In December 1945 a group of physical and social scientists at the University of Chicago published the first edition of the Bulletin of the Atomic Scientists of Chicago, though the city name was soon dropped from the title. The readership of the Bulletin remained small, but the journal gained public attention in June 1947, when editors placed on its cover the Doomsday Clock, whose minute hand indicated the level of crisis then facing the world. Hands at midnight meant nuclear war; in mid-1947 the editors showed the time as seven minutes to midnight. Following Truman’s announcement of the Soviet atomic-bomb test, the large hand moved forward four minutes. The changed situation was reflected as well in the reaction in the scientific community. I. I. Rabi thought the Russian shot ‘brought the prospect of war much closer’. William Golden, an aide to Lewis Strauss, heard the news in Italy. He stayed up all night writing a letter to Strauss, urging the development of the next generation of nuclear ‘superweapons’. Edward Teller called Oppenheimer on the phone. ‘What should we do now?’ he wailed. ‘Keep your shirt on,’ came the sharp reply. But for most Americans, it was no time for patience.40
The ‘superweapons’ of which Golden wrote had for years been a gleam in Teller’s eye. At Los Alamos, Teller had run afoul of fellow scientists by insisting that work be done on the creation of an awesomely powerful ‘Super’ bomb, in which a fission bomb would serve as a mere trigger for a far greater explosion. It was Enrico Fermi who imagined such a weapon in the fall of 1941. What if, Fermi asked Teller, a fission bomb was used to set off a larger device that would cause a thermonuclear reaction, similar in nature to the energy produced by the sun? Experiments existed to suggest that the intense heat generated by the fissioning might cause the fusion of two chemically light nucleii—in this case of deuterium, an isotope of hydrogen with a neutron added to its proton
nucleus—into a nucleus of helium, which had two protons and one neutron. The offspring of this union would be an incredible burst of energy, its limit determined only by the amount of liquid deuterium fired by the fission bomb. In theory, Fermi calculated, 12 kilograms of deuterium would produce a blast equivalent to a million tons of TNT. A cubic meter of deuterium ought to make an explosion worth ten million tons.41
Teller’s near-obsessiveness about the Super at Los Alamos had been an annoyance. The focus of the Manhattan Project, thought Oppenheimer, must be a fission weapon, far less complicated than a hydrogen bomb (the Super’s less casual name) and thus more likely of attainment before the end of the war. He placated Teller as best he could, meeting him weekly to discuss whatever was on the Hungarian’s mind and promising him that the Super would have its day, after the group had succeeded in making a fission bomb. Teller took out his frustrations by banging away on his piano. Perhaps because Hiroshima and Nagasaki had changed him, or perhaps because he had never had much faith that a fusion bomb was practical or desirable, after the war Oppenheimer pulled away from his pledge to build the Super. In September 1945, writing for a Scientific Advisory Panel including Fermi, Arthur Compton, and Ernest Lawrence, Oppenheimer urged that the Super be temporarily shelved. Compton added, in a letter to Henry Wallace, that the Panel advised against going forward ‘primarily because we should prefer defeat in war to victory obtained at the expense of the enormous human disaster that would be caused by its determined use’. There was more than a hint here of ethical qualm. As most scientists left the mesa in the fall of 1945, Teller continued to work on the Super there, even writing a top-secret report titled ‘The Super Handbook’. But he felt isolated and dispirited. On 1 February 1946 he and his family headed for Chicago, where Edward had accepted a position at the university.42
The Soviet atomic-bomb test seemed to change the political and scientific climate overnight. Oppenheimer at first remained sanguine, unconvinced of the Super’s practicality. ‘I am not sure the miserable thing will work’, he wrote Conant, ‘nor that it can be gotten to a target except by ox-cart.’ He would later point out that, had the Americans had the Super in August 1945, they could not have used it over Hiroshima: the target was ‘too small’. Conant reinforced Oppenheimer by insisting that the H-bomb would be built only ‘over my dead body’. Hans Bethe agonized but decided against, Compton had enduring moral doubts, and David Lilienthal drew back in horror at the prospect of the Super: ‘Is this all we have to offer?’ he asked in despair. Berkeley’s Luis Alvarez and Ernest Lawrence joined Teller as enthusiasts for the new weapon; Lilienthal found their ‘drooling’ over the Super unseemly. The military leadership, not fully apprised of the Super, did not speak with one voice on the issue, but airforce chief of staff Hoyt Vandenberg told a Congressional committee in mid-October ‘that it was the military point of view that the super-bomb should be pushed to completion as soon as possible, and that the general staff has so recommended’. Brien McMahon, the Democratic senator from Connecticut whose name adorned the Bill that had created the Atomic Energy Commission (AEC) at the end of 1946, and now chair of the Joint Committee on Atomic Energy, was not given to subtlety. Regarding the Soviets, ‘what he says adds up to one thing,’ wrote an observer. ‘Blow them off the face of the earth, quick, before they do the same to us—and we haven’t much time.’43
The AEC had a General Advisory Committee made up of scientists and appointed by the president. Oppenheimer was its chair. The GAC met over the weekend of 28 October 1949, amidst the rising volume of alarm over the new strategic situation, to discuss what to do about the Super. Gregg Herken has astutely pieced together an account of the committee’s discussion. The generals in attendance thought the United States needed an H-bomb. Lewis Strauss agreed, while Bethe simply summarized the state of work on the Super and Oppenheimer merely listened. Conant spoke emotionally against the new bomb on moral grounds, and he apparently pulled other committee members with him, notably Rabi and Fermi. On Sunday afternoon Oppenheimer brought the meeting to a close with a report, written by himself and John Manley, who was associate director at Los Alamos. It strongly reflected Conant’s views: ‘We believe a super bomb should never be produced. Mankind would be far better off not to have a demonstration of the feasibility of such a weapon, until the present climate of world opinion changes.’ A majority of committee members signed the report. Rabi and Fermi produced instead a one-page letter, in which they called the Super ‘necessarily an evil thing considered in any light’, though their insistence that the United States not go forward with a program was contingent on other nations also exercising forbearance. Oppie signed the more strongly worded majority report and adjourned the meeting.44
Teller was profoundly discouraged by the GAC recommendation; he told Manley that he now expected to ‘be a Russian prisoner of war in the United States within five years’. Oppie, ‘naively’, thought the H-bomb was scrapped, at least for now. But Brien McMahon was furious. Reading the GAC report at an AEC meeting the night after it had been finalized— Halloween 1949—McMahon declared that its conclusion ‘just makes me sick’ and resolved to pressure the President to reject it and move ahead with the hydrogen bomb. Lobbied in one ear by McMahon, Strauss, and other advocates for the Super, and in the other by Lilienthal and a few other members of the AEC, Truman decided, in mid-November, to appoint a special committee (Committee Z of the National Security Council) to resolve the matter. He chose for its membership Louis Johnson, the Secretary of Defense whom he knew to support the Super, Lilienthal, whom he knew to oppose it, and Acheson, now Secretary of State, whose position was unclear to the President, as it was to Acheson himself. The secretary had far more respect for Lilienthal than for Johnson, and a better working relationship with him. He talked to Vannevar Bush and Oppenheimer. ‘I saw my duty’, he would write in his memoirs, ‘as gathering all the wisdom available and communicating it amid considerable competition.’ That is slightly self-serving. In fact, Acheson believed in the existence of evil, and thought it naive to compromise with it—or, in this case, to hope that forbearance in building an H-bomb would encourage similar forbearance by the Soviets. He would not have said publicly, as Louis Johnson did, that ‘we want a military establishment sufficient to deter [an] aggressor and sufficient to kick the hell out of her if she doesn’t stay deterred’. But neither would he have taken issue with such sentiment.45
Acheson may also have sensed that Truman wanted the Super. What happened, ultimately, was that the Joint Chiefs grew impatient over the GAC’s placidity and the evident divisions on the Z Committee. In mid-January they wrote to Johnson endorsing the Super, calling it ‘foolhardy altruism’ to suppose that the Soviets would fail to build a hydrogen bomb if the Americans renounced theirs. Johnson forwarded this memo to the President without showing it to the Committee. ‘And that’, writes Richard Rhodes, ‘was that.’ Truman read the JCS memo and told Sidney Souers, director of the NSC, that the Chiefs’ proposal ‘made a lot of sense and that he was inclined to think that was what we should do’. The Z Committee met Truman on the last day of January 1950 and recommended that the United States try to establish the ‘feasibility’ of the Super. Lilienthal took the floor to dissent; Truman cut him off after a few minutes: ‘What the hell are we waiting for? Let’s get on with it.’ It was, Lilienthal remarked ruefully, like saying ‘ “No” to a steamroller’. Later that day Truman announced that the AEC was ‘to continue its work on all forms of atomic weapons, including the so-called hydrogen or superbomb’. The President’s phrasing elided any differences between fission and thermonuclear weapons—both types coexisted under the rubric ‘all forms’—in much the same way that American strategists had allowed themselves to imagine that using atomic bombs on Japanese cities was no different from using firebombs, which practice seemed to have been accepted by all the belligerents. Four days after making his decision, Truman told an aide that ‘there was actually no decision to be made on the H-bomb... We had to do it—make the [H-]bomb—though no one wants to use it. But,’ he said, ‘we have got to have it if only for bargaining purposes with the Russians.’46
Once more, the lights came on at Los Alamos, and another massive effort of physics and engineering began. Teller would have his day, at last. He had difficulty getting other scientists to rejoin him in the desert: many were busy elsewhere, while others had moral reasons to avoid building the Super. Teller faced serious design problems. Another scientist had helpfully suggested using not deuterium but tritium to create a thermonuclear reaction; tritium is radioactive hydrogen 3 (that is, with one proton and two neutrons in its nucleus), and it requires a much lower ignition temperature than deuterium. But tritium was rare, and for the effort needed to make enough for an H-bomb one could manufacture enough plutonium for twenty fission weapons. When analysts drew plans for Teller’s Super, the result more closely resembled a house than a bomb: 30 feet long, 162 feet wide, with an imbedded fission core weighing 30,000 pounds and craving much more tritium than Teller had earlier estimated. No existing plane could carry it; it might have to be delivered to its target aboard a warship, presumably unmanned. If a way could be found to use the weapon, especially by dropping it, somehow, from the sky, it was likely to destroy everything within a 1,000-square-mile radius ‘by shock’, and inflict burns at an astonishing distance of 100 miles from ground zero. The morality of such a bomb remained, for obvious reasons, an issue. So did its utility.47
By 1949 the Russians had been working seriously to make a hydrogen bomb for over three years. The Russian decision may have been prompted by material on American thinking about the Super provided by Klaus Fuchs. The German-born spy had in April 1946 attended a conference on the Super at Los Alamos, and Soviet scientists, including Yakov Zeldovich, who had explored chain reactions with Yuli Khariton, read Fuchs’s report ofthis meeting with care. But the Soviets had already begun to speculate on how fusion might be generated. Given the rudimentary state of American thinking about the Super, Fuchs could not have managed more than to signal to his employers that there was American interest in the subject; to have pursued to any length American theorizing at that stage would have left Russian physicists on the wrong foot altogether. Fuchs himself doubted that he gave the Russians much help with the project—a self-exculpatory judgment, but accurate. The Soviets were already managing fine on their own. ‘By the summer of 1948’, according to Holloway, Zeldovich and others ‘had done calculations for a specific design’ for a hydrogen bomb.48
Kurchatov now asked Igor Tamm, a theoretical physicist at Moscow University’s Physics Institute (FIAN), to check Zeldovich’s math and oversee the project. Tamm, in turn, tapped several of FIAN’s young physicists to help with the work. One of them was Andrei Sakharov, the 27-year-old son of a physics teacher. The joke was that Tamm picked Sakharov because he pitied his young colleague’s housing situation, and knew that elevating Sakharov to the thermonuclear team would bring quick improvement. Tamm knew better: Sakharov was already well known and deeply respected by Soviet physicists. ‘He distinguished himself’, wrote a colleague, ‘through the clarity and correctness of his thought, and the conciseness of expression of his ideals.’ Sakharov joined the quest to develop an H-bomb. Partly, he felt, there was no choice: if he demurred he might be marginalized, arrested, or worse. He also admitted that he was drawn to the beauty of the physics involved. For Sakharov, as for Fermi and even Oppenheimer, the intellectual excitement of fashioning bombs, coupled with an attraction to the work that was aesthetic and even sensual, was irresistible. And this principled man, like many other men, was strongly affected by his direct experience of total war and Cold War. ‘I understood, of course, the terrifying, inhuman nature of the weapons we were building,’ wrote Sakharov. ‘But the recent war had also been an exercise in barbarity; and although I hadn’t fought in that conflict, I regarded myself as a soldier in this new scientific war.’ He would later say that the rough balance of terror achieved by the Soviet triumph in both fission and fusion weapons forged a deterrent to all-out war, though he confessed that he may not have imagined such a thing when he accepted Tamm’s invitation.49
Sakharov devised in his head a new design proposal for a hydrogen bomb. In his memoirs, he calls this the ‘First Idea’, but it became known to his project colleagues as a sloika, roughly ‘Layer Cake’. It was so named because it layered fission and fusion, heavy and light elements, and encased them in a high-explosive frosting. The explosive would cause the cake to implode, setting off an explosion of the fission trigger at its center and in this way initiating, in theory, fusion in the light element layers. In early 1949 Sakharov and his promising design were bundled off to Sarov and Yuli Khariton, over Tamm’s fruitless objections: ‘Things seem to have taken a serious turn,’ observed Tamm. Meanwhile, if Stalin, through his representative Beria, was initially disinclined to pursue another expensive and powerful weapon, Truman’s announcement on 31 January 1950 that the AEC was to ‘continue work’ on a hydrogen bomb turned the leadership around. Almost immediately Beria demanded from Kurchatov a progress report on H-bomb research, and within the month Stalin had ordered that such a bomb be built. ‘In other words,’ writes Gerard DeGroot, ‘the Americans decided to build the Super because they thought Soviets were doing so. And the Soviets did so because they were certain the Americans were building one.’ Indeed, these mutual perceptions were basically correct.50
Sensing himself vindicated by Truman’s decision, Teller pressed forward with his work on the Super. He continued to be frustrated, however, by the reluctance of some prominent scientists to embrace the project, and especially by technical problems with his weapon designs. Teller’s penchant for losing his temper made him a poor administrator, and he was frequently unwilling to take advice from others. His suggested designs for the Super had flaws, and the project seemed in jeopardy at the end of 1950. The mathematician Stanislaw Ulam bailed Teller out early in 1951. Ulam’s wife found him gazing out the window one afternoon ‘with a very strange expression on his face’. When she asked what he was thinking, he replied: ‘I found a way to make it work.’ His idea was to create compression at the enormous heart of the Super, thereby pushing nuclei closer to each other and causing a faster burning of fuel and a greater production of heat. The fission explosion of the initiating device would release X-rays that would in turn cause compression of the thermonuclear material (this was Teller’s contribution). Substituting radiation for blast to implode the thermonuclear fuel, now separated from the fission bomb initiator, would provide the speed necessary to ensure that heat was produced rather than lost. ‘This is how you make a hydrogen bomb,’ said Teller proudly soon after his meeting of minds with Ulam, sketching on the blackboard the new, ‘two-stage’ implosion sequence. At that moment, recalled physicist Herbert York, ‘I realized: That was it.’ Even Oppenheimer, so wary of bigger bombs, so skeptical of the feasibility of building the Super, would admit: ‘When I saw how to do it, it was clear to me that one had at least to make the thing.. .The program in 1951 was technically so sweet that you could not argue about that.’ Development now moved forward. The Americans built a hydrogen bomb called ‘Mike’ (or ‘The Sausage’, after its shape) that weighed 60 metric tons. The test shot took place on 1 November 1952 at the south Pacific coral atoll of Eniewetok, liberated from the Japanese in early 1944. The blast produced a fireball 3 miles wide— ‘You would swear that the whole world was on fire,’ wrote a sailor who witnessed it—a mushroom cloud that blotted the sky, and a sea-water-filled crater 200 feet deep and over a mile across where the island of Elugelab had been. Mike was 1,000 times more powerful than Little Boy had been.51
Beria panicked and demanded that Soviet scientists increase their pace; they now worked, according to Kurchatov’s secretary, ‘as if American bombs would start raining down on them in a month or two’. The Soviets had technical problems of their own to solve; Kurchatov and Beria pushed them, the latter not gently. The Layer Cake design proved sound, and deuterium and tritium were gradually produced in sufficient quantities to yield a thermonuclear reaction. Their goal was to make a horrible but deliverable H-bomb, unlike the unwieldy Mike a weapon that could conceivably be used against an enemy. Stalin’s death in early March 1953 and Beria’s arrest on 26 June—the scientists at Sarov learned about Beria when one morning the signs denoting ‘Beria Street’ had been taken down—did not slow the process. There was an eleventh-hour glitch when Kurchatov realized that the Semipalatinsk test site, which was to be used again, was surrounded by inhabitants whose homes might be reached by fallout from the H-bomb’s blast. An evacuation plan was hastily put into effect, and thousands of people were sent away, without explanation, some as late as the eve of the test shot. At dawn on 12 August 1953 Kurchatov started the countdown. The blast nearly knocked the scientists off their feet, exceeding their fondest expectations for power and effect. Awesome as they had been, ‘the effects of the first atomic bomb had not inspired such flesh-creeping terror’, wrote one scientist afterward. Oppenheimer had rescued a turtle after the Trinity test eight years earlier. At Semipalatinsk, birds that had taken flight with the bomb’s flash twitched on the ground, ‘their wings scorched and their eyes burned out’.52