When Appleton first enquired whether this possibility was anything to be worried about, Chadwick played it straight:12
It is not easy to say anything definite about it. It is certainly a possibility that under suitable conditions the uranium fission process might develop explosively. There is one point which must have occurred to you at once and that is, how to prepare a uranium bomb that will not blow up immediately. ‘Hoist with his own petard’ will almost certainly be the fate of the man first successful with this process. But I do not think this difficulty is insuperable.
He concluded by saying that he would ‘look into it carefully and write again’. This was typical of Chadwick: asked a question, he could be reliably expected to give a sensible, cautious reply off the top of his head and then undertake to think about it more deeply.
Chadwick ran his physics department in Liverpool with the same authority as Rutherford had led the Cavendish, without his charm though with rather more tolerance. Lean, dark and brooding, Chadwick would have passed as an ambitious bank manager, his manner brisk, his attire spruce, his hair combed neatly over the sides of his shining forehead. His health had been poor since he left the detention camp in Germany. In his correspondence, he comes across as a man who, if not a hypochondriac, spent most of his time either sick, going down with an illness or recovering from one. Although universally admired for his scientific achievements and for his industriousness, he was a forbidding figure to his younger colleagues – his ‘boys’, as he called them.13 When one of his students knocked on his door in the laboratory, Chadwick would not answer, obliging his visitor to peer round the door, often to find him sitting with his head in his hands. ‘What do you want?’ he would ask, looking over the glasses perched on his nose, before standing up and pressing his hands into his back and complaining about his lumbago (‘My God, my back’). Once he had warmed up, however, he was courteous, helpful and inspirational, in his downbeat way.
Chadwick’s connections with local industry ensured that funds flowed copiously into his department’s coffers and that he was not short of visitors, many of them seeking his advice. The most able scientist to beat a path to his door was Joseph Rotblat, a bright-eyed Polish physicist in his early thirties. He had arrived in Liverpool in the spring of 1939 without his wife – he was too poor to support her – and knew so little English that he had to steel himself before beginning a conversation. Homesick and miserable, his mood was not improved a few weeks later when he read Siegfried Flügge’s paper on the possibility of building an explosive nuclear device. If Flügge knew this much, there was a good chance that at least some of his colleagues were actually working on the idea. After weeks of hand-wringing, Rotblat agreed with most of his colleagues that ‘the only way to stop the Germans from using it against us would be if we too had the bomb and threatened to retaliate’.14 Sensing that war was imminent, he returned to Warsaw to bring his wife back to England, but appendicitis made it impossible for her to make the journey. He left her behind, intending to pick her up later.15 When he read soon afterwards of Hitler’s savaging of Poland he felt, as he later wrote, that ‘the might of Germany stood revealed, and the whole of civilisation was in mortal peril’. Hearing nothing from his wife, he was bereft.
At Chadwick’s suggestion, Rotblat started to work on the nuclear bomb. Chadwick had filled pages of his notebooks with calculations on the putative weapon’s viability, and after five weeks came to a disappointingly vague conclusion, which he sent to Appleton: ‘I can give no definite answer to this question.’16 He promised, however, to pursue the problem experimentally and delegated it to the ‘very able and very quick’ Rotblat, assuming they were able to get hold of enough uranium oxide.
Appleton, though ignorant of the underlying nuclear physics, kept the Cabinet informed and reassured.17 G. P. Thomson, at Imperial College London, and Mark Oliphant, another of Rutherford’s former ‘boys’, at Birmingham University, had long been independently working on chain reactions. Eight months before, Thomson had felt like a character in a pulp thriller when he sheepishly requested a ton of uranium oxide from an Air Ministry official, for purposes he was not at liberty to explain.18 Thomson’s status as a recent winner of the Nobel Prize for physics would not have harmed his case. He was duly supplied with the ore and became the first scientist in Britain to secure government resources to investigate nuclear chain reactions. Appleton visited the Air Ministry to get a proper brief, after one of their officials had described the state of affairs as an ‘illuminating example of the scientists’ right hand not knowing what their left hand was doing’.19 Ministry staff had been even less amused when Tizard put forward an idea – conceived independently by him and Thomson – that the government should lay a trap for the Germans by issuing a spoof report stating that Britain had made a nuclear bomb, in effect replying to Hitler’s ‘secret weapon’ speech.20 As Tizard recalled later, the authorities were ‘horrified’.
The idea of a nuclear weapon was now being taken seriously in Whitehall. Government officials, many of them worked off their feet, now found themselves looking into what they thought was arcane science, boning up on geochemistry and locating the world’s most plentiful supplies of uranium. It turned out that uranium ore was relatively cheap (uranium-based chemicals then cost about two dollars a pound) and was being mined in the Congo – ruled by the friendly Belgian government – and the Great Bear Lake region of Canada, a British ally.21 The bad news was that the most abundant sources of high-quality uranium ore were to be found in Joachimsthal, in Nazi-occupied Czechoslovakia, and were being refined in Berlin.
Chadwick focused on the key question: if a nuclear chain reaction could take place, how could it be used to make a bomb? He and his Liverpool colleagues were using their brand-new cyclotron to investigate whether a nuclear chain reaction might be possible, squeezing in precious hours of research between teaching and administration.22 Yet these and similar experiments were only desultory, not part of a coherent programme. In January, Chadwick wrote to his former colleague John Cockcroft, then working on radar: ‘Our laboratories seem to be so disorganised that very little useful work of any kind – peace or war work – is going on.’ If the chaos lasted much longer, Chadwick fretted, ‘we shall be hopelessly behind the Americans’.23
He was right to be concerned. Although the Great Depression had left many physicists in the United States short of resources, the country’s nuclear physics had been given a substantial boost by the arrival of hundreds of first-class refugee scientists. Several of them had landed first in Britain but were then redirected to America, the British authorities waving them on like mindless policemen on a traffic island, eager to keep the vehicles moving. One of those who had been waved on was the Austrian refugee Viki Weisskopf, who emerged as a leader in the nuclear community. He later said that he would have happily stayed in Britain if the authorities had shown any interest in keeping him: ‘The English had a very short-sighted policy toward refugees,’ he said in 1966. ‘Gosh, what they could have gotten at that time for nothing.’24
Europe, the crucible of both quantum theory and relativity, was losing its lead over the US in the field of physics. American physicists, so far free of the pressures of war, could scarcely be better placed to pick up and run with ideas hatched in a devastated Europe. And if such an initiative could win the support of the American government, there would be no stopping them.
Unknown to Chadwick and his colleagues, the idea of developing a nuclear bomb was being pondered not only in American laboratories but also in the White House.
OCTOBER 1939 TO JULY 1940
FDR receives a nuclear warning
QUESTION: Why are Franklin Roosevelt and Columbus alike?
ANSWER: Like Columbus, Roosevelt didn’t know where he was going or where he was when he got there, nor where he had been when he got back.
Joke told shortly before the war in the presence of a stony-faced Churchill.1
When the war broke out, Franklin Roosevelt was appro
aching the end of his second Presidential term and, with the economy still in the doldrums, another period in office looked – to use one of his favourite words – iffy. His focus over the past seven years had been on his homeland, but Hitler and his allies put paid to that: by early October 1939, the President was walking on eggshells,2 trying to persuade sceptical lawmakers to repeal the 1937 Neutrality Act, which had attempted to make it impossible for the United States to become embroiled in foreign conflicts. He faced opposition both from adamant isolationists, who wanted their country to stay out of what they saw as an imperialist power game, and from those who thought it the duty of America to stop the spread of Fascism.3
On the day Britain entered the war, Roosevelt gave one of his fireside chats on the radio, reassuring his listeners that their country ‘will remain a neutral nation’, though adding, ‘Even a neutral cannot be asked to close his mind or close his conscience.’4 The prevailing view in the country was that it was best not to get involved: for every American voter who wanted to send the US army to Europe, nineteen did not.5
The possibility of nuclear weapons was first drawn to his attention at a meeting in the White House on Wednesday 11 October 1939. A few days before, he had spoken to Churchill on the phone for the first time, a month after sending him a telegram to congratulate him on his appointment to the War Cabinet.6 The two men had not been in touch since October 1933, when Churchill sent a copy of the first volume of his biography of the Duke of Marlborough to the new President, inscribing the book: ‘With earnest best wishes for the success of the greatest crusade of modern times.’7 In his congratulatory telegram, the President underlined his preference for direct personal diplomacy: ‘What I want you and the Prime Minister to know is that I shall at all times welcome it if you will keep me in touch personally with anything you want me to know about.’ Thus began Churchill and Roosevelt’s wartime correspondence, which eventually ran to some two thousand telegrams and letters.
The 11 October meeting took place after another day of hard lobbying on Capitol Hill. Between the President’s first appointment at 11 a.m. and his pre-dinner dip in the White House pool, his diary was packed with fourteen engagements. Somehow, his secretaries had to squeeze in time for a meeting with his occasionally obtrusive acquaintance Alexander Sachs, who had been pressing for weeks to bring the Bomb to the President’s attention.8 Sachs had been one of the President’s economic advisers since 1932, a director of Lehman Brothers and an avid reader of popular articles on modern nuclear physics.9 Though a quick learner, he had no talent for précis and was well known for writing documents that had to be fought through rather than read. During an earlier meeting with Roosevelt, Sachs had mentioned that nuclear weapons might be possible, but Enrico Fermi had as usual smothered the idea in scepticism.10 Leó Szilárd, having sniffed out Sachs as a willing messenger to the White House, sought to trump Fermi’s wariness with a supportive message from Albert Einstein, who had visited the White House in January 1934 and chatted with the President about their shared interest in sailing.11 Assisted by his fellow Hungarian refugees Edward Teller and Eugene Wigner, Szilárd had visited Einstein in August at his vacation home on Long Island to explain to him that it might be possible to build nuclear weapons, and to press him to alert Roosevelt.12 The idea of a nuclear chain reaction was a revelation to the world’s most famous scientist, who did not take much persuading to write to the President: on 19 August he signed a letter, drafted by Szilárd, warning the President that it might be possible to construct new and ‘extremely powerful bombs’, based on nuclear chain reactions in uranium. He concluded by pointing out that the Nazis might be working on this project and now had access to uranium ore.
When Sachs walked into the Oval Office that autumn afternoon, the President greeted him with his customary geniality: ‘Alex, what are you up to?’13 Among the clutch of papers Sachs was cradling in his arms were Einstein’s signed letter, Szilárd’s ramblings and his own eight-hundred-word summary of nuclear energy and ‘bombs of hitherto unenvisaged potency and scope’. Sachs read his words to the President, who got straight to the point: ‘What you are after is to see the Nazis don’t blow us up.’ After Sachs agreed, Roosevelt – sitting at his huge desk – told an aide, ‘This requires action.’ Within minutes, the government’s Advisory Committee on Uranium was gestating. It was suggested that a good chairman would be the veteran Lyman Briggs, head of the National Bureau of Standards (America’s national physics laboratory), once a soil scientist, now a competent bureaucrat, but never anyone’s idea of a visionary. The Committee’s first meeting on 21 October was attended by military personnel, Sachs and the Hungarian scientists Szilárd, Teller and Wigner, but not Einstein, who was already backing away from front-line involvement.14 The American nuclear bomb project was now under way.
Roosevelt had behaved true to form. If a trusted colleague presented him with a well-argued idea, backed up by expert opinion, he would usually go along with it. If, however, he had already made up his mind about the topic under discussion, he could be extremely tricky – he liked to tell officials and other visitors what they wanted to hear, even if he later had to spend a little time backtracking or soothing wounded egos. For him, consistency was overrated as a virtue – what mattered was that events went in broadly his direction, ideally in precisely his direction. Beneath the veneer of bonhomie was a resolution so strong it could be chilling. His successor Harry Truman later remarked that he was ‘the coldest man I ever met’.15
Roosevelt entered politics when he was twenty-eight, in 1910. Like Churchill, he had been born into a wealthy family and was blessed with so many political gifts that his rise to power was all but inevitable. Not only was he bright, charming and energetic, he even looked the part – broad-shouldered, six feet two inches tall and weighing 190 pounds. Former President Woodrow Wilson called him ‘the handsomest young giant I have ever seen’.16 Roosevelt’s political career had been blessed and without serious misfortune until, at the age of thirty-nine, he contracted polio and had to spend most of the rest of his life in a wheelchair. Never quite giving up hope that he would walk again, he crawled from room to room, submitted to being carried around like a child. The press took care to photograph him only from the waist up – usually capturing his toothy, confident grin – so few Americans knew of his disability.
Unlike Churchill, Roosevelt had few interests outside politics, and they did not include modern science and technology. At school in Groton, he had studied basic science and in his first two years at Harvard had taken courses in geology and palaeontology. He left full-time education, however, with a Churchillian indifference to abstraction, but with little of Churchill’s concern for using the products of scientific thinking to help the military.17 For Roosevelt, science was something that for the most part went on outside politics – he had no Lindemann and never showed much interest in acquiring one. The idea of Roosevelt taking time off from preparing an important speech to review his understanding of atomic physics is unimaginable – his idea of a quiet morning’s pleasure was to spend a few hours annotating his collection of postage stamps.
Roosevelt’s New Deal policies of high taxes and aggressive government intervention had made him many enemies, who regarded him, in his own words, as an ‘ogre – a consorter with Communists, a destroyer of the rich, a breaker of our ancient traditions’.18 Even Churchill, an admirer of the President’s boldness and spirit, openly criticised his record. In an article published in late 1937, Churchill complained that ‘the Washington administration has waged so ruthless a war on private enterprise’ that it was ‘leading the world back into the trough of depression’.19
The President was unpopular among some of the leaders of the cash-strapped science community who had long been pressing for government money to fund basic research.20 Even though Roosevelt had little money for them, he always had plenty of warm words, assuring physicists in 1935 that he was ‘wholly in sympathy’ with a government programme to support them. But his heart was no
t in curiosity-driven science that was of no immediate benefit to the ravaged economy, and none of the physicists’ federal funding initiatives made much progress.
The President was more interested in the role science could play in improving society. As he remarked in 1937, during his second inaugural address, government husbandry was essential to ‘create those moral controls over the services of science which are necessary to make science a useful servant instead of a ruthless master of mankind’.21 By the time nuclear fission had been discovered in late 1938, American physics was in good health, largely because of the munificence of private funders, such as the Rockefeller Foundation. With physicists of the calibre of the cyclotron inventor Ernest Lawrence and the theoretician Robert Oppenheimer, both of them at Berkeley and running excellent research programmes, the community was well placed to answer any call on its services the President might care to make.
Within two weeks of the inaugural meeting of Lyman Briggs’s Uranium Committee, its first report was delivered to the White House. The problem was that the document was too dull to stand any chance of inspiring the President, whose heart must have sunk when he read the yawningly predictable recommendation that the government should fund more research into nuclear chain reactions. More likely to have caught his eye was the statement that if the reactions were explosive, then they ‘would provide a possible source of bombs with a destructiveness vastly greater than anything now known’.22 Yet even that phrase did not seize Roosevelt’s attention, assuming he read it. Without a Lindemann to keep a scientific eye on incoming technical papers, to translate them into readable prose and draw out the key points, he gave a pat response. He merely asked an aide to ensure that copies were sent to the army and navy but otherwise to ‘keep it on file for reference’. For the next few months, the file gathered dust. Szilárd, Fermi and their colleagues in New York received the funding and made progress, but heard nothing from Washington, where Briggs’s dozy leadership had ensured that the idea of investigating the possibility of a nuclear bomb lay deep in Capitol Hill’s longest grass.
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