A few months ago, I received an e-mail from Mike Wilson, a professor of mathematics at the University of Vermont, which challenged my use of a physics metaphor. He found it in my 1986 book The Second Creation: Makers of the Revolution in 20th-Century Physics, where my co-author Charles Mann and I explained how accelerators slam particles into targets inside detectors and track fragments for clues about their structure. In a parenthetical remark, we likened this process “to firing a gun at a watch to see what is inside”.

Wilson was dubious. “Has anyone ever tried that?” he asked. We had supposed that, in principle, one could “reverse engineer” the watch by applying conservation of momentum to the debris. But Wilson wondered if you could really deduce a watch’s internal structure from such pieces. Mann and I hadn’t done the watch experiment, nor had we any intention to. Why bother? We’d painted an imaginable picture.

Wilson was unconvinced. “Such experiments,” he wrote, “could give a valuable check on the confidence we put in physicists’ statements about what goes on inside atoms”. His remark made me wonder if other physics metaphors could withstand empirical verification. I first thought of the one often wheeled out to explain the Higgs field and the Higgs boson. It was devised in 1993 by David Miller, a physicist at University College London, after the then UK science minister William Waldegrave promised a bottle of champagne for the best explanation of the Higgs boson on a single A4 sheet of paper (Physics World June 2024 p27).

The metaphor, which Higgs admitted was the least objectionable of all those posited to describe his eponymous boson, begins with a room full of political-party workers. If a person nobody knows walks through, people keep their same positions – that’s like a massless boson. But when a celebrity walks through (Miller envisaged ex-British prime minister Margaret Thatcher), people cluster around that person, who then has to move more slowly – that’s like being massive.

I wonder what would have happened if the Higgs-boson metaphor were empirically tested using different kinds of celebrities

Don Lincoln, a physicist at Fermilab in the US, once made an animated video of this metaphor. Attempting to make it more palatable to physicists, he cast Peter Higgs as the entrant, but the video nevertheless posts the disclaimer “ANALOGY!” Still, I wonder what would have happened if Waldegrave had empirically tested Miller’s metaphor using different kinds of celebrities.

Claim to fame

I’ve come within about two metres of several celebrities: filmmaker Spike Lee and actor Denzel Washington (I was an extra in a scene in their movie Malcolm X); jazz musician Sun Ra (I emceed one of his concerts); and Mia Farrow and Stephen Sondheim (I sat next to them in a club). The vibe in the room was very different in each case – sometimes with worshippers, sometimes with autograph hounds, and sometimes with people holding back at an awed and respectful distance. If hadronic mass depended on the vibe in the room, the universe would be a quite different place.

Gino Elia, a graduate philosophy student at Stony Brook University, ticked off a few other untested metaphors. He told me how Blake Stacey, a physicist at the University of Massachusetts, Boston, once described non-overlapping probability distributions as relatives staying away at Thanksgiving. In Drawing Theories Apart, David Kaiser – a science historian at the Massachusetts Institute of Technology – pictured the complementary variables of energy and time “as a kid running out of the classroom when the lights are off (breaking conservation of energy) and the kid being in their seat when the teacher turns the light back on”.

The grandest, most extended, and awe-inspiring metaphor I have ever come across is at the start of chapter 20 of Leo Tolstoy’s War and Peace, which describes Moscow just before its occupation by Napoleon’s forces. “It was empty,” Tolstoy writes, “in the sense that a dying queenless hive is empty”. The beekeeper sees only “hundreds of dull, listless, and sleepy shells of bees.” They have almost all perished, reeking of death. “Only a few of them still move, rise, and feebly fly to settle on the enemy’s hand, lacking the spirit to die stinging him; the rest are dead and fall as lightly as fish scales,” Tolstoy concludes.

I don’t know a thing about beehives, but Tolstoy did because he was a beekeeper. Even if he didn’t, I don’t care. The metaphor worked for me, vivid and compelling.

The critical point

Early in 1849 the British poet Matthew Arnold published a poem entitled “The Forsaken Merman”, in which the merman, the king of the sea, has married an earthly woman. At one point, she is at her spinning wheel when she remembers her former world. The “shuttle falls” from her hand as she decides to leave him. An alert friend – fellow poet Arthur Clough – wrote to Arnold that a shuttle is used in weaving and Arnold surely meant spindle.

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Arnold realized Clough was right, insisted his publishers revise the poem, and when it was republished a quarter-century later it read that the “spindle drops” from the woman’s hand. While Arnold wrote to Clough that he had a “great poetical interest” in both weaving and spinning, he admitted apologetically that his error was due to a “default of experience”.

That flabberghasted me. Arnold writes a poem about a merman and then worries about the difference between a shuttle and a spindle? Furthermore, the person who picked it up was a fellow poet, not a weaver or spinster? Arnold’s public seem not to have noticed the error – there is no record of anybody complaining – and only his poet-friend did? More importantly, does any of this really matter?

Love is not a rose – despite what Robert Burns or Neil Young might have claimed. Nor is a man a wolf – despite the ancient Latin proverb. So if it’s acceptable to use incorrect metaphors in literature and music, then why not in physics? Are they any less effective? E-mail me your favourite physics metaphors and let me know if they have been empirically tested and why it matters. I’ll write about your responses in a future column.