Diana Preston - Before the Fallout

Suspicion about Heisenberg’s visit spread quickly. Lise Meitner was alarmed to learn of it from the young Danish physicist Christian Moller when he visited Stockholm several months later. He reported Heisenberg to be “entirely filled with the wish-dream of a German victory.” Meitner wrote hastily to Max von Laue in Berlin, who, unknown to his colleagues, had been corresponding regularly with her. They took the precaution of numbering their letters so that they would know whether any had been intercepted. Like Fritz Strassmann, risking his life and that of his family to save the Wolffenstein sisters, von Laue stayed true to his principles, visiting the elderly and lonely Jewish former editor of the scientific journal Naturwissenschaften, Arnold Berliner, marooned in his apartment by fears of anti-Semitic violence until his imminent deportation induced him to commit suicide. Meitner warned von Laue, in guarded, elliptical language, to be wary of Heisenberg and von Weizsacker. She conveyed that she had once thought very highly of the two but added grimly, “It was a mistake.”

Von Laue was not particularly surprised by Meitner’s warning, replying to her with remarkable perception, “I have often wondered about the inner attitude of Werner and Carl Friedrich, but I believe I understand their psychology. Many people, especially young ones, cannot reconcile themselves with the great irrationality of the present, and so in their imagination they construct castles in the air. It is an enormous task they have undertaken, to find a good side in things they can do nothing about.” Heisenberg and von Weizsacker were not, he added, alone in this.

FRANKLIN ROOSEVELT’S OFFER to Britain in October 1941 of a partnership received a lukewarm reception. Churchill’s preference, like that of his chiefs of staff and some scientists, including James Chadwick, was that any nuclear bomb should be developed in Britain. Not only did Churchill wish to keep control, but he mistrusted American security. In fact, the desire for secrecy was guiding much British thinking. The research director of Imperial Chemical Industries, Wallace Akers, had recently been appointed to head work on both civil and military uses of nuclear energy. He and officials racked their brains for a name for his new organization that had “a specious air of probability about it” while concealing its true purpose. They came up with the plausible-sounding “Directorate of Tube Alloys.”

Churchill allowed two months to elapse before replying to Roosevelt’s letter. He wrote blandly, “I need not assure you of our readiness to collaborate with the United States Administration in this matter.” He told the president that he had arranged for the U.S. scientific liaison officer in London, Mr. Hovde, to have full discussions with Sir John Anderson, the government minister responsible for the Tube Alloys Project, and Churchill’s adviser the recently ennobled Frederick Lindemann, now Lord Cherwell. When they met in November 1941, Anderson, an able man but so haughty and inflexible in manner that he was nicknamed “God’s butler,” coolly informed Hovde that while the British were anxious to collaborate, they were “disturbed about the possibility of leakage of information to the enemy” through the officially neutral United States. Britain wanted strict assurances that the American project would be run in such a way as to preserve maximum secrecy. Unsurprisingly, given Anderson’s approach, instead of agreeing on a joint project, the meeting ended with a simple agreement to share some information and with condescending British offers to help “improve” the American organization.

As Britain would soon discover, collaboration restricted to an exchange of information would not be enough to keep it in the race. Ironically, the brilliant Maud Report had provided the impetus for an American program that would soon surge ahead with increasingly little need of, or desire for, British assistance. The French scientist Bertrand Goldschmidt, observing from the sidelines, later wrote that “in this ballet of Anglo-American nuclear relations, the Americans Bush and Conant revealed themselves to be by far the best and most perspicacious advisers.” By contrast British officials, in his view “imbued with the antiquated dogma of imperial superiority,” missed the boat.

By late October 1941 the National Academy of Sciences submitted its new report, which, Conant wrote approvingly, “radiated a more martial spirit than the first two.” It concluded that a fission bomb “of superlative destructive power” was possible. Based on calculations by Enrico Fermi at Columbia, it estimated that the amount of U-235 required to achieve this could “hardly be less than 2 kg nor greater than 100 kg.” It predicted a somewhat lower destructive force than had the Maud Committee but that the loss of life from the effects of radioactivity might “be as important as those of the explosion itself.” Furthermore, fission bombs might be achievable “in significant quantity within three or four years” at a cost of between $80 million and $130 million. It defined the priority tasks, in particular assessing the different techniques for separating isotopes of uranium and understanding the engineering requirements of separation plants. Like the Maud Report, it did not mention plutonium. Exactly as German scientists had told the German army, the report warned that in years to come, military superiority would depend on who had nuclear bombs and that “adequate care for our national defense seems to demand urgent development of this program.” On 27 November Bush handed the report to President Roosevelt.

In Russia Hitler’s exhausted troops were making one last attempt to capture Moscow before winter closed in, inevitably prolonging the war in the East. On Friday 5 December 1941, three feet of snow fell. Nevertheless, eighty-eight new Russian divisions attacked on a five-hundred-mile front and broke through for eleven miles in places before the Germans could stabilize their lines. The next day, 6 December, Hitler was forced to accept that Moscow would not fall quickly.

On that same Saturday, Vannevar Bush told members of the Uranium Committee, gathered in Washington, how he had allocated tasks within the expanded program sanctioned by Roosevelt—known as the “S-1 Project.” He appointed three program chiefs, all Nobel Prize winners: Ernest Lawrence was to explore electromagnetic techniques for separating U-235 at Berkeley and to supply the first samples of enriched uranium for experiments; Harold Urey, the discoverer of deuterium, was to develop gaseous diffusion separation methods, as advocated by the Maud Committee, at Columbia University; Arthur Compton, the pioneer of gamma ray research, was responsible for theoretical studies and bomb design at the University of Chicago, where he himself was based, and elsewhere. In addition, the industrialist Eger Murphee, Standard Oil of New Jersey’s research director, was to oversee the development of high-speed centrifuge technology for separating U-235. and to take responsibility for broad engineering issues such as procuring materials and constructing pilot and production plants.

Lawrence had become an increasingly strong proponent of electromagnetic separation as the simplest route for U-235 production. The process used magnetic force in a device called a mass spectrograph to bend beams of charged uranium particles into circular paths. The precise path of each particle was determined by its mass. Therefore, the heavier isotope U-238, with its greater mass, took a different path than the lighter U-235, making it possible to collect the two in separate containers. Lawrence ordered his team to convert Berkeley’s thirty-seven-inch cyclotron into a mass spectrograph. On the very morning that Bush was assigning work to his top scientists, news came that the Berkeley spectrograph had started work. It was producing a microgram of U-235 an hour—not much, but a start.