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(Courtesy: iStock/MATJAZ SLANIC)
06 Sep 2018 Robert P Crease
Taken from the September 2018 issue of Physics World

Robert P Crease muses on the metaphors for physics that you sent him

Physics is a quiz where the first step is guessing the questions…where you have to keep rewriting the questions and your answers change the questions.

Physics is like watching a dance when you have to figure out how the partners come together and break apart…or figure out the music to which they are responding.

Physics is like modelling new structures using Meccano or Lego…or like modelling the same structures by inventing new construction materials.

These are some of the metaphors readers sent to me in response to my June column, in which I cited dramatic metaphors about the activity of mathematics. I wondered if there were equally good metaphors specifically for physics. Richard Feynman once compared physics to the activity of watching a chess game played by the gods, in which physicists are observers who watch and collaborate in guessing the rules. But could Physics World readers do better?

Some responses were amusing. “If it’s slimy it’s biology, if it stinks it’s chemistry and if it doesn’t work it’s physics,” Colin Pykett recalled from his high-school days. He also learned the difference between physicists and engineers: “A physicist only has to make it work once but an engineer has to make it work every time.” More originally, tapping his musical training, Pykett compared doing physics to “watching a movie of an orchestra but with the sound turned down, and you have to work out what they are playing”.

Several people produced extended metaphors. Peter Lamb wrote that a theoretical physicist is a high priest, a quantum-computer developer is a Ponzi scheme promoter (“too good to be true”), and a real physicist is a “faithful dog” who watches patiently, ignores distractions, and waits for the master to come home.

All at sea

In the frontispiece of Francis Bacon’s influential 17th-century opus The Great Instauration, scientific research was depicted as a form of seafaring. It was a comparison also made by one reader, John Bevan. As he put it, research requires sailing into and charting unknown waters; applying physics means sailing into charted waters; while understanding physics is like having an overall familiarity with the sea’s behaviour.

Peter Kenny, meanwhile, likened physics to assembling furniture, without instruction, from a jumble of unidentified parts. Theory predicts whether the end product will be strong and stable. Symmetry notes the substitutability of pieces. Dead ends are things that come together but are useless. Aesthetics is the judgment that something that fits doesn’t look right. Confirmation is finding that you can create several identical pieces of something.

David Jones, proposed that physicists are like palaeontologists who are concerned with bones – their shape, structure, bone density and grooves. Physicists use experience, knowledge and training to figure out the original creature – a rabbit, say. Children naturally find “grimy old bones” uninteresting compared with the cuddly live thing, meaning that physics requires a certain retraining of one’s attention and devotion.

I myself have often compared physics experiments to performances. Performance involves the conceiving, producing and witnessing of events that give back more than was put into them. Performances are not automatic; if we are sure of the outcomes, they aren’t performances but demonstrations.

I myself have often compared physics experiments to performances.

Robert P Crease

In research, you plan an event, understand the elements that go into it – the materials, instruments and theories – yet when it unfolds you can get more back than is in these elements, something you could not get by reading books. In this sense, performance is not a suggestive metaphor carried over from the performing arts into scientific inquiry but a descriptive term.

Some respondents went deep or dark. An example of the first was Fabien Paillusson, who cited the French philosopher of science Alexandre Koyré’s point that modern physics involves a revolutionary gestalt switch involving the eradication of the common-sense perception of the world and the projection into the world instead of what Koyré called a “new approach to being” involving an abstract and unnatural mathematical framework.

Paillusson then cited the French physicist and philosopher of science Etienne Klein’s paraphrase of all this as: “what (modern) physics seeks is to explain the real with the inconceivable”. Fredy Zypman, head of physics at Yeshiva University in New York, captured this point more dramatically: “Physics is the act of escaping reality to create it.”

An example of going dark was Homer Johnson, a retired teacher of English, who while reading the June issue of Physics World became aware of a bird pecking diligently and determinedly but unsuccessfully at his upstairs window. The physicist, he said, is like that bird, because no matter how hard or cleverly it tries it cannot gain the sought-after entrance to the deeper level of reality beyond the glass.

My column inspired some respondents to mull the limitations of metaphors themselves. Jones pointed out that when you use a metaphor, you have to trust people to interpret it correctly and figure out what is pertinent and what irrelevant. Consider, he said, the story of Humpty Dumpty, which is often used to exemplify the second law of thermodynamics (it’s even in Mr Dumpty’s Wikipedia entry). It illustrates the difficulty (but not impossibility) of returning him to his lower entropy state after his fall, but the metaphor works only if the audience focuses on his shell rather than on his hat or bow tie.

The critical point

Feynman’s chess metaphor has limitations. For one thing, it depicts only the theorist’s perspective; for another – like Stephen Hawking’s view that having a theory of everything means knowing “the mind of God” – it invokes deities a little too casually. Still, like the rest of Feynman’s Lectures on Physics, it is splendid in its clarity and conciseness. Physics – with its theoretical and experimental dimensions, its fallible and ever-incomplete nature, its applications, and its aesthetic sides – may be simply too complex to capture in a single image.

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