of a uranium gun bomb, which Los Alamos expected would explode with a force equivalent to about 10,000 tons of TNT, now depended only on the separation of sufficient U235. Implosion looked far more questionable; intensive work was just then getting under way following Oppenheimer's August reorganization of the laboratory. Conant estimated the yield of the first implosion design, whether lensed or not, “as an order of magnitude only” at about 1,000 tons TNT equivalent. That was so relatively modest a result that he invited Bush to consider the gun bomb strategic and the implosion bomb tactical.
For the past three years Bush and Conant had concentrated their efforts entirely on these first crude bombs. Now they were interested in improvements. During the summer of 1944, Conant says, on an earlier inspection trip to Los Alamos, he and Bush had found leisure and privacy to discuss “what the policy of the United States should be after the war was over.” As a result they had sent Secretary of War Henry L. Stimson a joint memorandum on September 19 that independently raised some of the issues Niels Bohr had raised with Franklin Roosevelt in August, in particular that “the progress of this art and science is bound to be so rapid in the next five years in some countries that it would be extremely dangerous for this government to assume that by holding secret its present knowledge we should be secure.” They did not see the bomb's complementarity, but did see that whatever control arrangement the United States and Great Britain devised — they favored a treaty — would somehow have to include the Soviet Union; if the Soviets were not informed, as Bush told Conant, the exclusion would lead “to a very undesirable relationship indeed on the subject with Russia.”
Roosevelt had returned from Hyde Park troubled that Felix Frankfurter and Bohr had somehow breached Manhattan Project security, Bush and perhaps Conant had talked to Bohr and the two administrators had submitted to Stimson at his request a more detailed proposal incorporating Bohr's ideas. In doing so they had explicitly recommended that the United States sacrifice some portion of its national sovereignty in exchange for effective international control, understanding as they did so that they would have to answer vigorous opposition:
In order to meet the unique situation created by the development of this new art we would propose that free interchange of all scientific information on this subject be established under the auspices of an international office deriving its power from whatever association of nations is developed at the close of the present war. We would propose further that as soon as practical the technical staff of this office be given free access in all countries not only to the scientific laboratories where such work is contained, but to the military establishments as well. We recognize that there will be great resistance to this measure, but believe the hazards to the future of the world are sufficiently great to warrant this attempt.
But how great in fact were the hazards? That was something else Conant traveled to Los Alamos in October to find out. If the argument for allowing the nation's military establishments to be inspected depended on the dangers of a thermonuclear explosive, it was speculative and therefore weak: the thermonuclear was still only an idea on paper that might not work. How much could fission weapons be improved? How much destruc-tiveness of either kind might a bomber — or, as Bush and Conant briefed Stimson, “a robot plane or guided missile” — eventually visit upon the cities of the world?
What Conant learned first of all was that others had already begun to ask the same questions. The technological imperative, the urge to improvement even if the objects to be improved are weapons of mass destruction, was already operating at Los Alamos. Under intense pressure to produce a first crude weapon in time to affect the outcome of the war, people had found occasion nevertheless to think about building a better bomb. Conant reported to Bush:
By various methods that seem quite possible of development within six months after the first bomb is perfected, it should be possible to increase the efficiency… in which case the same amount of material would yield something like 24,000 Tons TNT equivalent. Further developments along this same line hold a possibility of producing a single bomb with such amounts of materials and such efficiencies as to run this figure up to several hundred thousand Tons TNT equivalent, or even perhaps a million Tons TNT equivalent… All these possibilities reside only in perfecting the efficiency of the use of elements “25” [U235] and “49” [Pu239]. You will thus see that a considerable “super” bomb is in the offing quite apart from the use of other nuclear reactions.
A million tons TNT equivalent was devastation indeed — the world war then raging would consume a total of about three million tons of explosives by its end — but Edward Teller, Conant found, had already dismissed such improvements as picayune:
It seems that the possibility of inciting a thermonuclear reaction involving heavy hydrogen is somewhat less now than appeared at first sight two years ago. I heard an hour's talk on this subject by the leading theoretical man at L.A. The most hopeful procedure is to use tritium (the radioactive isotope of hydrogen made in a pile) as a sort of booster in the reaction, the fission bomb being used as the detonator and the reaction involving the atoms of liquid deuterium being the prime explosive. Such a gadget should produce an explosive equivalent to 100,000,000 Tons of TNT, which in turn should produce Class B damage over an area of 3,000 square miles!
This last real super bomb is probably at least as distant now as was the fission bomb when you and I first heard of the enterprise.
The thermonuclear was something of a Rorschach test. If it could be made to work at all it was, like a fire, potentially unlimited; to build it larger you only piled on more heavy hydrogen. As Los Alamos paid less attention to Teller's Super his projection of its destructive potential grew more-grandiose.
Robert Oppenheimer also commited himself at that time to exploring the thermonuclear — after the war was won — in a letter to Richard Tolman on September 20, 1944. “I should like,” he emphasized, “… to put in writing at an early date the recommendation that the subject of initiating violent thermonuclear reactions be pursued with vigor and diligence, and promptly.” A way station on the road to a full-scale thermonuclear might be a boosted fission bomb with a small charge of heavy hydrogen confined possibly within the core of an implosion device:
In this connection I should like to point out that [fission] gadgets of reasonable efficiency and suitable design can almost certainly induct significant thermonuclear reactions in deuterium even under conditions where these reactions are not self-sustaining… It is not at all clear whether we shall actually make this development during the present project, but it is of great importance that such… gadgets form an experimentally possible transition from a simple gadget to the super and thus open the possibility of a not purely theoretical approach to the latter.
(In fact not deuterium but tritium proved to be the necessary ingredient of a boosted fission bomb, and such weapons were not developed until long after the end of the war.)
Alluding then to the larger consequences that Bohr had revealed, Oppenheimer emphasized once more the urgency he attached to the pursuit of an H-bomb: “In general, not only for the scientific but also for the political evaluation of the possibilities of our project, the critical, prompt, and effective exploration of the extent to which energy can be released by thermonuclear reactions is clearly of profound importance.”
Working against the clock to build weapons that might end a long and bloody war strained life at Los Alamos but also heightened it. “I always pitied our Army doctors for their thankless job,” comments Laura Fermi:
They had prepared for the emergencies of the battlefields, and they were faced instead with a high-strung bunch of men, women, and children. High-strung because altitude affected us, because our men worked long hours under unrelenting pressure; high-strung because we were too many of a kind, too close to one another, too unavoidable even during relaxation hours, and we were all [as Groves had warned his officers not entirely tongue- in-cheek] crackpots; high-strung because we felt powerless under strange circumstances, irked by minor annoyances that we blamed on the Army and that drove us to unreasonable and pointless rebellion.
They made the best of it. Mici Teller waged pointed rebellion saving the backyard trees to preserve a playground for her son. “I told the soldier in his big plow to leave me please the trees here,” one of her friends remembers her recounting, “so Paul could have shade but he said, ‘I got orders to level off everything so we can
