Brotherhood of the Bomb

by Gregg Herken

  The group chose a site at MIT for the radar work, giving it the deliberately misleading title “Radiation Laboratory” in hopes of deceiving Nazi spies. Lawrence resisted Loomis’s appeal that he head the enterprise. Instead, Ernest picked its director, Rochester University physicist Lee DuBridge, a Lawrence protégé, and further demonstrated his commitment to the cause by volunteering two of his best scientists, McMillan and Alvarez, for the East Coast Rad Lab. By November, the duo was already on their way to Cambridge. Oppenheimer gave each a bottle of whiskey as a going-away gift; Cooksey arranged for the university’s brass band to serenade the departing heroes on the train platform.78

  * * *

  The reason for Lawrence’s reluctance to personally take part in the scientific mobilization for which he had become a willing recruiter was already beginning to take shape on the land above campus. In August, construction had begun of the steep road that would wind up Charter Hill to the site of the 184-inch. Early that October, the 1,000-ton concrete base for the cyclotron was poured. The first shipment of steel was trucked up to the construction site at the end of the month. By November, the metal skeleton of the distinctive twenty-four-sided building that would house the machine had begun to go up.79

  Following McMillan’s departure, the job of identifying the properties of element 94 had been taken over by Seaborg and Segrè. In December, while at Columbia University on a recruiting drive for MIT’s radar lab, Lawrence volunteered use of the 60-inch to create enough of the element for experiments.

  Because of the war, funding at least had ceased to be a problem for Berkeley’s Rad Lab. No longer was Lawrence’s enterprise dependent upon the largesse of foundations and grants from philanthropists. By underwriting the investigation into elements 93 and 94, the NDRC supplemented the Rad Lab’s budget with monies from another and most welcome source: the federal government.

  The change was both sudden and apparent. “This war is achieving alterations we would never have seen under other circumstances,” Kamen wrote to McMillan at MIT.80 Depression-era parsimony had ended. Given free rein to purchase equipment from a scientific catalog, Kamen ordered one of everything in the book—including “a ‘Podbielniak fractional distillation apparatus’ with gold-plated seals and ground joints, which cost in the neighborhood of a thousand dollars and which I included mostly out of curiosity to see what such an apparatus looked like.” Cooksey took one quick look at Kamen’s request and suggested he triple it.81

  Taking the place of the boys was an unfamiliar army of young engineers and technicians who were put to work building the 184-inch. Strapped for personnel because of the draft, the Rad Lab’s personnel manager turned to Hollywood. The man he put in charge of fabricating sheet metal for the new cyclotron had previously made fake armor for the movies’ medieval knights.82 For the first time, the magnet yoke of the 60-inch was no longer large enough to accommodate the lab’s research staff in the annual holiday party photograph. “The esprit has perked up considerably with everybody conscious of the necessity to work like the devil,” wrote Kamen to his homesick compatriots in snowy Boston.83

  * * *

  Early in 1941, as the war news worsened, Lawrence resolved to focus attention upon what seemed the most stubborn roadblocks on the way to a bomb. Separating uranium was highest on his list. Three different methods were then being investigated under NDRC sponsorship: a high-speed centrifuge, diffusion through a permeable membrane, and electromagnetic means. All three relied upon the slight difference in mass between natural uranium, U-238, and its lighter, more fissionable isotope, U-235.

  The centrifuge and gaseous diffusion, deemed most promising, were being studied at the University of Virginia and Columbia, respectively. The third method, electromagnetic separation, was the means that Minnesota’s Nier had used to obtain the tiny amount of U-235 available. But the difficulties had been so great that Nier himself dismissed the electromagnetic method as simply not feasible on an industrial scale.84

  Lawrence was not so easily discouraged. The apparatus that Nier had used, a mass spectrograph, was mechanically similar to a cyclotron; both required a powerful magnet, a vacuum chamber, and a high-voltage power supply. Lawrence ordered the boys to investigate the feasibility of converting the idled 37-inch into a mass spectrograph for separating uranium.

  In early March, Lawrence used the occasion of a Charter Day dinner to urge Conant to “light a fire under” Briggs.85 Visiting MIT in mid-month, Lawrence repeated his concern with the pace of the Uranium Committee to Karl Compton and Alfred Loomis. Lawrence also told of his own plans to convert the 37-inch and to carry out uranium experiments at the Rad Lab. In relaying Lawrence’s message, Compton went so far as to suggest that Bush appoint Lawrence his deputy until the uranium project was as well launched as MIT’s radar lab.

  Initially fearful that Lawrence might decide to sit out the war, Bush now worried about Ernest usurping his authority. While insisting that he was “running the show,” Bush named Lawrence to a recently appointed scientific panel, headed by Arthur Compton, which was meant to take things out of Briggs’s hands and bypass the Uranium Committee.86

  On May 17, 1941, Compton’s panel submitted its first report. Listed under the category of things that it said fission might make possible were radiological poisons and a new form of propulsion for ships and submarines. But the atomic bomb was a distant third on the list, and nowhere, Bush felt, was there a sense of urgency. Unsatisfied with this first effort, Bush and Conant urged Compton to take another look, adding two engineers to the panel for the purpose.

  In the interim, Lawrence had received information that seemed to move the atomic bomb closer to realization. Seaborg and Segrè, having completed their experiments with the mysterious element 94, pronounced it not only fissionable but nearly twice as likely as U-235 to sustain an atomic chain reaction. Ernest immediately telephoned the news to Compton, who passed the word to Bush.

  Due to the illness of his daughter, Margaret, Ernest missed the meeting that drafted the second report, which Compton sent to Bush in mid-July. In it, the news about element 94 received curiously little prominence. Indeed, the second report remained substantially unchanged from the first and expressed “primarily the engineers’ point of view,” Compton sniffed.87 Hoping in vain to drum up some enthusiasm for a bomb, Lawrence had appended his own memorandum announcing the fission-ability of element 94.88

  Before Bush sent the panel back for a third try, he decided to reorganize the government apparatus that was preparing the country for war. The NDRC was superseded in June 1941 by a larger umbrella organization, the Office of Scientific Research and Development, which reported directly to Roosevelt. Bush took control of OSRD, leaving the NDRC to Conant.89

  While he was certainly patriotic, Lawrence’s reasons for belatedly rallying to the colors were not wholly altruistic. The slowly accelerating mobilization had opened his eyes to what could be done in science with government support. Alvarez remembered Ernest returning from meetings at MIT’s Rad Lab with Loomis, bubbling over about the possibilities if one had the money, the resources, and the motivation.90

  With German tanks rolling across Russia by July, motivation was soon in abundance. But Bush cannily declined to give construction of the 184-inch a wartime priority as a way of keeping a rein upon Lawrence.91

  It was a visitor from overseas that fall who finally spurred Ernest to action. An Australian-born physicist working at the Cavendish, Marc Oliphant had been one of those to challenge Lawrence’s disintegration hypothesis at the Solvay Congress.92 By mid-1941, Oliphant shared the worry of his British colleagues that their American counterparts, Lawrence included, were too sanguine about fission’s peaceful potential and too naive about its prospects for a bomb.93

  Weeks earlier, England’s scientists had come to their own conclusions about the feasibility of a uranium weapon. Their top-secret M.A.U.D. report speculated that as little as 22 pounds of U-235 might be required for a bomb. The British also estimated that build
ing the device would take approximately two years and cost $25 million. As with radar’s cavity magnetron, they had deliberately leaked the secrets of the M.A.U.D. report to the Americans. But Briggs, in another fit of security-inspired paranoia, locked the document in his safe, leaving his Uranium Committee colleagues in the dark.94

  Oliphant had come to Washington in late August to find out why there had been no reaction to the M.A.U.D. report and was “amazed and distressed” to discover the reason. He flew to California to brief Lawrence, the only person Oliphant trusted to salvage the situation.95

  On Sunday, September 21, 1941, Lawrence drove Oliphant up the twisting dirt road of what was already called “Cyclotron Hill” for the obligatory tour. Cooksey took a picture of the two men standing next to the magnet frame for the 184-inch—which sat, like the magnet itself, out in the open, surrounded by a green sward of grass and weeds. Returning to Lawrence’s office, the two were joined by Oppenheimer. As Oliphant proceeded to tell the Americans about the M.A.U.D. report, he realized, from Oppenheimer’s expression, that it was the first Oppie had heard of plans to build an atomic bomb.96

  Oliphant’s visit made Lawrence more confident than ever that a fission bomb could be made to work. Ernest set out with his characteristic energy to spread the word and was soon dismayed at the response. At Lawrence’s urging, Bush and Conant agreed to see Oliphant, but were unwilling at that meeting even to acknowledge the existence of the M.A.U.D. report, since it had not yet been officially transmitted to the U.S. government. (“Oliphant’s behavior does not help the cause of secrecy!” Conant wrote in a peeved note to Bush afterward.)97

  Lawrence had also contacted Arthur Compton and relayed Oliphant’s news, coloring it with his own opinion that such a weapon “might well determine the outcome of the war.”98 Compton told Lawrence that he should make his case to Conant personally. The Harvard president and Lawrence were scheduled to be Compton’s guests the following week, at a celebration honoring the fiftieth anniversary of the founding of the University of Chicago.

  On a chill evening in late September, following a lecture by Ernest at Chicago’s Museum of Science and Industry on the medical uses of the cyclotron, Lawrence and Conant stood huddled before Compton’s fireplace with their host.99 Over coffee, Lawrence gave a brief account of the recent research in Britain, summarized the work he was planning to undertake at Berkeley, and spoke with some passion—he was “very vigorous in his expression of dissatisfaction,” Compton recalled—of Washington’s complacency in the face of mounting evidence of German interest in an atomic bomb.100 Compton, content to remain in the background, chimed in occasionally to echo Lawrence’s message.

  Lawrence had gone to Chicago merely intending to play the role of cheerleader for the bomb project.101 Just three days earlier, he had written to Cottrell’s Research Corporation with assurances that the Rad Lab intended to continue its basic research into high-energy physics, despite the war.102 Construction of the giant cyclotron had resumed earlier that month, after Bush finally granted the 184-inch a defense priority. Lawrence hoped to carry out the first trials of the machine sometime in 1943, a full year ahead of schedule.103

  Moreover, the concrete foundation for a major addition to the Crocker lab had just been poured the previous May. Ground-breaking for another new edifice, the Donner Laboratory, where John would carry out biomedical experiments, followed in June. He was overseeing “at least a three-ring circus,” Ernest recently wrote a friend.104

  To Lawrence’s surprise, it was Conant who seized the initiative in the meeting at Compton’s house, bringing Ernest up short with what amounted to an ultimatum.105 Claiming that he was considering putting the uranium project “in wraps,” Conant asked Lawrence if he were willing to devote the next several years of his life to building the bomb that he saw as so important. Caught unawares by Conant’s question, Ernest hesitated for a moment, openmouthed, before responding. “If you tell me this is my job, I’ll do it,” he said finally.106

  Lawrence and Conant asked Compton to convey the new, now-collective sense of urgency to Vice President Henry Wallace, an amateur expert in plant genetics and thus the closest thing to a scientist in Roosevelt’s high circle.107 Compton left by train the following day on a tour d’horizon that ultimately took him not only to Washington but also to see Fermi and Urey at Columbia and Wigner at Princeton. All affirmed Lawrence’s view that a bomb could be made and would work.108

  But, for Bush, still a nagging concern was Lawrence’s cavalier attitude toward security in the project. On more than one occasion, the head of OSRD had told Conant that Ernest could not be trusted to keep a secret. For the past year, Lawrence had been complaining to various scientists about Briggs, when even the existence of the Uranium Committee was still a secret. More recently, as they gathered in Compton’s living room, Conant had reprimanded Ernest for telling Oppenheimer about the bomb without authorization.109

  On October 9, 1941, Roosevelt authorized Bush to speed up the preparatory work in any way possible. The president also decided that he would look to a small group of senior advisers—the so-called Top Policy Group—to make recommendations on whether to proceed with building the weapon and subsequent steps he should take.110 Later that day, Bush asked Compton’s review panel to take a third and final look at how the project might be organized.111

  On his own, Bush put together a short list of scientists to advise OSRD on the bomb. Bush sent the list to the National Academy’s Frank Jewett, along with a self-justifying apologia for earlier delays: “Much of the difficulty in the past has been due to the fact that Ernest Lawrence in particular had strong ideas in regard to policy, and talked about them generally.”112 Bush had already decided who he did not want to head the group. Since the project “would have to be handled under the strictest sort of secrecy,” he wrote Jewett, “I hesitate at the name of Ernest Lawrence.”113

  * * *

  Alarmed by Lawrence’s volubility, Bush and Conant were torn over who else to initiate into the secret bomb project. It was already obvious that Berkeley’s top theorist was aware of what was afoot. Moreover, the next report by Compton’s panel would necessarily need to come to some conclusions about the internal workings of an atomic bomb—conclusions based upon complex calculations involving hitherto unimaginable pressures and temperatures, which only a theoretical physicist could provide.

  Compton had been having trouble getting answers to such questions from the Uranium Committee’s head theorist, Wisconsin’s Gregory Breit. Physical chemists W. K. Lewis from MIT and George Kistiakowsky from Harvard, as well as Robert Mulliken, a physicist at Chicago, had been hurriedly added to the review panel to fill in the gap. Recognizing the urgency of the task, Compton scheduled a meeting of the expanded group for Tuesday, October 21, at General Electric’s research laboratory in Schenectady, New York.114

  A week before the meeting, Lawrence cabled Compton with a request that he be allowed to add another name to the roster: “Oppenheimer has important new ideas. Think it desirable he meet with us Tuesday. Can you arrange invitation?”

  Compton telegraphed back that Lawrence was welcome to bring Oppenheimer, but suggested instead that Ernest simply relay Oppie’s ideas—“to avoid duplication travel cost.” Lawrence countered that, if necessary, he would use the Loomis fund to pay for his friend’s travel. “I have a great deal of confidence in Oppenheimer,” Ernest added, “and, when I see you, I will tell you why I am anxious to have the benefit of his judgment in our deliberations.”115

  3

  A USEFUL ADVISER

  BY MID - 1941, OPPENHEIMER probably welcomed the opportunity to become involved in the bomb project—if only out of simple loneliness and boredom. “The situation in Berkeley & here in Pasadena is in some ways very gloomy … almost all the men active in physics have been taken away for war work,” he wrote to friends that May.1 Oppie predicted “that physics in our sense will just about stop by next year.”

  But Oppenheimer may also have begun to
feel guilty about sitting out the war. The German invasion of the Soviet Union in June had caused a sudden turnabout in the Communist Party’s position on intervention.2 There would not be a third Report to Our Colleagues. In October, Lawrence and Oppenheimer—his ticket paid by the Loomis fund—boarded the eastbound streamliner City of San Francisco for the final meeting of Compton’s panel.

  Ernest opened the Schenectady meeting by reading aloud Oliphant’s summary of the M.A.U.D. report. The discussion ranged widely, with various techniques for separating uranium being debated. But the group agreed that the electromagnetic method—Lawrence’s approach—deserved “especially urgent attention.”3

  Oppenheimer’s contribution included an all-important estimate of how much uranium would be necessary for a bomb. Oppie had calculated that a critical mass of U-235 might weigh more than 200 pounds. This estimate accorded closely with a guess made earlier by Fermi, but was nearly ten times the figure cited in the M.A.U.D. report. The difference depended upon assumptions made about the bomb’s efficiency, one of the most difficult things to calculate.4

  Compton confronted the group with other frustrating unknowns: how long would it take to build a weapon, and what would it cost? Unable to prod the engineers on his panel even to speculate, Compton hazarded his own guesses: three to five years to build the bomb, at a cost of “some hundreds of millions of dollars.”5 He decided against including a cost estimate—“lest the government should be frightened off.”

  Disappointed and vexed by such indecision, Lawrence and Oppenheimer left for California the following day, October 22. On the streamliner, Lawrence drafted an angry letter to Compton, decrying the panel’s timidity and hinting darkly that any failure would be on Compton’s head.