The Quantum Story: A History in 40 Moments, Jim Baggott, Oxford U. Press, New York, 2011. $29.95 (469 pp.). ISBN 978-0-19-956684-6
Both history and popularization of science are essential for public understanding, but the relationship between them is akin to Niels Bohr’s complementarity. Books that attempt to present scientific ideas in a straightforward manner often simplify historical issues to the point of distortion. On the other hand, attempts at maximum historical accuracy unnecessarily complicate the task of popularization since original and now-accepted interpretations rarely coincide.
In The Quantum Story: A History in 40 Moments, Jim Baggott achieves a balanced synthesis between both approaches while avoiding the above extremes. His primary goal is to explain, using historical and biographical vignettes, the contemporary state of quantum theory to nonspecialists who understand basic physics. Baggott has a talent for elucidating scientific ideas, including some of the latest sophisticated developments. Quantum physicists and professional historians of physics will also find much novel in his presentation, though they might disagree with him in places.
The book encompasses two rather different quantum stories under one cover. The first, more expected narrative presents the key steps on the road to quantum mechanics—from the 1900 Planck formula to the 1926 Schrödinger equation, interpretations leading to the uncertainty relation and complementarity, and the series of debates between Albert Einstein and Bohr that culminated with the 1936 Einstein-Podolsky-Rosen paradox. With lesser attention to the middle decades of the century, The Quantum Story proceeds to more recent conceptual developments involving Bell’s inequalities, entanglement, and decoherence.
In comparison with Baggott’s earlier book, The Meaning of Quantum Theory: A Guide for Students of Chemistry and Physics (Oxford Science, 1992), this edition adds some of the latest experiments but also shifts the tone of conclusion. The 1992 work praised quantum dissidents whose doubts about the Copenhagen interpretation had opened new theoretical and experimental questions and made several competing interpretations possible. Today, the author appears less interested in the alternatives: David Bohm’s hidden-variables approach is still explained at length, but the many-worlds interpretation is discussed only briefly, and the more realistic ensemble interpretation is not mentioned at all. Baggott seems more satisfied with the simple lesson that quantum mechanics is “spooky” and involves some “weird” action at a distance; he does not mean to criticize but rather expects such words to please today’s general audiences.
The book’s second story goes beyond the continuing struggle to understand quantum mechanics’s murky foundations and discusses its subsequent applications and developments. Here the author faces a daunting task because quantum physics has branched out into a number of fields, each with its own set of basic concepts. Anyone trying to represent the richness of this diversity must make difficult choices. Baggott is very good at explaining the topics he selects, but he seems completely unreflective about the rather narrow road chosen. He focuses on quantum field theory and the standard model of particle physics, while practically ignoring condensed matter, nuclear physics, astrophysics, quantum optics, and complex systems. Selected episodes center almost exclusively in the Anglo American world, with little attention given to the international character of quantum physics and important developments that took place in Calcutta, Moscow, Osaka, Rome, São Paulo, and Trieste.
Even when dealing with quantum fields, Baggott skips the theory’s crucial founding stage and proceeds directly to the second act, which begins with renormalization and ends with W and Z bosons and superstrings. Some of the most fundamental quantum concepts thus remain unexplained, including the very idea of a quantized field, advocated by Pascual Jordan; antiparticles, predicted by Paul Dirac; the loss of individuality, uncovered by Satyendra Nath Bose and Paul Ehrenfest; quasiparticles (for example, holes, phonons, and excitons), introduced by Yakov Frenkel and Lev Landau; and the concepts of weak and strong interactions, developed by Enrico Fermi and Hideki Yukawa, respectively.
The second narrative’s selected focus gives the book an unintended new meaning, since the reader cannot help but notice a striking contrast between its two stories. One reads like a suspense drama, with physicists absorbed in critical dialogs and challenging each other’s fundamental beliefs. The other reflects the style of banquet speeches celebrating Nobel Prizes; disagreeing voices are no longer heard and debating the foundations is often dismissed as “metaphysics” and discouraged in favor of constant pushing forward.
The Quantum Story characterizes the current situation in quantum field theory as a crisis caused by theoretical speculations running ahead of experimentalists’ limited financial resources. But it may also be that theorists have gone far too long without looking back at and critically re-examining their basic assumptions. After all, a hundred years ago authoritative physicists were also expecting sophisticated experiments to prove their latest “theory of everything” and a grand unification under electromagnetism. Instead, the developments took an unexpected turn after an unknown patent clerk in Bern, Switzerland, published a paper that contained some thought experiments and a “mere philosophical” analysis of the concept of simultaneity.
