DEATH COMES (AND COMES AND COMES) TO THE QUANTUM PHYSICIST
“MANY WORLDS” THEORIST HUGH EVERETT III BELIEVED THAT A CAT COULD BE BOTH DEAD AND ALIVE. HE WAS ALSO A RADICAL REALIST.
I. A RESURRECTION OF CATS
In 1957, a physics graduate student at Princeton, Hugh Everett III, proposed a cryptic and seductive solution to the central paradox of quantum mechanics. He argued that the paradox—roughly stated, that the Schrödinger equation perfectly predicts an electron’s behavior in every quantum mechanical experiment ever imagined but also entails some sort of nonsense about an unobserved cat being simultaneously alive and dead—is in fact no paradox at all. Everett made a case for reading the Schrödinger equation literally. The cat is both dead and alive: dead in one world, and still alive in another. One consequence of Everett’s idea is that the universe consists of infinite worlds, embodying every possibility, such that, for example, in one world I die of rheumatic fever in childhood, in another I’m writing a slightly different version of this article, in most I do not exist at all, and, in a few, you and I are in love. Everett’s argument, originally set out in the rather prosaically titled “The Theory of the Universal Wave Function,” received virtually no attention, after which the dispirited young Everett left academia forever. Applying his mathematical innovations to private and government defense analysis projects, he became a heavy-drinking, chain-smoking millionaire; his employees say he avoided mention of his physics background altogether.
Thirteen years later, in 1970, the physicist Bryce DeWitt published in Physics Today a short article, “Quantum Mechanics and Reality.” DeWitt, one of the few academics who had noticed Everett’s work, began:
Despite its enormous practical success, quantum theory is so contrary to intuition that, even after 45 years, the experts themselves still do not all agree what to make of it. The area of disagreement centers primarily around the problem of describing observations… Of the three main proposals for solving this dilemma, I shall focus on one that pictures the universe as continually splitting into a multiplicity of mutually unobservable but equally real worlds… Although this proposal leads to a bizarre world view, it may be the most satisfying answer advanced yet.
DeWitt’s flatly sincere, hand-holding article, which led to the catchy “Many Worlds” moniker for Everett’s long-ignored idea, elicited an enormous response from the physics community. Physics Today ran a follow-up article half a year later, with six (handsomely photographed) physicists responding at some length to DeWitt, and DeWitt responding more in kind. Many Worlds was thus officially sexy, and by 1973 Everett’s dormant thesis work was finally, through DeWitt’s arrangement, published. Seemingly aloof to the renewed interest in his hypothesis, Everett claimed he couldn’t be bothered to write an introduction. So DeWitt wrote one instead. As epigraphs he used quotes from Borges and William James.
Soon thereafter the elder statesman of science fiction magazines, ANALOG (formerly known as Astounding Stories!), featured, in its “Science Fact” column, a lengthy discussion of the Many Worlds Interpretation (MWI). The subheading: “Alternate universes are not merely gimmicks for SF writers—they’re necessary for the salvation of quantum physicists!” Again, interest, if of a slightly different flavor, was enormous. Everett—by then spending his time on classified consulting projects such as the development of a Quick General War Game Simulator for the Department of Defense—was rapidly becoming a rock star in the science and science fiction communities both. When he made his one and only post-fame appearance at an academic conference in Austin in 1977, student groupies engulfed him, the no-smoking rules for the auditorium were suspended exclusively for the duration of his four-hour talk, and internet debate continues to this day concerning the rumor that Everett arrived at the conference in a black Cadillac with horns.
But just what Everett’s proposal actually means—or should have meant—remains ambiguous; Everett was never successfully lured back to academia, and, in 1982, at age fifty-one, he died of a heart attack. (Or, if one is to believe rumors on the internet, he died at the hands—or claws?—of aliens angered by the global-scale UFO research Everett conducted on behalf of the Pentagon; recent declassification of Pentagon documents corroborates the existence of the research but not the aliens.) Despite the semi-embittered withdrawal of its originator, the core of Everett’s idea has aged quite well. Its earliest flaws have been (arguably) remedied, and among the several interpretations of quantum mechanics currently under serious consideration, many prominent physicists—Stephen Hawking, Murray Gell-Mann—subscribe to MWI, holding not simply that it’s a successful method for making scientifically accurate predictions but also that it’s literally true. In fact, Oxford’s most revered recluse, the physicist David Deutsch, claims Everett’s Many Worlds Interpretation of quantum mechanics as one of four strands of a Theory of Everything. (The other three strands, if you’re curious, are Richard Dawkins’s refinements of Darwinian evolution, Alan Turing’s theory of computation, and Karl Popper’s epistemology.) However, others’ assessments of Everett’s idea are closer in spirit to that of the brilliant Irish physicist J. S. Bell, who wrote in 1981 that “if such a theory were taken seriously it would hardly be possible to take anything else seriously.”
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