This page introduces the use of analogy in discussing science. The list of examples of analogies from various sources (scientists' writing, science journalism, popular science books, etc.) has now been moved to a separate page
Analogy
An analogy is a comparison between two things that shows how they are in some sense structurally similar. The analogue (the thing that something of interest is said to be like) is said to map onto the target (the thing of focal interest).
Some ways in which it might be said 'the atom is like a tiny solar system'.
For example, the figure above shows how some aspects of a simple atomic are similar to the solar system (as in the common trope that 'an atom is like a tiny solar system'). This comparisons is problematic in some ways (Taber, 2013), but is simply used here to illustrate one way of mapping in an analogy. In effect, this figure comprises of two parallel concept maps which have been set out to show which features of the two systems are supposed to map across.
Some other examples of analogies presented in this form and discussed on this site are included among the images in the slide show below:
COVID is like a fire because… 
COVID is like a fire because… 
Perception is like palaeontology because… 
Cognition is like palaeontology because… 
A black hole is like a shaggy dog because… 
A faecal transplant is like wild flower seeds in some soil because… 
Medical screening is like job shortlisting 
Is working memory analogous to triglyceride structure? 
A well designed curriculum is like a protein because… 
animals and plants are like different classes of engine because… 
Popping corn is like radioactive decay because… 
'fossil turbulence' is like the aftermath of a party 
Nuclear fusion is like cooking rice because… 
Scientists claim to have made a molecular Newton's cradle 
A visual analogy for the photoelectric effect 
Zygote is to child as light bulb is to office block? 
A chromoosme is like a music tape 
Metabolism is like the water cycle 
A neuron is like an automatic vote counting machine 
An ion channel is like a turnstile 
Binding to a protein is like conceptual learning because… 
the World Economic Forum at Davos is like a chemical experiment because…
Analogies are similar in some ways to similes, which point out that one thing is like another. However, analogy goes beyond simile by explaining (or justifying) the comparison. (Metaphors are similar to similes, except the comparison is made in a implicit way, by suggesting X is Y. See the note at the foot of this page.)
Analogies can be used as thinking tools and also for communicating ideas to others. In teaching, comparisons such as similes and analogies may be used as one way to 'make the unfamiliar familiar'.
Read more about 'Making the unfamiliar familiar'
For example, it is known that circuit electricity is a difficult topic for many secondary age students, so often analogies are used with more familiar or more easily imagined systems, as a way of helping students conceptualise electricity. (This approach was used in the epiSTEMe project to develop a teaching module for 11-12 year olds.)
Read about 'the epiSTEMe project – electricity module'
An simile that has commonly been used in teaching about atomic structure is that 'the atom is like a tiny solar system'. This becomes an analogy once the comparison is explained by drawing parallels between the two systems. Such teaching analogies usually have both positive and negative features (positive analogy – things that map, and negative analogy – things that do not map across), and in teaching it is important to success both so that students do not inadvertently make inappropriate mappings. (In one study more students suggested the force attracting the electrons to the nucleus in an atom was gravitational than suggested it was electrical!)
Read about a research paper on 'Upper Secondary Students' Understanding of the Basic Physical Interactions in Analogous Atomic and Solar Systems'
It has been suggested that learners may cope better with the plurality of models they meet in science (for example the progression of models about atomic structure, with shells giving way to orbitals; or the shift in how oxidation or acid may be understood) if they are asked to consider the concepts and models they have been taught as components of a toolbox where they might have to choose a different tool for a different task.
Read the article about 'An Analogy For Discussing Progression in Learning Chemistry'
Analogies are also used in explaining scientific ideas in popular science books and in the news and other media.
Read about 'Science in public discourse and the media'
However analogies have also been used in the processes of science itself, where scientists develop their own thinking, and explain their ideas in their scientific research publications. Scientific analogies can be seen as a kind of model, where considering the phenomenon of interest as being analogous to some other system can be seen as a conjecture – an idea to be tested.
Examples of analogies:
A list of examples of analogies compiled form a range of courses (such as the writing of scientists, popular science works, science journalism, etc.) can be found here:
The following examples are discussed elsewhere on the site (follow the links):
The nucleus as the brain of the cell (Bert in Y10)
A duster and matchboxes used to explain spectroscopy (a teacher analogy reported by Amy, college student)
Scaffolding learning as akin to enzymatic catalysis (using catalysis as a comparison to explain 'scaffolding' of learning)
Perceiving and remembering are like palaeontology (a text book analogy to explain cognitive processes)
A black hole with a magnetic field is like a shaggy dog (science news item)
A faecal transplant is like wild flower seeds in some soil (an analogy used in a radio science programme/podcast)
Medical screening is like job-shortlisting (an analogy used in a public science talk / podcast)
Viral infection triggering an immune response is like igniting a fire (an analogy used by a scientist interviewed for the radio)
Effect of a plant toxin is like the valves of a car's engine being stuck open (example from a scientist's blog)
NASA's solar probe entering the Sun's corona is like putting your hand in the oven (analogy used by NASA scientist in media interview)
Working memory is a bit like triglyceride structure (an analogy for explaining 'chunking' to science teachers?)
A well-planned curriculum is like an enzyme (an analogy for thinking about curriculum structure)
Animals and plants are like two different types of engine (a historical analogy)
A synchrotron is like a race track (scientist's comparison used in a public talk)
Photosynthesis as an analogy for the COVID-19 pandemic (used by an academic explaining his work on ther social impacts of the pandemic)
The brain's reward pathway is like a teeter-totter (see-saw) (used by an academic and clinician work on addition)
Popping corn is like radioactive decay (a teaching analogy)
Stars are like trees in a forest, in that you can infer life cycles from observing them at one time (Prof. Martin Rees, Astronomer Royal, talking on the radio – compare with the Herschel analogy below)
A molecular chain reaction is like a Newton's cradle (analogy used to report a scientific study)
An atomic nucleus may behave like a liquid droplet that divides into two smaller droplets (Meitner & Frisch propose nuclear fission in the scientific literature)
The structure of buckminsterfullerene is like a football (Kroto and colleagues report the discovery of a new allotrope of the element carbon)
Mea culpa
And as a teacher, it almost becomes instinctive to use them!
Nuclear fusion is like cooking rice in that mass may appear to not be conserved.
Children next to a garden fence as an analogy for the photoelectric effect threshold
Note on analogies, similes and metaphors.
In practice the precise demarcations between similes, metaphors (and anthropomorphisms) and analogies may not be absolutely clear. I have tried to follow the rule that if a comparison is set out to make a structural mapping clear (even if this is not spelt out as a mapping: e.g., an atom with its electrons is like a sun with its planets) this counts as an analogy. Where I do not think a comparison is an analogy, but the comparison is made explicit ("…as if…", "…like…": e.g., the atom, like a tiny solar system) I consider this a simile. When the audience is left to spot a comparison (rather than a literal identity) is being made (e.g., the oxygen atom, this tiny solar system) I class this a metaphor.
Anthropomorphism may be seen as a particular kind of metaphor where a metaphorical feature implies a non-human entity has human attributes (e.g., meteors can be impetuous).
I reserve the right to reassign some of these comparisons in due course!
Work cited:
- Taber, K. S. (2013). Upper Secondary Students' Understanding of the Basic Physical Interactions in Analogous Atomic and Solar Systems. Research in Science Education, 43(4), 1377-1406. doi:10.1007/s11165-012-9312-3 [Download this article]
