Hard work as it was, it was also thrilling. To be among the greatest floating seminar of physicists ever assembled, confronting some of the most fundamental problems of the universe and wedding the solutions to these problems to a device that might end the war, created a magisterial, almost holy feeling. ‘It was the most exciting part of my career,’ recalled Hans Bethe some years later. ‘It was our whole life to make this test work.’ The scientists imagined themselves as Prometheus, stealing fire, or the openers of Pandora’s box, or, in Oppenheimer’s case, the Hindu god Brahma in the epic Mahabharata: ‘I am become Death|The shatterer of worlds.’ They worked, wrote Robert Wilson, with ‘missionary zeal’. As they raced to build a weapon that would bring victory over Fascism, their language reflected their feelings of rectitude about the enterprise and their role in it: they were serving freedom by unlocking the atom’s secrets, ‘liberating’ the energy of the nucleus, or ‘releasing the forces of nature’—there could hardly be anything more natural or noble than that. And it was, after all, ‘superb physics’, as Enrico Fermi liked to say to silence doubters, with an aesthetic beauty, or a ‘technical sweetness’, in Oppie’s phrase. The enchantment with science and technique may also have allowed the physicists to distance themselves from the obvious implications of their work. ‘I don’t believe’, wrote the perceptive Laura Fermi, ‘they had visualized a destruction whose equivalent in tons of TNT they had calculated with utmost accuracy.’
In fact, before they tested the bomb, the men who built it were not entirely sure how powerful it would be. At one point during the summer of 1942 Edward Teller estimated that a bomb might ignite the atmosphere’s nitrogen and thus destroy the world. Oppenheimer, briefly rattled, had rushed off to consult Compton, and the men agreed that, if Teller’s calculus held, the project must end. Hans Bethe ran the numbers again and found the chances of apocalypse to be a mere three in a million. The experiments had resumed. Prior to the test explosion at Alamogordo on 16 July 1945, the scientists famously organized a betting pool, in which each participant was to guess how much blast the shot would generate. The most powerful high-explosive bomb then in use was the British ‘Blockbuster’, which packed the equivalent of 4.6 metric tons of TNT, with a metric ton being about 10 percent heavier than a conventional ton. The pessimist in the pool was Oppenheimer, who guessed 300 tons, while Teller, who had earlier predicted the destruction of the atmosphere, picked highest at 45,000. I. I. Rabi entered the game late, and with few options left took 18,000. Rabi won the pool bet when the Trinity test gadget produced 18.6 kilotons of blast.50
The test atomic bomb would thus deliver an explosion orders of magnitude larger than any weapon previously used. Still, the blast effect of the bomb was measurable on the same scale that was used for what would soon be called, misleadingly, conventional (that is, non-nuclear) weapons. Those who dropped the first two atomic bombs anticipated that the bombs’ explosive effects would be profound yet recognizable. Those whose cities were struck by the bombs, to some extent anyway, would also recognize the explosive effects of the bomb blasts and the fires that followed them: while Hiroshima and Nagasaki were largely undamaged by bombs before August 1945, they were not entirely so, and information about other bombed Japanese cities was sufficient to bring the residents of the two fated places to a fearful understanding of what might be coming. There is no suggestion here that humans can prepare themselves psychologically for the shock of being bombed. There is also no comfort to be sought in the vague familiarity that one has with bombing on a second or subsequent— or second-hand—encounter with it. But there was, in Japan in 1945, a vague familiarity with bombing: we, or someone like ourselves, have been through this before. Indeed, millions had suffered blast and fire from bombing raids across the globe—in Shanghai and Pearl Harbor, in Warsaw and Rotterdam, London and Coventry, Hamburg and Dresden, and in Tokyo in March 1945, when in one night American bombs took some
90,000 lives. But no one had been through an atomic bombing before Hiroshima in August. No one had suffered such an intense blast and searing fire resulting from a single bomb. And, above all, no one had experienced the effects of indiscriminate radioactivity, which spewed from the core of the Little Boy uranium bomb and fell to earth that day. Hiroshimans would call the hidden killer ‘poison’, and the word was appropriate, given how excess radiation acted upon the human body. Radioactivity was insidious in the way that gas had been during the First World War. It was mute and invisible. It seemed even less discriminate than fire. It killed from the inside out, violating the body more outrageously than any other hideous result of bombing.
To what extent did the scientists who conceived and built the bomb and the civilian and military officials who authorized its use know that radiation from the weapon would kill human beings? They knew some things. The Frisch-Peierls Memorandum of 1940 had warned that a significant portion of ‘the energy liberated in the explosion’ would be in radioactive form, and that radiation might cling to the debris created by the blast and thus ‘be fatal to living beings even a long time after the explosion’. The MAUD Committee thereafter discussed radioactivity in some detail. Anyone exposed directly to the bomb’s fissions would die of blood damage. ‘The effects of radioactive products would be considerable,’ Margaret Gowing summarizes the Committee’s finding, and ‘they might or might not be of secondary importance’. The committee urged that the possible impact of the bomb’s radioactivity be thoroughly studied before the weapon was used. The committee’s interest seems to have been technical, not moral. And the MAUD report itself, which would transform the American weapon project, made scarce mention of the radioactivity issue. ‘Perhaps ...we should have considered whether radioactivity was a poison outlawed in spirit by the Geneva Convention,’ one of the MAUD scientists later reflected. ‘But we didn’t.’ Neither did the Americans, at least to any great extent. Compton was concerned enough to implement safety measures at the Met Lab by the middle of 1942, calling in medical experts to check employees’ levels of radiation exposure and issuing radiation-sensitive badges to those who worked in the most vulnerable areas. One of Groves’s nightmares was runaway radioactivity after the Trinity test in July 1945; he prepared evacuation plans for the surrounding ranches and communities just in case.
But, like the MAUD Committee members, scientists working on the Manhattan Project never dwelled on the bomb’s radioactivity, and tended to avoid conjecture that they were producing a dirty weapon. This was partly because they did not believe, or would not let themselves believe, that radioactivity would cause damage beyond the enormous blast area of the bomb. Briefing the Los Alamos scientists, Robert Serber estimated that radiation would kill everyone within 1,000 yards of the blast center— but that it wouldn’t matter because the blast itself would kill everyone within 2,000 yards. Norman Ramsey, the Columbia physicist who served as science adviser to the Air Force on Tinian Island, whence the atomic bombers took off for both their missions, affirmed that ‘the people who made the decision to drop the bomb made it on the assumption that all casualties would be standard explosions casualties... Any person with radiation damage would have been killed with a brick first.’ Oppenheimer himself told the membership of the Interim Committee, formed to advise President Truman on how (not whether) to use the atomic bomb, that the ‘neutron effect of the explosion would be dangerous to life for a radius of at least two-thirds of a mile’—an assertion more open-ended than those made earlier by Serber and later by Ramsey, but one that nevertheless implied that radiation damage would be circumscribed by the scope of the blast. Groves claimed, in his postwar memoir, that he ‘had always insisted that casualties resulting from direct radiation and fallout be held to a minimum’, and that he had decided on an airburst, above the target cities, for that reason; the radioactivity from the bomb would disperse in the air, rather than spreading over the ground or pushing into the earth, like H. G. Wells’s Carolinum, and thus contaminating much of the surrounding area.
Groves, then, was well aware of the potential impact of radioactivity, and the Interim Committee, whose members included not only Secretary of War Stimson but Bush, Conant, near-future Secretary of State James F. Byrnes, and Army Chief of Staff George C. Marshall, heard Oppenheimer’s judgment about the ‘neutron effect’. Stimson briefed Truman on committee deliberations. But it is not clear how much Truman, or for that matter his predecessor, knew about the potential for human damage by radioactivity from the bomb. In his 1961 memoir, Clement Attlee, who became British Prime Minister in late July 1945, claimed that neither he nor Churchill nor Truman knew anything about ‘the genetic effects of an atomic explosion’ or about ‘fall-out and the rest of what emerged after Hiroshima’. Attlee’s view is not authoritative, since he hardly knew about the bomb until he became Prime Minister, and it is telling that he conflates radioactivity’s ‘genetic effects’ with ‘fall-out and the rest’. These are not the same thing. There were, in fact, several ways in which bomb-borne radioactivity could injure or kill human beings. First, radiation could affect those who were not killed by blast or fire; Serber and the others were wrong to think that the blast would cover more ground than the radioactivity. This was ‘direct radiation’. It was possible, second, that radioactivity could remain in the bombed area, potent enough to sicken those who came into it hoping to help or in search of loved ones in the days after the bomb had been dropped; this was ‘indirect radiation’. Finally, either those immediately exposed or those affected later might, while remaining alive, carry cellular radiation damage to children as yet unborn or conceived.
Gowing finds little evidence that scientists anticipated the genetic effects of radiation on a bombed population. She notes that experiments had shown, in 1928, that radiation distorted the genes of plants and insects, but the studies apparently stopped there. With one exception: during the war a British doctor raised the possibility that human mutations would occur should the Germans attack Britain with ‘radioactive fission products’ in some form. It would not have been a great intellectual leap to the conclusion that an atomic bomb might produce the same effects. Evidently, no one made the leap. The first volume of the official account of the atomic bomb, written on behalf of the US Atomic Energy Commission and 655 pages long, contains but a single paragraph on radioactivity, and it concerns Compton’s worries about exposing Met Lab workers.
Were the scientists and statesmen ignorant about radioactivity? Probably so. To what extent was their ignorance willful, predicated, that is, on a desire not to know about the harm that radioactivity could do? That is a harder question to answer. To read about the men who built the bomb is to feel some sympathy for them. They thought carefully about their place in the world and were not slaves to an arbitrary authority. They read the Bible (Compton), Shakespeare (Edward Condon), and the Bhagavad Gita (Oppenheimer, in Sanskrit). They hiked, fished, played music, drank, punned, and played jokes on each other. They loved their wives and children.
They were enraptured by their technically sweet and Promethean mission to build the bomb. And they hated Nazi Germany. The moral implications of what they were doing, especially with regard to the insidious killing power of radioactivity, paled unto disappearance when they contemplated the evil of Nazism. (Japan, as we will see, was for some of them another story.) They willed away their scruples because they came to believe that anything that would destroy Hitler’s Germany was morally admissible. The world had rushed to condemn the use of poison gas after the First World War, and in the early 1940s most continued to regard it as abhorrent, a touchstone of the inconceivable even in a world gone mad with otherwise-total war. In December 1941, just as the United States entered the war, the Princeton physicists Henry DeWolf Smyth and Eugene Wigner issued a report in which they compared radiation to ‘a particularly vicious form of poison gas’. The comparison proved an inspiration to Edward Teller, who, in the spring of 1943, contemplating the worrisome prospect that an atomic bomb might not be possible, suggested instead spraying fission products from Hanford over 100 square miles of German territory, killing its inhabitants and leaving the area a no man’s land. Enrico Fermi also raised with Oppenheimer the possibility of using radioactivity as a weapon against Germany; Oppie replied, casually, that plans existed to poison ‘food sufficient to kill a half million men’, though how he planned to prevent women and children from dying instead he did not say. Ernest Lawrence embraced radiological warfare after 1945 as a way to make war more humane. Bands of radioactivity, he declared, would create a ‘cordon msanitaire’ around the people and territory one wished to protect.
Convinced of their rectitude, absorbed by the project and hope of saving lives by quickly ending the war, willing to work on behalf of the US military and the government if not always on the military’s terms, their minds at least temporarily closed against moral doubt, the scientists and engineers at Los Alamos, supported by thousands of men and women in Chicago, Berkeley, Oak Ridge, and Hanford, built the bomb between 1943 and 1945. It was America’s bomb, of course, authorized by the President and paid for, albeit unwittingly, by American citizens. It was also the world’s bomb. Its fabricators and components, the ideas that enabled it, came from everywhere. Its victims would be mainly Japanese, but also Koreans, Chinese, and even some Americans, luckless enough to be caught in Hiroshima in early August 1945. Like the republic of science that produced it, and like the radiation that issued from it, the bomb’s impact would respect no boundaries.