The project might have stayed there had it not been for the shake-up initiated by a spry newcomer in Washington DC, Vannevar Bush, known to his friends and colleagues as ‘Van’, recently appointed President of the Carnegie Institution. He had arrived in Washington eighteen months before, determined to make his mark on the national administration of science by joining several influential committees. Born to a family of New England seafarers, he rose to a professorship of electrical engineering at the Massachusetts Institute of Technology, where his intellect and technical ingenuity marked him out, his lucrative patents affording him a measure of financial independence. His appointment to the vice-presidency of MIT did not sate his ambition – which was to be the chief science policy-maker in Washington, and to leave an indelible mark on his country’s history. Just turned fifty, he had the energy, ability and will to shake things up in the capital: determined and business-like, his self-assurance was obvious from every word he spoke.23 When upset, he didn’t talk, he growled.
A little less than six feet tall and slightly stooped, he was always smartly dressed, wearing wire-rimmed spectacles and habitually puffing on a pipe he had carved in his home workshop. Although he looked like a beardless Uncle Sam and had the folksy charm of the cowboy entertainer Will Rogers, Bush had the hard-headed pragmatism of a seasoned political operator. A registered Republican and a scabrous critic of the New Deal, he was nonetheless happy to do business with Roosevelt: ‘I knew you couldn’t get anything done in that damn town unless you organized under the wing of the President.’24
Bush was aware of the discontent among scientists on the spavined Uranium Committee – a symptom, he knew, of a much wider malaise: there was no mechanism to bring America’s scientists together with the military and to ensure constructive collaboration. He achieved this on a June afternoon in 1940 in a power grab that had the audacity of a heist. A few weeks before, Bush had inveigled Roosevelt’s uncle Frederic Delano into persuading the President’s friend and colleague Harry Hopkins to give him a coveted slot in the White House diary.25 In the Oval Office, with Hopkins looking on, Bush introduced himself and set out his ideas for mobilising America’s military technology by coordinating and supervising scientific research on military equipment and weapons. Theatrically pulling out a single sheet of paper summarising his plans, Bush handed it to Roosevelt, who promptly instructed Hopkins to write on the paper ‘OK – FDR’. The meeting had lasted about ten minutes.
Roosevelt’s intuition was sound – and his appointment of Bush was a masterstroke. He had sanctioned what became known as the National Defense Research Committee, soon to give new energy and focus to the application of science to warfare by American academics and military personnel. It went without saying that Bush would chair the Committee. Working with Hopkins, he quickly appointed its members and recruited dozens of scientists, giving them accommodation in his own Carnegie Institution and the National Academy of Sciences; soon his staff was spilling over into other buildings. Delegation was the key to his success: rather than setting up laboratories and institutes to do the Committee’s work, he devolved projects to thousands of contracts with universities and industrial organisations all over the United States. He was building up what one American reporter aptly described two years later as ‘a scientific organization such as the country has never seen before’.26
At first, the putative nuclear weapons barely figured in the Bush Committee’s deliberations. A year before, when the media chatter about the possibility of these bombs and of cheap power was at its most feverish, Bush ridiculed the journalists’ most outlandish predictions and went out of his way to debunk them.27 At one point, he feared a repeat of the panic that followed Orson Welles’s radio drama based on H. G. Wells’s War of the Worlds, which persuaded thousands of Americans that Martians had landed in New Jersey. Soon, however, Bush accepted that the press speculation was harmless and that the ‘great impracticability’ of the supposed bombs meant that it was wise to continue ‘soft pedaling a bit’.
Van was right to give the President cautious advice as no one had any idea how to build such a bomb. Szilárd and his colleagues were in some ways ‘all talk’ – they were terrified of something that appeared unfeasible to everyone who had an informed opinion on the matter. Soon, however, Van heard that it may well be possible to make the weapon, following a brilliantly simple idea conceived in England by two scientists classified there as ‘enemy aliens’.
MARCH TO JUNE 1940
Frisch and Peierls discover how to make the Bomb
‘As a weapon the super-bomb would be practically irresistible. There is no material or structure that could be expected to resist the force of the explosion.’
OTTO FRISCH and RUDOLF PEIERLS, March 19401
The timing was, perhaps, not ideal. In March 1940, when the world was about to plunge into the most destructive global conflict in its history, two Jewish refugee physicists – the Austrian Otto Frisch and the German Rudolf (‘Rudi’) Peierls – showed that nuclear bombs could, in principle, be built.
A memorandum written by the two physicists in just a few days provided a basic blueprint of a nuclear bomb to the British government. The document obliged officials to consider the possibility that the Nazis might also be developing such a weapon, and the unpalatable truth that Britain was poorly placed to build one of its own. The consequences for Britain and the United States were momentous – not for nothing has the Frisch–Peierls document been called ‘a memorandum that changed the world’.2 Yet, for decades, many experts on nuclear weapons – scientists, politicians and military strategists – were unaware that this was the memo that kick-started the development of the Bomb. This was partly because it went missing after the war. A copy of the main part of the text turned up two decades later in the UK Atomic Energy Authority’s strongroom – according to legend, the document was stuffed inside a Corn Flakes packet.
Frisch and Peierls, both in their thirties, were not working in the academic powerhouses of Cambridge and Oxford but in the relatively modest ambience of Birmingham, capital of the West Midlands. Apart from Hitler, the person most responsible for bringing them together was Mark Oliphant, since October 1937 one of Birmingham University’s most energetic professors, and yet another of Rutherford’s ‘boys’. Just as Rutherford had done in Manchester and Cambridge, Oliphant arrived in his new department like a buccaneer storming a galleon. He reshaped Birmingham’s courses and research programme, made adventurous new appointments, and aggressively sought out research funds, stressing that nuclear experiments might one day benefit industry and have medical applications.3 He persuaded the car manufacturer and philanthropist Lord Nuffield to buy for the department ‘the world’s largest cyclotron’, reassuring locals that the new ‘atom-splitting machine’ was nothing to worry about.4 Oliphant become well known in Birmingham for promoting nuclear research to journalists and for persuading them of its potential usefulness. After an interview with him about his cyclotron, one of them wrote: ‘The purpose of the machine is not to release energy for destruction. It is for humanitarian work.’5
Lord Nuffield also paid for the handsome new building where Frisch and Peierls were working in March 1940, a few yards apart, in a single-storey redbrick extension to the main block. The whiff of fresh paint, wood shavings and glue still lingered in the offices. Frisch, then thirty-four, had arrived in Birmingham during the previous summer, after working in Bohr’s Institute in Copenhagen for the past five years. Fearful of a Nazi occupation of Denmark, Frisch had taken soundings in Britain about short-term posts he might apply for, and accepted an invitation from Oliphant to stay for a couple of months to work on nuclear fission.6 He was homesick, did little work and spent most of his time worrying about the fate of his wider family, including Lise Meitner, downhearted in Sweden after having turned down a post in Cambridge.7 An only child, Frisch felt a special responsibility to take care of his parents, who had also settled in Sweden after his father had spent months in Dachau, the Nazis’ first
concentration camp.8 In the autumn, he began a long and wearying campaign to try to persuade the British Home Office to allow his parents to join him.9
By the time war broke out Frisch felt at home in Birmingham, which was just as well, as there was no possibility that he would return to mainland Europe. After Oliphant extended his contract, Frisch put himself at the disposal of the Ministry of Labour,10 though he expected to sit out the war working on experiments, doing a modicum of teaching and writing a book on nuclear physics. Some aspects of English life grated on him – the endless talk about the weather, the reek of boiled mutton in the restaurants and a public transport system that would have benefited from a little Austrian discipline.11 A private and apolitical man, slow to form close friendships, he mastered English less through conversation than through visits to the theatre and evenings reading the novels of Aldous Huxley.12 What mattered most to Frisch was music, not words – he once said that if a piano was being played softly in a noisy and crowded room, he would hear the instrument’s sound above all the chatter. He was an outstanding pianist himself and gave several public concerts.13
By early 1940, Frisch had got to know Peierls well. The youngest professor of applied mathematics in Britain, Peierls was one of only a handful of European refugee scientists to hold a permanent post in the UK.14 Even before Oliphant took up his post in Birmingham, he offered Peierls a job and they began work there on the same day. It was an inspired appointment: the young German was a physicist of proven versatility, a popular colleague and quick to strike up collaborations, just the sort of person to make Birmingham one of the leading centres of theoretical physics research in the country. Formal in his manner but with no trace of pomposity, Peierls was politically moderate with an exceptionally strong sense of duty and fair play. As Rutherford remarked, ‘He would make a very good Englishman.’15
In August 1939, Peierls abruptly changed his priorities from building his career as a quantum physicist to helping to fight the Nazis. He wrote to government officials to underline his willingness to serve as a scientist, pointing out that he had left Germany when Hitler came to power in 1933 and had formally applied for British nationality in 1938.16 He might have added that he had no trouble making himself understood in his adopted country: Peierls and his wife had different mother tongues and decided soon after they met to speak in the one language they both spoke passably, English.17 In company, Peierls’s coolness was more than counterbalanced by the warmth of his Russian-born wife Genia, a physicist who had given up research. A flamboyant, generous host, she was also a hands-on mother to their two small children and was always ready to welcome guests, to whom she dispensed liberal quantities of advice, whether they liked it or not. At least one evening a week, Frisch left the tranquillity of his bachelor digs and walked to the Peierls’s noisy Georgian home, where the rich stew of their family life was always simmering.18
Birmingham did not appear to be as well prepared as London for war, but was certainly ready for air attacks, boasting that it had room in its shelters for nine hundred thousand people.19 Food supplies were now rationed, citizens went about their business carrying a rubber gas mask, and everyone had to get used to the strictly enforced blackouts. Frisch was ‘gradually developing the instincts of a cat’, he told a friend.20 In common with every other ‘alien’, he was obliged to carry identity papers everywhere, obey a curfew, and observe travel restrictions. He was also forbidden from owning a motor vehicle (Rudi Peierls easily got round that particular rule – he lent his car to an English friend and then borrowed it back).21 Frisch was philosophical about these restrictions, aware that he was much more comfortable than the rest of his close family.22 In mid-February 1940, he had to break the news to his parents that the British Home Office had refused them asylum.23 Peierls was spared this disappointment: his parents had arrived in England the year before and were then safely on their way to the United States.24
The British authorities spurned all the offers made by Frisch and Peierls to help with the scientific war effort, though Peierls signed up as a volunteer firefighter. They knew that several of their colleagues were working on radar, including John Randall and Harry Boot, who were developing the cavity magnetron, a device that made it possible to generate short-wavelength radar beams in machines so compact that they could be installed in aircraft. Frisch and Peierls were for the most part onlookers on this project – they were officially forbidden to know anything about it or to enter the laboratories where the research was being conducted. So the two men had plenty of time to think about a subject considered by security officials to be irrelevant to the war effort: nuclear physics.
They had worked independently on nuclear chain reactions and knew that the overwhelming consensus among physicists was that building a nuclear bomb was not feasible, as it would require tons of uranium to produce sufficient 235U to set up and sustain the reaction. But in a conversation that took place in the Nuffield Building in March 1940, probably early in the second week of the month, they realised that the conventional wisdom was almost certainly wrong. It was Frisch who posed the crucial question: if someone had a large quantity of pure 235U, ‘what would happen?’25
Szilárd had posed this question a year before, but he and his colleagues had left it hanging in the air. Frisch and Peierls were well prepared to solve it – Frisch contributed his uncanny ability to understand the workings of gadgets, while Peierls brought his wide knowledge of theoretical physics.26 Scratching out their formulae on the backs of envelopes, the two men did the calculations quickly, sometimes guestimating quantities not yet measured, such as the likelihood that a fast neutron will interact with a 235U nucleus. The conclusion left Frisch and Peierls ‘quite staggered’, as Peierls later recalled:27 the critical size needed to set up a sustained chain reaction was not several tons but roughly eleven pounds, which would have about the volume of an orange. It should, they found, be possible to make a bomb by taking two hemispheres of 235U, each with half the critical mass, and firing them directly at each other – when they formed the critical volume, a chain reaction would spread through it, making it about as hot as the core of the sun and giving rise to a pressure some ten billion times that of the Earth’s atmosphere. The result would be a huge explosion, equivalent to the blast of about a thousand tons of dynamite.
Frisch and Peierls stared at each other in silence. Could it be that Hitler’s scientists were already making the weapon? The risk was too great to ignore, even though it would cost a fortune to set up an industrial plant to produce enough 235U to make the Bomb. Frisch and Peierls agreed: ‘Even if this plant costs as much as a battleship, it would be worth having.’ Unsure of how to bring all this to the government’s attention, they consulted the streetwise Oliphant, who advised them to write a short document that he would then send to Henry Tizard, who would know the best levers to pull in Whitehall. Within only a few days, the two physicists had put flesh on the bones of the idea, and had also thought through some of the consequences of using the weapon they had conceived. They wrote up their findings in a two-part memo in flawless English that for the most part had a Lindemannian clarity. Despite a few venial errors, the document was a masterpiece of science writing.
In the main part of the memo, ‘On the Construction of a “Super-Bomb”’, Frisch and Peierls set out their idea using language intelligible to a high-school physics student and included only one, skippable equation. For officials intimidated by even a sprinkling of jargon, the memo’s more colloquial second part, ‘On the Properties of the Radioactive Super-Bomb’, was more digestible. Here, the authors graphically described the destructiveness of one of these bombs and the radioactive fallout that would ensure that ‘even for days after the explosion any person entering the affected area will be killed’. The conclusion made sobering reading. Prefacing it with the appropriately modest statement that they ‘do not feel competent to discuss the strategic value of such a weapon’, Frisch and Peierls enumerated a list of points, one of them smuggling in a fir
m policy recommendation, based on the assumption that Germany already had the Bomb or soon would:
The most effective reply would be a counter-threat with a similar bomb. Therefore it seems to us important to start production as soon and as rapidly as possible, even if it is not intended to use the bomb as a means of attack.
The whole matter was, Frisch and Peierls concluded, ‘very urgent’ and it was ‘of extreme importance to keep [the] report secret’. They finalised it in Peierls’s office, anxious that someone might overhear them – during one conversation, they were startled when a face suddenly appeared at the window, though the interloper turned out to be a technician innocently watering tomatoes.28 Unwilling to entrust the document to a secretary, Peierls typed up the final draft, keeping only a single carbon copy under lock and key. By 19 March, the top copy was on Tizard’s desk.29 If the memo had gone to Lindemann, he would probably have made up his own mind after talking privately with a few trusted colleagues. But Tizard, typically, sought a collective decision by setting up a committee, which first met on the afternoon of 10 April at the Royal Society’s headquarters, on the site today occupied by the Royal Academy of Arts. This was a day of grim news – the Nazis had begun their occupation of Denmark and Norway.30 The British operation in Norway – ‘half-prepared and half-baked’ according to Lloyd George – was a humiliation for the Prime Minister, who was savaged soon afterwards in the Commons and in the press.31 Although Churchill had, as First Lord of the Admiralty, championed the operation and been involved up to his ears in planning it, he escaped the worst of the blame.
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