by Ray Monk
Quite why Oppenheimer wanted to, or at the very least was willing to, blacken Peters’s reputation is unclear. Like many of the things he said to security officers during these years, his remarks about Peters would come back to haunt him and severely damage his own reputation. There are some indications that Oppenheimer came to dislike Peters personally (when Sam Goudsmit once asked him about Peters, Oppenheimer replied: ‘Just look at him. Can’t you see he can’t be trusted?’), which might explain his cavalier attitude towards Peters’s reputation. In the case of David Bohm, though, there is not even that possible explanation.
Just as he had with Peters, Oppenheimer had tried to recruit Bohm for Los Alamos. In March 1943, however, he was told that Bohm had been refused clearance, supposedly on the grounds that he still had relatives in Germany. Oppenheimer was understandably sceptical that those were the real grounds, and, despite his supposed remarks to de Silva about Bohm being potentially dangerous if led the wrong way, he was still, a year later, prepared to consider bringing Bohm to Los Alamos. On 12 March 1944, just two months after his conversation with de Silva, Oppenheimer was in Berkeley on business and, of course, being watched closely by army counter-intelligence agents. What they learned was that Oppenheimer, during this trip, stayed at a hotel with Frank. Agents saw the Oppenheimer brothers leave the hotel and walk up and down the road outside, ‘engaged in earnest conversation with each other’. Then David Bohm appeared, and ‘J.R. Oppenheimer and Bohm engaged in conversation for five minutes but Frank stood about 10 feet away from them and did not participate in the conversation.’
When he returned to Los Alamos, Oppenheimer – presumably realising that his conversation with Bohm had been observed, reported and filed – went to see de Silva to volunteer information about it. According to a memo written by de Silva on 22 March 1944, Oppenheimer told him that:
. . . just as he was preparing to leave his hotel at Berkeley on his return trip, David Joseph Bohm came to see him. Bohm inquired about the possibilities of his being transferred to project Y on a permanent basis, stating that he had a ‘strange feeling of insecurity’ in his present surroundings. Oppenheimer stated he did not commit himself to Bohm but told him that he would let Bohm know if an opportunity were open at this project, and that if Bohm did not hear from Oppenheimer he should assume that such an arrangement was not workable and to forget the matter. Oppenheimer asked the undersigned if he would have objections to Bohm coming to project Y. The undersigned answered yes. Oppenheimer agreed and said the matter was therefore closed.
Bohm, like Weinberg, would spend the rest of the war at Berkeley, with agents monitoring his every movement, listening to his every phone call and making sure he had no access whatsoever to classified information. Oppenheimer, meanwhile, was able to forget, at least for a time, the suspicions levelled against his loyalty to the United States, and get on with the task of designing and building an atomic bomb.
* * *
fn48 Despite being a heavy smoker and working for much of his life with powerfully radioactive materials, Serber lived to an impressive old age, dying in 1997 (some thirty years after Oppenheimer) at the age of eighty-eight.
fn49 This is how it appears in the transcript. Presumably what Oppenheimer actually said was: ‘No, in a word, it was not good practice.’
fn50 In his interview of 2001 Lomanitz said: ‘I remember that it was his [Oppenheimer’s] habit that if one talked about something, “Let’s just walk outside and talk about it out there.” In other words, he assumed that the phones were tapped.’
fn51 The idea that Lansdale would disobey an order given to him by his commanding officer is so unlikely that one is forced to speculate that he informed the FBI of Frank’s name with Groves’s full permission – the pretence that this was against Groves’s wishes allowing him to maintain that he had kept his promise to Oppenheimer, and the fact that Lansdale informed the FBI orally rather than in writing preventing anyone from proving otherwise. That he and Lansdale had connived to deceive Oppenheimer might also, I think, explain Groves’s uncharacteristically foggy recollection of the event.
13
Los Alamos 2: Implosion
A KEY MOMENT in the development of the Allied atomic bomb was the signing by Churchill and Roosevelt on 19 August 1943 of the Quebec Agreement, which, in effect, subsumed the British ‘Tube Alloys’ programme under the Manhattan Project. ‘It is vital to our common safety in the present war,’ the agreement stated, ‘to bring the Tube Alloys project to fruition at the earliest moment’, and ‘this may be more speedily achieved if all available British and American brains and resources are pooled’. One of the terms of this agreement was that: ‘In the field of scientific research and development there shall be full and effective interchange of information and ideas between those in the two countries engaged in the same sections of the field.’ Another was that ‘we will not either of us communicate any information about Tube Alloys to third parties except by mutual consent’. As it turned out, these two terms were not consistent with each other. As the Venona transcripts were later to reveal, so effective was the Soviet penetration of the British atomic-bomb project and so ineffective was British counter-intelligence that it was not possible to share information with the British without at the same time inadvertently communicating it to the Soviet Union.
Since the very beginning of the Tube Alloys project the Soviet Union had gained information on many of its secrets, primarily through the efforts of the Cambridge Five. Those five did not, however, have access to the detailed, technical information that the Soviets would need to build their own bomb. For that, they needed a scientist working on the project, and, from the summer of 1941, they had just such a person: a quiet, unobtrusive German, whom Hans Bethe once described as the only physicist he had ever met who had truly changed the course of history. His name was Klaus Fuchs.
Fuchs was a committed socialist and fervent anti-Nazi who had fled Germany in 1933, at the age of twenty-two. He studied at Bristol under Nevill Mott and at Edinburgh under Max Born, before, in May 1941, being invited by Rudolf Peierls to join the Tube Alloys project. By that time he had become a British citizen. Taking the view for which Oppenheimer had expressed sympathy in his discussions with Pash and Lansdale – namely that the Soviets had a right to know what their allies had discovered about the feasibility of making an atomic bomb – Fuchs considered it his duty to pass on to the Soviet Union any information that might be useful to them.
In August 1941, Fuchs established contact with an NKVD agent and from then on was, to the later dismay and astonishment of Peierls and his wife (with whom Fuchs lived in Birmingham), a regular informant on the progress of the Allied bomb project. That Fuchs was able to act so easily as a Soviet informant is an illustration of the differences between the British and the American attitudes to security, the British being more interested in the fact that Fuchs was an outstanding physicist with something to contribute to the Tube Alloys project than they were in the fact that he was a potential security risk – something they might well have discovered for themselves, had they shown a little more interest. As early as 1934, the German authorities had informed the British that Fuchs was a communist, but this tip-off was dismissed because it came from the Gestapo. In January 1943, the question of Fuchs’s political activities was again raised, this time by British security, but an MI5 officer declared herself unconcerned. Fuchs, she said, ‘bears a good personal reputation and is considered a decent fellow’. Later that year, the same officer observed: ‘As he [Fuchs] has been in his present job for some years without apparently causing any trouble, I think we can safely let him continue in it.’ In November 1943, as a result of the Quebec Agreement, the British scientists working on Tube Alloys were told they were transferring to the United States. Unfortunately for the US project, clearance for these scientists was in the hands of MI5, who, concerning Fuchs, reported: ‘He is rather safer in America. It would not be easy for Fuchs to make contacts with communists there.’ Before he
left the UK, Fuchs was given instructions via the Soviet intelligence service on how to do just that.
The first group of scientists to leave the UK to join the Manhattan Project included James Chadwick and Otto Frisch from Liverpool, William Penney from London, James Tuck from Cambridge and Peierls and Fuchs from Birmingham. While the others went to Los Alamos, Peierls and Fuchs went to New York to work at Columbia on the development of the gaseous-diffusion method of isotope separation. Much of this work was written up by Fuchs himself, who managed to send copies of all his papers to the Soviets. Fuchs’s contact in New York was Harry Gold, a chemist who had been acting as a Soviet courier since 1940. On 5 February 1944, Gold received from Fuchs a detailed report on gaseous diffusion and other aspects of the atomic-bomb project, which he then delivered to Soviet intelligence officers. Throughout his time in New York, which lasted until he was transferred to Los Alamos in August 1944, Fuchs met regularly with Gold, and, after a break of a few months, managed to resume contact with the Soviets while at Los Alamos.
Most of the scientists working on the Manhattan Project were shocked and disapproving when they learned after the war what Fuchs had done. They felt betrayed. On the other hand, the view that the Soviets, as allies, ought to be treated like the British and given access to information about the bomb was fairly widespread. What worried the scientists far more was the thought that the Germans might get the bomb. ‘We were desperately afraid that the Germans would beat us in our objective,’ Rudolf Peierls wrote. ‘Of course, everybody was anxious to know what progress, if any, the Germans were making with atomic energy.’ When Peierls was asked by British intelligence for suggestions on ways of finding out how far the German project had developed, he provided a list of names of people whose movements should, if possible, be watched. At the head of the list, of course, was Heisenberg. In reply, Peierls received a message from British intelligence that said Heisenberg had been in the UK shortly before the war, ‘and we have no record that he ever left the country’. ‘I was shocked by this reaction,’ Peierls writes, ‘and reflected that if this was a fair sample of British intelligence, the outlook seemed grim.’
His faith in the reliability of British security thus diminished, Peierls did a little intelligence-gathering of his own. He looked through recent editions of German academic journals in physics, copies of which were obtained by his university through neutral countries. In particular, he looked at the Physikalische Zeitschrift, which published a list of the lecture courses in physics in all German universities. With a few notable exceptions, such as Heisenberg, Peierls was reassured to find that most German physicists ‘were in their normal places and teaching their normal subjects’. He concluded that, though there ‘did seem to be some atomic research going on, and Heisenberg and a few others were probably connected with it . . . the picture emerged that Germany had no crash programme, no large-scale project that required a major participation by scientists’.
As the Alsos mission was soon to discover, Peierls was quite correct. Others, however, particularly those working for the Manhattan Project, were less sanguine. On 21 August 1943, Bethe and Teller wrote to Oppenheimer, expressing their concern about recent newspaper reports that the Germans might be in possession of a powerful new weapon, which was expected to be ready some time between November 1943 and January 1944. Their guess was that this new weapon was an atomic bomb: ‘It is not necessary to describe the probable consequences which would result if this proves to be the case.’
Until 1944, Allied information about the progress of the Nazi bomb project remained scarce. Outside Germany, one of the few people to have had any kind of contact with Heisenberg since the war started was Niels Bohr. The nature and purpose of that contact, however, have been the subject of controversy ever since an account of it was published in 1956 in the German edition of the book Brighter than a Thousand Suns, by the German journalist and writer Robert Jungk. The basis of that account was a letter written by Heisenberg to Jungk, in which he describes how, in September 1941, he took the opportunity of a visit to Copenhagen to attend a scientific meeting to call upon his old friend Bohr. At the outbreak of war Denmark had been a neutral country, but since April 1940 it had been under German occupation. As Bohr was half-Jewish and openly anti-Nazi, his position in Denmark was perilous, but, because of the semi-autonomy that the Nazis granted Denmark, he was not in any immediate danger.
He was, though – as both he and Heisenberg were fully aware – under close surveillance, and so, Heisenberg told Jungk, when he visited Bohr at his office, the two decided to take a walk through town while they talked. During this walk, Heisenberg claimed, he asked Bohr ‘whether it was right for physicists to devote themselves in wartime to the uranium problem – as there was the possibility that progress in that sphere could lead to grave consequences in the technique of war’. Heisenberg remembers that Bohr reacted to this question with frightened alarm. The last time Bohr had thought deeply about fission – in Princeton in 1939 together with John Wheeler – he had concluded that there was no danger of anyone actually making an atomic bomb because of the difficulties of isotope separation. ‘Do you really think that uranium fission could be utilised for the construction of weapons?’ Heisenberg recalls Bohr asking him, to which Heisenberg replied: ‘I know that this is in principle possible, but it would require a terrific technical effort, which, one can only hope, cannot be realised in this war.’ He went on:
Bohr was shocked by my reply, obviously assuming that I had intended to convey to him that Germany had made great progress in the direction of manufacturing atomic weapons. Although I tried subsequently to correct this false impression, I probably did not succeed in winning Bohr’s complete trust.
When Bohr read this account, he was appalled at how little it accorded with his own memory of that meeting, and so he wrote, but did not send, a letter to Heisenberg, repudiating it. ‘Personally,’ he wrote, ‘I remember every word of our conversations, which took place on a background of extreme sorrow and tension for us here in Denmark.’ What made a particularly strong impression on him, he told Heisenberg, was ‘that you and [Heisenberg’s colleague, Carl von] Weizsäcker expressed your definite conviction that Germany would win and that it was therefore quite foolish for us to maintain the hope of a different outcome of the war’. He also remembered Heisenberg giving him the ‘firm impression that, under your leadership, everything was being done in Germany to develop atomic weapons’:
I listened to this without speaking since [a] great matter for mankind was at issue in which, despite our personal friendship, we had to be regarded as representatives of two sides engaged in mortal combat. That my silence and gravity, as you write in the letter, could be taken as an expression of shock at your reports that it was possible to make an atomic bomb is a quite peculiar misunderstanding, which must be due to the great tension in your own mind. From the day three years earlier when I realized that slow neutrons could only cause fission in Uranium 235 and not 238, it was of course obvious to me that a bomb with certain effect could be produced by separating the uraniums. In June 1939 I had even given a public lecture in Birmingham about uranium fission, where I talked about the effects of such a bomb but of course added that the technical preparations would be so large that one did not know how soon they could be overcome. If anything in my behaviour could be interpreted as shock, it did not derive from such reports but rather from the news, as I had to understand it, that Germany was participating vigorously in a race to be the first with atomic weapons.
Years later Oppenheimer, evidently basing his account on what he had heard from Bohr, said that Bohr had thought that Heisenberg and Weizsäcker came to Copenhagen ‘less to tell what they knew than to see if Bohr knew anything that they did not’.
After his visit from Heisenberg, Bohr stayed in Denmark for another two years, during which time the situation for Danes hostile to the Nazis became ever worse. In the summer of 1943, the semi-autonomy enjoyed by Denmark throughout its occupation by Germ
any came to an abrupt end when, enraged by the Danes’ refusal to obey an order to declare martial law, the Nazis reoccupied Copenhagen. Soon afterwards it became very clear that Danish Jews – even those who were internationally renowned, Nobel Prize-winning physicists – were no longer safe. In the autumn of 1943, Bohr received a warning that he was about to be arrested by the Gestapo, whereupon he made plans to escape to Britain with his family.
Earlier that year, in January, Bohr had received, through clandestine means, a letter from James Chadwick, urging him to leave Denmark and promising him a warm welcome in Britain ‘and an opportunity of service in the common cause’. Realising that this was an effort to enlist him for the Allied attempt to build an atom bomb, Bohr replied turning the offer down. Not only, he told Chadwick, did he feel it his duty ‘to help resist the threat against the freedom of our institutions and to assist in the protection of the exiled scientists who have sought refuge here’, but also ‘I have to the best of my judgment convinced myself that, in spite of all future prospects, any immediate use of the latest marvellous discoveries of atomic physics is impracticable’. However, he did not rule out a change of prospects, circumstances or mind in the future, and then, he promised Chadwick, ‘I shall make an effort to join my friends and I shall be most thankful for any support they might be able to give me for this purpose.’