After Stephen Hawking conceded that he'd lost his bet about the Higgs boson, I wondered why he had been on the wrong side of the bet. Why had he doubted the existence of a particle widely assumed to be an essential constituent of physical reality?
Hawking wasn't available to answer that question, but I did manage to have a long conversation with an American physicist who had also doubted the existence of the Higgs--Lawrence Krauss, author of The Physics of Star Trek and A Universe From Nothing . Krauss explained the generic reason that a number of physicists had doubted the Higgs: Its posited existence was suspiciously convenient. When you understand what he meant, I think you may conclude that physical reality is cooler than you'd thought. Here, as I understand it, is the deal:
Decades ago, physicists had found a way to unify--that is, fit into a common theoretical framework--two of the four basic physical forces: the electromagnetic force and the weak nuclear force. But there was one hitch: photons, the particles that mediate the electromagnetic force, have no mass, whereas the particles that mediate the weak force--the W and Z bosons--seem to have mass. And this theoretical unification wouldn't make complete sense unless the W and Z bosons were, like photons, massless.
So--here comes the suspiciously convenient part--physicists supposed that maybe the W and Z bosons didn't really have mass; rather, there was something--some feature of the universe--that made them behave as if they had mass. That "something" was dubbed the Higgs boson.
Actually, both the Higgs boson and the Higgs field--the pervasive invisible thing energized, kind of, by the Higgs boson--were posited as part of the process that imparted mass to the intrinsically massless W and Z bosons. But if you want to get off on a tangent about the relationship of the particle to the field, you'll have to watch this excerpt from my conversation with Krauss and this excerpt, because if I tried to explain the relationship now my failure to fully understand it would pose something of an obstacle. So back to the story:
Positing the existence of the Higgs particle/field struck some physicists as a bit kludgy--a kind of deus ex machina wheeled onto the stage to salvage an otherwise incomplete plotline. As Krauss puts it, "It seemed too easy... It seemed to me that introducing an invisible field to explain stuff is more like religion than science... Great, I invented invisible hobgoblins to make things right."
But the hobgoblins seem to actually exist--and the funny thing is that, though positing their existence sounds like a kludgy solution, the recent corroboration of their existence was, in a way, testament not to nature's kludginess but to its elegance. Remember, what was driving the search for the Higgs was an assumption about deep physical unity: these two seemingly different forces, the electromagnetic and the weak, must be two faces of the same thing; that's why they must have this common denominator of massless particles. And this assumption turned out to be true. As has happened so often in the past--in biology with Darwin's theory and in physics with lots of theories--surface-level diversity turned out to mask a deeper unity.
True, nature in this case found an arguably kludgy way to reconcile deep unity with surface diversity--the Higgs boson/field. But maybe that just means that
nature, in addition to being deeply elegant, is very clever.
In case you want to watch my interrogation of Lawrence from beginning to end, here it is:
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