Comparisons – Page 34 – Science-Education-Research

nucleons are like sardines in a can

An example of an analogy used in a popular science book:

"Thus, in contrast to the outer body of the atom, where the electrons forming various atomic shells have plenty of space in which to move about, the picture of the nucleus is that of a large number of nucleons packed as tightly together as sardines in a can."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

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pre-nuclear age was like living in subzero temperatures

An example of an analogy used in popular science writing:

"In respect to nuclear energy we live (or rather lived until quite recently) in a world similar to that of an Eskimo dwelling in a subfreezing temperature for whom the only solid is ice and the only liquid alcohol. Such an [hypothetical] Eskimo would never have heard about fire, since one cannot get fire by rubbing two pieces of ice against each other, and would consider alcohol as nothing but a pleasant drink*, since he would have no way of raising its temperature to the boiling point.

And the great perplexity of humanity caused by the recently discovered process of liberating on a large scale the energy hidden in the interior of the atom can be compared to the astonishment of pour imaginary Eskimo when shown an ordinary alcohol burner for the first time."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

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* Note: it is unlikely anyone drinking pure alcohol would find it a 'pleasant drink' as ethanol will 'burn' the mouth and throat if not diluted by sufficient water. (Even Vodka is mostly water.)

interstellar clouds accumulate charge like ordinary thunderclouds in our atmosphere

An example of an analogy used in popular science writing

"The most trivial, but probably also the most plausible, explanation of the origin of these high-energy particles moving with speeds of up to 99.999 999 999 999 99 per cent of the speed of light, lies in the assumption that they are accelerated by very high electric potentials presumably existing between the giant gas and dust clouds (nebulae) floating in cosmic space. In fact [sic], one could expect that such interstellar clouds would accumulate electric charges in a way similar to the ordinary thunderclouds in our atmosphere, and that the electric potential differences thus created would be much higher than those responsible for the phenomenon of lightning striking between the clouds during thunderstorms."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

Gamow does not offer any details of how these phenomena are similar (this is presumably not a direct equivalence, given that the atmospheric processes surely involve much higher density of matter {and so 'frictional' interactions}, and depend on mixing due to convective processes that rely on the Earth's gravitational field and atmospheric heating by the Sun).

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The usual meaning of 'floating' (at least in science) refers to a buoyant effect due to the upthrust on a fluid matching weight. As these forces are not relevant to gas and dust clouds found in cosmic space the use of floating here would seem to be a metaphor.

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Many examples of science metaphors are listed in 'Creative comparisons: Making science familiar through language. An illustrative catalogue of figurative comparisons and analogies for science concepts'. Free Download.

N.b. 'In fact…' seems to be a rhetorical flourish, as

In fact, one could expect that…
One could expect that…

offer the reader the same information content.

electron-positron annihilation is like a wild marriage

An example of similes (or metaphors) for a science concept:

"The phenomenon which results from the encounter of a positive and a negative electron is described by Prof. Born as a 'wild marriage' and by the more gloomy Prof. Brown as the 'mutual suicide' of the two electrons."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

(As Gamow is quoting other authors, it is not clear if the original uses were simile or metaphor.)

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Many examples of science similes are listed in 'Creative Comparisons: Making Science Familiar through Language. An illustrative catalogue of figurative comparisons and analogies for science concepts'. Free Download.

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immune system is like a computer programmed by old friends

An example of an analogy used in public science discourse:

"What we need is our immune system to be regulated so its kills harmful microbes and tolerates other things. How do we get to that immune system? Well it's because of exposure to microbes, these old friends microbes, okay. And the best way to describe it is to think of our immune system like a computer program, we're born with a fully formed immune system, but as we go through the first days, months, hours and so forth of our life, we're gradually exposed to more and more organisms – when we come down the birth canal we're exposed to these important old friends, organisms, when our mother breast feeds us we're exposed to them, with our sisters and brothers we're exposed to them, importantly also when we go outdoors, so it's not just human organisms it's also outdoor organisms – and these old friends programme our immune system, so they will react to harmful things and they won't react to the non-harmful things"

Prof. Sally Bloomfield (London School of Hygiene and Tropical Medicine), was talking on an episode ('The 5 second rule') of BBC radio show/podcast Curious Cases.

(As the immune system is 'fully formed' at birth but then programmed, the sense here seems to be that the immune system is like a computer, and the effect of interacting with other organisms ('old friends') akin to programming.)

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pathogenic microbes will look for a new host

An example of anthropomorphism in public science discourse:

"Most pathogenic bacteria and all viruses cannot live outside people, so if they get into the environment they're looking for a new host, they need to get into your body before they can start breeding again. So finding a bit of toast, they are not going to be be able to live there. Non-pathogenic organisms, yes they can live anywhere…what we call ubiquitous, but the really harmful ones need to get into a human body where they've got special nutrients like vitamins and things like that. And the same, viruses have got to live inside, go inside living cells. They can, you know, jig around, but until they find a new host that suits them they won't start breeding again."

Prof. Sally Bloomfield (London School of Hygiene and Tropical Medicine), was talking on an episode ('The 5 second rule') of BBC radio show/podcast Curious Cases.

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Many examples of anthropomorphism are listed in 'Creative comparisons: Making science familiar through language. An illustrative catalogue of figurative comparisons and analogies for science concepts'. Free Download.

N.b. Species other than humans suffer pathogens, so presumably Professor Bloomfield's reference to 'Most pathogenic bacteria and all viruses cannot live outside people' refers specifically to human pathogens.

That viruses 'jig around' seems to be a metaphor. (A virus does not have anything like cilia or flagella to enable it to move about. Outside of cells viruses are effectively inert so are presumably 'jigging' refers to being passively moved.)

Breeding normally refers to sexual reproduction so seems to be used metaphorically here (on a programme with a diverse, non-specialist audience) for 'reproducing'.

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giving up mechanical particle trajectories is like giving up optical rays

An analogy used in science:

"It is easy to see that the failure of the notion of a light ray in application to the optical diffraction phenomena is very similar to the failure of the notion of a mechanical trajectory in the phenomena of quantum physics. Just as we cannot form in optics an infinitely thin light beam, the quantum principles of mechanics prevent us from speaking about the infinitely thin trajectories of moving particles. In both cases we have to give up all attempts to describe the phenomena by saying something (light or particles) propagates along certain mathematical lines (optical rays or mechanical trajectories), and are forced to go over to the presentation of the observed phenomena by means of 'something' which is spread continuously over the entire space."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

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conduction electrons are like a crowd of displaced persons

An example of simile used in popular science writing:

"The metallic substances differ from all other materials by the fact that the outer shells of their atoms are bound rather loosely, and often let one of their electrons go free. Thus the interior of a metal is filled up with a large number of unattached electrons that travel aimlessly around like a crowd of displaced persons. When a metal wire is subjected to electric force applied on its its opposite ends, these free electrons rush in the direction of the force, thus forming what we call an electric current."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

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The reference to outer shells being bound 'loosely' could be seen as a metaphor (and the shells are themselves abstractions). To say that electrons 'rush' or 'travel aimlessly' is to anthropomorphise. (The electrons do not have 'aims' for their motion, so it is 'aimless', but to describe it this way makes an implicit contrast with purposeful motion – as perhaps when they rush to form a current?)

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Antarctica is the heartbeat of the world

An example of an analogy used in science communication

"You could think of it as kind of the heartbeat of the world because most of the world's oceans' water passes through the Southern Ocean."
Prof. Steven L. Chown.

Prof. Steven L. Chown, Professor of Biological Sciences at Monash University, Melbourne and Director of Australian Research Council Special Research Initiative Securing Antarctica's Environmental Future, was speaking on and episode ('Should Antarctica be off limits?') of BBC Inside Science.

I have initially classified this as a simile – "as kind of the heartbeat of the world" – rather than an analogy, as there is limited explicit 'mapping' to explain the references.

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However, Professor Chown does include some explanation ("because most of the world's oceans' water passes through the Southern Ocean"), so I am considering this as analogy although the listener has to do some interpretation to fully appreciate the comparison.

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sodium atom electron goes to a chlorine atom to form a molecule

Examples of alternative conceptions in a popular science book:

"Why, for example, do the atoms of sodium and chlorine stick together to form a molecule of table salt? … an atom of chlorine lacks one electron in order to complete the third shell, whereas an atom of sodium has one extra electron left after the completion of its second shell. Thus there must be the tendency for the extra electron from sodium to go over into chlorine to complete the unfinished shell…the two charged atoms (or ions as they are called) will cling together forming a molecule of sodium chloride, or in plain words table salt. In the same way an atom of oxygen that lacks two electrons in its outer shell will 'kidnap' from two hydrogen atoms their single electrons thus forming a molecule of water (H₂O). On the other hand, there will be no tendency to combine between the atoms of oxygen and chlorine, or between those of hydrogen and sodium, since in the first case both have the desire to take and not to give, whereas in the second case neither wants to take.

The atoms with completed electronic shells, such as those of helium, argon, neon, and xenon, are completely self-satisfied and do not need to give or take electrons; they prefer to remain gloriously lonely making the corresponding elements (so called 'rare gases') chemically inert."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

This extract form a work by a well respected physicist reflect a number of common misconceptions.

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The process described of an electron moving from a single sodium atom to a single chlorine atom would not happen as it is energetically nonviable. This is a common description of the formation of ionic bonds (and in the book is accompanied by a common image representing the process) but is wrong. Sodium chloride, table salt, does not contain molecules – although this is a common misconception found among learners.

Gamow describes the formation of a water molecule (using the simile, 'kidnap') as if the bond in water is also ionic (rather than basically covalent).

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The implication is that compounds do not form of oxygen and chlorine (when Cl₂O was first synthesised in 1834) nor of hydrogen and sodium (although NaH is a well-known salt, widely used as a reagent in organic chemistry).

Gamow suggests (using anthropomorphic language) that the noble gases do not form compounds, although many such compounds are now known (though helium, neon and argon do not readily form stable compounds). Also, only helium and argon actually have complete outer electronic shells – for example, argon is ten electrons short of a full outer shell.

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The most serious problem here is the suggestion that chemical reactions occur to allow atoms to obtain full shells. This is a widely repeated 'fairy tale', but is an empty explanation as nearly all familiar chemical reactions BEGIN (as well as end) with species (molecules, ions) that have noble gas electronic configurations.

Read about the octet framework – a common alternative conceptual framework

atom model was like a watermelon with electrons for seeds

An example of an analogy used to describe an historical model of the atom:

"Thus Rutherford's discovery shrank the originally widespread positive charge of Thomson's atomic model into a tiny atomic nucleus in the very centre of the atom, leaving the swarm of negative electrons on the outside, so that instead of being similar to a watermelon with electrons playing the role of seeds, the picture of the atom began to look more like a miniature solar system with an atomic nucleus for the sun, and electrons for planets…"

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

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Describing the electrons as being in a swarm is an example of metaphor.

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atomic electrons influence alpha particles as mosquitoes influence a charging elephant

An example of an analogy used to explain science:

"As an 𝛂-particle passes through the atoms of the target material, it is influenced by the forces of attraction towards atomic electrons and the forces of repulsion from the positive parts of the atom. Since, however, the electrons are so exceedingly light, they are no more able to influence the motion of the incident 𝛂-particle, than a swarm of mosquitoes can influence the run of a scared elephant. On the other hand the repulsion between the massive positive parts of the atom and the positive charge of incident 𝛂-particles must be able to deflect the latter from their ordinary trajectory and to scatter them in all directions , provided they pass sufficiently close by one another."

George Gamow (1961) One, Two, Three…Infinity. Facts and speculations of science, Revised Edition, Dover Publications, Inc., New York.

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