had known George for many years… I had asked him to be head of the NDRC division on explosives… I had complete faith in his judgment. If he was sold on Arthur Compton's program, who was I to have reservations?
Oliphant convinced Lawrence, Lawrence convinced Compton, Kistiakowsky convinced Conant. Conant says Compton's and Lawrence's attitudes “counted heavily with Bush.” But “more significant” was the MAUD Report, which G. P. Thomson, now British scientific liaison officer in Ottawa, officially transmitted to Conant on October 3. On October 9, without waiting for the third National Academy of Sciences review, Bush carried the report directly to the President.
Franklin Roosevelt, Henry Wallace and the director of the OSRD met that Thursday at the White House. In a memorandum Bush wrote to Conant the same day he makes it clear that the MAUD Report was the basis for the discussion: “I told the conference of the British conclusions.” He told the President and the Vice President that the explosive core of an atomic bomb might weigh twenty-five pounds, that it might explode with a force equivalent to some eighteen hundred tons of TNT, that a vast industrial plant costing many times as much as a major oil refinery would be necessary to separate the U235, that the raw material might come from Canada and the Belgian Congo, that the British estimated the first bombs might be ready by the end of 1943. Bush tried to explain that an atomic bomb plant would produce no more than two or three bombs a month but doubted if the President took in that “relatively low yield.” He emphasized that he was basing his statements “primarily on calculation with some laboratory investigation, but not on a proved case” and therefore could not guarantee success.
Bush was presenting, essentially, British calculations and British conclusions. Such a presentation made it appear that Britain was further advanced in the field than America. The discussion therefore shifted to the question of how the United States was attached or might attach itself to the British program. “I told of complete interchange with Britain on technical matters, and this was endorsed.” Bush explained that the “technical people” in Britain had also formulated policy — had proposed that the government develop the atomic bomb as a weapon of war — and had passed their formulations along directly to the War Cabinet. In the United States, Bush said, an NDRC section and an advisory committee considered technical matters and only he and Conant considered policy.
Policy was the President's prerogative. As soon as Bush exposed it to view Roosevelt seized it. Bush took that decision to be the most important outcome of the meeting and put it emphatically first in his memorandum to Conant. Roosevelt wanted policy consideration restricted to a small group (it came to be called the Top Policy Group). He named its members: Vice President Wallace, Secretary of War Henry L. Stimson, Army Chief of Staff George C. Marshall, Bush and Conant. Every man owed his authority to the President. Roosevelt had instinctively reserved nuclear weapons policy to himself.
Thus at the outset of the U.S. atomic energy program scientists were summarily denied a voice in deciding the political and military uses of the weapons they were proposing to build. Bush accepted the usurpation happily. To him it was simply a matter of who would run the show. It left him on top and inside and he put it to use immediately to shoulder the physics community into line. Within hours, as he wrote Frank Jewett in November, he had “emphasized to Arthur Compton and his people the fact that they are asked to report upon the techniques, and that consideration of general policy has not been turned over to them as a subject.”
Significantly, Bush associated the reservation of policy with relief from criticism: “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… I cannot… bring him into the discussions, as I am not authorized by the President to do so.” He applied just this test — silence on policy — to measure Lawrence's and Compton's loyalty: “I think [Lawrence] now understands this, and I am sure that Arthur Compton does, and I think our difficulties in this regard are over.”
A scientist could choose to help or not to help build nuclear weapons. That was his only choice. The surrender of any further authority in the matter was the price of admission to what would grow to be a separate, secret state with separate sovereignty linked to the public state through the person and by the sole authority of the President.
Patriotism contributed to many decisions, but a deeper motive among the physicists, by the measure of their statements, was fear — fear of German triumph, fear of a thousand-year Reich made invulnerable with atomic bombs. And deeper even than fear was fatalism. The bomb was latent in nature as a genome is latent in flesh. Any nation might learn to command its expression. The race was therefore not merely against Germany. As Roosevelt apparently sensed, the race was against time.
There are indications in Bush's memorandum that Roosevelt was concerned less with a German challenge than with the long-term consequences of acquiring so decisive a new class of destructive instruments. “We discussed at some length after-war control,” Bush wrote Conant, “together with sources of raw material” (sources of raw material were then believed to be few and far between; whoever commanded them might well, it seemed, monopolize the bomb). Roosevelt was thinking beyond developing bombs for the war that the United States had not yet entered. He was thinking about a military development that would change the political organization of the world.
Bush, who was a successful administrator partly because he knew the limits of his charter, then suggested that a “broader program” — industrial production — ought to be handled when the time came by some larger organization than the OSRD. Roosevelt agreed. Summarizing his assignment, Bush told the President he understood he was to expedite in every possible way the necessary research but was “not [to] proceed with any definite steps on this expanded plan until further instructions from him… He indicated that this was correct.” The money, the President told him, “would have to come from a special source available for such an unusual purpose and.. he could arrange this.”
The United States was not yet committed to building an atomic bomb. But it was committed to exploring thoroughly whether or not an atomic bomb could be built. One man, Franklin Roosevelt, decided that commitment — secretly, without consulting Congress or courts. It seemed to be a military decision and he was Commander in Chief.
Bush and Conant proceeded to order up from Arthur Compton a third NAS review. Compton asked Samuel Allison for the name of someone who could help him calculate the critical mass of U235. Allison had been corresponding with Enrico Fermi on the subject of carbon absorption cross sections and recommended him highly. Compton “called on Fermi in his office at Columbia University. Stepping to the blackboard he worked out for me, simply and directly, the equation from which could be calculated the critical size of a chain-reacting sphere. He had at his fingertips the most recent experimental values of the constants. He discussed for me the reliability of the data… Even the most conservative estimate showed that the amount of fissionable metal needed to effect a nuclear explosion could hardly be greater than a hundred pounds.”[5]
Compton moved on to Harold Urey's office to look into isotope separation. Urey was the recognized world leader in the field as a result of his Nobel Prize-winning work with hydrogen isotopes; he had directed isotope separation studies for the Uranium Committee and the Naval Research Laboratory since the beginning. He personally investigated chemical separation of U235 (which turned out to be impossible given the chemical compounds of the day) and separation by centrifuge. Estimating that a centrifuge plant that would produce one kilogram of U235 per day would require 40,000 to 50,000 yard-long centrifuges and would cost about $100 million, he had recently contracted with Westinghouse in the name of the Uranium Committtee for a prototype unit.
Urey was initially skeptical of gaseous barrier diffusion. He and John Dunning were not compatible, perhaps because they were both enthusiasts, and only when centrifuge development was well under way, in late 1940, did Urey turn his attention to the process that Dunning and Eugene Booth were working hard at their own expense to develop. They had chosen gaseous diffusion at dinner one evening in 1940 on their way home from a trip to Schenectady by systematically ruling out other methods as unsuitable for large-scale production, much as Peierls and Simon had done. They were interested in nuclear power, Booth remembers, not bomb-making. “Our reasons for pursuing the isotope separation path toward power production were simple and general. If a chain reaction became possible with normal uranium, a smaller and probably cheaper power plant could be made with enriched uranium.”
Dunning and Urey produced a joint appraisal of the gaseous-diffusion process in November 1940. Dunning's barrier material at the time was fritted glass — partially fused and therefore porous silica, the material from which porcelain is made — which uranium hexafluoride was likely to corrode. They estimated that a gaseous-diffusion plant would involve some five thousand separate barrier tanks — “stages” — but made no attempt to determine cost and power requirements.
