Prof. Thomson is wrong, he is in good company – as one of the most common alternative conceptions reported is assuming that a moving body must be subject to a force. Which, as I pointed out last time, is not so daft as in everyday experience cars and boats and planes only keep on moving as long as their propulsion systems function (to balance resistive forces); and footballs and cricket balls and javelins that do not have a source of motive power (to overcome resistive forces) soon fall to earth. So, these are understandable and, in one sense, very forgiveable slips. It is just unfortunate they appear in an otherwise informative book about science.
Sources cited:
Thomson, K. (2005). The Watch on the Heath: Science and religion before Darwin. HarperCollins.
Thomson, W. (1862). On the Age of the Sun's Heat. Macmillan's Magazine, 5, 388-393.
Thorn, C. E., & Welford, M. R. (1994). The Equilibrium Concept in Geomorphology. Annals of the Association of American Geographers, 84(4), 666-696. http://www.jstor.org/stable/2564149
Notes
1 Although there are plenty of 'academic' books in many fields of scholarship (usually highly focused so the author is writing about their specialist work), the natural sciences tend to be communicated and debated in research journals. Most books written by scientists tend to be for a more general audience – and publishers expect popular science books to appeal to a wide readership, so these books are likely to have a much broader scope than academic monographs.
2 When he was ennobled, William Thomson chose to be called Baron Kelvin – after his local river, the river Kelvin. So the SI unit of temperature is named, indirectly, after a Scottish River.
Kelvin's reputation was such that when he modelled the cooling earth and suggested the planet was less that a 100 000 000 years old, this caused considerable concerns given that geologists were suggesting that much longer had been needed for it to have reached its present state.
4 The rate of change of momentum is proportional to the magnitude of the applied force and takes place in the direction of the applied force.
As momentum is mv, and as mass is usually assumed fixed (if the motion is well below light speeds) 'the rate of change of momentum' is the mass times the rate of change of the velocity – or ma. (F=ma.)
The key point about direction is that it is not that the body moves in the direction of the force, but the change of momentum (so change of velocity) is in the direction or the force.
As the body's momentum is a vector, and the change in momentum is a vector, the new momentum is the vector sum of these two vectors: new momentum = old momentum + change in momentum.
The object's new direction after being deflected by a force is in the direction of the new momentum
5 When there is force between two bodies (let's call them A, B) the force acting on body B is the same size as the force acting on body A, but is anti-parallel in direction.
The force between the earth and the sun acts on both (not shown to scale)
6 This is an ideal case.
A real table would not be perfectly rigid. A real table would initially distort ever so slightly with the area under the mass being ever so slightly compressed, and the weight dropping to an ever so slightly lower level. The very slight lowering of the weight does a tiny amount of work compressing the table surface.
Then, nothing more happens, and no more work is done.
7 Thorn and Welford (1994) have referred to "the fuzzy and frequently erroneous use of the term…equilibrium in geomorphology" (p.861), and how an 1876 introduction of the "concept of dynamic equilibrium resembles the balance-of-forces equilibrium that appears in dynamics, but by analogy rather than formal derivation" (p.862).
Being a science professor is no assurance of understanding Newton's mechanics
Keith S. Taber
…this author had just written that all matter is in uniform motion unless acted upon by an external force but did not seem to appreciate that any matter acted upon by an external force will not be in uniform motion
I started a new book today. 'The Watch on the Heath. Science and Religion before Darwin' had been on my pile of books to read for a while (as one can acquire interesting titles faster than find time to actually read them).
'The Watch on the Heath'
by Prof. Keith Thomson
The title is a reference to the analogy adopted at the start of William Paley's classic book on natural theology. Paley (1802) argued that if one was out walking across a heath and a foot struck an object on the ground, one would make very different assumptions if the object transpired to be a stone or a pocket watch. The stone would pass without much thought – there was no great mystery about how it came to be on the heath. But a pocket watch is an intricate mechanism composed of a multitude of especially shaped and arranged pieces fashioned from different materials. A reasonable person could not think it was an arbitrary and accidentally collated object – rather it clearly had a purpose, and so had a creator – a watchmaker.
Paley developed a detailed argument based on the analogy that organisms are like intricate mechanisms that offer obvious evidence of having been designed (Images by Thomas Wolter and Gerd Altmann from Pixabay)
Paley used this as an analogy for the complexity of the living world. Analogies are often used by teachers and science communicators as a means of making the unfamiliar familiar – a way of suggesting something that is being introduced is actually like something the audience already knows about and feels comfortable with.
Paley was doing something a little different – his readers would already know about both watches and living things, and he was developing the analogyto make an argument about the nature of living things as being designed. (Living things would be familiar, but Paley wanted to invite his reader to think about them in a way they might find unfamiliar.) According to this argument, organisms were so complex that, by analogy with a watch, it followed they also were created for a purpose, and by a creator.
Even today, Paley's book is an impressive read. It is 'one long argument' (as Darwin said of his 'Origin of Species') that collates a massive amount of evidence about the seeming design of human anatomy and the living world. Paley was not a scientist in the modern sense, and he was not even a naturalist who collected natural history specimens. He was a priest and philosopher / theologian who clearly thought that publishing his argument was important enough to require him to engage in such extensive scholarship that in places the volume gives the impression of being a medical textbook.
Paley's work was influential and widely read, but when Darwin (1859) presented his own long argument for evolution by natural selection there began to be a coherent alternative explanation for all that intricate complexity. By the mid-twentieth century a neo-Darwinian synthesis (incorporating work initiated by Mendel, developments in statistics, and the advent of molecular biology) made it possible to offer a feasible account that did not need a watch-maker who carefully made his or her creatures directly from a pre-designed pattern. Richard Dawkins perverted Paley's analogy in calling one of his books 'The Blind Watchmaker' reflecting the idea that evolution is little more than the operation of 'blind' chance.
Arguably, Darwin's work did nothing to undermine the possibility of a great cosmic architect and master craft-person having designed the intricacies of the biota – but only showed the subtlety required of such a creator by giving insight into the natural mechanisms set up to slowly bring about the productions. (The real challenge of Darwin's work was that it overturned the idea that there was any absolute distinction between humans and the rest of life on earth – if humans are uniquely in the image of God then how does that work in relation to the gradual transition from pre-human ancestors to the first humans?)
Arguably Darwin said nothing to undermine the omnipotence of God, only the arrogance of one branch of the bush of life (i.e., ours) to want to remake that God in their image. Anyway, there are of course today a range of positions taken on all this, but this was the context for my reading some questionable statements about Newtonian mechanics.
My reading went well till I got to p.27. Then I was perturbed. It started with a couple of quibbles. The first was a reference to
"…the modern world of quantum physics, where Einstein's relativity and Heisenberg's uncertainty reign."
Thomson, 2005: 27
"Er, no" I thought. Relativity and quantum theory are not only quite distinct theories, but, famously, the challenge of finding a way to make these two areas of physics, relativity theory and quantum mechanics, consistent is seen as a major challenge. The theories of relativity seem to work really well on the large scale and quantum theory works really well on the smallest scales, but they do not seem to fit together. "Einstein's relativity" is not (yet, at least) found within the "world of quantum physics".
Still, this was perhaps just a rhetorical flourish.
The Newtonian principle of inertia
But later in the same paragraph I read about how,
"Newton…showed that all matter is in uniform motion (constant velocity, including a velocity of zero) unless acted upon by an external force…Newton showed that an object will remain still or continue to move at a constant speed in the same direction unless some external force changes things."
Thomson, 2005: 27
This is known as Newton's first law of motion (or the principle of inertia). Now, being pedantic, I thought that surely Newton did notshow this.
It is fair to say, I suggest, that Newton suggested this, proposed it, mooted it; perhaps claimed it was the case; perhaps showed it was part of a self-consistent description – but I am not sure he demonstrated it was so.
Misunderstanding Newton's first law
This is perhaps being picky and, of itself, hardly worth posting about, but this provides important background for what I read a little later (indeed, still in the same paragraph):
"Single forces always act in straight lines, not circles. Any trajectory other than a straight line must be the result of multiple forces acting together."
Thomson, 2005: 27
No!
The first part of this is fair enough – a force acts between two bodies (say the earth and the sun) and is considered to act along a 'line of action' (such as the line between the centres of mass of the earth and the sun). In the Newtonian world-view, the gravitational force between the earth and sun acts on both bodies along that line of action. 1
However, the second sentence ("any trajectory other than a straight line must be the result of multiple forces acting together") is completely wrong.
These two sentences are juxtaposed as though there is a logical link: "Single forces always act in straight lines, not circles. [So therefore] any trajectory other than a straight line must be the result of multiple forces acting together." This only follows if we assume that an object must always be moving in the direction of a force acting on it. But Newton's second law tells us that acceleration (and so the change in velocity) occurs in the direction of the force.
This is confusing the sense of a change with its outcome – a bit like thinking that a 10 m rise in sea level will lead to the sea being 10 m deep, or that if someone 'puts on 20 kilos' they will weigh 200 N. A 'swing to Labour' in an election does not assure Labour of a victory unless the parties were initially on par.
The error here is like assuming that any debit from a bank account must send it overdrawn: taking £10 from a bank account means there will be £10 less in the account, but not necessary that the balance becomes -£10!
Changing direction is effortless (if there is an external force acting)
Whenever a single force acts on a moving object where the line of action does not coincide with the object's direction of travel then the object will change direction. (That is, a single force will only not lead to a change of direction in the very special case where the force aligns with or directly against to the direction of travel.) So, electrons in a cathode ray tube can be shown to follow a curved path when a (single) magnetic force is applied, and an arrow shot from a castle battlement horizontally will curve down to the grounds because of the (single) effect of gravitational force. (There are frictional forces acting as well, but they only modify the precise shape of that curve which would still be found if the castle was on a planet with no atmosphere – as long as the archer could hold her breath long enough to get the arrow away.)
The lyrics of a popular song declare "arc of a diver – effortlessly". 2 But diving into a pool is only effortless (once you have pushed off) because the diver is pulled into an arc by their gravitational attraction with the earth – so even if you dive at an angle above the horizontal, a single force is enough to change your direction and bring you down.
So, there is a mistake in the science here. Either the author has simply made a slip (which can happen to anyone) or he is operating with an alternative conception inconsistent with Newton's laws. The same can presumably be said about any editor or copy editor who checked the manuscript for the publisher.
That might not be so unlikely – as force and motion might be considered the prototype case of a science topic where there are common alternative conceptions. I have seen estimates of 80%+ of people having alternative conceptions inconsistent with basic Newtonian physics. After all, in everyday life, you give something a pull or a push, and it usually moves a bit, but then always come to a stop. In our ordinary experience stones, footballs, cricket balls, javelins, paper planes, darts – or anything else we might push or pull – fail to move in a straight line at a constant speed for the rest of eternity.
That does not mean Newton was wrong, but his ideas were revolutionary because he was able to abstract to situations where the usual resistive forces that are not immediately obvious (friction, air resistance, viscosity) might be absent. That is, ideal scenarios that probably never actually occur. (Thus my questioning above whether Newton really 'showed' rather than postulated these principles.)
all matter is in uniform motion unless acted upon by an external force
yet did not seem to appreciate the corollary that
any matter acted upon by an external force will not be in uniform motion
So, it seems someone can happily quote Newton's laws of motion but still find them so counter-intuitive that they do not apply them in their thinking. Again, this reflects research which has shown that graduates who have studied physics and done well in the examinations can still show alternative conceptions when asked questions outside the formal classroom setting. It is as if they learn the formalism for the exams, but never really believe it (as, after all, real life constantly shows us otherwise).
So, this is all understandable, but it seems unfortunate in a science book that is seeking to explain the science to readers. At this point I decided to remind myself who had written the book.
We all have alternative conceptions
Keith Thomson is a retired academic, an Emeritus Fellow at Kellog College Oxford, having had an impressive career including having been a Professor of Biology at Yale University and later Director of the Oxford University Museum and Professor of Natural History. So, here we have a highly successful academic scientist (not just a lecturer in some obscure university somewhere – a professor at both Yale and Oxford), albeit with expertise in the life sciences, who seems to misunderstand the basic laws of physics that Newton postulated back in 1687.
Prof. Thomson seems to have flaws in his knowledge in this area, yet is confident enough of his own understanding to expose his thinking in writing a science book. This, again, is what we often find in science teaching – students who hold alternative conceptions may think they understand what they have been taught even though their thinking is not consistent with the scientific accounts. (This is probably true of all of us to some degree. I am sure there must be areas of science where I am confident in my understanding, but where that confidence is misplaced. I likely have misconceptions in topics areas where Prof. Thomson has great expertise.)
A balance of forces?
This could have been just a careless slip (of the kind which once made often looks just right when we reread our work multiple times – I know this can happen). But, over the page, I read:
"…in addition to the technical importance of Newton's mathematics, the concept of 'a balance of forces' keeping the moon circling the earth and the earth in orbit around the sun, quickly became a valuable metaphor…"
Thomson, 2005: 27
Again – No!
If there is 'balance of forces' then the forces effectively cancel, and there is no net force. So, as "all matter is in uniform motion (constant velocity, including a velocity of zero) unless acted upon by an external force", a body subject to a balance of forces continues in "uniform motion (constant velocity…)" – that is, it continues in a straight line at a constant speed. It does not circle (or move in an ellipse). 3
Again, this seems to be an area where people commonly misunderstand Newton's principles, and operate with alternative conceptions. Learners often think that Newton's third law (sometimes phrased in terms of 'equal and opposite forces') implies there will always be balanced forces!
The reason the moon orbits the earth, and the reason the earth orbits the sun, in the Newtonian world-view is because in each case the orbiting body is subject to a single force which is NOT balanced by any countering force. As the object is "acted upon by an external force" (which is not balanced by any other force) it does not move "in uniform motion" but constantly changes direction – along its curved orbit. According to Newton's law of motion, one thing we can always know about a body with changing motion (such as one orbiting another body) is that the forces on it are not balanced.
But once circular motion was assumed as being the 'natural' state of affairs for heavenly bodies, and I know from my own teaching experience that students who understand Newtonian principle in the context of linear motion can still struggle to apply this to circular motion. 4
I even developed a scaffolding tool to help students make this transition, by helping them work through an example in very simple steps, but which on testing had modest effect – that is, it seemed to considerably help some students apply Newton's laws to orbital motion, but could not bridge that transition for others (Taber & Brock, 2018). I concluded even more basic step-wise support must be needed by many learners. Circular motion being linked to a net (unbalanced) centripetal force seems to be very counter-intuitive to many people.
To balance or not to balance
The suggestion that a balance of forces leads to change occurs again a little later in the book, in reference to James Hutton's geology,
"…Hutton supported his new ideas both with solid empirical evidence and an underlying theory based on a Newtonian balance of forces. He saw a pattern in the history of the rocks: gradually worn down by erosion, washed into the seas, accumulating as sediments, raised up as new dry land, only to be eroded again."
Thomson, 2005: 39
A balance of forces would not lead to rocks being "gradually worn down by erosion, washed into the seas, accumulating as sediments, raised up as new dry land, only to be eroded again". Indeed if all the relevant forces were balanced there would be no erosion, washing, sedimentation, or raising.
Erosion, washing, sedimentation, raising up ALL require an imbalance of forces, that is, a net force to bring about a change. 5
Reading on…
This is not going to stop me persevering with reading the book*, but one can begin to lose confidence in a text in situations such as these. If you know the author is wrong on some points that you already know about, how can you be confident of their accounts of other topics that you are hoping to learn about?
Still, Prof. Thomson seems to be wrong about something that the majority of people tend to get wrong, often even after having studied the topic – so, perhaps this says more about the hold of common intuitive conceptions of motion than the quality of Prof. Thomson's scholarship. Just like many physics learners – he has learnt Newton's laws, but just does not seem to find them credible.
Sources cited:
Darwin, C. (1859). The Origin of Species by Means of Natural Selection, or the preservation of favoured races in the struggle for life. John Murray.
Dawkins, R. (1988). The Blind Watchmaker. Penguin Books.
Paley, W. (1802/2006). Natural Theology: Or Evidence of the Existence and Attributes of the Deity, Collected from the Appearances of Nature(M. D. Eddy & D. Knight, Eds.). Oxford University Press.
Rosen, E. (1965/1995) Copernicus on the phases and the light of the planets, in Rosen, E. (1995). Copernicus and his successors (E. Hilfstein, Ed.). The Hambledon Press.
Thomson, K. (2005). The Watch on the Heath: Science and religion before Darwin. HarperCollins.
Watts, M. and Taber, K. S. (1996) An explanatory gestalt of essence: students' conceptions of the 'natural' in physical phenomena, International Journal of Science Education, 18 (8), pp.939-954.
Notes
1 Though not in the world-view offered by general relativity where the mass of the sun distorts space-time enough for the earth to orbit.
2 The title track from Steve Winwood's 1980 solo album 'Arc of a Diver'
3 We have known since Kepler that the planets orbit the sun following ellipses (to a first order of approximation*), not perfect circles – but this does not change the fundamental point here: moving in an ellipse involves continuous changes of velocity. (* i.e., ignoring the perturbations due to the {much smaller} forces between the orbiting bodies.**)
[Added, 20220711]: these perturbations are very small compared with the main sun-planet interactions, but they can still be significant in other ways:
"…the single most spectacular achievement in the long history of computational astronomy, namely, the discovery of the planet Neptune through the perturbations which it produced in the motion of Uranus."
Rosen, 1965/1995, p.81
4 What is judged as 'natural' is often considered by people as not needing any further explanation (Watts and Taber, 1996).
5 This reference to Hutton's ideas seems to preview a more detailed treatment of the new geology in a later chapter in the book (that I have not yet reached), so perhaps as I read on I will find a clearer explanation of what is meant by these changes being based on a theory of balance of forces.* Still, the impression given in the extract quoted is that, as with orbits, a balance of forces brings about change.
Photosynthesis illuminating a plant? (Image by OpenClipart-Vectors from Pixabay)
Analogies, metaphors and similes are used in communication to help make the unfamiliar familiar by suggesting that some novel idea or phenomena being introduced is in some ways like something the reader/listener is already familiar with. Analogies, metaphors and similes are commonly used in science teaching, and also in science writing and journalism.
An analogy maps out similarities in structure between two phenomena or concepts. This example, from a radio programme, compared the COVID pandemic with photosynthesis.
"So, what we were particularly aiming to do, was to understand the collision between a range of different political economic factors of a pre-2020 world, and how they were sort of reassembled and deployed to cope with something which was without question unprecedented.
We used this metaphor of photosynthesis because if you think about photosynthesis in relation to plants, the sun both lights things up but at the same time it feeds them and helps them to grow, and I think one of the things the pandemic has done for social scientists is to serve both as a kind of illumination of things that previously maybe critical political economists and heterodox scholars were pointing to but now became very visible to the mainstream media and to mainstream politics. But at the same time it also accentuated and deepened some of those tendencies such as our reliance on various digital platforms, certain gender dynamics of work in the household, these sort of things that became acute and undeniable and potentially politicised over the course of 2020, 2021."
Prof. Will Davies, talking on 'Thinking Allowed' 1
Will Davies, Professor in Political Economy at Goldsmiths, University of London was talking to sociologist Prof. Laurie Taylor who presents the BBC programme 'Thinking Aloud' as part of an episode called 'Covid and change'
A scientific idea used as analogue
Prof. Davies refers to using "this metaphorof photosynthesis". However he goes on to suggest how the two things he is comparing are structurally similar – the pandemic has shone a light on social issues at the same time as providing the conditions for them to become more extreme, akin to how light both illuminates plants and changes them. A metaphor is an implicit comparison where the reader/listener is left to interpret the comparison, but a metaphor or simile that is explicitly developed to explain the comparison can become an analogy.
Often science concepts are introduced by analogy to more familiar everyday ideas, objects or events. Here, however, a scientific concept, photosynthesis is used as the analogue – the source used to explain something novel. Prof. Davies assumes listeners will be familiar enough with this science concept for it to helpful in introducing his research.
Mischaracterising photosynthesis?
A science teacher might not like the notion that the sun feeds plants – indeed if a student suggested this in a science class it would likely be judged as an alternative conception. In photosynthesis, carbon dioxide (from the atmosphere) and water (usually absorbed from the soil) provide the starting materials, and the glucose that is produced (along with oxygen) enables other processes – such as growth which relies on other substances also being absorbed from the soil. (So-called 'plant foods', which would be better characterised as plant nutritional supplements, contain sources of elements such as nitrogen, phosphorus and potassium). Light is necessary for photosynthesis, but the sunlight is not best considered 'food'.
One might also argue that Prof. Davies has misidentified the source for his analogy, and perhaps he should rather have suggested sunlight as the source metaphor for his comparison as sunlight both illuminates plants and enables them to grow. Photosynthesis takes place inside chloroplasts within a plant's tissues, and does not illuminate the plant. However, Prof. Davies' expertise is in political economy, not natural science, and it was good to see a social scientist looking to use a scientific idea to explain his research.
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.
One of the supposed features of scientific knowledge is that it is always, strictly speaking, provisional. Science seeks generalisable, theoretical knowledge – and no matter how strong the case for some general claim may seem, a scientist is supposed to be open-minded, and always willing to consider that their opinion might be changed by new evidence or a new way of looking at things.
Perhaps the strongest illustration of this is Newtonian physics that seemed to work so well for so many decades that for many it seemed unquestionable. Yet we now know that it is not a precise account that always fits nature. (And by 'we know' I mean we know in the sense of having scientific knowledge – we think this, and have very strong grounds to think this, but reserve the right to change our minds in the light of new information!)
When science is presented in the media, this provisional nature of scientific knowledge – with its inbuilt caveat of uncertainty – is often ignored. News reports, and sometimes scientists when being interviewed by journalists, often imply that we now know…for certain… Science documentaries are commonly stitched together with the trope 'and this can only mean' (Taber, 2007) when any scientist worth their salt could offer (even if seemingly less feasible) alternative scenarios that fit the data.
One might understand this as people charged with communicating science to a general audience seeking to make things as simple and straightforward as possible. However it does reinforce the alternative conception that in science theories are tested allowing them to be straightforwardly dismissed or proved for all time. What is less easy to understand is why scientists seeking to publish work in academic journals to be read by other scientists would claim to know anything for certain – as that is surely likely to seem arrogant and unscientific to editors, reviewers, and those who might read their published work
Science that is indisputable
So, one of two things that immediately made me lack confidence in a published paper about the origin of SARS-CoV-2, the infectious agent considered responsible for the COVID pandemic (Sehgal, 2021), was that the first word was 'Undisputedly'. Assuming the author was not going to follow up with Descartes' famous 'Cogito' ("Undisputedly… I think, therefore I am"), this seemed to be a clear example of something I always advised my own research students to avoid in their writing – a hostage to fortune.
A bold first sentence for this article in a supposedly peer-reviewed research journal
The good scientist learns to use phrases like "this seems to suggest…" rather than "I have therefore proved beyond all possible doubt…"!
Prestigious research journals are selective in what they publish – and reject most submissions, or at least require major revisions based on reviewer evaluations. Predatory journals seek to maximise their income from charging authors for publication; and so do not have the concern for quality that traditionally characterised academic publishing. If some of the published output I have seen is a guide, some of these journals would publish virtually anything submitted regardless of quality.
Genetic relatedness of bats and viruses
Now it would be very unfair to dismiss a scientific article based purely on the first word of the abstract. Even if 'undisputedly' is a word that does not sit easily in scientific discourse, I have to acknowledge that writing a scientific paper is in part a rhetorical activity, and authors may sometimes struggle to balance the need to adopt scientific values (such as always being open to the possibility of another interpretation) with the construction of a convincing argument.
"Undisputedly, the horseshoe bats are the nearest known genetic relatives of the Sars-CoV-2 virus."
Sehgal, 2021, p.29 341
Always start a piece of writing with a strong statement
Closest genetic relatives?
Okay, I was done.
I am not a biologist, and so perhaps I am just very ignorant on the topic, but this seemed an incredible claim. Our current understanding of the earth biota is that there has (probably) been descent from a common ancestor of all living things on the planet today. So, just as I am related, even if often only very distantly, to every other cospecific specimen of Homo sapiens on the planet, I am also related by descent from common ancestors (even more distantly) to every chimpanzee, indeed every primate, every mammal, every chordate; indeed every animal; plus all the plants, fungi, protists and monera.
But clearly I share a common ancestor with all humans in the 'brotherhood of man' more recently than all other primates, and that more recently than all other mammals. And when we get to the non-animal kingdoms we are not even kissing cousins.
And viruses – with their RNA based genetics? These are often not even considered to be living entities in their own right.
There is certainly a theory that there was an 'RNA world', a time when some kind of primitive life based on RNA genes existed from which DNA and lifeforms with DNA genomes later evolved, so one can stretch the argument to say I am related to viruses – that if one went back far enough, both viruses and humans (or viruses and horseshoe bats, more to the point of the claim in this article) around today could be considered to be derived from a common ancestor, and that this is reflected in patterns that can be found in their genomes today.
The nearest genetic relative to SARS-CoV-2 virus?
The genome of a virus is not going to be especially similar to the genome of a mammal. The SARS-CoV-2 virus is a single stranded RNA virus which will be much more genetically similar to other such viruses that to organisms with double stranded DNA. It is famously a coronavirus – so surely it is most likely to be strongly related to other coronaviruses? It is called 'SARS-CoV-2' because of its similarity to the virus that causes SARS (severe acute respiratory syndrome): SARS-CoV. These seems strong clues.
And the nearest genetic relative to horseshoe bats are…
And bats are mammals. The nearest relatives to any specific horseshoe bat are other bats of that species. And if we focus at the species level, and ask what other species would comprise the nearest genetic relatives to a species of horseshoe bats? I am not an expert, but I would have guessed other species of horseshoe bat (there are over a hundred such species). Beyond that family – well I imagine other species of bat. Looking on the web, it seems that Old World leaf-nosed bats (and not viruses) have been mooted from genetic studies (Amador, Moyers Arévalo, Almeida, Catalano & Giannini, 2018) as the nearest genetic relatives of the horsehoe bats.
Annotated copy of Figure 7 from Amador et al., 2018
So, although I am not an expert, and I am prepared to be corrected by someone who is, I am pretty sure the nearest relative that is not a bat would be another mammal – not a bird, not a fish, certainly not a mollusc or insect. Mushrooms and ferns are right out of contention. And, no, not a virus. 1
Judge me on what I mean to say – not what I say
Perhaps I am being picky here. A little reflection suggests that surely Sehgal (in stating that "the horseshoe bats are the nearest known genetic relatives of the Sars-CoV-2 virus") did not actually mean to imply that "the horseshoe bats are the nearest known genetic relatives of the Sars-CoV-2 virus", but rather perhaps something along the lines that an RNA virus known to infect horseshoe bats was the nearest known genetic relative of the Sars-CoV-2 virus.
Perhaps I should have read "the horseshoe bats are the nearest known genetic relatives of the Sars-CoV-2 virus" as "the horseshoe bats are hosts to the nearest known genetic relatives of the Sars-CoV-2 virus"? If I had read on, I would have found reference to a "bat virus RaTG13 having a genome resembling the extent of 98.7% to that of the Sars-CoV-2 virus" (p.29 341).
Yet if a research paper, that has supposedly been subject to rigorous peer review, manages to both misrepresent the nature of science AND make an obviously factually incorrect claim in its very first sentence, then I think I can be forgiven for suspecting it may not be the most trustworthy source of information.
Work cited
Amador, L. I., Moyers Arévalo, R. L., Almeida, F. C., Catalano, S. A., & Giannini, N. P. (2018). Bat Systematics in the Light of Unconstrained Analyses of a Comprehensive Molecular Supermatrix. Journal of Mammalian Evolution, 25(1), 37-70. https://doi.org/10.1007/s10914-016-9363-8
Sehgal, M.L. (2021) Origin of SARS-CoV-2: Two Schools of Thought, Biomedical Journal of Scientific & Technical Research, July, 2020, Volume 37, 2, pp 29341-29356
1 It is perfectly possible logically for organism Y (say a horseshoe bat) to be the closest genetic relative of organism X (say a coronavirus) without organism X being the closest genetic relative of organism Y. (By analogy, someone's closest living genetic relative could be a grandchild whose closest genetic relative is their own child or their parent that was not a child of that grandparent.) However, the point here is that bat is not even quite closely related to the virus.
Can we be certain about something that happened half a million years ago?
Keith S. Taber
What was going on in Java when Homo erectus lived there? (Image by Kanenori from Pixabay )
About half a million years ago a hominid, of the Homo erectus species, living in Java took a shell and deliberately engraved a mark on it. Now, I was not there when this happened, so my testimony is second hand, but I can be confident about this as I was told by a scientist that she was sure that this definitely happened.
"…we knew for sure that it must have been made by Homo erectus"
But how can we be so sure about something alleged to have occurred so long ago?
"A long time ago [if not] in a galaxy far, far away…." the skull of a specimen of Homo erectus (Image by Mohamed Noor from Pixabay ) [Was this an inspiration for the Star Wars stormtrooper helmet?]
I doubt Fifi would be convinced.1 Fifi was a Y12 student (c.16 years old) interviewed as part of the LASAR project who had reservations about palaeontology as it did not provide certain scientific knowledge,
"I like fossils though, I think they're interesting but I don't think I'd really like [working as a palaeontologist]…I don't think you could ever really know unless you were there… There'll always be an element of uncertainty because no matter how much evidence you supply there will always be, like, doubt because of the fact that you were never there…there'll always be uncertainty."
Learners can have alternative conceptions of the nature of science, just as much as they often do for forces or chemical bonding or plant nutrition. They often think that scientific knowledge has been 'proved', and so is certain (e.g., Taber, Billingsley, Riga & Newdick, 2015). An area like palaeontology where direct observation is not possible may therefore seem to fall short of offering genuine scientific knowledge.
The uncertain nature of scientific knowledge
One key feature of the nature of science is that it seeks to produce general or theoretical knowledge of the natural world. That is, science is not just concerned with providing factual reports about specific events but with developing general accounts that can explain and apply to broad categories of objects and events. Such general and theoretical knowledge is clearly more useful than a catalogue of specific facts – which can never tell us about the next occasion or what might happen in hypothetical situations.
However, a cost of seeking such applicable and useful knowledge is that it can never be certain. It relies on our ways of classifying objects and events, the evidence we have collected so far, our ability to spot the most important patterns -and the deductions this might support. So, scientific knowledge is always provisional in the sense that it is open to revision in response to new data, or new ways of thinking about existing data as evidence.
Yet often reports of science in the media give the impression that science has made absolute discoveries. Some years ago I wrote about the tendency in science documentaries for the narrative to be driven by links that claimed "...this could only mean…" when we know that in science the available data always underdetermines theory (Taber, 2007). Or, to put it another way, we could always think up other ways of explaining the data. Sometimes these alternatives might seem convoluted and unlikely, but if we can suggest a possible (even when unconvincing) alternative, then the available data can never "only mean" any one particular proposed interpretation.
The scientist concerned was J.C.A (José) Joordens who is Professor in Hominin Paleoecology and Evolution, at Maastricht University. Prof. Joordens holds the Naturalis Dubois Chair in Hominin Paleoecology and Evolution. The reference to Dubois relates to the naturist responsible for finding a so-called 'missing link' in the chain of descent to modern humans,
"One of the most exciting episodes of palaeoanthropology was the find of the first transitional form, the Pithecanthropus erectus, by the Dutchman Eugène Dubois in Java during 1891-1892. …Besides the human remains, Dubois made a large collection of vertebrate fossils, mostly of mammals, now united in the so-called Dubois Collection."
de Vos, 2004
The Java man species, Pithecanthropus erectus (an upright ape/mokey-man), was later renamed as Homo erectus, the upright man.
On an edition of BBC Radio 4's 'In Our Time' taking 'Homo erectus' as its theme, Prof. Joordens explained how some fossil shells collected by Dubois as part of the context of the hominid fossils had remained in storage for over a century ("The shells had been, well, shelved…"!), before a graduate student set out to photograph them all for a thesis project. This led to the discovery that one of the shells appeared to have been engraved.
This could only mean one thing…
This is what Prof. Joordens told the host, Melvyn Bragg,
"One shell that had a very strange marking that we could not understand how it ended up there…
It was geometric, like a W, and this is of course something that animals don't produce. We had to conclude that it must have been made by Homo erectus. And it must have been a very deliberate marking because of, we did experimental research trying to replicate it, and then we actually found it was quite hard to do. Because, especially fresh shells, they have a kind of organic exterior, and it's hard to push some sharp objects through and make those lines, so that was when we knew for sure that it must have been made by Homo erectus."
We may consider this claim to be composed of a number of components, such as:
There is a shell with some 'very strange' markings
The shell was collected in Java in the nineteenth century
The shell had the markings when first collected
The markings were not caused by some natural phenomenon
The markings were deliberate not accidental
The markings were made by a specimen of Homo erectus
A sceptic might ask such questions as
How can we be sure this shell was part of the original collection? Could it have been substituted by mistake or deliberately?
How do we know the marks were not made more recently? perhaps by someone in the field in Java, or during transit form Java to the Netherlands, or by someone inspecting the collection?
Given that even unusual markings will occur by chance occasionally, how can we be certain these markings were deliberate? Does the mark really look like a 'W 'or might that be an over-interpretation. 2
And so forth.
It is worth bearing in mind that no one noticed these markings in the field, or when the collection was taken back to the Netherlands – indeed Prof. Joordens noted she had carried the shell around in her backpack (could that have been with an open penknife?) unaware of the markings
Of course, Prof. Joordens may have convincing responses to many of these questions – but a popular radio show is not the place to detail all the argument and evidence. Indeed, I found a report in the top journal Nature ('Homo erectus at Trinil on Java used shells for tool production and engraving') by Prof. Joordens and her team 3, claiming,
"One of the Pseudodon shells, specimen DUB1006-fL, displays a geometric pattern of grooves on the central part of the left valve [*]. The pattern consists, from posterior to anterior, of a zigzag line with three sharp turns producing an 'M' shape, a set of more superficial parallel lines, and a zigzag with two turns producing a mirrored 'N' shape. Our study of the morphology of the zigzags, internal morphology of the grooves, and differential roughness of the surrounding shell area demonstrates that the grooves were deliberately engraved and pre-date shell burial and weathering"
It may seem most likely that the markings were made by a Homo erectus, as no other explanation so far considered fits all the data, but theory is always under-determined – one can never be certain another scenario might be found which also fits the known facts.
Strictly, Prof. Joordens' contradicts herself. She claims the marks are "something that animals don't produce" and then claims an animal is responsible. She presumably meant that no non-hominid animal makes such marks. Even if we accept that (and, as they say, absence of evidence is not evidence of absence 4), can we be absolutely certain some other hominid might not have been present in Java at the time, marking the odd shell? As the 'In Our Time' episode discussed, Homo erectus often co-existed with other hominids.
Probably not, but … can we confidently say absolutely, definitely, not?
As Fifi might say: "I don't think you could ever really know unless you were there".
My point is not that I think Prof. Joordens is wrong (she is an expert, so I think she is likely correct), but just that her group cannot be absolutely certain. When Prof. Joordens says she knows for sure I assume (because she is a scientist, and I am a scientist) that this means something like "based on all the evidence currently available, our best, and only convincing, interpretation is…" Unfortunately lay people often do not have the background to insert such provisos themselves, and so often hear such claims literally – science has proved its case, so we know for sure. Where listeners already think scientific knowledge is certain, this misconception gets reinforced.
Meanwhile, Prof. Joordens continues her study of hominids in Java in the Studying Homo erectus Lifestyle and Location project (yes, the acronym is SHeLL).
Joordens, J., d'Errico, F., Wesselingh, F. et al. Homo erectus at Trinil on Java used shells for tool production and engraving. Nature 518, 228-231 (2015). https://doi.org/10.1038/nature13962
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 As is usual practice in such research, Fifi is an assumed name. Fifi gave permission for data she contributed to the research to be used in publications on the assumption it would be associated with a pseudonym. (See: 'Using pseudonyms in reporting research'.)
2 No one is suggesting that the hominid deliberately marked the shell with a letter of the Roman alphabet, just that s/he deliberately made a mark that represented a definite and deliberate pattern. Yet human beings tend to spot patterns in random data. Could it just be some marks that seem to fit into a single pattern?
3 Josephine C. A. Joordens, Francesco d'Errico, Frank P. Wesselingh, Stephen Munro, John de Vos, Jakob Wallinga, Christina Ankjærgaard, Tony Reimann, Jan R. Wijbrans, Klaudia F. Kuiper, Herman J. Mücher, Hélène Coqueugniot, Vincent Prié, Ineke Joosten, Bertil van Os, Anne S. Schulp, Michel Panuel, Victoria van der Haas, Wim Lustenhouwer, John J. G. Reijmer & Wil Roebroeks.
4 At one time there was no evidence of 'noble' gases reacting. At one time there was no evidence of ozone depletion. At one time there was no evidence of superconductivity. At one time there was no evidence that the blood circulates around the body. At one time there was no evidence of any other planet having moons. At one time there was no evidence of protons being composed of even more fundamental particles. At one time there was no evidence of black holes. At one time there was no evidence that smoking tobacco was harmful. At one time there was no evidence of … [fill in your choice scientific discovery!]
Scientific literacy and desk accessories in science fiction
Keith S. Taber
Is the principle of conservation of mass that is taught in school science falsified all the time?
I am not really a serious sci-fi buff, but I liked Star Trek (perhaps in part because it was the first television programme I got to see in colour 1) and I did enjoy Blakes7 when it was broadcast by the BBC (from 1978-1981).
Logo of the BBC television series 'Blakes7' with (a) home desk equipment or (b) manual control lever for the most advanced spaceship in the galaxy (Image by Francis Ray from Pixabay).
Blakes7 was made with the same kind of low budget production values of Dr Who of the time. Given that space scenes in early episodes involved what seemed to be a flat image of a spacecraft moving across a star field with no sense of depth or perspective (for later series someone had built a model), and in one early episode the crew were clearly given angle-poise lamps to control the craft, it was certainly not a case of 'no expense spared'. So, it was never quite clear if the BBC budget had also fallen short of a possessive apostrophe in the show title credits or Blakes7 was to be read in some other way.
After all, it was not made explicit who was part of Blake's 7 if that was what the title meant, and no one referred to "Blake's 7" in the script (perhaps reflecting how the doctor in Dr Who was not actually called Dr Who?).
The Blakes7 team on the flight desk of the Liberator – which was the most advanced spaceship in the galaxy (and was, for plot purposes, conveniently found drifting in space without a crew) – at least until they forgot to clean the hull once too often and it corroded away while they were on an away mission.
Blake's group was formed from a kind of prison break and so Blake was something of a 'rough-hero' – but not as much as his sometime unofficial lieutenant, sometime friend, sometime apparent rival, Avon, who seemed to be ruled by self-interest (at least until the script regularly required some act of selfless heroism from him). 'Rough-heroes' are fictional characters presented in the hero role but who have some traits that the audience are likely to find morally questionable if not repugnant.
As well as Blake (a rebel condemned as a traitor, having 'recovered' from brainwashing-supported rehabilitation to rebel again) and Avon (a hacker convicted of a massive computer fraud intended to make himself extremely rich) the rest of the original team were a smuggler, a murderer and a petty thief, to which was added a terrorist (or freedom fighter if you prefer) picked up on an early mission. That aside, they seemed an entirely reasonable and decent bunch, and they set out to rid the galaxy of 'The Federation's tyrannical oppression. At least, that was Blake's aspiration even if most of his companions seemed to see this as a stop-gap activity till they had decided on something with more of a long-term future.
At the end of one season, where the fight with the Federation was temporarily put aside to deal with an intergalactic incursion, Blake went AWOL (well, intergalactic wars can be very disruptive) and was assumed dead/injured/lost/captured/?… for much of the remaining run without affecting the nature of the stories too much.
Among its positive aspects for its time were strong (if not exactly model) roles for women. The main villain, Servalan, was a woman – Supreme Commander of the Federation security forces (and later Federation president).
As the ruthless Supreme Commander of the Federation security forces, Servalan got to wear whatever she liked (a Kid Creole, or Mel and Kim, look comes to mind here) and could insist her staff wore hats that would not upstage hers
In Blake's original team (i.e., 7?), his pilot is a woman. (Reflecting other SciFi series, the spacecraft used by Blakes7 require n crew members to operate effectively, where n is an integer that varies between 0 and 6 depending on the specific plot requirements of an episode.) In a later series, after Avon has taken over the role of 'ipso facto leader-among-equals', the group recruits a female advanced weapons designer/technologist and a female sharpshooter.
The Blakes7 team later in the run. (Presumably they are checking the monitor and having a quick recount.) Was Soolin (played by Glynis Barber, far right) styled as a subtle reference to the 'Seven Samurai'?
When I saw Blakes7 was getting a rerun recently I re-watched the series I had not seen since it was first aired. Despite very silly special effects, dodgy story-lines, and morally questionable choices (the series would make a great focus for a philosophy class) the interactions between the main characters made it an enjoyable watch.
But, it is not science
Of course, the problem with science fiction is that it is fiction, not science. Star Trek may have prided itself on seeking to at least make the science sound feasible, but that is something of an outlier in the genre.
Egrorian and his young assistant Pinder (unfortunately prematurely aged somewhat by a laboratory mishap) show Avon and Vila around their lab.
This is clear, for example, in an episode called 'Orbit' where Avon discuses the tachyon funnel, an 'ultimate weapon', with Egrorian, a renegade scientist. Tachyons are hypothetical particles that travel faster than the speed of light. The theory of special relatively suggests the speed of light is the theoretical maximum speed anything can have, but some other theories suggest tachyons may exist in some circumstances. As always in science, theories that are widely accepted as our current best understanding of some aspect of nature (e.g., relativity) are still open to modification or replacement if new evidence is found that suggests this is indicated.
In the Blakes7 universe, there seemed to be a surprisingly high frequency of genius scientists/engineers who had successfully absconded from the tyrannical and paranoid Federation with sufficient resources to build private research facilities on various obscure deserted planets. Although these bases are secret and hidden away, and the scientists concerned have normally been missing for years or even decades, it usually transpires that the Blakes7 crew and the Federation manage to locate any particular renegade scientist during the same episode.
This is part of the exchange between this particular flawed genius scientist and our flawed and reluctant 'rough hero', Kerr Avon:
Egrorian: You've heard of Hoffal's radiation?
Avon: No.
Ah… Hoffal had a unique mind. Over a century ago he predicted most of the properties that would be found in neutron material.
Neutron material?
Material from a neutron star. That is a… a giant sun which has collapsed and become so tightly compressed that its electrons and protons combine, making neutrons.
I don't need a lecture in astrophysics. [But presumably the scriptwriter felt the audience would need to be told this.]
When neutrons are subjected to intense magnetic force, they form Hoffal's radiation. Poor Pinder [Egrorian's lab. assistant] was subjected for less than a millionth of a second. He aged 50 years in as many seconds. …
So neutrons are part of the tachyon funnel.
Um, eight of them … form the core of the accelerator.
Now, for anyone with any kind of science background such dialogue stretches credibility. Chadwick discovered the neutron in everyday matter in 1932, so the neutron's properties could be explored without having to obtain samples from a neutron star – which would certainly be challenging. When bound in nuclei, neutrons (which are electrically neutral, thus the name, and so not usually affected by magnetic fields) are stable.
Thinking at the scale of a neutron
However, any suspension of disbelief (which fiction demands, of course) was stretched past breaking point at the end of this exchange. Not only were the generally inert neutrons the basis of a weapon that could destroy whole worlds – but the core of the accelerator was formed of, not a neutron star, nor a tonne of 'neutron matter', but eight neutrons (i.e., one for each member of Blake's 7 with just a few left over?)
That is, the intensely destructive beam of radiation that could destroy a planet from a distant solar system was generated by subjecting to a magnetic field: a core equivalent to (the arguably less interesting) half of a single oxygen atomic nucleus.
Warning – keep this away from strong magnetic fields if you value your planet! (Image by Gerd Altmann from Pixabay )
Now free neutrons (that is, outside of an atomic nuclei – or neutron star) are unstable, and decay on a timescale of around a quarter of an hour (that is, the half-life is of this order – following the exponential decay familiar with other kinds of radioactivity), to give a proton, an electron and a neutrino. The energy 'released' in this process is significant on the scale of a subatomic particle: 782 343 eV or nearly eight hundred thousand eV.
Eight hundred thousand seems a very large number, but the unit here is electron volt, a unit used for processes at this submicroscopic scale. (An eV is the amount of work that is done when one single electron is moved though a potential difference of 1v – this is about 1.6 x10-19 J). In the more familiar units of joules, this is about 1.25 x 10-13 J. That is,
0.000 000 000 000 125 J
To boil enough water at room temperature to make a single cup of tea would require about 67 200 J. 2 So, if the energy from decaying neutrons were used to boil the water, it would require the decay of about
538 000 000 000 000 000 neutrons.3
That is just to make one cup of tea, so imagine how many more neutrons would have to decay to provide the means to destroy a planet. Certainly, one would imagine,
more than 8.
E=mc2
Now since Einstein (special relativity, again), mass and energy have been considered to have an equivalence. It is commonly thought that mass can be converted to energy and the equation E=mc2 tells you how much of one would be converted to the other: how many J per kg or kg per J. (Spoiler alert – this is not quite right.)
In that way of thinking, the energy released by a free neutron when it decays is due to a tiny part of the neutrino's mass being converted to energy.
The neutron's mass defect
The mass (or so called 'rest mass') of a neutrino is about 1.67 x 10-27 kg. In the usual mode of decay the neutrino gives rise to a proton (which is nearly, but not quite, as heavy as a neutron), an electron (which is much lighter), and a neutrino (which is considered to have zero rest mass.)
Before decay
Rest mass / 10-31 kg
After decay
Rest mass / 10-31 kg
neutron
16 749.3
proton
16 726.2
electron
9.1
neutrino
–
total
16 749.3
16 735.3
[rest] mass defect in neutrino decay
So, it seems like some mass has disappeared. (And this is the mass sometimes said to have been converted into the released energy.) This might lead us to ask the question of whether Hoffal's discovery was a way to completely annihilate neutrons, so that instead of a tiny proportion of their mass being converted to energy as in neutron decay – all of it was.
Mass as latent energy?
However, when considered from the perspective of special relativity, it is not that mass is being converted to energy in processes such as neutron decay, but rather that mass and energy are considered as being different aspects of something more unified -'mass-energy' if you like. Energy in a sense carries mass, and mass in a sense is a manifestation of energy. The table above may mislead because it only refers to 'rest mass' and that does not tell us all we need to know.
When the neutron decays, the products move apart, so have kinetic energy. According to the principle of mass-energy equivalence there is always a mass equivalence of any energy. So, in relativity, a moving object has more mass than when it is at rest. That is, the 'mass defect' table shows what the mass would be if we compared a motionless neutron with motionless products, not the actual products.
The theory of special relativity boldly asserts that mass and energy are not the independent quantities they were once thought to be. Rather, they are two measures of a single quantity. Since that single quantity does not have its own name, it is called mass-energy, and the relationship between its two measures is known as mass-energy equivalence. We may regard c2 as a conversion factor that enables us to calculate one measurement from the other. Every mass has an energy-equivalent and every energy has a mass-equivalent. If a body emits energy to its surroundings it also emits a quantity of mass equivalent to that energy. The surroundings acquire both the energy and mass in the process.
Treptow, 2005, p.1636
So, rather than thinking mass has been converted to energy, it may be more appropriate to think that the mass of a neutron has a certain (latent) energy associated with it, and that, after decay, most of this energy is divided between products (according to their rest masses), but a small proportion has been converted to kinetic energy (which can be considered to have a mass equivalence).
So, whenever any process involves some kind of energy change, there is an associated change in the equivalent masses. Every time you boil the kettle, or go up in an elevator, there is a tiny increase of mass involved – the hot water is heavier than when it was cold; you are heavier than when you were at a lower level. When you lie down or burn some natural gas, there is a tiny reduction in mass (you weigh less lying down; the products of the chemical reaction weigh less than the reactants).
How much heavier is hot water?
Only in nuclear processes does the energy change involved become large enough for any change in mass to be considered significant. In other processes, the changes are so small, they are insignificant. The water we boiled earlier to make a cup of tea required 67 200J of energy, and at the end of the process the water would not just be hotter, but also heavier by about
0.000 000 000 000 747 kg
0r about 0.000 000 000 75 g. That is easy to calculate 4, but not so easy to notice.
Is mass conserved in chemical reactions?
On this basis, we might suggest that the principle of conservation of mass that is taught in school science is falsified all the time – or at least needs to be understood differently from how it is usually presented.
Type of reaction
Mass change
endothermic
mass of products > mass of reactants
exothermic
mass of products < mass of reactants
If we just consider the masses of the substances then mass is not conserved in chemical change
Yet, the discrepancies really are tiny – so tiny that in school examinations candidates are expected to pretend there is no difference. But, strictly, when (as an example) copper carbonate is heated in a crucible and decomposes to give copper oxide and carbon dioxide there is a mass decrease even if you could capture all the CO2. But it would not be measurable with our usual laboratory equipment – so, as far as chemistry is concerned, mass is conserved. 'To all intense and purposes' (even if not absolutely true) mass is always conserved in chemical reactions.
Mass is conserved overall
But actually, according to current scientific thinking, mass is always conserved (not just very nearly conserved), as long as we make sure we consider all relevant factors. The energy that allowed us to boil the kettle or be lifted in an elevator must have been provided from some source (which has lost mass by the same extent). In an exothermic chemical reaction there is an extremely slight difference of mass between the reactants and products, but the surroundings have been warmed and so have got (ever so slightly) heavier.
Type of reaction
Mass change
endothermic
energy (and equivalent mass) from the surroundings
exothermic
energy (and equivalent mass) to the surroundings
If we just consider the masses of the substances then mass does not seem to be conserved in chemical change
As Einstein himself expressed it,
"The inertial mass of a system of bodies can even be regarded as a measure of its energy. The law of the conservation of the mass of a system becomes identical with the law of the conservation of energy, and is only valid provided that the system neither takes up nor sends out energy."
Einstein, 1917/2015, p.59
Annihilate the neutrons!
So, if we read about how in particle accelerators, particles are accelerated to immense speeds, and collided, and so converted to pure energy we should be suspicious. The particles may well have been destroyed – but something else has now acquired the mass (and not just the rest mass of the annihilated particles, but also the mass associated with their high kinetic energy).
So, we cannot convert all of the mass of a neutron into energy – only reconfigure and redistribute its mass-energy. But we can still ask: what if all the mass of the neutron were to be converted into some kind of radiation that carried away all of its mass as high energy rays (perhaps Hoffal's radiation?)
Perhaps the genius scientist Hoffal, with his "unique mind", had found a way to do this (hm, with a magnetic field?) Even if that does not seem very feasible, it does give us a theoretical limit to the energy that could be produced by a process that converted a neutron into radiation.6 Each neutron has a rest mass of about
1.67 x 10-27 kg
now the conversion factor is c2 (where c is the speed of light, which is near enough 3 x 108 ms-1, so c2 =(3×108ms-1)2 , i.e., about 1017m2s-2), so that mass is equivalent to about 1.50 x 10-10 J 5 or,
0.000 000 000 150 J
Now that is a lot more energy than the 1.25 x 10-13 J released in the decay of a neutron,
0.000 000 000 150 000 J
>
0.000 000 000 000 125 J
and now we could in theory boil the water to make our cup of tea with many fewer neutrons. Indeed, we could do this by annihilating 'only' about 7
448 000 000 000 000 neutrons
This is a lot less neutrons than before, i.e.,
448 000 000 000 000 neutrons
< 538 000 000 000 000 000 neutrons
but it seems fair to say that it remains the case that the number of neutrons needed (now 'only' about 448 million million) is still a good deal more than 8.
448 000 000 000 000 neutrons
> 8 neutrons
So, if over 400 million million neutrons would need to be completely annihilated to make a single cup of tea, how much damage can 8 neutrons do to a distant planet?
A common learning difficulty
In any reasonable scenario we might imagine 8 neutrons would not be significant. This is worth emphasising as it reflates to a common learning difficulty. Quanticles such as atoms, atomic nuclei, neutrons and the like are tiny. Not tiny like specs of dust or grains of salt, but tiny on a scale where specs of dust and grains of salt themselves seem gigantic. The scales involved in considering electronic charge (i.e., 10-19C) or neutron mass (10-27 kg) can reasonably said to be unimaginatively small – no one can readily visualise the shift in scale going from the familiar scale of objects we normally think of as 'small', to the scale of individual molecules or subatomic particles.
Students therefore commonly form alternative conceptions of these types of entities (atoms, electrons, etc.) being too small to see, but yet not being so far beyond reach. And it is not just learners who struggle here. I have even heard someone on a national news programme put forward as an 'expert' make a very similar suggestion to Egrorian, in this case that a "couple of molecules" could be a serious threat to public health after the use of chemical nerve agent. This is a preposterous suggestion to a chemist, but was, I am sure, made in good faith by the international chemical weapons expert.
It is this type of conceptual difficulty which allows scriptwriters to refer to 8 neutrons as being of some significance without expecting the audience to simply laugh at the suggestion (even if some of us do).
It also explains how science fiction writers get away with such plot devices given that many in their audiences will readily accept that a few especially malicious molecules or naughty neutrons is a genuine threat to life.8 But that still does not justify using angle-poise lamps as futuristic spacecraft joysticks.
Jenna pilots the most advanced spacecraft in the galaxy
Works cited:
Einstein, A. (1917/2015). Relativity. The special and the general theory. (100th Anniversary ed.). Princeton: Princeton Univerity Press.
Treptow, R. S. (2005). E = mc2 for the Chemist: When Is Mass Conserved? Journal of Chemical Education, 82(11), 1636. doi:10.1021/ed082p1636
Notes:
1 To explain: For younger readers, television was first broadcast in monochrome (black and white – in effect shades of grey). My family first got a television after I started primary school – the justification for this luxury was that the teachers sometimes suggested programmes we might watch.
Colour television did not arrive in the UK till 1967, and initially it was only used for selected broadcasts. The first colour sets were too expensive for many families, so most people initially stayed with monochrome. This led to the infamous 'helpful' statement offered by the commentator of the weekly half-hour snooker coverage: "And for those of you who are watching in black and white, the pink [ball] is next to the green". (While this is well known as a famous example of misspeaking, a commentator's blooper, those of a more suspicious mind might bear in mind the BBC chose snooker for broadcast in part because it might encourage more people to watch in colour.)
Snooker – not ideal viewing on 'black and white' television (Image by MasterTux from Pixabay )
My father had a part-time weekend job supervising washing machine rental collections (I kid you not, many people only rented such appliances in those days), to supplement income from his full time job, and this meant on Monday evenings after his day job he had to visit his part-time boss and report and they would go throughout the paperwork to ensure things tallied. I would go with him, and was allowed to watch television whilst they did this – it coincided with Star Trek, and the boss had a colour set!
2 Assuming water had to be heated from 20˚C to 100˚C, and the cup took 200 ml (200 cm3) of tea then the calculation is 4.2 x 80 x 200
4.2 J g-1K-1 is the approximate specific heat capacity of water.
Changing these parameters (perhaps you have a small tea cup and I use a mug?) will change the precise value.
3 That is the energy needed divided by the energy released by each neutron: 67200 J ÷ 1.25 x 10-13 J/neutron = 537 600 000 000 000 000 neutrons
4 E=mc2
so m = E/c2 = 67 200 ÷ (3.00 x 108)2 = 7.47 x 10-13
5 E=mc2 = 1.67 x 10-27 x (3.00 x 108)2 = 1.50 x 10-10
6 Well, we could imagine that somehow Hoffal had devised a process where the neutrons somehow redirect energy provided to initially generate the magnetic field, and perhaps the weapon was actually an enormous field generator producing a massive magnetic field that the funnel somehow converted into a beam (of tachyons?) that could pass across vast amounts of space without being absorbed by space dust, remaining highly collimated, and intense enough to destroy a world.
So, perhaps the neutrons are analogous to the core of a laser.
I somehow think it would still need more than 8 of them.
7 That is the energy needed divided by the energy released by each neutron: 67200 J ÷ 1.50 x 10-10 J/neutron = 4.48 x 1014 neutrons
8 Of course molecules are not actually malicious and neutrons cannot be naughty as they are inanimate entities. I am not anthropomorphising, just alliterating.
There might be a couple of molecules left in the Salisbury area. . ."
Expert interviewed on national news
The subject of chemical weapons is not to be taken lightly, and is currently in the news in relation to the Russian invasion of Ukraine, and the concern that the limited progress made by the Russian invaders may lead to the use of chemical or biological weapons to supplement the deadly enough effects of projectiles and explosives.
Organophosphorus nerve agents (OPNA) were used in Syria in 2013 (Pita, & Domingo, 2014), and the Russians have used such nerve agents in illicit activities – as in the case of the poisoning of Sergey Skripal and his daughter Yulia in Salisbury. Skripal had been a Russian military intelligence officer who had acted for the British (i.e., as a double agent), and was convicted of treason – but later came to the UK in a prisoner swap and settled in Salisbury (renown among Russian secret agents for its cathedral). 1
Salisbury, England – a town that featured in the news when it was the site of a Russian 'hit' on a former spy (Image by falco from Pixabay )
These substances are very nasty,
OPNAs are odorless and colorless [and] act by blocking the binding site of acetylcholinesterase, inhibiting the breakdown of acetylcholine… The resulting buildup of acetylcholine leads to the inhibition of neural communication to muscles and glands and can lead to increased saliva and tear production, diarrhea, vomiting, muscle tremors, confusion, paralysis and even death
Kammer, et al., 2019, p.119
So, a substance that occurs normally in cells, but is kept in check by an enzyme that breaks it down, starts to accumulate because the enzyme is inactivated when molecules of the toxin bind with the enzyme molecules stopping them binding with acetylcholine molecules. Enzymes are protein based molecules which rely for their activity on complex shapes (as discussed in 'How is a well-planned curriculum like a protein?' .)
Acetylcholine is a neurotransmitter. It allows signals to pass across synapses. It is important then that acetylcholine concentrations are controlled for nerves to function (Image source: Wikipedia).
Acetylcholinesterase is a protein based enzyme that has an active site (red) that can bind and break up acetylcholine molecules (which takes about 80 microseconds per molecule). The neurotransmitter molecule is broken down into two precursors that are then available to be synthesised back into acetylcholine when appropriate. 2
Toxins (e.g., green, blue) that bind to the enzyme's active site block it from breaking down acetylcholine.
A need to clear up after the release of chemical agents
The effects of these agents can be horrific – but, so of course, can the effects of 'conventional' weapons on those subjected to aggression. One reason that chemical and biological weapons are banned from use in war is their uncontrollable nature – once an agent is released in an environment it may remain active for some time – and so hurt or kill civilians or even personnel from the side using those weapons if they move into the attacked areas. The gases used in the 1912-1918 'world' war, were sometimes blown back towards those using them when the wind changed direction.
This is why, when small amounts of nerve agents were used in the U.K. by covert Russian agents to attack their targets, there was so much care put into tracing and decontaminating any residues in the environment. This is a specialised task, and it is right that the public are warned to keep clear of areas of suspected contamination. Very small quantities of some agents can be very harmful – depending upon what we mean by such relative terms as 'small'. Indeed, two police officers sent to the scene of the crime became ill. But what does 'very small quantities' mean in terms of molecules?
A recent posting discussed the plot of a Blakes7 television show episode where a weapon capable of destroying whole planets incorporated eight neutronsas a core component. This seemed ridiculous: how much damage can eight neutrons do?
But, I also pointed out that, sadly, not all those who watched this programme would find such a claim as comical as I did. Presumably, the train of thought suggested by the plot was that a weapon based on eight neutrons is a lot more scary than a single neutron design, and neutrons are found in super-dense neutron stars (which would instantly crush anyone getting too near), so they are clearly very dangerous entities!
A common enough misconception
This type of thinking reflects a common learning difficulty. Quanticles such as atoms, atomic nuclei, neutrons and the like are tiny. Not tiny like specs of dust or grains of salt, but tiny on a scale where specs of dust and grains of salt themselves seem gigantic. The scales involves in considering electronic charge (i.e., 10-19C) or neutron mass (10-27 kg) can reasonably be said to be unimaginatively small – no one can readily visualise the shift in scale going from the familiar scale of objects we normally experience as small (e.g., salt grains), to the scale of individual molecules or subatomic particles.
People therefore commonly form alternative conceptions of these types of entities (atoms, electrons, etc.) being too small to see, but yet not being so far beyond reach. It perhaps does not help that it is sometimes said that atoms can now be 'seen' with the most powerful microscopes. The instruments concerned are microscopes only by analogy with familiar optical microscopes, and they produce images, but these are more like computer simulations than magnified images seen through the light microscope. 3
It is this type of difficulty which allows scriptwriters to refer to eight neutrons as being of some significance without expecting the audience to simply laugh at the suggestion (even if some of us do).
An expert opinion
Although television viewers might have trouble grasping the insignificance of a handful of neutrons (or atoms or molecules), one would expect experts to be very clear about the vast difference in scale between us (people for example) and them (nanoscopic entities of the molecular realm). Yet experts may sometimes be stretched beyond their expertise without themselves apparently being aware of this – as when a highly qualified and experienced medical expert agreed with an attorney that the brain sends out signals to the body faster than the speed of light. If a scientific expert in a high profile murder trial can confidently make statements that are scientifically ridiculous then this underlines just how challenging some key scientific ideas are.
For any of us, knowing what we do not know, recognising when we are moving outside out of areas where we have a good understanding, is challenging. Part of the reason that student alternative conceptions are so relevant to science learning is that a person's misunderstanding can seem subjectively to be just as well supported, sensible, coherent and reasonable as a correct understanding. Where a teacher themself has an alternative conception (which sometimes happens, of course) they can teach this with as much enthusiasm and confidence as anything they understand canonically. Expertise always has limitations.
A chemical weapons expert
I therefore should not have been as surprised as I was when I heard a news broadcast featuring an expert who was considered to know about chemical weapons refer to the potential danger of "a couple of molecules". This was in relation to the poisoning by Russian agents of the Salisbury residents,
"During an interview on a BBC Radio 4 news programme (July 5th, 2018), Hamish de Bretton-Gordon, who brands himself as one of the world's leading chemical weapons experts, warned listeners that there may be risks to the public due to residue from the original incident in the area. Whilst that may have been the case, his suggestion that "we are only talking about molecules here. . .There might be a couple of molecules left in the Salisbury area. . ." seemed to suggest that even someone presented to the public as a chemistry expert might completely fail to appreciate the submicroscopic scale of individual molecules in relation to the macroscopic scale of a human being."
Now Colonel de Bretton-Gordon is a visiting fellow at Magdalene College Cambridge, and the College website describes him as "a world-leading expert in Chemical and Biological weapons". I am sure he is, and I would not seek to underplay the importance of decontamination after the use of such agents; but if someone who has such expertise would assume that a couple of molecules of any substance posed a realistic threat to a human being with its something like 30 000 000 000 000 cells, each containing something like 40 000 000 molecules of protein (to just refer to one class of cellular components), then it just underlines how difficult it is to appreciate the gulf in scale between molecules and men.
Regarding samples of nerve agents, they may be deadly even in small quantities, but that still means a lot of molecules.
Novichok cocktails
The attacks in Salisbury (from which the intended victims recovered, but another person died in nearby Amesbury apparently having come into contact with material assumed to have been discarded by the criminals), were reported to have used 'Novichok', a label given to group of compounds.
"Based on analyses carried out by the British "Defence Science and Technology Laboratory" in Porton Down it was concluded that the Skripals were poisoned by a nerve agent of the so-called Novichok group. Novichok … is the name of a group of nerve agents developed and produced by Russia in the last stage of the Cold War."
Carlsen, 2019, p.1
Testing of toxins is often based on the LD50 – which means finding the dose that has an even chance of being lethal. This is not an actual amount, as clearly the amount of material that is needed to kill a large adult will be more than that to kill a small child, but the amount of the toxin needed per unit mass of victim. Although no doubt these chemicals have been directly tested on some poor test specimens of non-consenting small mammals, such information is not in the public domain.
Indeed, being based on state secrets, there is limited public data on Novichok and related agents. Carlsen (2019) estimates the LD50 for oral administration of 9 compounds in the Novichok group and some closely related agents to vary between 0.1 to 96.16 mg/kg.
Carlsen suggest the most toxic of these compounds is one known as VX. VX was actually first developed by British Scientists, although almost equivalent nerve agents were later developed elsewhere, including Russia.
'Chemical structures of V-agents.' (Figure 2 from Nepovimova & Kuca, 2018 – subject to http://creativecommons.org/licenses/BY-NC-ND/4.0/) n.b. This figure shows more than a couple of molecules of nerve agent – so might this be a lethal dose?
Carlsen then argues that the actual compounds in Novachok are probably less toxic than XV, which might explain…
"…why did the Skripals not die following expose to such high potent agents; just compare to the killing of Kim Jong-nam on February 13, 2017 in Kuala Lumpur International Airport, where he was attacked by the highly toxic VX, and died shortly after."
Carlsen, 2019, p1
So, for the most sensitive agent, known as XV (LD50 c. 0.1 mg/kg), a person of 50 kg mass would it is estimated have a 50% chance of being killed by an oral dose of 0.1 x 50 mg. That is 5 mg or 0.005 g by mouth. A single drop of water is said to have a volume of about 0.05 ml, and so a mass of about 0.05 g. So, a tenth of a drop of this toxin can kill. That is a very small amount. So, if as little as 0.005 g of a nerve agent will potentially kill you then that is clearly a very toxic substance.
The molecular structure of XV is given in the figure above taken from Nepovimova and Kuca (2018). These three structures shown appear to be isomeric – that is the three molecules are structural isomers. They would have the same empirical formula (and the same molecular mass).
Chemical shorthand
This type of structural formula is often used for complex organic molecules as it is easy for experts to read. It is one of many special types of representation used in chemistry. It is based on the assumption that most organic compounds can be understood as if substituted hydrocarbons. (They may or may not be derived that way – this is jut a formalism used as a thinking tool.) Hydrocarbons comprise chains of carbon atomic cores bonded to each other, and with their other valencies 'satisfied' by being bonded to hydrogen atomic cores. These compounds can easily be represented by lines where each line shows the bond between two carbon atomic cores. The hydrogen centres are not shown at all, but are implicit in the figure (they must be there to 'satisfy' the rules of valency – i.e., carbon centres in a stable structures nearly always have four bonds ).
Anything other than carbon and hydrogen is shown with elemental symbols, and in most organic compounds these other atomic centres take up on a minority of positions in the structure. So, for compounds, such as the 'VX' compounds, these kinds of structural representations are a kind of hybrid, with some atomic centres shown by their elemental symbols – but others having to be inferred.
From the point of view of the novice learner, this form of abstract representation is challenging as carbon and hydrogen centres need to be actively read into the structure (whereas an expert has learnt to do this automatically). But for the expert this type of representation is useful as complex organic molecules can contain hundreds or thousands of atomic centres (e.g., the acetylcholinesterase molecule, as represented above) and structural formulae that show all the atomic centres with elemental symbols would get very crowded.
So, below I have annotated the first version of XV:
The VX compound seems to have a molecular mass of 267
This makes the figure much more busy, but helps me count up the numbers of different types of atomic centres present and therefore work out the molecular mass – which, if I had not made a mistake, is 267. I am working here with the nearest whole numbers, so not being very precise, but this is good enough for my present purposes. That means that the molecule has a mass of 267 atomic mass units, and so (by one of the most powerful 'tricks' in chemistry) a mole of this compound, the actual substance, would have a mass of 267g.
The trick is that chemists have chosen their conversion factor between molecules and moles, the Avogadro constant of c. 6.02 x 1023, such that adding up atomic masses in a molecule gives a number that directly scales to grammes for the macroscopic quantity of choice: the mole. 5
So, if one had 267 g of this nerve agent, that would mean approximately 6.02 x 1023 molecules. Of course here we are talking about a much smaller amount – just 0.005 g (0.005/267, about 0.000 02 moles) – and so many fewer molecules. Indeed we can easily work out 0.005 g contains something like
(0.005 / 267) x 6.02 x 1o23 = 11 273 408 239 700 374 000 = 1×1019 (1 s.f.)
That is about
10 000 000 000 000 000 000 molecules
So, because of the vast gulf in scale between the amount of material we can readily see and manipulate, and the individual quanticle such as a molecule, even when we are talking about a tiny amount of material, a tenth of a drop, this still represent a very, very large number of molecules. This is something chemistry experts are very aware of, but most people (even experts in related fields) may not fully appreciate.
The calculation here is approximate, and based on various estimates and assumptions. It may typically take about 10 000 000 000 000 000 000 molecules of the most toxic Novichok-like agent to be likely to kill someone – or this estimate could be seriously wrong. Perhaps it takes a lot more, or perhaps many fewer, molecules than this.
But even if this estimate is out by several orders of magnitude and it 'only' takes a few thousand million million molecules of XV for a potential lethal dose, that can in no way be reasonably described as "a couple of molecules".
It takes very special equipment to detect individual quanticles. The human retina is in its own way very sophisticated, and comes quite close to being able to detect individual photons – but that is pretty exceptional. As a rule of thumb, when anyone tells us that a few molecules or a few atoms or a few ions or a few electrons or a few neutrons or a few gamma rays or… can produce any macroscopic effect (that we can see, feel, or notice) we should be VERY skeptical.
Kammer, M., Kussrow, A., Carter, M. D., Isenberg, S. L., Johnson, R. C., Batchelor, R. H., . . . Bornhop, D. J. (2019). Rapid quantification of two chemical nerve agent metabolites in serum. Biosensors and Bioelectronics, 131, 119-127. doi:https://doi.org/10.1016/j.bios.2019.01.056
Nepovimova, E., & Kuca, K. (2018). Chemical warfare agent NOVICHOK – mini-review of available data. Food and Chemical Toxicology, 121, 343-350. doi:https://doi.org/10.1016/j.fct.2018.09.015
Pita, R., & Domingo, J. (2014). The Use of Chemical Weapons in the Syrian Conflict. Toxics, 2(3), 391-402.
1 Two men claiming to be the suspects whose photographs had been circulated by the British Police, and claimed by the authorities here to be Russian military intelligence officers, appeared on Russian television to explain they were tourists who had visited Salisbury sightseeing because of the Cathedral.
2 According to the RCSB Protein Data Bank website
"Acetylcholinesterase is found in the synapse between nerve cells and muscle cells. It waits patiently and springs into action soon after a signal is passed, breaking down the acetylcholine into its two component parts, acetic acid and choline."
Of course, it does not 'wait patiently': that is anthropomorphism.
3 We might think it is easy to decide if we are directly observing something, or not. But perhaps not:
"If a chemist heats some white powder, and sees it turns yellow, then this seems a pretty clear example of direct observation. But what if the chemist was rightly conscious of the importance of safe working, and undertook the manipulation in a fume cupboard, observing the phenomenon through the glass screen. That would not seem to undermine our idea of direct observation – as we believe that the glass will not make any difference to what we see. Well, at least, assuming that suitable plane glass of the kind normally used in fume cupboards has been used, and not, say a decorative multicoloured glass screen more like the windows found in many churches. Assuming, also, that there is not bright sunlight passing through a window and reflecting off the glass door of the fume cupboard to obscure the chemist's view of the powder being heated. So, assuming some basic things we could reasonably expect about fume cupboards, in conjunction with favourable viewing conditions, and taking into account our knowledge of the effect of plane glass, we would likely not consider the glass screen as an impediment to something akin to direct observation.
Might we start to question an instance of direct observation if instead of looking at the phenomenon through plane glass, there was clear, colourless convex glass between the chemist and the powder being heated? This might distort the image, but should not change the colours observed. If the glass in question was in the form of spectacle lenses, without which the chemist could not readily focus on the powder, then even if – technically – the observations were mediated by an instrument, this instrument corrects for a defect of vision such that our chemist would feel that direct observation is not compromised by, but rather requires, the glasses.
If we are happy to consider the bespectacled chemist is still observing the phenomenon rather than some instrumental indication of it, then we would presumably feel much the same about an observation being made with a magnifying glass, which is basically the same technical fix as the spectacles. So, might we consider observation down a microscope as direct observation? Early microscopes were little more than magnifying glasses mounted in stands. Modern compound microscopes use more than one lens. A system of lenses (and some additional illumination, usually) reveals details not possible to the naked eye – just as the use of convex spectacles allow the longsighted chemist to focus on objects that are too close to see clearly when unaided.
If the chemist is looking down the microscope at crystal structures in a polished slice of mineral, then, it may become easier to distinguish the different grains present by using a Polaroid filter to selectively filter some of the light reaching the eye from the observed sample. This seems a little further from what we might normally think of as direct observation. Yet, this is surely analogous to someone putting on Polaroid sunglasses to help obtain clear vision when driving towards the setting sun, or donning Polaroid glasses to help when observing the living things at the bottom of a seaside rock pool on a sunny day when strong reflections from the surface prevent clear vision of what is beneath.
A further step might be the use of an electron microscope, where the visual image observed has been produced by processing the data from sensors collecting reflections from an electron beam impacting on the sample. Here, conceptually, we have a more obvious discontinuity although the perceptual process (certainly if the image is of some salt crystal surface) may make this seem no different to looking down a powerful optical microscope. An analogy here might be using night-vision goggles that allow someone to see objects in conditions where it would be too dark to see them directly. I have a camera my late wife bought me that is designed for catching images of wildlife and that switches in low light conditions to detecting infrared. I have a picture of a local cat that triggered an image when the camera was left set up in the garden overnight. The cat looks different from how it would appear in day-light, but I still see a cat in the image (where if the camera had taken a normal image I would not have been able to detect the cat as the image would have appeared like the proverbial picture of a 'black cat in a coal cellar'). Someone using night-vision goggles considers that they see the fox, or the escaped convict, not that they see an image produced by electronic circuits.
If we accept that we can see the cat in the photograph, and the surface details of crystal grains in the electron microscope image, then can we actually see atoms in the STM [scanning tunneling microscope] image? There is no cat in or on my image, it is just a pattern of pixels that my brain determines to represent a cat. I never saw the cat directly (I was presumably asleep) so I have no direct evidence there really was a cat if I do not accept the photograph taken using infrared sensors. I believe there are cats in the world, and have seen uninvited cats in my garden in daylight, and think the camera imaged one of them at night. So it seems reasonable I am seeing a cat in the image, and therefore I might wonder if it is reasonable to doubt that I can also see atoms in an STM image.
One could shift further from simple sensory experience. News media might give the impression that physicists have seen the Higgs boson in data collected at CERN. This might lead us to ask: did they see it with their eyes? Or through spectacles? Or using a microscope? Or with night-vision goggles? Of course, they actually used particle detectors.
Feyerabend suggests that if we look at cloud chamber photographs, we do not doubt that we have a 'direct' method of detecting elementary particles …. Perhaps, but CERN were not using something like a very large cloud chamber where they could see the trails of condensation left in the 'wake' of a passing alpha particle, and that could be photographed for posterity. The detection of the Higgs involved very sophisticated detectors, complex theory about the particle cascades a Higgs particle interaction might cause, and very complex simulations to allow for all kinds of issues relating to how the performance of the detectors might vary (for example as they age) and how a signal that might be close to random noise could be identified…. No one was looking at a detector hoping to see the telltale pattern that would clearly be left by a Higgs, and only a Higgs. In one sense, to borrow a phrase, 'there's nothing to see'. Interpreting the data considered to provide evidence of the Higgs was less like using a sophisticated microscope, and more like taking a mixture of many highly complex organic substances, and – without any attempt to separate them – running a mass spectrum, and hoping to make sense of the pattern of peaks obtained.
4 That is not to suggest that one should automatically assume that one molecule of a toxin can only ever damage one protein molecule somewhere in one body cell. After all, one of the reasons that CFCs (chlorofluorocarbons, which used to be used as propellants in all kinds of spray cans for example) were so damaging to the ozone 'layer' was because they could initiate a chain reaction.
In reactions that involve free radicals, each propagation step can produce another free radical to continue the reaction. Eventually two free radicals are likely to interact to terminate the process – but that might only be after a great many cycles, and the removal of a great many ozone molecules from the stratosphere. However, even if one free radical initiated the destruction of many molecules of ozone, that would still be a very small quantity of ozone, as molecules are so tiny. The problem was of course that a vast number of CFC molecules were being released.
5 So one mole of hydrogen gas, H2, is 2g, and so forth.
Specimens of two different types of natural 'engines'. Portrait of Sir Kenelm Digby, 1603-65 (Anthony van Dyck: From Wikimedia Commons, the free media repository)
In this post I discuss a historical scientific analogy used to discuss the distinction between animals and plants. The analogy was used in a book which is said to be the first major work of philosophy published in the English language, written by one of the founders of The Royal Society of London for Improving Natural Knowledge ('The Royal Society'), Sir Kenelm Digby.
Why take interest in an out-of-date analogy?
It is quite easy to criticise some of the ideas of early modern scientists in the light of current scientific knowledge. Digby had some ideas which seem quite bizarre to today's reader, but perhaps some of today's canonical scientific ideas, and especially more speculative theories being actively proposed, may seem equally ill-informed in a few centuries time!
There is a value in considering historical scientific ideas, in part because they help us understand a little about the path that scientists took towards current scientific thinking. This might be valuable in avoiding the 'rhetoric of conclusions', where well-accepted ideas become so familiar that we come to take them for granted, and fail to appreciate the ways in which such ideas often came to be accepted in the face of competing notions and mixed experimental evidence.
For the science educator there are added benefits. It reminds us that highly intelligent and well motivated scholars, without the value of the body of scientific discourse and evidence available today, might sensibly come up with ideas that seem today ill-conceived, sometimes convoluted, and perhaps even foolish. That is useful to bear in mind when our students fail to immediately understand the science they are taught and present with alternative conceptions that may seem illogical or fantastic to the teacher. Insight into the thought of others can help us consider how to shift their thinking and so can make us better teachers.
Analogies are used in teaching and in science communication to help 'make the unfamiliar familiar', to show someone that something they do not (yet) know about is actually, in some sense at least, a bit like something they are already familiar with. In an analogy, there is a mapping between some aspect(s) of the structure of the target ideas and the structure of the familiar phenomenon or idea being offered as an analogue. Such teaching analogies can be useful to the extent that someone is indeed highly familiar with the 'analogue' (and more so than with the target knowledge being communicated); that there is a helpful mapping across between the analogue and the target; and that comparison is clearly explained (making clear which features of the analogue are relevant, and how).
Digby presents his analogy for considering the difference between plants and animals in his 'Discourse on Bodies', the first part of his comprehensive text known as his 'Two Discourses' completed in 1644, and in which he sets out something of a system of the world.1 Although, to a modern scientific mind, many of Digby's ideas seem odd, and his complex schemes sometimes feel rather forced, he shared the modern scientific commitment that natural phenomena should be explained in terms of natural causes and mechanisms. (That is certainly not to suggest he was an atheist, as he was a committed Roman Catholic, but he assumed that nature had been set up to work without 'occult' influences.)
Before introducing an analogy between types of living things and types of engines, Digby had already prepared his readers by using the term 'engine' metaphorically to refer to living things. He did this after making a distinction between matter dug out of the ground as a single material, and other specimens which although highly compacted into single bodies of material clearly comprised of "differing parts" that did not work together to carry out any function, and seemed to have come together by "chance and by accident"; and where, unlike in living things (where removed parts tended to stop functioning), the separate parts could be "severed from [one] another" without destroying any underlying harmonic whole. He contrasted these accidental complexes with,
"other bodies in which this manifest and notable difference of parts, carries with it such subordination of one of them unto another, as we cannot doubt but that nature made such engines (if so I may call them) by design; and intended that this variety should be in one thing; whole unity and being what it is, should depend of the harmony of the several differing parts, and should be destroyed by their separation".
Digby emphasising the non-accidental structure of living things (language slightly tidied for a modern reader).
Digby was writing long before Charles Darwin's work, and accepted the then widely shared idea that there was design in nature. Today this would be seen as teleological, and not appropriate in a scientific account.A teleological account can be circular (tautological) if the end result of some process is explained as due to that process having a purpose. [Consider the usefulness as an 'explanation' that 'oganisms tend to become more complex over time as nature strives for complexity'. 2]
Scientists today are expected to offer accounts which do not presuppose endpoints. That does not mean that a scientists cannot believe there is purpose in the world, or even that the universe was created by a purposeful God – simply that scientific accounts cannot 'cheat' by using arguments that something happens because God wished it, or nature was working towards it. That is, it should not make any difference whether a scientist believes God is the ultimate cause of some phenomena (through creating the world, and setting up the laws of nature) as science is concerned with the natural 'mechanisms' and causes of events.
In the part of his treatise on bodies that concerns living things, Digby gives an account of two 'engines' he had seen many years before when he was travelling in Spain. This was prior to the invention of the modern steam engine, and these engines were driven by water (as in water mills). 3
Digby introduces two machines which he considers illustrate "the natures of these two kinds of bodies [i.e., plants and animals]"
He gives a detailed account of one of the engines, explaining that the mechanism has one basic function – to supply water to an elevated place above a river.
1/4
2/4
3/4
4/4
His other engine example (apparently recalled in less detail – he acknowledges having a "confused and cloudy remembrance" ) was installed in a mint in a mine where it had a number of different functions, including:
producing metal of the correct thickness for coinage
stamping the metal with the coinage markings
cutting the coins from the metal
transferring the completed coins into the supply room.
These days we might see it as a kind of conveyor belt moving materials through several specialist processes.
Different classes of engine
Digby seems to think this is a superior sort of engine to the single function example.
For Digby, the first type of engine is like a plant,
"Thus then; all sorts of plants, both great and small, may be compared to our first engine of the waterwork at Toledo, for in them all the motion we can discern, is of one part transmitting unto the next to it, the juice which it received from that immediately before it…"
Digby comparing a plant to a single function machine
The comments here about juice may seem a bit obscure, as Digby has an extended explanation (over several pages) of how the growth and structure of a plant are based on a single kind of vascular tissue and a one-way transport of liquid. 4 Liquid rises up through the plant just as it was raised up by the mechanism at Toldeo
The multi-function 'engine' (perhaps ironically better considered in today's terms as an industrial plant!) is however more like an animal,
"But sensible living creatures, we may fitly compare to the second machine of the mint at Segovia. For in them, though every part and member be as it were a complete thing of itself, yet every one requires to be directed and put on in its motion by another; and they must all of them (though of very different natures and kinds of motion) conspire together to effect any thing that may be for the use and service of the whole. And thus we find in them perfectly the nature of a mover and a moveable; each of them moving differently from one another, and framing to themselves their own motions, in such sort as is more agreeable to their nature, when that part which sets them on work hath stirred them up.
And now because these parts (the movers and the moved) are parts of one whole; we call the entire thing automaton or…a living creature".
Digby comparing animals to more complex machines (language slightly tidied for a modern reader)
So plants were to animals as a single purpose mechanism was to a complex production line.
Animals as super-plants
Digby thought animals and plants shared in key characteristics of generation (we would say reproduction), nutrition, and augmentation (i.e., growth), as well as suffering sickness, decay and death. But Digby did not just think animals were different to plants, but a superior kind.
He explains this both in terms of the animal having functions that be did not beleive applied to plants,
And thus you see this plant [sic] has the virtue both of sense or feeling; that is, of being moved and affected by external objects lightly striking upon it; as also of moving itself, to or from such an object; according as nature shall have ordained.
but he also related to this as animals being more complex. Whereas the plant was based on a vascular system involving only one fluid, this super-plant-like-entity, had three. In summary,
this plant [sic, the animal] is a sensitive creature, composed of three sources, the heart, the brain, and the liver: whose are the arteries, the nerves, and the veins; which are filled with vital spirits, with animal spirits, and with blood: and by these the animal is heated, nourished, and made partaker of sense and motion.
A historical analogy to explain the superiority of animals to plants
[The account here does not seem entirely consistent with other parts of the book, especially if the reader is supposed to associate a different fluid with each of the three systems. Later in the treatise, Digby refers to Harvey's work about circulation of the blood (including to the liver), leaving the heart through arteries, and to veins returning blood to the heart. His discussion of sensory nerves suggest they contain 'vital spirits'.]
Some comments on Digby's analogy
Although some of this detail seems bizarre by today's standards, Digby was discussing ideas about the body that were fairly widely accepted. As suggested above, we should not criticise those living in previous times for not sharing current understandings (just as we have to hope that future generations are kind to our reasonable mistakes). There are, however, two features of this use of analogy I thought worth commenting on from a modern point of view.
The logic of making the unfamiliar familiar
If such analogies are to be used in teaching and science communication, then they are a tactic we can use to 'make the unfamiliar familiar', that is to help others understand what are sometimes difficult (e.g., abstract, counter-intuitive) ideas by pointing out they are somewhat like something the person is already familiar with and feels comfortable that they understand.
In a teaching context, or when a scientist is being interviewed by a journalist, it is usually important that the analogue is chosen so it is already familiar to the audience. Otherwise either the analogy does not help explain anything, or time has to be spent first explaining the analogy, before it can be employed.
In that sense, then, we might question Digby's example as not being ideal. He has to exemplify the two types of machines he is setting up as the analogue before he can make an analogy with it. Yet this is not a major problem here for two reasons.
Firstly, a book affords a generosity to an author that may not be available to a teacher or a scientist talking to a journalist or public audience. Reading a book (unlike a magazine, say) is a commitment to engagement in depth and over time, and a reader who is still with Digby by his Chapter 23 has probably decided that continued engagement is worth the effort.
Secondly, although most of his readers will not be familiar with the specific 'engines' he discusses from his Spanish travels, they will likely be familiar enough with water mills and other machines and devices to readily appreciate the distinction he makes through those examples. The abstract distinction between two classes of 'engine' is therefore clear enough, and can then be used as an analogy for the difference between plants and animals.
A biased account
However, today we would not consider this analogy to be applicable, even in general terms, leaving aside the now discredited details of plant and animal anatomy and physiology. An assumption behind the comparison is that animals are superior to plants.
In part, this is explained in terms of the plants apparent lack of sensitivity (later 'irritability' would be added as a characteristic of living things, shared by plants) and their their lack of ability in getting around, and so not being able to cross the room to pick up some object. In part, this may be seen as an anthropocentric notion: as humans who move around and can handle objects, it clearly seems to us with our embodied experience of being in the world that a form of life that does not do this (n.b., does not NEED to do this) is inferior. This is a bit like the argument that bacteria are primitive forms of life as they have evolved so little (a simplification, of course) over billions of years: which can alternatively be understood as showing how remarkably adapted they already were, to be able to successfully occupy so many niches on earth without changing their basic form.
There is also a level of ignorance about plants. Digby saw the plant as having a mechanism that moved moisture from the soil through the plant, but had no awareness of the phloem (only named in the nineteenth century) that means that transport in a plant is not all in one direction. He also did not seem to appreciate the complexity of seasonal changes in plants which are much more complex than a mechanism carrying out a linear function (like lifting water to a privileged person who lives above a river). He saw much of the variation in plant structures as passive responses to external agents. His idea of human physiology are also flawed by today's standards, of course.
Moreover, in Digby's scheme (from simple minerals dug from the ground, to accidentally compacted complex materials, to plants and then animals) there is a clear sense of that long-standing notion of hierarchy within nature.
The great chain of being
That is, the great chain of being, which is a system for setting out the world as a kind of ladder of superior and inferior forms. Ontology is sometimes described as the study of being , and typologies of different classes of entities are sometimes referred to as ontologies. The great chain of being can be understood as a kind of ontology distinguishing the different types of things that exist – and ranking them.
In this scheme (or rather schemes, as various versions with different levels of detail and specificity had been produced – for example discriminating the different classes of angels) minerals come below plants, which come below animals. To some extent Digby's analogymay reflect his own observations of animals and plants leading him to think animals were collectively and necessarily more complex than plants. However, ideas about the great chain of being were part of common metaphysical assumptions about the world. That is, most people took it for granted that there was such hierarchy in nature, and therefore they were likely to interpret what they observed in those terms.
Digby made the comparison between increasing complexity in moving from plant to animal as being a similar kind of step-up as when moving from inorganic material to plants,
But a sensitive creature, being compared to a plant, [is] as a plant is to a mixed [inorganic] body; you cannot but conceive that he must be compounded as it were of many plants, in like sort as a plant is of many mixed bodies.
Digby, then, was surely building his scheme upon his prior metaphysical commitments. Or, as we might say these days, his observations of the world were 'theory-laden'. So, Digby was not only offering an analogy to help discriminate between animals and plants, but was discriminating against plants in assuming they were inherently inferior to animals. I think that is a bias that is still common today.
Work cited:
Digby, K. (1644/1665). Two Treatises: In the one of which, the nature of bodies; In the other, the nature of mans soule, is looked into: in ways of the discovery of the immortality of reasonable soules. (P. S. MacDonald Ed.). London: John Williams.
Digby, K. (1644/2013). Two Treatises: Of Bodies and of Man's Soul (P. S. MacDonald Ed.): The Gresham Press.
1 This is a fascinating book with many interesting examples of analogies, similes, metaphor, personification and the like, and an interesting early attempt to unify forces (here, gravity and magnetism). (I expect to write more about this over time.) The version I am reading is a 2013 edition (Digby, 1644/2013) which has been edited to offer consistent spellings (as that was not something many authors or publishers concerned themselves with at the time). The illustrations, however, are from a facsimile of an original publication (Digby, 1644/1645: which is now out of copyright so can be freely reproduced).
2 Such explanations may be considered as a class of 'pseudo-explanations': that give the semblance of explanation without actually explaining very much (Taber & Watts, 2000).
3 The aeolipile (e.g., Hero's engine) was a kind of steam engine – but was little more than a novelty where water boiled in a vessel with suitably directed outlets and free to rotate, causing it to spin. However, the only 'useful' work done was in turning the engine itself.
4 This relates to his broader theory of matter which still invokes the medieval notion of the four elements, but is also an atomic theory involving tiny particles that can pass into apparently solid materials due to pores and channels much too small to be visible.
It seems atoms are not quite as chemists imagine them not to be
Keith S. Taber
A research paper presenting a new model of atomic and molecular structure was recently brought to my attention. 1
The paper header
'New Atomic Model with Identical Electrons Position in the Orbital's and Modification of Chemical Bonds and MOT [molecular orbital theory]' 2 is published in a recently-launched journal with the impressive title of Annals of Atoms and Molecules. This is an open-access journal available free on the web – so readily accessible to chemistry experts, as well as students studying the subject and lay-people looking to learn from a scholarly source. [Spoiler alert – it may not be an ideal source for scholarly information!]
In the paper, Dr Morshed proposes a new model of the atom that he suggests overcomes many problems with the model currently used in chemistry.
A new model of atomic structure envisages East and West poles as well as North and South poles) (Morshed, 2020a, p.8)
Of course, as I have often pointed out on this blog, one of the downsides of the explosion in on-line publishing and the move to open access models of publication, is that anyone can set up as an academic journal publisher and it can be hard for the non-expert to know what reflects genuine academic quality when what gets published in many new journals often seems to depend primarily upon an author being willing to pay the publisher a hefty fee (Taber, 2013).
That is not to suggest open-access publishing has to compromise quality: the well-established, recognised-as-prestigious journals can afford to charge many hundreds of pounds for open-access publication and still be selective. But, new journals, often unable to persuade experienced experts to act as reviewers, will not attract many quality papers, and so cannot be very selective if they are to cover costs (or indeed make the hoped-for profits for their publishers).
A peer reviewed journal
The journal with the impressive title of Annals of Atom and Molecules has a website which explains that
"Annals of Atoms and Molecules is an open access, peer reviewed journal that publishes novel research insights covering but not limited to constituents of atoms, isotopes of an element, models of atoms and molecules, excitations and de-excitations, ionizations, radiation laws, temperatures and characteristic wavelengths of atoms and molecules. All the published manuscripts are subjected to standardized peer review processing".
So, in principle at least, the journal has experts in the field critique submissions, and advise the editors on (i) whether a manuscript has potential to be of sufficient interest and quality to be worth publishing, and (ii) if so, what changes might be needed before publications is wise.
Standardisedpeer review gives the impression of some kind of moderation (perhaps renormalisation given the focus of the journal? 3) of review reports, which would involve a lot of extra work and another layer of administration in the review process…but I somehow suspect this claim really just meant a 'standard' process. This does not seem to be a journal where great care is taken over the language used.
Effective peer review relies on suitable experts taking on the reviewing, and editors prepared to act on their recommendations. The website lists five members of the editorial board, most of whom seem to be associated with science departments in academic institutions:
Prof. Farid Menaa (Fluorotronics Inc) 4
Prof. Sabrin Ragab Mohamed Ibrahim (Department of Pharmacognosy and Pharmaceutical chemistry, Taibah University)
Prof. Mina Yoon (Department of Physics and Astronomy, University of Tennessee)
Dr. Christian G Parigger (Department of Physics, University of Tennessee Space Institute)
Dr. Essam Hammam El-Behaedi (Department of Chemistry and Biochemistry, University of North Carolina Wilmington)
The members of a journal Editorial Board will not necessarily undertake the reviewing themselves, but are the people entrusted by the publisher with scholarly oversight of the quality of the journal. For this journal it is claimed that "Initially the editorial board member handles the manuscript and may assign or the editorial staff may assign the reviewers for the received manuscript". This sounds promising, as at least (it is claimed) all submissions are initially seen by a Board member, whether or not they actually select the expert reviewers. (The 'or' means that the claim is, of course, logically true even if in actuality all of the reviewers are assigned by the unidentified office staff.)
At the time of writing only three papers have been published in the Annals. One reviews a spectroscopic method, one is a short essay on quantum ideas in chemistry – and then there is Dr Morshed's new atomic theory.
A new theory of atomic structure
The abstract of Dr Morshed's paper immediately suggests that this is a manuscript which was either not carefully prepared or has been mistreated in production. The first sentence is:
The concept of atom has undergone numerous changes in the history of chemistry, most notably the realization that atoms are divisible and have internal structure Scientists have known about atoms long before they could produce images of them with powerful magnifying tools because atoms could not be seen, the early ideas about atoms were mostly founded in philosophical and religion-based reasoning.
Morshed, 2020a, p.6
Presumably, this was intended to be more than one sentence. If the author made errors in the text, they should have been queried by the copy editor. If the production department introduced errors, then they should have been corrected by the author when sent the proofs for checking. Of course, a few errors can sometimes still slip through, but this paper has many of them. Precise language is important in a research paper, and sloppy errors do not give the reader confidence in the work being reported.
The novelty of the work is also set out in the abstract:
In my new atomic model, I have presented the definite position of electron/electron pairs in the different orbital (energy shells) with the identical distance among all nearby electron pairs and the degree position of electrons/electron pairs with the Center Point of Atoms (nucleus) in atomic structure, also in the molecular orbital.
Morshed, 2020a, p.6
This suggests more serious issues with the submission than simple typographical errors.
Orbital /energy shells
The term "orbital (energy shells)" is an obvious red flag to any chemist asked to evaluate this paper. There are serious philosophical arguments about precisely what a model is and the extent to which a model of the atom might be considered to be realistic. Arguably, models that are not mathematical and which rely on visualising the atom are inherently not realistic as atoms are not the kinds of things one could see. So, terms such as shell or orbital are either being used to refer to some feature in a mathematical description or are to some extent metaphorical. BUT, when the term shell is used, it conventionally means something different from an orbital.
That is, in the chemical community, the electron shell (sic, not energy shell) and the orbital refer to different classes of entity (even if in the case of the K shell there is only one associated orbital). Energy levels are related, but again somewhat distinct – an energy level is ontologically quite different to an orbital or a shell in a similar way to how sea level is very different in kind to a harbour or a lagoon; or how 'mains voltage' is quite different from the house's distribution box or mains ring; or how an IQ measurement is a different kind of thing to the brain of the person being assessed.
Definite positions of electrons
An orbital is often understood as a description of the distribution of the electron density – we might picture (bearing in mind my point that the most authentic models are mathematical) the electron smeared out as in a kind of time-lapse representation of where the electron moves around the volume of space designated as an orbital. Although, as an entity small enough for quantum effects to be significant (a 'quanticle'? – with some wave-like characteristics, rather than a particle that is just like a bearing ball only much smaller), it may be better not to think of the electron actually being at any specific point in space, but rather having different probabilities of being located at specific points if we could detect precisely where it was at any moment.
That is, if one wants to consider the electron as being at specific points in space then this can only be done probabilistically. The notion of "the definite position of electron/electron pairs in the different orbital" is simply nonsensical when the orbital is understood in terms of a wave function. Any expert asked to review this manuscript would surely have been troubled by this description.
It is often said that electrons are sometimes particles and sometimes waves but that is a very anthropocentric view deriving from how at the scale humans experience the world, these seem very distinct types of things. Perhaps it is better to think that electrons are neither particles nor waves as we experience them, but something else (quanticles) with more subtle behavioural repertoires. We think that there is a fundamental inherent fuzziness to matter at the scale where we describe atoms and molecules.
So, Dr Morshed wants to define 'definite positions' for electrons in his model, but electrons in atoms do not have a fixed position. (Later there is reference to circulation – so perhaps these are considered as definite relative positions?) In any case, due to the inherent fuzziness in matter, if an electron's position was known absolutely then there would would (by the Heisenberg uncertainty principle) be an infinite uncertainty in its momentum, so although we might know 'exactly' where it was 'now' (or rather 'just now' when the measurement occurred as it would take time for the signal to be processed through first our laboratory, and then our nervous, apparatus!) this would come with having little idea where it was a moment later. Over any duration of time, the electron in an atom does not have a definite position – so there is little value in any model that seeks to represent such a fixed position.
The problem addressed
Dr Morshed begins by giving some general historical introduction to ideas about the atom, before going on to set out what is argued to be the limitation of current theory:
Electrons are arranged in different orbital[s] by different numbers in pairs/unpaired around the nuclei. Electrons pairs are associated by opposite spin together to restrict opposite movement for stability in orbital rather angular movements. The structural description is obeyed for the last more than hundred years but the exact positions of electrons/pairs in the energy shells of atomic orbital are not described with the exact locations among different orbital/shells.
Morshed, 2020a, p.6
Some of this is incoherent. It may well be that English is not Dr Morshed's native language, in which case it is understandable that producing clear English prose may be challenging. What is less forgivable is that whichever of Profs. Ibrahim, Yoon, or Drs Menaa, Parigger, or El-Behaedi initially handled the manuscript did not point out that it needed to be corrected and in clear English before it could be considered for publication, which could have helped the author avoid the ignominy of having his work published with so many errors.
That assumes, of course, that whichever of Ibrahim, Yoon, Menaa, Parigger, or El-Behaedi initially handled the manuscript were so ignorant of chemistry to be excused for not spotting that a paper addressing the issue of how current atomic models fail to assign "exact positions of electrons/pairs in the energy shells of atomic orbital are not described with the exact locations among different orbital/shells" both confused distinct basic atomic conceptsand seemed to be criticising a model of atomic structure that students move beyond before completing upper secondary chemistry. In other words, this paper should have been rejected on editorial screening, and never should have been sent to review, as its basic premise was inconsistent with modern chemical theory.
If, as claimed, all papers are seen by the one of the editorial board, then the person assigned as handling editor for this one does not seem to have taken the job seriously. (And as only three papers have been published since the journal started, the workload shared among five board members does not seem especially onerous.)
Just in case the handling editorial board member was not reading the text closely enough, Dr Morshed offered some images of the atomic model which is being critiqued as inadequate in the paper:
A model of the atom criticised in the paper in Annals of Atoms and Molecules (Morshed, 2020a, p.7)
Again, the handling editor should have noticed that these images in the figure reflect the basic model of the atom taught in introductory school classes as commonly represented in simple two-dimensional images. These are not the models used to progress knowledge in academic chemistry today.
These images are not being reproduced in the research paper as part of some discussion of atomic representations in school textbooks. Rather this is the model that the author is suggesting falls short as part of current chemical theory – but it is actually an introductory pedagogical model that is not the basis of any contemporary chemical research, and indeed has not been so for the best part of a century. Even though the expression "the electrons/electron pairs position is not identical by their position, alignments or distribution" does not have any clear meaning in normal English, what is clear is that these very simple models are only used today for introductory pedagogic purposes.
Symmetrical atoms?
The criticism of the model continues:
The existing electrons pair coupling model is not also shown clearly in figure by which a clear structure of opposite spine pair can be drowned. Also there are no proper distribution of electron/s around the center (nuclei) to maintain equal number of electrons/electronic charge (charge proportionality) around the total mass area of atomic circle (360°) in the existing atomic model (Figure 1). There are no clear ideas about the speed proportion and time of circulation of electrons/electron pairs in the atomic orbital/shells so there is no answer about the possibility of uneven number of electrons/electron pairs at any position /side of atomic body can arise that must make any atom unstable.
Morshed, 2020a, p.7
Again, this makes little sense (to me at least – perhaps the Editorial Board members are better at hermeneutics than I am). Now we are told that electrons are 'circulating' in the orbitals/shell which seems inconsistent with them having the "definite positions" that Dr Morshed's model supposedly offers. Although I can have a guess at some of the intended meaning, I really would love to know what is meant by "a clear structure of opposite spine pair can be drowned".
Protecting an atom from drowning? (Images by Image by ZedH and Clker-Free-Vector-Images from Pixabay)
A flat model of the atom
I initially thought that Dr Morshed is concerned that the model shown in figure 1 cannot effectively show how in the three dimensional atomic structure the electrons must be arranged to give a totally symmetric patterns: and (in his argument) that this would be needed else it would leave the atoms unstable. Of course, two dimensional images do not easily show three dimensional structure. So when Dr Morshed referred to the "atomic circle (360°) in the existing atomic model" I assumed he was actually referring to the sphere.
On reflection, I am not so sure. I was unimpressed by the introduction of cardinal points for the atom (see Dr Morshed's figure 2 above, and figure 4 below). I could understand the idea of a nominal North and South pole in relation to the angular momentum of the nucleus and electrons 'spinning up or down' – but surely the East and West poles are completely arbitrary for an atom as any point on the 'equator' could be used as the basis for assigning these poles. However, if Dr Morshed is actually thinking in terms of a circular (i.e., flat) model of the atom, and not circular representations of a spherical model of atomic structure then atoms would indeed have an Occident and an Orient! The East pole WOULD be to the right when the atom has the North pole at the top as is conventional in most maps today. 5
But atoms are not all symmetrical?
But surely most atoms are not fully symmetrical, and indeed this is linked to why most elements do not commonly exist as discrete atoms. The elements of those that do, the noble gas elements, are renown for not readily reacting because they (atypically for atoms) have a symmetrical electronic 'shield' for the nuclear charge. However, even some of these elements can be made cold enough to solidify – as the van der Waals forces allow transient fluctuating dipoles. So the argument seems to be based on a serious alternative conception of the usual models of atomic structure.
It is the lack of full symmetry in an atom of say, fluorine, or chlorine, which means that although it is a neutral species it has an electron affinity (that is, energy is released when the anion is formed) as an electron can be attracted to the core charge where it is not fully shielded.
The reference to "time of circulation of electrons/electron pairs in the atomic orbital/shells" seems to refer to a mechanical model of orbital motion, which again, has no part in current chemical theory.
Preventing negative electron pairs repelling each other
Dr Morshed suggests that the existing model of atomic structure cannot explain
Why the similar charged electrons don't feel repulsion among themselves within the same nearby atomic orbital of same atom or even in the molecular orbital when two or more atomic orbital come closer to form molecular orbital within tinier space though there is more possibility of repulsion between similar charged electrons according to existing atomic model.
Morshed, 2020a, p.7
Electrons do not feel repulsion for the same reason they do not feel shame or hunger or boredom – or disdain for poor quality journals. Electrons are not the kind of objects that can feel anything. However, this anthropomorphic expression is clearly being used metaphorically.
I think Dr Morshed is suggesting that the conventional models of atomic structure do not explain why electrons/electron pairs do not repel each other. Of course, they do repel each other – so there is no need to look for an explanation. This then seems to be an alternative conception of current models of the atom. (The electrons do not get ejected from the atom as they are also attracted to the nucleus – but, if they did not repel each other, there would be no equilibrium of forces, and the structure of the atom would not be stable.)
A new model of atomic structure supposedly reflects the 'proper' angles between electrons in atoms (Morshed, 2020, p.9)
Dr Morshed suggests that his model (see his Figure 4) 'proves the impossibility of repulsion between any electron pairs' – even those with similar charges. All electron pairs have negative (so similar) charges – it is part of the accepted definition of an electron that is is a negatively charged entity. I do not think Dr Morshed is actually suggesting otherwise, even if he thinks the electrons in different atoms have different magnitudes of negative charge (Morshad, 2020b).
Dr Morshed introduces a new concept that he calls 'center of electron pairs neutralization point'.
This is the pin-point situated in a middle position between two electrons of opposite spin pairs. The point is exactly between of opposite spine electron pairs so how the opposite electronic spin is neutralized to remaining a stable electron pair consisting of two opposite spin electrons. This CENP points are assumed to be situated between the cross section of opposite spine electronic pair's magnetic momentum field diameter (Figure 3).
Morshed, 2020a, p.8
The yellow dot represents a point able to neutralise the opposite spin of a pair of electrons(!), and is located at the point found by drawing a cross from the ends of the ⥯ symbols used to show the electron spin! This seems to be envisaged a real point that has real effects, despite being located in terms of the geometry of a totally arbitrary symbol.
So, the electron pair is shown as a closely bound pair of electrons with the midspot of the complex highlighted (yellow in the figure) as the 'center of electron pairs neutralization point'. Although the angular momentum of the electrons with opposite spin leads to a magnetic interaction between them, they are still giving rise to an electric field which permeates through the space around them. Dr Morshed seems to be suggesting that in his model there is no repulsion between the electron pairs. He argues that:
According to magnetic attraction/repulsion characteristics any similar charges repulse or opposite charges attract when the charges energy line is in straight points. If similar charged or opposite charged end are even close but their center of energy points is not in straight line, there will be no attraction or repulsion between the charges (positive/negative). Similarly, when electrons are arranged in energy shells around the nucleus the electrons remain in pairs within opposite spin electrons where the poses a point which represent as the center of repulsion/attraction points (CENP) and two CENP never come to a straight within the atomic orbital so the similar charged electrons pairs don't feel repulsion within the energy shells.
Morshed, 2020a, pp.8-9
A literal reading of this makes little sense as any two charges will always have their centres in a straight line (from the definition of a straight line!) regardless of whether similar or opposite charges or whether close or far apart.
My best interpretation of this (and I am happy to hear a better one) is that because the atom is flat, and because the electron pairs have spin up and spin down electrons, with are represented by a kind of ⥮ symbol, the electrons in some way shield the 'CENP' so that the electron pair can only interact with another charge that has a direct line of sight to the CENP.
Morshed seems to be suggesting that although electron pairs are aligned to allow attractions with the nucleus (e.g., blue arrows) any repulsion between electron pairs is blocked because an electron in the pair shields the central point of the pair (e.g., red arrow and lines)
There are some obvious problems here from a canonical perspective, even leaving aside the flat model of the atom. One issue is that although electrons are sometimes represented as ↿ or ⇂ to indicate spin, electrons are not actually physically shaped like ↿. Secondly, pairing allows electrons to occupy the same orbital (that is, have the same set of principal, azimuthal and magnetic quantum numbers) – but this does not mean they are meant to be fixed into a closely bound entity. Also, this model works by taking the idea of spin direction literally, when – if we do that – electrons can have only have spin of ±1/2. In a literal representation such as used by Dr Morshed he would need to have ALL his electrons orientated vertically (or at least all at the same angle from the vertical). So, the model does not work in its own terms as it would prevent most of the electron pairs being attracted to the nucleus.
Morshed's figure 4 'corrected' given that electrons can only exist in two spin states. In the (corrected version of the representation of the) Morshed model most electron pairs would not be attracted to the nucleus.
A new (mis)conception of ionic bonding
Dr Morshed argues that
In case of ionic compound formation problem with the existing atomic model is where the transferred electron will take position in the new location on transferred atom? If the electrons position is not proportionally distributed along total 360 circulating area of atom, then the position of new transferred electron will cause the polarity in every ion (both cation and anion forms by every transformation of electrons) so the desired ionization is not possible thus every atom (ion) would become dipolar. On the point of view any ionization would not possible i.e., no ionic bonded compound would have formed.
Morshed, 2020, p.7
Again, although the argument may have been very clear to the author, this seems incoherent to a reader. I think Dr Morshed may be arguing that unless atoms have totally symmetrical electrons distributions ("proportionally distributed along total 360 circulating area of atom") then when the ion is formed it will have a polarity. Yet, this seems entirely back to front.
If the atom to be ionised was totally symmetric (as Dr Morshed thinks it should be), then forming an ion from the atom would require disrupting the symmetry. Whereas, by contrast, in the current canonical model, we assume most atoms are not symmetrical, and the formation of simple ions leads to a symmetric distribution of electrons (but unlike in the noble gas atoms, a symmetrical electron distribution which does not balance the nuclear charge).
Dr Morshad illustrates his idea:
Ionic bond formation represented by an non-viable interaction between atoms (Morshed, 2020, p.10)
Now these images show interactions between discrete atoms (a chemically quite unlikely scenario, as discrete atoms of sodium and chlorine are not readily found) that are energetically non-viable. As has often been pointed out, the energy released when the chloride ion is formed is much less than the energy required to ionise the sodium atom, so although this scheme is very common on the web and in poor quality textbooks, it is a kind of chemical fairy tale that does not relate to any likely chemical context. (See, for example, Salt is like two atoms joined together.)
The only obvious difference between these two versions of the fairly tale (if we ignore that in the new version both protons and neutrons appear to be indicated by + signs which is unhelpful) seems to be that the transferred electron changes its spin for some reason that does not seem to be explained in the accompanying text. The explanation that is given is
My new atomic model with identical electrons pair angle position is able to give logical solution to the problems of ion/ionic bond formation. As follows: The metallic atom which donate electrons during ion formation from outermost orbital, the electrons are arranged maintaining definite degree angle around 360° atomic mass body shown in (Figure 4). After the transformation the transferred electron take position at the vacant place of the transferred atoms outermost orbital, then instant the near most electrons/pairs rearrange their position in the orbital changing their angle position with the CPA [central point of the atom, i.e., the nucleus] due to electromagnetic repulsion feeling among the similar charged electrons/pairs. Thus the ionic atom gets equal electron charge density around whole of their 360° atomic mass body resulting the cation and anion due to the positive and negative charge difference in atomic orbital with their respective nucleus. Thus every ion becomes non polar ion to form ionic bond within two opposite charged ion (Figure 5).
Morshed, 2020, p.9
So, I think, supposedly part (b) of Dr Morshed's figure 5 is meant to show, better than part (a), how the electron distribution is modified when the ion is formed. It would of course be quite possible to show this in the kind of representations used in (a), but in any case it does not look any more obvious in (b) to my eye!
So, figure 5 does not seem to show very well Dr Morshed's solution to a problem I do not think actually exists in the context on a non-viable chemical process. Hm.
Finding space for the forces
Another problem with the conventional models, according to Dr Morshed, is that, as suggested in his figures 6 and 7 is that the current models do not leave space for the 'intermolecular' [sic, intramolecular] force of attraction in covalent bonds.
In current models, according to Morshed's paper, electrons get in the way of the covalent bond (Morshed, 2020, p.11)
Dr Morshad writes that
According to present structural presentation of shared paired electrons remain at the juncture of the bonded atomic orbital, if they remain like such position they will restrict the Inter [sic] Molecular Force (IMF) between the bonded atomic nuclei because the shared paired electron restricts the attraction force lying at the straight attraction line of the bonded nuclei the shown in (Figure 6a).
Morshed, 2020, p.11
There seem to be several alternative conceptions operating here – reflecting some of the kind of confusions reported in the literature from studies on students' ideas.
Just because the images are static two dimensional representations, this does not mean electrons are envisaged to be stationary at some point on a shell;
and just because we draw representations of atoms on flat paper, this does not mean atoms are flat;
The figure is meant to represent the bond, which is an overall configuration of the nuclei and the electrons, so there is not a distinct intramolecular force operating separately;
Without the electrons there would be no "Inter [sic] Molecular Force (IMF) between the bonded atomic nuclei" as the nuclei repel each other: the bonding electrons do not restrict the intramolecular force (blocking it, because they lie between the nuclei), but are crucial to it existing.
Regarding the first point here, Dr Morshed suggests
Covalent bonds are formed by sharing of electrons between the bonded atoms and the shared paired electrons are formed by contribution of one electron each of the participating atoms. The shared paired electrons remain at the overlapping chamber (at the juncture of the overlapped atomic orbital).
Morshed, 2020, p.9
That is, according to Dr Morshed's account of current atomic theory, in drawing overlapping electron shells, the electrons of the bond which are 'shared' (and that is just a metaphor, of course) are limited to the area shown as overlapping. This is treating an abstract and simplistic representation as if it is realistic. There is no chamber. Indeed, the molecular orbital formed by the overlap of the atomic orbitals will 'allow' the electrons to be likely to be found within quite a (relatively – on an atomic scale) large volume of space around the bond axis. Atomic orbitals that overlap to form molecular orbitals are in effect replaced by those molecular orbitals – the new orbital geometry reflects the new wavefunction that takes into account both electrons in the orbital.
So, if there has been overlap, the contributing atomic orbitals should be considered to have been replaced (not simply formed a chamber where the circles overlap), except of course Dr Morshed 's figures 6 and 7 show shells and do not actually represent the system of atomic orbitals.
Double bonds
This same failure to interpret the intentions and limitation of the simplistic form of representation used in introductory school chemistry leads to similar issues when Dr Morshed considers double bonding.
A new model of atomic structure suggests an odd geometry for pi bonds (Morshed, 2020, p.12)
Dr Morshed objects to the kind of representation on the left in his figure 8 as two electron pairs occupy the same area of overlap ('chamber'),
It is shown for an Oxygen molecule; two electron shared pairs are formed and take place at the overlapping chamber result from the outermost orbital of two bonded Oxygen atoms. But in real séance [sic?] that is impossible because two shared paired electrons cannot remain in a single overlapping chamber because of repulsion among each pairs and among individual electrons.
Morshed, 2020, p.12.
Yet, in the model Dr Morshed employs he had claimed that electron pairs do not repel unless they are aligned to allow a direct line of sight between their CNPs. In any case, the figure he criticises does not show overlapping orbitals, but overlapping L shells. He suggests that the existing models (which of course are not models currently used in chemistry except in introductory classes) imply the double bond in oxygen must be two sigma bonds: "The present structure of O2 molecule show only two pairs of electron with head to head overlapping in the overlapping chamber i.e., two sigma bond together which is impossible" (p.12).
However, this is because a shell type presentation is being used which is suitable for considering whether a bond is single or double (or triple), but no more. In order to discuss sigma and pi bonds with their geometrical and symmetry characteristics, one must work with orbitals, not shells. 6
Yet Dr Morshed has conflated shells and orbitals throughout his paper. His figure 8a that supposedly shows "Present molecular orbital structural showing two shared paired electrons in the same overlapped chamber" does not represent (atomic, let alone molecular) orbitals, and is not intended to suggest that the space between overlapping circles is some kind of chamber.
"The remaining two opposite spin unpaired electrons in the two bonded [sic?] Oxygen's outer- most orbital [sic, shell?] getting little distorted towards the shared paired electrons in their respective atomic orbital then they feel an attraction among the opposite spin electrons thus they make a bond pairs by side to side overlapping forms the pi-bond"
Morshed, 2020, p.12.
It is not at all clear to see how this overlap occurs in this representation (i.e., 8b). Moreover, the unpaired electrons will not "feel an attraction" as they are both negatively charged even if they have anti-parallel spins. The scheme also makes it very difficult to see how the pi bond could have the right symmetry around the bond axis, if the 'new molecular orbital structure' was taken at face value.
Conclusion
Dr Morshed's paper is clearly well meant, but it does not offer any useful new ideas to progress chemistry. It is highly flawed. There is no shame in producing highly flawed manuscripts – no one is perfect, which is why we have peer review to support authors in pointing out weaknesses and mistakes in their work and so allowing them to develop their ideas till they are suitable for publication. Dr Morshed has been badly let down by the publishers and editors of Annals of Atoms and Molecules. I wonder how much he was charged for this lack of service? 7
Publishing a journal paper like this, which is clearly not ready to make a contribution to the scholarly community through publication, does not only do a disservice to the author (who will have this publication in the public domain for anyone to evaluate) but can potentially confuse or mislead students who come across the journal. Confusing shells with orbitals, misrepresenting how ionic bonds form, implying that covalent bonds are due to a force between nuclei, suggesting that electron pairs need not repel each other, suggesting a flat model of the atom with four poles… there are many points in this paper that can initiate or reinforce student misconceptions.
Supposedly, this manuscript was handled by a member of the editorial board, sent to peer reviewers and the publication decision based on those review reports. It is hard to imagine any peer reviewer who is actually an academic chemist (let alone an expert in the topics published in this journal) considering this paper would be publishable, even with extensive major revisions. The whole premise of the paper (that simple representations of atoms with concentric shells of electrons reflect the models of atomic and molecular structure used today in chemistry research) is fundamentally flawed. So:
were there actually any reviews? (Really?)
if so, were the reviews carried out by experts in the field? (Or even graduate chemists or physicists?)
were the reviews positive enough to justify publication?
If the journal feels I am being unfair, then I am happy to publish any response submitted as a comment below.
Dr Menaa, Prof. Ibrahim, Prof. Yoon, Dr Parigger, Dr El-Behaedi…
If you were the Board Member who handled this submission and you feel my criticisms are unfair, please feel free to submit a comment. I am happy to publish your response.
Or, if you were not the Board Member who (allegedly) handled this submission, and would like to make that clear…
Works cited:
Gilbert, W. (1600/2016). On the Magnet, Magnetic Bodies, and the Great Magnet of the Earth. A new science, with many both arguments and experiment proofs. (V. Wilmont, Trans.): Lulu.com.
Morshed, A. M. A. (2020a). New Atomic Model with Identical Electrons Position in the Orbital's and Modification of Chemical Bonds and MOT. Annals of Atoms and Molecules, 2(1), 6-13.
1 I thank Professor Eric Scerri of UCLA for bringing my attention to the deliciously named 'Annals of Atoms and Molecules', and this specific contribution.
2 That is my reading of the abbreviation, although the author uses the term a number of times before rather imprecisely defining it: "Similar solution can be made for molecular orbital (MOT) as such as: The molecular orbital (MO) theory…" (p.10).
3 Renormalisation is the name given to a set of mathematical techniques used in areas such as quantum field theory when calculations give implausible infinite results in order to 'lose' the unwanted infinities. Whilst this might seem like cheating – it is tolerated as it works very well.
4 I was intrigued that 'Prof.' Farid Menaa seemed to work for a non-academic institution, as generally companies cannot award the title of Professor. Of course, Prof. Meena may also have an appointment at a university that partners the company, or could have emeritus status having retired from academia.
I found him profiled on another publisher's site as "Professor, Principal Investigator, Director, Consultant Editor, Reviewer, Event Organizer and Entrepreneur,…" who had worked in oncology, dermatology, haemotology (when "he pioneered new genetic variants of stroke in sickle cell anemia patients" which presumably is much more positive than it reads). Reading on, I found he had 'followed' complementary formations in "Medecine [sic], Pharmacy, Biology, Biochemistry, Food Sciences and Technology, Marine Biology, Chemistry, Physics, Nano-Biotechnology, Bio-Computation, and Bio-Statistics" and was "involved in various R&D projects in multiple areas of medicine, pharmacy, biology, genetics, genomics, chemistry, biophysics, food science, and technology". All of which seemed very impressive (nearly as wide a range of expertise as predatory journal publishers claim for me), but made me none the wiser about the source of his Professorial title.
5 Today. Although interestingly, in the first major comprehensive account of magnetism, Gilbert (1600/2016) tended to draw the North-South axis of the earth horizontally in his figures.
6 The representations we draw are simple depictions of something more subtle. If the circles did represent orbitals then they could not show the entire volume of space where the electron might be found (as this is theoretically infinite) but rather an envelope enclosing a volume where there is the highest probability (or 'electron density'). So orbitals will actually overlap to some extent even when simple images suggest otherwise.
Being flummoxed by a student question was the inspiration for a teaching metaphor
Keith S. Taber
An artist's impression of the author being lost for words (Image actually by Christian Dorn from Pixabay)
In my teaching on the 'Educational Research' course I used to present a diagram of a shape something like the lemniscate – the infinity symbol, ∞ – and tell students that was the shape their research project and thesis should take. I would suggest this was a kind of visual metaphor.
This may seem a rather odd idea, but I was actually responding to a question I had previously been asked by a student. Albeit, this was a rather deferred response.
'Lost for words'
As a teacher one gets asked all kinds of questions. I've often suggested that preparing for teaching is more difficult than preparing for an examination. When taking an examination it is usually reasonable to assume that the examination question have been set by experts in the subject.
A candidate therefore has a reasonable chance of foreseeing at least the general form of the questions that night asked. There is usually a syllabus or specification which gives a good indication of the subject matter and the kinds of skills expected to be demonstrated – and usually there are past papers (or, if not, specimen papers) giving examples of what might be asked. The documentation reflects some authority's decisions about the bounds of the subject being examined (e.g., what counts as included in 'chemistry' or whatever), the selection of topics to be included in the course, and the level of treatment excepted at this level of study (Taber, 2019). Examiners may try to find novel applications and examples and contexts – but good preparation should avoid the candidate ever being completely stumped and having no basis to try to develop a response.
However, teachers are being 'examined' so to speak, by people who by definition are not experts and so may be approaching a subject or topic from a wide range of different perspectives. In science teaching, one of the key issues is how students do not simply come to class ignorant about topics to be studied, but often bring a wide range of existing ideas and intuitions ('alternative conceptions') that may match, oppose, or simply be totally unconnected with, the canonical accounts.
This can happen in any subject area. But a well prepared teacher, even if never able to have ready answers to all question or suggestions learners might offer, will seldom be lost for words and have no idea how to answer. But I do recall an occasion when I was indeed flummoxed.
I was in what is known as the 'Street' in the main Faculty of Education Building (the Donald McIntyre Building) at Cambridge at a time when students were milling about as classes were just ending and starting. Suddenly out of the crowd a student I recognised from teaching the Educational Research course loomed at me and indicated he wanted to talk. I saw he was clutching a hardbound A4 notebook.
We moved out of the melee to an area where we could talk. He told me he had a pressing question about the dissertation he had to write for his M.Phil. programme.
"What should the thesis look like?"
His question sounded simple enough – "What should the thesis look like?"
Now at one level I had an answer – it should be an A4 document that would be eventually bound in blue cloth with gold lettering on the spine. However, I was pretty sure that was not what he meant.
What does a thesis look like?
I said I was not sure what he meant. He opened his notebook at a fresh double page and started sketching, as he asked me: 'Should the thesis look like this?' as he drew a grid on one page of his book. Whilst I was still trying to make good sense of this option, he started sketching on the facing page. "Or, should it look like this?"
I have often thought back to this exchange as I was really unsure how to respond. He seemed no more able to explain these suggestions than I was able to appreciate how these representations related to my understanding of the thesis. As I looked at the first option I was starting to think in terms of the cells as perhaps being the successive chapters – but the alternative option seemed to undermine this. For, surely, if the question was about whether to have 6 or 8 chapters – a question that has no sensible answer in abstract without considering the specific project – it would have been simpler just to pose the question verbally. Were the two columns (if that is what they were) meant to be significant? Were the figures somehow challenging the usual linear nature of a thesis?
I could certainly offer advice on structuring a thesis, but as a teacher – at least as the kind of constructivist teacher I aspired to be – I failed here. I was able to approach the topic from my own perspective, but not to appreciate the student's own existing conceptual framework and work from there. This if of course what research suggests teachers usually need to do to help learners with alternative conceptions shift their thinking.
Afterwards I would remember this incident (in a way I cannot recall the responses I gave to student questions on hundreds of other occasions) and reflect on it – without ever appreciating what the student was thinking. I know the student had a background in a range of artistic fields including as a composer – and I wondered if this was informing his thinking. Perhaps if I had studied music at a higher level I might have appreciated the question as being along the lines of, say, whether the should the thesis be, metaphorically speaking, in sonata form or better seen as a suite?
I think it was because the question played on my mind that later, indeed several years later, I had the insight that 'the thesis' (a 'typical' thesis) did not look like either of those rectangular shapes, but rather more like the leminscape:
A visual metaphor for a thesis project (after Taber, 2013)
The focus of a thesis
My choice of the leminscate was because its figure-of-eight nature made it two loops which are connected by a point – which can be seen as some kind of focal point of the image:
A thesis project has a kind of focal point
This 'focus' represents the research question or questions (RQ). The RQ are not the starting point of most projects, as good RQ have to be carefully chosen and refined, and that usually take a lot of reading around a topic.
However, they act as a kind of fulcrum around which the thesis is organised because the sections of the thesis leading up to the RQ are building up to them – offering a case for why those particular questions are interesting, important, and so-phrased. And everything beyond that point reflects the RQ, as the thesis then describes how evidence was collected and analysed in order to try to answer the questions.
Two cycles of activity
A thesis project cycles through expansive and focusing phases
Moreover, the research project described in a thesis reflects two cycles of activity.
The first cycle has an expansive phase where the researcher is reading around the topic, and exposing themselves to a wide range of literature and perspectives that might be relevant. Then, once a conceptual framework is developed from this reading (in the literature review), the researcher focuses in, perhaps selecting one of several relevant theoretical perspectives, and informed by prior research and scholarship, crystallises the purpose of the project in the RQ.
Then the research is planned in order to seek to answer the RQ, which involves selecting or developing instruments, going out and collecting data – often quite a substantive amount of data. After this expansive phase, there is another focusing stage. The collected data is then processed into evidence – interpreted, sifted, selected, summarised, coded and tallied, categorised – and so forth – in analysis. The data analysis is summarised in the results, allow conclusions to be formed: conclusions which reflect back to the RQ.
The lemniscate, then, acts a simple visual metaphor that I think acts as a useful device for symbolising some important features of a research project, and so, in one sense at least, what a thesis 'looks' like. If any of my students (or readers) have found this metaphor useful then they have benefited from a rare occasion when a student question left me lost for words.
