January 17, 2010


EXCERPT: Chapter 1: The Socks (Louisa Gilder, The Age of Entanglement)

In 1978, when John Bell first met Reinhold Bertlmann, at the weekly tea party at the Organisation Européenne pour la Recherche Nucléaire, near Geneva, he could not know that the thin young Austrian, smiling at him through a short black beard, was wearing mismatched socks. And Bertlmann did not notice the characteristically logical extension of Bell’s vegetarianism—plastic shoes.

Deep under the ground beneath these two pairs of maverick feet, ever-increasing magnetic fields were accelerating protons (pieces of the tiny center of the atom) around and around a doughnut-shaped track a quarter of a kilometer in diameter. Studying these particles was part of the daily work of CERN, as the organization was called (a tangled history left the acronym no longer correlated with the name). In the early 1950s, at the age of twenty-five, Bell had acted as consultant to the team that designed this subterranean accelerator, christened in scientific pseudo-Greek “the Proton Synchrotron.” In 1960, the Irish physicist returned to Switzerland to live, with his Scottish wife, Mary, also a physicist and a designer of accelorators. CERN’s charmless, colorless campus of box-shaped buildings with protons flying through their foundations became Bell’s intellectual home for the rest of his life, in the green pastureland between Geneva and the mountains. At such a huge and impersonal place, Bell believed, newcomers should be welcomed. He had never seen Bertlmann before, and so he walked up to him and said, his brogue still clear despite almost two decades in Geneva: “I’m John Bell.”

This was a familiar name to Bertlmann—familiar, in fact, to almost anyone who studied the high-speed crashes and collisions taking place under Bell’s and Bertlmann’s feet (in other words, the disciplines known as particle physics and quantum field theory). Bell had spent the last quarter of a century conducting piercing investigations into these flying, decaying, and shattering particles. Like Sherlock Holmes, he focused on details others ignored and was wont to make startlingly clear and unexpected assessments. “He did not like to take commonly held views for granted but tended to ask, ‘How do you know?,’ ” said his professor, Sir Rudolf Peierls, a great physicist of the previous generation. “John always stood out through his ability to penetrate to the bottom of any argument,” an early co-?worker remembered, “and to find the flaws in it by very simple reasoning.” His papers—numbering over one hundred by 1978—were an inventory of such questions answered, and flaws or treasures discovered as a result.

Bertlmann already knew this, and that Bell was a theorist with an almost quaint sense of responsibility who shied away from grand speculations and rooted himself in what was directly related to experiments at CERN. Yet it was this same responsibility that would not let him ignore what he called a “rottenness” or a “dirtiness” in the foundations of quantum mechanics, the theory with which they all worked. Probing the weak points of these foundations—the places in the plumbing where the theory was, as he put it, “unprofessional”—occupied Bell’s free time. Had those in the lab known of this hobby, almost none of them would have approved. But on a sabbatical in California in 1964, six thousand miles from his responsibilities at CERN, Bell had made a fascinating discovery down there in the plumbing of the theory.

Revealed in that extraordinary paper of 1964, Bell’s theorem showed that the world of quantum mechanics—the base upon which the world we see is built—is composed of entities which are either, in the jargon of physics, not locally causal, not fully separable, or even not real unless observed.

If the entities of the quantum world are not locally causal, then an action like measuring a particle can have instantaneous “spooky” effects across the universe. As for separability: “Without such an assumption of the mutually independent existence (the ‘being-?thus’) of spatially distant things…,” Einstein insisted, “physical thought in the sense familiar to us would not be possible. Nor does one see how physical laws could be formulated and tested without such a clean separation.” The most extreme version of nonseparability is the idea that the quantum entities are not independently real: that atoms do not become solid until they are observed, like the proverbial tree that makes no sound when it falls unless a listener is around. Einstein found the implications ludicrous: “Do you really believe the moon is not there if nobody looks?”

Up to that point, the idea of science rested on separability, as Einstein had said. It could be summarized as humankind’s long intellectual journey away from magic (not locally causal) and from anthropocentricism (not independently real). Perversely, and to the consternation of Bell himself, his theorem brought physics to the point where it seemingly had to choose between these absurdities.

Science took the long way round to agreeing with the Church: Galileo was a heretic.

Posted by Orrin Judd at January 17, 2010 7:45 PM
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