The suggestion that the world should be informed regarding Tube Alloys, with a view to an international agreement regarding its control and use, is not accepted. The matter should continue to be regarded as of the utmost secrecy . . .
Roosevelt compounded his duplicity by signing up to the Churchillian line that Bohr was potentially dangerous and should be watched carefully:
Enquiries should be made regarding the activities of Professor Bohr and steps taken to ensure that he is responsible for no leakage of information, particularly to the Russians.
On the following evening, the President accompanied the Prime Minister to the nearby railway station in Poughkeepsie, their car surrounded by Cadillacs full of security guards and special agents. Churchill, preoccupied with the threat he believed Bohr posed, was still fulminating. In a letter the next day to Lindemann, recently returned from Washington, Churchill condemned the Danish physicist as a publicity-seeker, complaining that he had leaked information to Frankfurter and that he was in close correspondence about the Bomb with a professorial friend in Russia (this was Peter Kapitza).36 ‘What is this all about?’ seethed Churchill, who wrote that he and Roosevelt were ‘much worried’: ‘It seems to me that Bohr ought to be confined or at any rate made to see that he is very near the edge of mortal crimes.’
Roosevelt met soon afterwards with his Chief of Staff Admiral William Leahy, Vannevar Bush and Frederick Lindemann, who sent Churchill a summary of the meeting.37 The President underlined what his guest wanted to hear: that Britain and America should share all their nuclear discoveries, and should collaborate not only during the war but afterwards. It was a matter for later governments to decide whether they wanted to continue with this arrangement, Roosevelt said – the only thing he could see that would interrupt it ‘would be if he and the Prime Minister, Bush and [Lindemann] were all killed in a railway accident since we all saw eye to eye’. Bush, Lindemann noted, ‘said nothing’. The outcome was that Bush would ‘check up on Bohr’, though he thought there was no reason to worry.
Bohr’s supporters and friends on Capitol Hill and in Whitehall sprang to his defence, and the case against him was quickly dropped. Lindemann was among his defenders, replying quickly to Churchill’s letter, putting the record straight and pointing out that although the Dane had ‘some rather woolly ideas’ about how nuclear weapons could induce countries that have them to live in peace and confidence, he was someone of unimpeachable integrity and loyalty.38 A surprisingly curt comment by Lindemann in this letter shows how little confidence he had that Churchill remembered much about the early public discussions of nuclear energy, a debate the Prime Minister had been among the first to stir: ‘I do not know whether you realise that the possibilities of a super weapon . . . have been publicly discussed for at least six or seven years.’
Lindemann stayed in the United States for several weeks, touring sites where the American military was carrying out research and development. His hosts transported him around the country in style and even put an aircraft at his disposal.39 During this trip he visited the sites of the Manhattan Project and, perhaps, appreciated for the first time how wrong he had been to imagine that such an enormous venture could have been carried out in the UK. He had hardly been alone in making this error of judgement, which had now been proved ridiculous: another who had initially shared this delusion was the leader of the British scientists now working at a frantic pace on the Manhattan Project, James Chadwick.
FEBRUARY 1944 TO JULY 1945
Chadwick witnesses the first nuclear explosion
‘[For much of my present duties] I am fitted neither by temperament, training nor ability.’
SIR JAMES CHADWICK writing to Robert Oppenheimer, 25 April 19451
Rutherford would have been amused. The first leading nuclear physicist to be obliged to morph into a back-room diplomat was his deputy ‘Jimmy Chadwick’, known for his drive, terseness and intolerance of foolishness, not for his skills as a tactful negotiator. He was also a strong patriot, so when duty called on him to be the Churchill government’s chief representative on the Manhattan Project, he accepted without demur. Although first and foremost a nuclear experimentalist, he had not done much science in the past year – he spent most of his time embroiled in negotiations with dilatory politicians in Whitehall, and with General Groves, who displayed his chauvinism and his indifference to British interests with some pride, like epaulettes. The contrast with the scientific director of the project was painful to behold – whereas Chadwick always looked harassed, everyone could see that Oppenheimer was having the time of his life.
A welcome bonus of the Chadwicks’ move to North America was that they would be reunited with their daughters, who had been living in Nova Scotia for three years. In January 1944, when the family was together briefly in Halifax, Aileen was surprised to see that her daughters had matured from demure young girls to sparky teenagers, wearing make-up and speaking in a mid-Atlantic accent.
Having left their daughters to study at a school in Nova Scotia for another three months, the Chadwicks travelled to Site Y, where Groves allocated them a small wooden cottage next to the Oppenheimers. The Chadwicks’ home had the luxuries of two bedrooms, an iron bathtub, indoor plumbing and a roomy living room with a handsome stone fireplace. All this made them the envy of Chadwick’s junior colleagues, who had to make do with the spartan accommodation provided in the dorms, with their shared bathrooms and hard beds. Yet life on The Hill was too primitive for Mrs Chadwick’s genteel tastes. The absence of the tedious nightly blackouts, the abundance of food, the views across to the snow-capped peaks of the Sangre de Cristo mountains, did not compensate for the temporary loss of their roomy house in Liverpool, the company of friends, the studied calm of the BBC’s radio announcers. Uncomfortable in the thin mountain air and often feeling under the weather, she chain-smoked her way through the long days and made no secret of her homesickness or of her dislike of life in America. At one of her afternoon tea parties, she complained of ‘the primitive nature of life in the United States’, a remark some of her guests found less than endearing.2
It was no wonder she felt so lonely: during the year she and her family lived at Site Y, most of the time her husband was away, visiting other Manhattan Project sites and talking with officials in Washington. His longest stay on The Hill was the few weeks he spent there recovering from a debilitating attack of shingles. Permanently tired, when he had a free evening at home all he wanted to do was sit in his armchair with his nose in a book.
Chadwick’s greatest diplomatic success was to persuade his American colleagues to support the development of a new nuclear facility in Canada. The cards had been stacked against him. By late 1943, the morale of the Montreal project was rock bottom – mainly owing to the chaotic leadership of Hans von Halban – and the Americans were disinclined to support a satellite project not under their direct control. Yet Chadwick won the day, arranging for the Canadian Atomic Energy project to be led by his former Cavendish colleague John Cockcroft, who had one of the safest pairs of hands in British science.3 At the picturesque site of Chalk River, just over a hundred miles north-west of Ottawa, Cockcroft oversaw the construction of a prototype reactor, moderated by heavy water, giving Britain and Canada experience in developing a large nuclear facility that was certain to prove crucial after the war. The heavy water and uranium were both supplied by the Americans. When Chadwick scored a victory like this, he seemed to relax, a thin smile appearing across his face like an acute-angled slit. On one occasion, he celebrated a success by putting the best possible spin on the Anglo-American project with a phrase he probably picked up during his Lancashire youth – ‘It’s all jam and kippers.’4
Unlike his junior colleagues, Chadwick found himself worse off financially than he had been at home in England. Although he was the highest-paid British scientist on the project (his pay cheque was 142 pounds a month),5 much of his salary was spent on travel and hotel expenses that he had no time to reclaim. Nor could the
British authorities find a simple way to reimburse him. Eventually, a senior civil servant in Washington made a plea to Whitehall for fairness: ‘For us, [Chadwick] is as much of a key figure as Groves on the American side . . . He will certainly not be able to approach the task without wearing himself to death, unless he has a very real personal relief from financial worries.’6 Fairness eventually prevailed, and the Treasury in London increased his salary by five hundred pounds, backdated to November 1943. Other parts of Whitehall were not always so cooperative, failing to support wholeheartedly the clear vision that Britain’s participation in the Manhattan Project was crucial to the country’s post-war nuclear programme. In June 1944, when Anderson and Lindemann responded disappointingly to another of his requests for action, Chadwick confided to Akers that the British government was demonstrating a ‘complacency, almost amounting to indifference’ to the entire project.7
The physicists working on the construction of the Bomb made great progress until they appeared to hit a brick wall in the spring of 1944.8 The problem was not with Frisch and Peierls’s original idea of firing two lumps of 235U at each other to form a critical mass. By then, it seemed virtually certain that this method would work – the physicists had only to wait for the chemists and engineers at Oak Ridge to produce enough 235U. Much more serious was the problem of making a nuclear bomb from plutonium, as the scientists found out when substantial amounts of it began to arrive, also from Oak Ridge. The element turned out to have some unexpected properties, several of them inconvenient for the purpose of making a nuclear bomb. The most serious problem was that plutonium fissions quite naturally at an extraordinarily high rate – with no need for the judicious prod of a neutron – so high that the samples of the element loaded in a Frisch–Peierls ‘gun’ would fizzle out before there was any chance of an explosion. Nature was making life extremely difficult for Oppenheimer and his team. His response was decisive: after consulting with his experts, in July he reorganised the work of his entire lab, terminating all projects on the gun-type plutonium bomb and redeploying staff to develop a different, more complex way of using the element to build an explosive. This method used an ‘implosion’ to create the critical mass, by employing a blanket of ordinary explosives to crush a hollow shell of plutonium into the critical mass so quickly that it would explode instantly. Never in the history of human conflict had so many resources been invested, so quickly, to develop a weapon of such power.
One of the leaders of the implosion project was Rudi Peierls, who headed the team of theoreticians investigating the detonation- and shock-waves generated by the plutonium device. One of his colleagues was Lindemann’s protégé James Tuck – for the Americans, the great English eccentric of the British mission – who did crucial work on optimising the explosion. Peierls also served as Chadwick’s eyes and ears, later compiling for him regular summaries of progress on the entire project, notes that Groves also found useful.9 Although Peierls’s conscience was as well developed as anybody’s on the site, he found the atmosphere at Site Y in many ways idyllic, especially after the earlier Anglo-American tensions that had done much to stymie collaboration – ‘It is an enormous pleasure’, he wrote, ‘to be at a place where no distinction is made between members of the American and British organisations and where work is guided by the necessity to get the best answer in the shortest possible time rather than by questions of formal organisation and prestige.’10
Most of the credit for creating this agreeable environment was, he knew, due to Oppenheimer, who had persuaded Groves to abandon his attempt to force the scientists to work in compartments, and who understood how to get the best out of everyone in his team, including Peierls’s friend Otto Frisch. Later, the American authorities praised Frisch’s ‘exceptional experimental skill’ and ‘his ability to see the relation between a laboratory experiment and its practical application to an atomic weapon’.11 Yet he found plenty of time to play the piano, to draw caricatures of his colleagues, and to go to many of the parties on the site, including one thrown by Robert Oppenheimer (on behalf of ‘Insecurity’) and Oppenheimer’s wife Kitty (on behalf of ‘Unintelligence’), their invitation marked ‘For Orgy Only’.12 Perhaps the finest pianist on the site, he often gave evening concerts – his repertoire ranged from Bach to Shostakovich via Schubert – some of them broadcast on The Hill’s radio station. Whether he liked it or not, Frisch was given hours of personal advice by Peierls’s domineering but kind-hearted wife Genia. She was one of The Hill’s great characters, a fortissimo diva, generous host and always the life and soul of every gathering. When the news of D-Day arrived on 6 June she climbed on to the nearest table and danced with a fetching abandon.
One of the waifs and strays that the Peierlses took under their wing was their former lodger Klaus Fuchs, an introspective theoretician whom Genia was gradually coaxing out of his shell. He called her ‘Mother Peierls’.13 Fuchs shared an office with Rudi, working with him on the mathematical physics of the imploding plutonium weapon and becoming one of the British mission’s most powerful calculators. Although Fuchs was for many of his colleagues a closed book, he was popular – a willing babysitter, an enthusiast for games of chess and charades, and always ready to relax over a beer or two in the evening, though he could hold his drink.14 He was a sought-after partner on the dance floor, having proved himself to be the nearest The Hill had to its own Fred Astaire. Like every other member of the British mission, Fuchs’s movements were monitored on site, though the security officers left him alone when he ventured outside (for the American scientists, the security services did the opposite). One of the few British physicists to own a car, he went on long drives during the weekends, unhindered by any police presence.15
On Sundays, Oppenheimer virtually shut down the lab, urging his colleagues to have at least one day each week away from their punishing schedule. Although the Chadwicks were not the most enthusiastic participants in the week-night activities – the outdoor movies, the dances, the impromptu parties on the staircases of the dorms – they did unwind with everyone else on the lab’s days off. Chadwick was fond of trout fishing in local streams and occasionally went on long hikes in the wooded mountainsides. Other colleagues took horse-riding lessons, drove into Santa Fe and read books from the library, which Szilárd had ensured was stocked with a copy of Harold Nicolson’s Public Faces and H. G. Wells’s The World Set Free.16 In the end, though, many of the inhabitants of The Hill found themselves with plenty of time on their hands, which may explain the soaring birth rate on the site – one of the medical staff told Groves that the number of babies born to the scientific personnel at Site Y broke all records.17
It was said that identifying the members of the British mission was easy – they had Germanic accents. This was an exaggeration. Some of the American team were refugees from Europe, too, including the head of the theory division Hans Bethe and the protean Enrico Fermi, who had arrived from Chicago in September and quickly been given an entire division of his own, to tackle multi-disciplinary problems. European refugees constituted only about a third of the British mission, but they were among its most prominent members. Niels Bohr – regarded as an honorary Brit – returned to Site Y for several short stays in 1944 to do technical work on the project and to talk about the implications of the Bomb with the scientists, especially with Chadwick and with Oppenheimer, who came to think of him as a demigod (‘the noblest man I ever knew’).18 After his foray into power politics, Bohr seemed unperturbed either by the treatment he and Lindemann had been given by Churchill (‘He scolded us like two schoolboys!’)19 or by the duplicitous sympathy he had been shown by Roosevelt. Instead, Bohr flouted the British government’s directives to steer clear of political discussions and preached the need for statesmanship and openness in order to avoid a long-term disaster in international relations.20 His influence was growing steadily among some of the scientists on The Hill, as their political masters would soon find out.
Of all the British scientists working on the Manh
attan Project, Joseph Rotblat was the most ill at ease. When he arrived in March 1944, he was billeted with the Chadwicks, sleeping in their spare bedroom until their daughters arrived from Canada. With newspapers and radio broadcasts supplying daily reports of the collapse of the Germans’ war effort, it seemed increasingly implausible to him that Hitler could be matching the Allies’ Bomb programme. Why, then, was the weapon being built? Chadwick listened respectfully, countering that such decisions should be left to political leaders. Over dinner one evening at the Chadwicks’, in the company of General Groves, Rotblat’s unease turned to disillusion when the General remarked that the real purpose of the Bomb was to subdue the Soviets.21 Rotblat was flabbergasted. Until then, he later wrote, he had thought the Bomb was being built ‘to prevent a Nazi victory’. But he was now being told that the weapon was intended for use against Britain and America’s allies – ‘the people who were making extreme sacrifices for that very aim’.22
A few months later, when it was commonly accepted on Site Y that the Germans had all but abandoned their Bomb project, the disillusioned Rotblat asked for permission to quit. When Chadwick was considering the request, the authorities disclosed that they had evidence that Rotblat had Communist associates outside the site, and Rotblat made it clear that he wanted to return to Europe to search for his missing family.23 After Chadwick decided it was best to have his colleague out of the way, Groves quickly agreed that Rotblat could return to Britain, provided that he told no one why he had left.
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