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Physics meets America’s defense agenda

Quantum Legacies: Dispatches from an Uncertain World

David Kaiser
University of Chicago Press
360 pp.
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While historically naïve, Thomas Kuhn’s 1962 treatise The Structure of Scientific Revolutions succeeded in revealing that science is not as rational and objective as many imagined it to be, opening the doors to a new kind of history of science, one that pays attention to the complex interactions between science’s conceptual frameworks and its social contexts. Yet, to this day, most history books written for the wider public favor a narrower understanding of science. David Kaiser’s work is a welcomed exception.

In Quantum Legacies: Dispatches from an Uncertain World, Kaiser, who teaches both particle cosmology and history of science at the Massachusetts Institute of Technology, gives a witty and insightful overview of the development of modern physics. Through a series of previously published but carefully reedited essays, he explores how America’s defense agenda has shaped physics research and education, from the ever-increasing size of research teams to the way we talk about quantum phenomena.

Initially, only taciturn physicists such as Paul Dirac preferred to focus on the mathematical formalism of quantum physics rather than engaging in public debates on its philosophical implications as Albert Einstein and Erwin Schrödinger often did. Why then are so many physicists now favoring Dirac’s “shut up and calculate” approach? Kaiser seems unconvinced by the oft-repeated claim that most physicists were satisfied by Niels Bohr’s answers to Einstein’s and Schrödinger’s worries and simply turned their attention to more practical problems. The change of focus, he argues, was brought about by the complex ways in which war transformed physics.

Historians usually underline the role that new military technology, from computers to atomic bombs, played in the Allies’ victory in World War II. But according to Kaiser, the most important contribution that physics departments made to the war effort was the training of soldiers. As he reminds us, this was a “physicists’ war” first and foremost, because soldiers needed a basic grasp of physics to operate everyday military technology.

Across the country, classroom discussions of the interpretation of quantum mechanics were replaced by lectures on the fundamentals of radio transmission and artillery. Far from being temporary, these drastic changes became entrenched during the Cold War as Americans feared—albeit incorrectly—that the USSR would match and perhaps surpass their scientific and military outputs. Fear of a nuclear conflict, Kaiser explains, made nuclear physicists key to national security during this period. Generous governmental funding in research and education led to soaring enrollments in physics departments.

As Kaiser demonstrates through an examination of mid-20th-century textbooks, increasingly large classes encouraged professors to continue their move away from philosophical musings in favor of more practical (and undoubtedly easier-to-grade) calculations. Gone were the days when textbooks discussed the reality of the energy levels of hydrogen atoms; now the aim was to calculate them.

The Cold War led to a golden age during which physics saw the development of the standard model and the discovery of new particles, from neutrinos to the Higgs boson. To his credit, Kaiser never suggests that military funding is key to rapid scientific development. Not only does he remind us that the reactionary counterculture of the 1960s and 1970s played a crucial role in fundamental research [for example, (1)], he convincingly argues that the waning of nuclear research funding caused by the détente unwittingly led to the creation of particle cosmology.

Peppered with interesting anecdotes from Kaiser’s own career, Quantum Legacies offers a series of perceptive essays on why and how America has trained physicists in the past century. The one “legacy”­­ the book fails to address is the flagrant absence of female and minority researchers in particle cosmology. Despite this want, Quantum Legacies remains an engrossing read that will give specialists and nonspecialists alike a deeper understanding of how phenom­­ena as diverse as geopolitics and eastern mysticism have shaped physics in the past century.

References and Notes
1. W. P. McCray, D. Kaiser, Science 365, 550 (2019).

About the author

The reviewer is at the History of Science and Technology Program, University of King’s College, Halifax, NS B3H 2A1, Canada.