Clash of the Titans

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books and arts pandemics match the documented symp- story up to the Solvay Conference of 1930. toms of today’s plague. That Y. pestis was the In discussions at the conference, Einstein’s aetiological agent of the third pandemic is ‘photon-in-a-box’ challenged the energy– irrefutable — the plague bacillus was first time uncertainty relation. After a sleepless isolated and identified by Alexander Yersin night, Bohr brought considerations of clock ARCHIVES VISUAL during this outbreak. Recent molecular times from general relativity to bear, and studies with Y. pestis provide additional evi- saved the day for quantum uncertainty. dence linking the bacterium with the earlier Bolles uses this triumph as a nice counter- great pandemics. The ‘molecular clock’ point to Bohr’s earlier defeat over the (baseline mutations in housekeeping genes) Bohr–Kramer–Slater theory in which,letting suggests that Y. pestis evolved somewhere go of strict energy conservation, Bohr had between 1,500 and 20,000 years ago, the for- hoped to maintain a wave picture. mer figure in remarkable agreement with the By jolting the reader around in space- UL EHRENFEST/AIP EMILIO SEGRE appearance of the justinian plague. Addi- time, Bolles’ nonlinear history produces PA tionally, molecular phylogeny has revealed vivid impressions of times, places and three genetically defined groups of Y. pestis, personalities. Moreover, Bolles manages to and these appear to correspond to the groups describe developments in physics with of strains associated with the three pan- imaginative analogies and contrasts (wave demics of plague. packets as bulges moving through a bull- It should be possible to obtain conclusive whip, or the orbit-jumping electron of the evidence that Y. pestis was the causative agent Bohr theory as the ghost of Hamlet’s father because a large number of corpses were — it’s here, it’s there, it’s nowhere in buried anonymously under towns and cities between). Although equation-avoidance is during the Black Death. Viable bacteria will standard policy in semi-popular science be long gone, but tell-tale DNA might still In dispute: Niels Bohr (left) and Albert Einstein. writing, it frequently fails because one well- be present. But although one research placed equation may be worth more than group has reported the isolation of Y. pestis Einstein and Niels Bohr,and ‘defiant’reflects a thousand words. Nevertheless, the policy DNA from the teeth of presumed plague Einstein’s reservations about quantum works here because Bolles blends his analo- victims, others have been unable to repeat theory. Although Einstein initially respon- gies seamlessly into the historical vignettes these studies. ded with enthusiasm to the new physics, this around which he weaves his story. Together these books give a good account quickly gave way to disappointment. His Inevitably, some of the analogies that of the history of the three great plagues. reservations were twofold. First, he felt that carry the physics are strained but, overall, Other aspects are less convincing. We do quantum mechanics had abdicated the his- Bolles stays true to the physics while keeping not yet have conclusive proof that Y. pestis torical task of science to furnish us with the images lively (and his readers awake). was the cause of the three great plagues. knowledge of nature that is independent of One spot that does need attention is his Although I am not yet convinced that observers or their acts of observation. The account of the uncertainty formulas, where the mysterious and unidentified virus sug- role of the wave function in quantum theory he confuses the operators p and q with the gested by Scott and Duncan was the cause of was to provide probabilities for ‘results’ if uncertainties ∆p and ∆q and overlooks the the Black Death, these books do serve to appropriate measurements were made (the statistical character of quantum uncertainty. remind us never to be blinkered to other Born rule). The theory was silent about Of course, it is not only the physics that possibilities. ■ what, if anything, was likely to be true in the needs explaining. The philosophical con- Richard W. Titball is at the Defence Science and absence of observation. In this sense, it was cepts — especially realism and determinism, Technology Laboratory, Porton Down, irrealist. Second, quantum mechanics was and Bohr’s difficult ‘complementarity’— are Salisbury SP4 0JQ, UK. essentially statistical and, unlike probabili- no more transparent than is the Schrödinger ties in classical statistical mechanics, quan- equation. Bolles does an excellent job with tum probabilities were not understood as probability and determinism — his nuanced arising from ignorance of fine details. In this discussion of indeterminism in connection sense,the theory was indeterministic. with Heisenberg is particularly fine. He fares Clash of the titans Einstein began to probe how strongly less well in explaining the issues surrounding Einstein Defiant: Genius versus quantum theory was tied to irrealism and realism. Indeed, he makes it appear that Genius in the Quantum Revolution indeterminism, leading to a series of debates Bohr endorsed the idea that measurements by Edmund Blair Bolles over its interpretation, beginning around actually create the physical attributes that Joseph Henry Press: 2004. 256 pp. $27.95 the Solvay Conference of 1927 and culmi- correspond to their outcomes, and that Arthur Fine nating in the so-called EPR paper of 1935 quantum mechanics simply runs counter to (A. Einstein, B. Podolsky and N. Rosen Phys. the belief that the micro-world of electrons The authors of postmodern novels enjoy Rev. 47, 777–780). That paper introduced and such is real. As for complementarity, the liberty of moving around randomly quantum entanglement and laid the Bolles wisely begs off, noting early on that through time, thereby erasing the appear- groundwork not only for John Bell’s investi- trying to pin down Bohr is “like trying to cage ance of causality and challenging our sense gations into nonlocality, but also for the a beautiful cloud”. of rational action. In Einstein Defiant, contemporary development of quantum All in all, this is a delightful book. It Edmund Bolles also zigs and zags randomly information theory (computing, cryptogra- succeeds admirably in capturing the spirit through time, but he is not trying to erase phy and teleportation). of the people, the times, the science and the the modalities of human understanding. Einstein Defiant lays out the background intellectual passion that marked the rise of Rather, he is trying to show how entangled of these debates in the context of the ‘old’ quantum physics. ■ that understanding is with the concrete quantum theory,whose duality of waves and Arthur Fine is in the Department of Philosophy, particulars of time, place and culture. particles set the agenda for the new quantum University of Washington, Seattle, Washington The geniuses of the subtitle are Albert mechanics of 1925–27. It continues the 98195-3550 USA.