Inside the Centre: The Life of J. Robert Oppenheimer

by Ray Monk

  Oppenheimer’s opposition to Szilard’s views carried great weight at Los Alamos, a fact of which Szilard himself was well aware. ‘Of course,’ he wrote in a letter addressed to some of the scientists at Los Alamos whom he knew and liked best, ‘you will find only a few people on your project who are willing to sign such a petition. I am sure you will find many boys confused as to what kind of thing a moral issue is.’ In fact, the petition did not have even the limited influence that Szilard hoped for it, since it never reached the President. That Szilard’s views were shared by many of the scientists working on the project was, however, put on record when Compton was asked by Colonel Nichols about the views of his colleagues at the Met Lab. An opinion poll was conducted, in which about two-thirds of the scientists at the Met Lab took part. The poll asked the respondents to say which of five statements most accurately represented their view. Nearly half – 46 per cent – chose statement 2, which read: ‘Give a military demonstration in Japan, to be followed by a renewed opportunity for surrender before full use of the weapons is employed.’ A further 26 per cent chose statement 3: ‘Give an experimental demonstration in this country, with representatives of Japan present; followed by a new opportunity for surrender before full use of the weapons is employed.’ Thus, 72 per cent of those polled agreed with Franck and Szilard that the bomb should be demonstrated to the Japanese before being used against their cities. Only 15 per cent chose statement 1: ‘Use the weapons in the manner that is from the military point of view most effective in bringing about prompt Japanese surrender at minimum human cost to our armed forces.’ Nevertheless, by the time this poll was conducted,fn58 this last statement was the one that most accurately represented US government policy.

  According to Richard Rhodes’s excellent book The Making of the Atomic Bomb, Truman made the decision to drop the bomb on Japan on 1 June, the day after the Interim Committee had recommended at its 31 May meeting ‘that the bomb be used against Japan as soon as possible; that it be used on a war plant surrounded by workers’ homes; and that it be used without prior warning’. Henry Stimson, as Secretary for War, was ultimately responsible for that advice, but he remained deeply troubled by the thought of using the bomb to obliterate Japanese cities, while preferring that to the drawn-out bloodshed that would result from an attempted invasion. What Stimson wanted, ideally, was to make it possible for Japan to surrender before it was either invaded or bombed into submission.

  On 2 July, Stimson prepared a memo to Truman entitled ‘Proposed Program for Japan’, in which he reviewed the appalling loss of life that would result from an invasion of Japan and suggested that this prospect might be avoided by ‘giving them a warning of what is to come and a definite opportunity to capitulate’. After all, he argued, ‘Japan is not a nation composed wholly of mad fanatics of an entirely different mentality from ours’ and: ‘We have a national interest in creating, if possible, a condition wherein the Japanese nation may live as a peaceful and useful member of the future Pacific community.’ Because he realised it was an extremely important consideration for the Japanese, Stimson added that in his opinion, when giving the Japanese an opportunity to surrender, ‘we should add that we do not exclude a constitutional monarchy under the present dynasty’, which would, he advised the President, ‘substantially add to the chances of acceptance’. By this time, however, Stimson’s influence on Truman was much less than that of James Byrnes, who was sworn in as Secretary of State on 3 July and was inclined to take a much less conciliatory line on Japan.

  During the first few days of July, preparations were under way for two events that would coincide and would determine the shape of post-war politics: the Trinity test in New Mexico and the Potsdam summit in Germany. In the minds of those shaping the military and foreign policies of the United States, these two events were linked in the sense that, it was hoped, the Trinity test would strengthen Truman’s hand in the Potsdam negotiations.

  The date fixed for the Trinity test was 16 July, which was, not coincidentally, the day that the Potsdam conference began. The dress rehearsal conducted two months earlier – the ‘100-ton test’, as it came to be known (though that figure was an approximation) – had provided an invaluable opportunity to go through the complicated set of procedures that such a test would involve. On a wooden platform some 800 yards away from the proposed ground zero of the Trinity test, a huge pile of TNT was detonated, while the instruments developed by Bainbridge’s team measured, among other things, how far the radioactive particles were dispersed, the optical and nuclear effects of the blast and, most crucially for the coming test, the yield of the blast. This last measurement confirmed the accuracy of their gauges, which successfully showed that the 108 tons of TNT had exploded with the energy of 108 tons of TNT. Now they could be confident that they would indeed learn from the Trinity test itself exactly what the yield of the Fat Man implosion bomb was.

  Preparations for Trinity were, like almost everything associated with the Manhattan Project, conducted on an almost unimaginably vast scale. This was a scientific experiment like no other. Several roads and many houses had to be built specially for it. At the end of 1944, the camp at the Trinity site had housing for 160 military personnel. On 1 June 1945, there were, in addition to the military personnel, 210 scientists and technical aides there. By the middle of July this figure had grown to 250, and on the eve of the test there were 425 people camped there.

  The gadget itself was assembled on Friday 13 July, a date chosen with black humour by Kistiakowsky, in order, he said, to bring luck. The time chosen for the test was 4 a.m. on the morning of 16 July. ‘This hour,’ says Groves, ‘had been fixed with the thought that an explosion at that time would attract the least attention from casual observers in the surrounding area, since everyone would be asleep.’ Groves and Oppenheimer agreed to meet at 1 a.m. that morning. Groves urged Oppenheimer to get some sleep beforehand and ‘set the example by doing so myself’. Oppenheimer, however, slept not a wink.

  At the appointed hour, Oppenheimer and Groves met and went to the control dugout, ‘South 10,000’, an observation site named after its distance in yards (about five and a half miles) from ground zero. From then on, reports Groves:

  Every five or ten minutes, Oppenheimer and I would leave the dugout and go outside and discuss the weather. I was devoting myself during this period to shielding Oppenheimer from the excitement swirling around us, so that he could consider the situation as calmly as possible, for the decisions to be taken had to be governed largely by his appraisal of the technical factors involved.

  Because of bad weather, the test was delayed until 5.30 a.m. With twenty minutes to go, Samuel Allison started the countdown over a loudspeaker. At 5.25 a.m., to indicate that there were just five minutes to go, a rocket was fired into the air; another was fired at 5.29 to say that there was just one minute left. To everybody there, it felt like an awfully long minute. ‘I never realized seconds could be so long,’ James Conant whispered to Groves. Everyone else was silent.

  Then, finally, at precisely 5.29 and 45 seconds, those present witnessed the world’s first atomic explosion. ‘My first impression,’ Groves recalled, ‘was one of tremendous light, and then, as I turned, I saw the now familiar fireball.’ He had planned, after the test, on having discussions with Oppenheimer on some important points regarding the bomb, but:

  These plans proved utterly impracticable, for no one who had witnessed the test was in a frame of mind to discuss anything. The reaction was simply too great. It was not only that we had achieved success with the bomb; but that everyone – scientists, military officers, and engineers – realised that we had been personal participants in, and eyewitnesses to, a major milestone in the world’s history and had a sobering appreciation of what the results of our work would be.

  Oppenheimer’s recollections of Trinity, filmed for a television documentary in 1965, have provided what remains his most famous utterance – indeed, one of the most famous utterances of the twentieth century. ‘We
knew the world would not be the same,’ he said.

  A few people laughed, a few people cried. Most people were silent. I remembered the line from the Hindu scripture, the Bhagavad Gita: Vishnu is trying to persuade the prince that he should do his duty, and to impress him, takes on his multi-armed form and says: ‘Now I am become death, the destroyer of worlds.’ I suppose we all thought that one way or another.

  Because of its use in this context by Oppenheimer, ‘Now I am become death, the destroyer of worlds’ has become one of the best-known lines from the Bhagavad Gita. Those who go looking for them, however, often fail to find them, since in most English translations of the text they do not appear. The Sanskrit word that Oppenheimer translates as ‘death’ is more usually rendered as ‘time’, so that, for example, in the Penguin Classics edition, the line is given as: ‘I am all-powerful Time, which destroys all things.’ In the famous translation by the nineteenth-century poet Edwin Arnold it appears as: ‘Thou seest Me as Time, who kills, Time who brings all to doom, The Slayer Time, Ancient of Days, come hither to consume’, which conveys an image diametrically opposed to that of a sudden release of deadly power. Oppenheimer, however, was following the example of his Sanskrit teacher, Arthur Ryder, whose translation reads: ‘Death am I, and my present task destruction.’

  A vivid description of Oppenheimer at the moment of the explosion has been left by Groves’s assistant, Brigadier General Thomas F. Farrell. ‘Dr Oppenheimer,’ Farrell remembers, ‘on whom had rested a very heavy burden, grew tenser as the last second ticked off. He scarcely breathed.’

  He held on to a post to steady himself. For the last few seconds, he stared directly ahead and then when the announcer shouted ‘Now!’ and there came this tremendous burst of light followed shortly thereafter by the deep growling roar of the explosion, his face relaxed into an expression of tremendous relief.

  It was that sense of relief that was felt most palpably by the majority of the scientists there. ‘Some people claim to have wondered at the time about the future of mankind,’ Norris Bradbury remarked. ‘I didn’t. We were at war and the damned thing worked.’ Similarly, when Frank Oppenheimer, who was with his brother when the bomb went off, was asked about their initial reaction, he recalled: ‘I think we just said “It worked.”’

  The New York Times journalist William L. Laurence, who had been chosen by Groves to describe the event for posterity, remembers the euphoric emotional release brought on by the realisation among the scientists that their huge, complicated – and extremely expensive – task had been completed successfully: ‘A loud cry filled the air. The little groups that hitherto had stood rooted to the earth like desert plants broke into dance.’ Scientists took it in turns to howl jubilantly into the PA system.

  For some, that sense of euphoric relief was short-lived and tempered by exhaustion and anxiety. As Victor Weisskopf put it: ‘Our first feeling was one of elation, then we realized we were tired, and then we were worried.’ When Fermi returned to Los Alamos, his wife Laura remembers: ‘He seemed shrunken and aged, made of old parchment, so entirely dried out and browned was he by the desert sun and exhausted by the ordeal.’ Rabi has recalled that, though initially he was ‘thrilled’, after a few minutes, ‘I had goose flesh all over me when I realized what this meant for the future of humanity.’ When, back at base camp, Rabi caught sight of Oppenheimer returning from the dugout in a jeep he shared with Farrell, he did not see a man contemplating the Hindu scriptures, but a disconcerting triumphalism: ‘I’ll never forget his walk; I’ll never forget the way he stepped out of the car . . . his walk was like High Noon . . . this kind of strut. He had done it.’ Farrell walked over to Groves and said: ‘The war is over.’ ‘Yes,’ replied Groves, ‘after we drop two bombs on Japan.’

  The power of the bomb was estimated to be around 20,000 tons of TNT, which was at the high end of the various predictions made by the Los Alamos scientists. (The scientists had a betting pool to see who could come closest to guessing the exact yield of the bomb; the prize went to Rabi, who had guessed 18,000 tons.) The light from the blast could be seen more than 100 miles away and the heat generated by it could be felt twenty miles away. The US army did everything they could to keep it out of the newspapers, but there was no hope of keeping something of that magnitude a secret. ‘My God,’ one security official remarked, ‘you might as well try to hide the Mississippi River.’ Instead, they issued a press release claiming that the blast was due to the accidental explosion of a ‘remotely located ammunition magazine’.

  Just a few hours after the blast, at 8 a.m., Groves called George Harrison in Washington, who in turn sent a coded cable to Stimson in Potsdam:

  Operated on this morning. Diagnosis not yet complete but results seem satisfactory and already exceed expectations. Local press release necessary as interest extends great distance. Dr Groves pleased. He returns tomorrow. I will keep you posted.

  The following day, Harrison sent another message, using a more elaborate series of coded remarks to provide some details:

  Doctor Groves has just returned most enthusiastic and confident that the little boy is as husky as his big brother. The light in his eyes discernible from here to Highold and I could hear his screams from here to my farm.

  Decoded, this meant: 1. that the uranium ‘Little Boy’ device was likely to be as powerful as the plutonium ‘Fat Man’ bomb tested at Trinity; 2. that the light from the bomb could be seen 200 miles away (200 miles being the distance from Washington to Highold on Long Islandfn59); and 3. that the sound of the explosion travelled about forty miles (the distance from Washington to Stimson’s farm in Upperville, Virginia).

  Stimson immediately passed this information on to Truman, who was, Stimson later recalled, ‘tremendously pepped up by it’. A few days later, Stimson received a long memo from Groves, written together with Farrell, which combined statistical details of the test with personal impressions of what it was like to be there. ‘For the first time in history,’ Groves wrote, ‘there was a nuclear explosion. And what an explosion!’

  For a brief period there was a lighting effect within a radius of 20 miles equal to several suns in midday; a huge ball of fire was formed which lasted for several seconds. This ball mushroomed and rose to a height of over ten thousand feet before it dimmed.

  The mushroom cloud, Groves wrote, ‘deposited its dust and radioactive materials over a wide area’. Following and monitoring the cloud were several doctors and scientists, who reported finding some radioactive material as much as 120 miles away, but at no place, Groves told Stimson, was the level of radioactivity high enough to necessitate evacuation.

  With his memo, Groves enclosed a number of other descriptions of the test, including the one by Farrell quoted earlier, which concluded on an apocalyptic note. The ‘awesome roar’ of the blast, Farrell wrote, ‘warned of doomsday and made us feel that we puny things were blasphemous to dare tamper with the forces heretofore reserved to the Almighty’. ‘The feeling of the entire assembly,’ Groves added, ‘was similar to that described by General Farrell, with even the uninitiated feeling profound awe.’ An even stronger feeling, he went on, was that the faith of those responsible for this ‘Herculean project’ had been justified:

  I personally thought of Blondin crossing Niagara Falls on his tight rope, only to me this tight rope had lasted for three years and of my repeated confident-appearing assurances that such a thing was possible and that we would do it.

  Groves’s memo reached Potsdam on 21 July. By this time Churchill had already been told about Trinity, but Truman and his advisors were still unsure about how to play it with regard to the Russians. In a diary entry of 19 July, Stimson, reflecting on the repressiveness of Stalin’s regime and the contrast with ‘a nation whose system rests upon free speech and all the elements of freedom, as does ours’, recorded that he was ‘beginning to feel that our committee which met in Washington on this subject and was so set upon opening communications with the Russians on the subject may have been
thinking in a vacuum’. When, two days later, Groves’s memo arrived, Stimson read it out in its entirety to Truman and Byrnes: ‘They were immensely pleased. Truman said it gave him an entirely new feeling of confidence. The memo was then shown to Churchill. The four of them, Stimson recorded in his diary, were ‘unanimous in thinking that it was advisable to tell the Russians at least that we were working on that subject, and intended to use it if and when it was successfully finished’.

  * * *

  fn52 Thomas Powers (see Heisenberg’s War) believes that this drawing was given to Bohr by Heisenberg, but this was emphatically denied by Bohr’s son, which is why Bernstein developed the account that I have followed, which traces the origin of the drawing to Jensen’s visit to Bohr in 1943.

  fn53 The reason the word used in this context is ‘hydrodynamics’ rather than simply ‘dynamics’ is that, under the enormous pressure of implosion, the material used – uranium or plutonium – starts acting like a liquid rather than a solid.

  fn54 This was a more gradual process than Teller implies. The shift of focus from gun assembly to implosion, as I have tried to describe, was motivated by many different considerations and received many different impetuses, the visit to Los Alamos by John von Neumann being but one of them. The visit of Peierls was another. The really crucial development, however – the one that made it absolutely imperative to solve the problems of implosion – was the discovery in the spring of 1944 that it was impossible to build a gun-assembly bomb using reactor-generated plutonium.