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  The pedagogical pressures extended beyond high schools. The armed forces also called for massive numbers of military personnel to receive basic physics training at colleges and universities. Draft syllabi circulated between military officials and the AIP. The Army, for example, wanted the new courses to emphasize how to measure lengths and angles, air temperature, barometric pressure and relative humidity, and electric current and voltage. Lessons in geometrical optics would emphasize applications to battlefield scopes; lessons in acoustics would drop applications to music in favor of depth sounding and sound ranging. So acute was the need to teach elementary physics that a special committee recommended in October 1942 that university departments discontinue courses in atomic and nuclear physics for the duration of the war—topics later associated with exotic weapons like nuclear bombs—so as to devote more teaching resources to truly “essential” material.10

  The material might have been rudimentary, but the pace was grueling. Many colleges and universities shifted from semesters to trimester or quarter systems to fit more courses into a given calendar year. Small liberal arts colleges, such as Williams College in western Massachusetts, began to accept two hundred Navy cadets per month; enrollments in the college’s physics courses quadrupled. At larger institutions, such as MIT, students in both the Army and Navy programs quickly outnumbered civilian students; by winter 1943–44, the campus hosted three military students for every two civilian ones. Entire buildings on campuses throughout the United States were given over to the special Army and Navy courses and to housing the recruits. Between December 1942 and August 1945, by packing students into two ninety-minute lectures and one three-hour laboratory session each day—six days a week—accelerated courses across the country managed to train a quarter of a million students in elementary physics as part of the Army and Navy programs.11

  Figure 5.1. Students in the US Army Special Training Program attend lectures at MIT, ca. 1944. (Source: MIT Technique magazine [1944], courtesy of MIT Technique editorial board.)

  Staffing the inflated classrooms required military-style planning and logistics. Barton’s AIP bulletins warned that any universities found to be hoarding valuable physics teachers—much less poaching them from other schools—would be subject to “severe criticism.” Barton developed a complicated formula for what he termed the acceptable ratio of “genuine to ‘ersatz’ teachers of physics” in any given institution.12 Departments deemed to have higher ratios of “genuine” (experienced) physics teachers than Barton’s formula allowed would be subject to censure. Specialists in neighboring fields, such as mathematics, chemistry, and engineering, were to be “drafted” to begin teaching physics instead. At small colleges like Williams, an even wider mix of faculty pitched in. After some quick retooling, professors from music, theater, philosophy, geology, and biology helped to teach physics to the Navy recruits.13 Physics teachers became a rationed commodity: like rubber, gasoline, and sugar, they were in critically short supply.

  With undergraduate physics enrollments slated to triple by the end of 1943, draft policies quickly followed suit. The US government created the National Committee on Physicists in December 1942—the first of its kind for any academic specialty—to advise local draft boards on the need for teaching-related deferments. Soon the phrase “the physicists’ war” echoed throughout newspapers, popular magazines, and even congressional testimony. Use of the phrase peaked in 1943, long before there was much news to report (classified or otherwise) about the Manhattan Project.

  : : :

  After the war, use of the phrase “physicists’ war” rebounded every decade or so, usually around an anniversary of the bombings of Hiroshima and Nagasaki. The highest postwar peak accompanied the publication of Richard Rhodes’s Pulitzer Prize–winning book The Making of the Atomic Bomb in 1986.14 By then, Conant’s phrase had long since been linked with classified military projects rather than classroom instruction.

  The transition began nearly as soon as the bombs were dropped over Japan. Soon after work on the Manhattan Project had begun, its main overseer, General Leslie Groves, anticipated that the government would eventually need to have some information ready to release about the top-secret nuclear weapons project—pre-cleared and available for wide distribution—in case the bombs were ever used. He tapped Princeton nuclear physicist Henry DeWolf Smyth to spend the war visiting each Manhattan Project site, compiling a technical report on the project that would be suitable for public dissemination.15

  Figure 5.2. Google n-gram of the phrase “physicists’ war.” The vertical axis shows percentage (× 106) of occurrences of the bigram “physicists’ war” among all bigrams in the available English-language corpus. (Source: Figure by the author, based on data at https://books.google.com/ngrams.)

  On the evening of 11 August 1945, just two days after the bombing of Nagasaki, the US government released Smyth’s two-hundred-page document under the ponderous title A General Account of Methods of Using Atomic Energy for Military Purposes under the Auspices of the United States Government, 1940–1945. Quickly dubbed the “Smyth report,” copies flew off the shelves. The original Government Printing Office edition ran out so quickly that Princeton University Press soon published its own edition, under the more manageable title Atomic Energy for Military Purposes.16

  As historian Rebecca Press Schwartz has documented, security considerations dictated what Smyth could and could not include in his report. Only information that was already widely known to working scientists and engineers or that had “no real bearing on the production of atomic bombs” was deemed fit for release. Little of the messy combination of chemistry, metallurgy, engineering, or industrial-scale manufacturing met these criteria; those aspects of the huge project that were crucial to the actual design and production of nuclear weapons remained closely guarded.17 Instead, Smyth focused narrowly on ideas from physics, pushing theoretical physics in particular to the forefront. Ironically, most people read in Smyth’s report the lesson that physicists had built the bomb—and, by implication, had won the war.18

  It needn’t have been that way. Consider, for example, a long-forgotten press release issued by the War Department on 6 August 1945, the day that Hiroshima was bombed. This particular release was issued locally, in the state of Washington, and it played to the home crowd. More than two tightly packed pages extolled the great breakthroughs in chemistry and chemical engineering that had made the bomb possible—breakthroughs specifically associated with the massive Hanford site in Washington. Not one word of this particular press release referred to physics or physicists.19

  Yet rare examples like this press release could hardly compete with the overwhelming attention devoted to the Smyth report. Soon after Princeton University Press brought out its edition of the report, Smyth’s book spent fourteen weeks on the New York Times best-seller list; it sold more than a hundred thousand copies in a little over a year.20 Later reports, such as Essential Information on Atomic Energy, issued in 1946 by the new Special Committee on Atomic Energy of the US Senate, borrowed liberally from the Smyth report, depicting nuclear weapons as the latest in a series of developments in theoretical physics. A “chronological table” at the end extended the narrative as far back as 400 BC to the ancient Greek atomists—rather than, say, to the Berlin chemistry laboratory in which nuclear fission had been discovered late in 1938, much less to the work of DuPont chemical engineers who had managed to scale up plutonium-producing nuclear reactors during the war.21

  : : :

  The change in referent for the phrase “the physicists’ war”—from blackboards to bombs—had serious implications. After the war, physicists in the United States bore the largest brunt of any academic group during the McCarthy-era red scare. The House Un-American Activities Committee held twenty-seven separate hearings on allegations against physicists, twice the number for members of any other scholarly discipline. If nuclear weapons had been made by physicists, so the reasoning went, then physicists must have special access to t
he “atomic secrets” with which such bombs could be made. Hence the loyalties of this group required the closest scrutiny of all.22

  On the other hand, many policymakers quickly concluded after the war that if physicists really did hold the atomic secrets, then the United States needed many more physicists to secure the uneasy peace. Just six weeks after the war had ended, the Scientific Panel of the Interim Committee on Atomic Power—the selfsame group that had advised the secretary of war on possible uses for the new weapons during the war—recommended to General Groves that the Army continue to support university physics research, a plan that Groves quickly approved. Groves and his colleagues were eager “to prevent disintegration of [the Army’s] nuclear research organization” and hence to bolster “advanced training in nuclear studies.”23 The Office of Naval Research drew similar conclusions, investing heavily after the war in unclassified research projects so as to make up for the “deficit in technical people” left in the wake of the recent conflict. An official from the Office of Naval Research explained during a meeting with advisers at the Pentagon in 1947 that “graduate students working part time are slave labor”—hence, supporting the training of more physics graduate students was an easy investment for the Navy to justify.24

  The following year, as Congress oversaw a new fellowship program to encourage students to pursue graduate study of physics, the program’s director concurred with a leading senator that the program should “establish a nucleus of highly trained individuals who will increase the general knowledge in scientific fields and at the same time provide a pool from which some individuals will be drawn to active employment on the atomic energy program.” The plan worked: by 1953, three-quarters of the graduate students who completed their PhDs in physics with funding from the Atomic Energy Commission—the postwar successor to the Manhattan Project, which assumed control of the nation’s nuclear arsenal and oversaw research and development for the sprawling nuclear complex—took jobs with the commission upon graduation.25

  These postwar calculations had an immediate impact on how research in areas like physics was supported. In 1949, 96 percent of all funding for basic research in the physical sciences within the United States came from defense-related federal agencies, including the Department of Defense and the Atomic Energy Commission. In 1954—four years after the establishment of the civilian National Science Foundation—fully 98 percent of funding for basic research in the physical sciences came from federal defense agencies. The scale of funding, much like the source, bore little resemblance to the prewar patterns. By 1953, funding for basic research in physics in the United States was twenty-five times higher than its level in 1938 (in constant dollars).26

  With these vast infusions of spending, enrollments in physics skyrocketed. At a time when higher education was booming across all fields of study—the G.I. Bill brought more than two million veterans into the nation’s colleges and universities after the war—graduate enrollments in physics grew at the fastest pace of all, doubling almost twice as quickly as the rate for all fields combined. By the outbreak of fighting in the Korean War in June 1950, American physics departments were producing three times as many PhDs in a given year as the prewar highs.27 Weeks into the new conflict, officials with the National Research Council and the AIP scrambled to make sure those trends would continue. They hastily drew up a memorandum to establish “procedures for utilizing our manpower in physics,” emphasizing, above all, that “unless a very short emergency (not more than three years) is contemplated, it is of great importance to continue the training of promising students to full competence in physics.” After all, the administrators warned, “we have now no ‘stockpile’ of physicists.” Many heeded the new call. Citing the nation’s entry into the Korean War, the physics department at the University of Rochester immediately began offering four additional teaching assistantships and five new research assistantships to encourage more students to pursue graduate training in physics.28

  Just as they had during the Second World War, scientists and policymakers tracked the postwar training effort carefully, fearful that despite the rapid rise in physics enrollments the nation might suffer some critical shortfall. In the course of a single speech in 1951, Smyth—now in his role as a top member of the Atomic Energy Commission—described young physics graduate students as a “war commodity,” a “tool of war,” and a “major war asset,” to be “stockpiled” and “rationed.” Analysts at the Bureau of Labor Statistics agreed. “If the research in physics which is vital to the nation’s survival is to continue and grow,” they asserted in a 1952 report, “national policy must be concerned not only with keeping young men already in the field at work but also with insuring a continuing supply of new graduates.” Similar calculations produced huge numbers of newly trained physicists in other Cold War powers as well, including the United Kingdom and the Soviet Union. In fact, more physicists were trained during the quarter century after the Second World War than had ever been trained, cumulatively, in human history.29

  The language of “rationing” and “stockpiling” young physicists thus percolated with little interruption, starting in the closing weeks of 1941—before the Manhattan Project even existed—and continuing throughout the first decade of the nuclear age. However, although the terminology remained fairly constant, the aims of the training shifted considerably after the war. Rather than teach soldiers some elementary physics to prepare them for the battlefield, US officials began to talk about creating a “standing army” of physicists, specialized in the esoterica of nuclear reactions, who could work on weapons projects without delay should the Cold War ever turn hot.30 By the mid-1950s, Conant’s phrase about “the physicists’ war” had assumed a new meaning and a new urgency. But one underlying point remained unchanged: it was all about training, after all.

  6

  Boiling Electrons

  Two decades ago, while digging through a physicist’s archive, I stumbled upon a document that has haunted me ever since. It was a hand-typed table of integrals—long lists of mathematical functions and the numerical answers one should find upon integrating the functions between various limits—seemingly little different from the manuals and tables that I had kept handy as a student when trying to solve my homework problems. The familiarity of the contents jarred with the table’s front page. Precisely thirty-one copies of the table had been printed, their recipients carefully noted on the cover. The table, dated 24 June 1947, had been prepared to accompany a classified report. The distribution lists for the two documents were a close match; nearly all the recipients of the integral table (like all who received the main report) had attained security clearances to handle secret, defense-related materials.1

  How to reconcile the banal contents with the striking cover page? What disaster would have befallen the US government if enemies of the state had learned that the integral of x/(1 + x)2 between x = 0 and x = 1 equaled 0.1931? Moreover, how could the authorities have hoped to thwart the circulation of such basic mathematical results? Wouldn’t anyone schooled in the routines of calculus arrive at the same answers, whether or not their names appeared on the table’s special distribution list?

  The table of integrals was prepared as a supplement to a classified report written by renowned physicist and Nobel laureate Hans Bethe. (I found both items in Bethe’s papers at Cornell University in upstate New York.) In the 1930s, Bethe had become one of the world’s experts on nuclear physics; by 1938, he had pieced together the complicated nuclear reactions that make stars shine. He served as the director of the Theoretical Physics Division at wartime Los Alamos, reporting directly to J. Robert Oppenheimer. After the war, when he returned to teaching at Cornell, he remained an active consultant to the nuclear weapons program as well as to the budding nuclear power industry.2

  In 1947, Bethe had been asked to work on the problem of shielding for nuclear reactors. When heavy nuclei like uranium or plutonium get blasted apart by neutrons, they release energy—energy that can power a bomb or g
enerate electricity in a reactor—and they also release large doses of high-energy radiation. While working on the challenge of how best to block or absorb the radiation, Bethe kept finding that he needed to evaluate integrals of a particular form. A colleague—another PhD physicist, Manhattan Project veteran, and by then senior researcher at a nuclear reactor facility—prepared the accompanying table of integrals so that selected coworkers might be able to perform calculations like Bethe’s.

  Similar mathematical handbooks and tables had been prepared for centuries. Around the time of the French Revolution, for example, as historian Lorraine Daston has written, leading civil servants produced mammoth tables of logarithms and trigonometric functions calculated to fourteen or more decimal places—far greater accuracy than any practical application would have required at the time. Gaspard Riche de Prony’s tables were a deliberate demonstration of Enlightenment mastery, one more testament to the triumph of Reason, to be admired more than used.3

  Though the 1947 table of integrals was not prepared for public fanfare—just the opposite, as its closely watched distribution list made clear—the table stood closer to Prony’s time than to ours. Indeed, the table’s introduction explained the provenance of many of the results that would follow: most integrals had been evaluated by making clever changes of variables so that the functions of interest matched forms that had been reported in the venerable Nouvelles tables d’intégrales définies, published in Leiden in 1867 by the wealthy Dutch mathematician David Bierens de Haan.4

  Two years into the atomic age, the labor of calculation still resembled the virtuosity of the humanist scholar more than the pragmatics of the engineer. One needed access to a well-stocked library filled with old, foreign-language books. And here lies a key to understanding the limited distribution of the 1947 integral table: although in principle anyone should have been able to compute the integrals, completing such calculations in practice required substantial resources of time and skill. Soon after typists finished preparing Bethe’s report and the accompanying integral table, however, the nature of calculation would change forever.