American Prometheus (33 page)

Soon after his appointment as Coordinator of Rapid Rupture, Oppenheimer asked Serber to be his assistant, and by early May 1942 he and Charlotte were ensconced in a room above Oppie’s garage at One Eagle Hill. He considered Serber one of his closest friends. Since 1938, when Serber moved to the University of Illinois at Urbana, they had written each other almost every Sunday.
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Over the next few months, Serber became Oppie’s shadow, his note-taker and facilitator. “We were together almost all the time,” recalled Serber. “He had two people to talk to, that was Kitty or me.”

The summer seminar of 1942 met in the northwest corner of the fourthfloor attic of LeConte Hall, above Oppenheimer’s office on the second floor. The two rooms had French doors opening out onto a balcony, and so for security reasons a thick wire netting was securely fastened over the entire balcony. Oppenheimer had the only key to the room. One day, Joe Weinberg was sitting in the attic office with Oppenheimer and several other physicists when there was a pause in the conversation and Oppie said, “Oh geez, look.” And he pointed to the sunlight streaming through the French doors, which cast a shadow across the papers on the table and clearly outlined the wire netting. “It was as if for a moment,” Weinberg said, “all of us were dappled with the shadow of the wire netting.” It was eerie, Weinberg thought; they were trapped in a symbolic cage.

As the weeks went by, Oppie’s “luminaries” began to appreciate his talents as their instigator and rapporteur. “As Chairman,” Edward Teller later wrote, “Oppenheimer showed a refined, sure, informal touch. I don’t know.”

They began their deliberations by studying a previous man-made explosion: the detonation in 1917 of a fully loaded ammunition ship in Halifax, Nova Scotia. In this tragic accident, an estimated 5,000 tons of TNT had decimated 2½ square miles of downtown Halifax and killed 4,000 people. They quickly estimated that any fission weapon might easily explode with a force two to three times that of the Halifax explosion.

Oppenheimer then directed his colleagues’ attention to the development of the basic design of a fission device that could be small enough to be militarily deliverable. They quickly determined that a chain reaction could probably be achieved with a uranium core placed inside a metal sphere only eight inches in diameter. Other design specifications required extremely precise calculations. “We were forever inventing new tricks,” Bethe recalled, “finding ways to calculate, and rejecting most of the tricks on the basis of the calculations. Now I could see at firsthand the tremendous intellectual power of Oppenheimer who was the unquestioned leader of our group. . . . The intellectual experience was unforgettable.”

While Oppenheimer soon concluded that there were no major theoretical gaps to fill in designing a fast-neutron reaction device, the seminar’s calculations on the actual amount of fissionable material needed were necessarily vague. They simply lacked hard experimental data. But what they did know suggested that the amount of fissionable material necessary for a weapon might easily be twice the estimated amount indicated to the president just four months earlier. The discrepancy implied that the fissionable materials could not be refined in small amounts in a mere laboratory but would have to be manufactured in a large industrial plant. The bomb would be very expensive.

At times, Robert despaired of being able to solve so many imponderables. He so feared that they were already in a losing race against the Germans that he impatiently dismissed any research efforts that seemed too time-consuming. When one scientist proposed a laborious scheme for measuring fast-neutron scattering, Oppenheimer argued that “we would do better to have a rapid and qualitative survey of scattering. . . . Landenburg’s method [is] so tedious and uncertain that we may well have lost the war before he has found an answer.”

In July, their deliberations were temporarily sidetracked when Edward Teller informed the group of calculations he had completed on the feasibility of a hydrogen or “super” bomb. Teller had come to Berkeley that summer convinced that a fission bomb was a sure thing. But bored with discussions of a mere fission weapon, he had entertained himself with calculations on another problem, suggested to him by Enrico Fermi over lunch a year earlier. Fermi had observed that a fission weapon might be used to ignite a quantity of deuterium—a heavy form of hydrogen—thus producing a far more powerful
fusion
explosion, a super bomb. Teller stunned Oppenheimer’s group in July with calculations suggesting that a mere twenty-six pounds of liquid heavy hydrogen, ignited by a fission weapon, could produce an explosion equivalent to one million tons of TNT. Magnitudes of this scale raised the possibility, Teller suggested, that even a fission bomb might inadvertently ignite the earth’s atmosphere, seventy-eight percent of which was made of nitrogen. “I didn’t believe it from the first minute,” Bethe said later. But Oppenheimer thought it advisable to hop a train East and personally report to Compton on both the super bomb and Teller’s apocalyptic calculations. He tracked Compton down at his summer cottage on a lake in northern Michigan.

“I’ll never forget that morning,” Compton later wrote in a tone of high drama. “I drove Oppenheimer from the railroad station down to the beach looking out over the peaceful lake. There I listened to his story. . . . Was there really any chance that an atomic bomb would trigger the explosion of the nitrogen in the atmosphere or the hydrogen in the ocean? . . . Better to accept the slavery of the Nazis than to run a chance of drawing the final curtain on mankind.”

In the event, Bethe soon ran further calculations that convinced both Teller and Oppenheimer of the
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zero possibility of igniting the atmosphere. Oppenheimer spent the rest of the summer writing up the group’s summary report. In late August 1942, Conant sat reading it and scribbled notes to himself headed “Status of the Bomb.” According to Oppenheimer and his colleagues, an atomic device would explode with “150 times energy of previous calculation”—but it would need a critical mass of fissionable material six times the previous estimate. An atomic bomb was entirely feasible, but it would require the marshaling of massive technical, scientific and industrial resources.

One evening before the summer seminar ended, Oppenheimer invited the Tellers to dinner at his home on Eagle Hill. Teller vividly recalled Oppenheimer saying with absolute conviction that “only an atomic bomb could dislodge Hitler from Europe.”

By September 1942, Oppenheimer’s name was being floated within the bureaucracy as the obvious candidate to direct a secret weapons lab that would be dedicated to the development of an atomic bomb. Bush and Conant certainly thought Oppenheimer was the right man for the job; everything he had done over the summer had borne out their confidence. But there was a problem: The Army was still refusing to issue him a security clearance.

Oppenheimer himself was aware that one of his problems was his many communist friends. “I’m cutting off every communist connection,” he said in a phone conversation with Compton, “for if I don’t, the government will find it difficult to use me. I don’t want to let anything interfere with my usefulness to the nation.” Nevertheless, in August 1942, Compton was informed that the War Department had “turned thumbs down on O.” His security file contained numerous reports of his allegedly “questionable” and “Communistic” associations. Oppie himself had filled out a security questionnaire in early 1942, listing the many organizations he had joined, including some considered by the FBI to be communist front groups.

Despite all this, Conant and Bush began pushing the War Department to approve clearances for Oppenheimer and other scientists with left-wing backgrounds. In September, they took him with them to Bohemian Grove. In this beautiful setting, amid giant redwood trees, Oppenheimer attended his first meeting of the highly secret S-1 Committee. In early October, Bush told Secretary of War Stimson’s executive assistant, Harvey Bundy, that even though Oppenheimer was “decidedly left-wing politically,” he had “contributed substantially” to the project and ought to be cleared for further work.

By then, Bush and Conant had taken steps to bring the military into the project. Bush took his case to Gen. Brehon B. Somervell, the senior officer in charge of Army logistics. Somervell, already familiar with the S-1 project, informed Bush that he already had a man picked to supervise S-1 and lend it new urgency. On September 17, 1942, Somervell met with a forty-six-year-old career Army officer, Col. Leslie R. Groves, in the corridor outside a congressional hearing room. Groves had been the Army Corps of Engineers’ key man on the construction of the newly completed Pentagon. Now he wanted an overseas combat assignment. But Somervell told him to forget it: He was staying in Washington.

“I don’t want to stay in Washington,” Groves said evenly.

“If you do the job right,” Somervell replied, “it will win the war.”

“Oh, that thing,” said Groves, who was familiar with S-1. He was not impressed. He was already dispensing far more money on Army construction projects than S-1’s expected $100 million budget. But Somervell had made up his mind and Groves had to accept his fate, which included a promotion to the rank of general.

Leslie Groves was used to getting others to do his bidding, a talent he shared with Oppenheimer. Otherwise, the two men were opposites. Nearly six feet tall and weighing over 250 pounds, Groves had muscled his way through life. Gruff and plainspoken, he had no time for the subtleties of diplomacy. “Oh yes,” Oppenheimer once remarked, “Groves is a bastard, but he’s a straightforward one!” By temperament and training, he was an authoritarian. Politically, he was a conservative who barely concealed his contempt for the New Deal.

The son of a Presbyterian army chaplain, Groves had studied engineering at the University of Washington in Seattle and later at the Massachusetts Institute of Technology. He graduated fourth in his class at West Point. Men serving under him grudgingly admired his ability to get things done. “General Groves is the biggest S.O.B. I have ever worked for,” wrote Col. Kenneth D. Nichols, his aide throughout the war. “He is most demanding. He is most critical. He is always a driver, never a praiser. He is abrasive and sarcastic. He disregards all normal organizational channels. He is extremely intelligent. He has the guts to make timely, difficult decisions. He is the most egotistical man I know. . . . I hated his guts and so did everybody else, but we had our form of understanding.”

On September 18, 1942, Groves formally took charge of the bomb project—officially designated the Manhattan Engineer District, but most often referred to as the Manhattan Project. That very day, he arranged to buy 1,200 tons of high-grade uranium ore. The next day, he ordered the acquisition of a site in Oak Ridge, Tennessee, where the uranium could be processed. Later that month, he began a tour across the country of all the laboratories engaged in experimental work on uranium isotope separation. On October 8, 1942, he met Oppenheimer at a Berkeley luncheon hosted by the president of the university. Soon afterwards, Robert Serber saw Groves walk into Oppenheimer’s office, accompanied by Colonel Nichols. Groves took off his Army jacket and handed it to Nichols, saying, “Take this and find a dry cleaner and get it cleaned.” Serber was astounded by this treatment of a colonel as a mere errand boy: “That was Groves’ way.”

Oppenheimer understood that Groves guarded the entrance to the Manhattan Project, and he therefore turned on all his charm and brilliance. It was an irresistible performance, yet Groves was most struck by Oppie’s “overweening ambition,” a quality he thought would make him a reliable and perhaps even pliable partner. He was also intrigued by Robert’s suggestion that the new lab should be located in some isolated rural site rather than in a large city—a notion that fit nicely with Groves’ concerns for security. But more than anything else, he just liked the man. “He’s a genius,” Groves later told a reporter. “A real genius. While Lawrence is very bright, he’s not a genius, just a good hard worker. Why, Oppenheimer knows about everything. He can talk to you about anything you bring up. Well, not exactly. I guess there are a few things he doesn’t know about. He doesn’t know anything about sports.”

Oppenheimer was the first scientist Groves had met on his tour who grasped that building an atomic bomb required finding practical solutions to a variety of cross-disciplinary problems. Oppenheimer pointed out that the various groups working on fast-neutron fission at Princeton, Chicago and Berkeley were sometimes just duplicating each other’s work. These scientists needed to collaborate in a central location. This, too, appealed to the engineer in Groves, who found himself nodding in agreement when Oppenheimer pitched the notion of a central laboratory devoted to this purpose, where, as he later testified, “we could begin to come to grips with chemical, metallurgical, engineering, and ordnance problems that had so far received no consideration.”

A week after their first meeting, Groves had Oppenheimer flown to Chicago, where he could join him on the Twentieth Century Limited, a luxury passenger train bound for New York. They continued their discussions aboard the train. By then, Groves already had Oppenheimer in mind as a candidate for the directorship of the proposed central laboratory. He perceived three drawbacks to Oppenheimer’s selection. First, the physicist lacked a Nobel Prize, and Groves thought that fact might make it difficult for him to direct the activities of so many of his colleagues who had won that prestigious award. Second, he had no administrative experience. And third, “[his political] background included much that was not to our liking by any means.”

“It was not obvious that Oppenheimer would be director,” Hans Bethe noted. “He had, after all, no experience in directing a large group of people.” No one to whom Groves broached the idea showed any enthusiasm for Oppenheimer’s appointment. “I had no support, only opposition,” Groves later wrote, “from those who were the scientific leaders of that era.” For one thing, Oppenheimer was a theorist, and building an atomic bomb at this point required the talents of an experimentalist and engineer. As much as he admired Oppie, Ernest Lawrence, among others, was astonished that Groves had selected him. Another great friend and admirer, I. I. Rabi, simply thought him a most unlikely choice: “He was a very impractical fellow. He walked about with scuffed shoes and a funny hat, and more important, he didn’t know anything about equipment.” One Berkeley scientist remarked, “He couldn’t run a hamburger stand.”