by P. D. Smith
Adamson then proceeded to lecture the scientists. ‘He told us that it was naive to believe that we could make a significant contribution to defense by creating a new explosive,’ recalled Szilard. ‘He said that if a new weapon is created, it usually takes two wars before one can know whether the weapon is any good or not.’11 Eugene Wigner, a quiet and thoughtful man, had sat there impassively as the military man lectured them. But his next words made the mild-mannered Wigner hopping mad.
‘Gentlemen,’ said Colonel Adamson patronizingly, ‘armaments are not what decides war and makes history. Wars are won through the morale of the civilian population.’12
Barely able to conceal his anger, and speaking in a ‘high-pitched voice’,13 Wigner rounded on the colonel: ‘If this is true then perhaps we should cut the army budget thirty percent and spread that wonderful money through the civilian population.’14
It’s fair to say that this first official encounter between long-hairs and short-hairs did not produce a meeting of minds. However, it did result in the first government funding for the atomic bomb – a modest $6,000, a figure plucked out of the air by Teller, to help buy graphite for Szilard’s experimental reactor. ‘After the meeting,’ said Teller, ‘Szilard nearly murdered me for the modesty of my request; and Wigner, in his gentler way, seemed ready to assist him.’15 But the Hungarian conspiracy had made a big step forward in pushing the US Government towards a superbomb project, an enterprise that would eventually cost the American tax payers $2 billion, around $50 billion in today’s money.
The difficulties the scientists encountered in the Advisory Committee on Uranium set the trend for the next two years. At every step of the way, Leo Szilard and his colleagues had to overcome scepticism and constantly nag the government to commit funding. But tenacity was one of Szilard’s God-given gifts, and he kept at it until he got what he wanted. In the meantime, he and Enrico Fermi kept themselves busy designing a uranium–graphite pile at Columbia University. He also supplied Sachs with a steady stream of memos on potential applications of atomic energy. Armed with these science fictional speculations about vast ship-borne bombs, radiological weapons and atomic powerhouses, Sachs kept up the pressure on the government.
One of Szilard’s most important scientific contributions to the bomb project was his discovery that it was essential to remove the boron usually present in graphite. Because boron absorbed neutrons, it seemed at first that graphite would be unsuitable as a moderator in an atomic pile. This was what stymied the German attempts to build a reactor.16 Fortunately, unlike Joliot-Curie, Szilard decided to keep this important discovery secret from the scientific community. Despite heavy criticism from Fermi, he refused to publish his research because of its strategic importance. Szilard’s insight into this problem, and his skill at negotiating with industrial suppliers to secure pure graphite, gave the American project a head start. According to Bethe, ‘Szilard contributed in a very major way to the early success of perhaps the most important branch of the Manhattan Project.’17 As early as 1940, even German scientists realized that reactors were the key to producing the new fissile element, plutonium. And Leo Szilard now knew how to build a reactor.
* * *
From 5 September 1940 until the middle of November, London endured nightly bombing attacks by the Luftwaffe. In the Blitz, 13,000 tons of high explosives and 12,000 incendiary bombs were dropped on the British capital. When Bela’s wife expressed her sorrow at this outrage, Leo remarked gloomily that ‘Before this war is over there will be bombs thousands of times more powerful than those in the Blitz.’18
In Britain, other scientists exiled from Germany and driven by a fear of what Hitler’s physicists might be discovering were engaged in calculations that would make Szilard’s predictions a reality. The British scientific community believed – in common with Niels Bohr – that the technical difficulty of separating the fissile isotope uranium-235 from natural uranium would rule out an atomic bomb for many years. Churchill (advised by Szilard’s friend at Oxford, Frederick Lindemann) told his Cabinet this in August 1939. Rudolf Peierls, a German physicist now working in England, thought so too. He had calculated that a critical mass of natural uranium – the amount needed to create a self-sustaining and potentially explosive reaction – would be as much as several tons. He didn’t even bother to work out a critical mass for uranium-235 as no one thought it was possible to separate sufficient quantities of this isotope from the far more abundant uranium-238.
But that was before Lise Meitner’s nephew, Otto Frisch, began to consider the problem. Like Peierls, Frisch was now working in England, at Birmingham University. He decided that uranium-235 could be separated. But how much of it would be needed to create an explosion? For the answer to this he turned in 1940 to his friend Peierls. Together they calculated the critical mass of uranium-235. ‘To my amazement,’ said Frisch, ‘it was very much smaller than I had expected; it was not a matter of tons, but something like a pound or two’19 – in other words, about the size of a large egg (uranium is about as dense as gold). In a flash, both men saw that it was possible after all to build an atomic bomb, and not one that had to be carried to its target on a ship, as Einstein and Szilard had told Roosevelt, but a bomb small enough to be dropped from an aircraft.
Frisch and Peierls went to see Mark Oliphant, their Australian boss at Birmingham, with their discovery. He immediately realized its significance and told them to write up their findings in a report for the British Government. Their brief memorandum, ‘On the Construction of a “Super-bomb”, Based on a Nuclear Chain Reaction in Uranium’, was finished in March 1940. Oliphant sent it with a covering note to Henry Tizard, chair of the government committee set up to explore ways of using science in the war against Germany. Tizard was impressed, and Oliphant was instructed to set up a small subcommittee to assess the feasibility of the atomic bomb. The members of the subcommittee included John Cockcroft and James Chadwick. They met at Burlington House, Piccadilly, where twenty years earlier – beneath the portrait of Sir Isaac Newton – the announcement had been made that eclipse observations had confirmed Einstein’s general theory of relativity. Now another group of British scientists met to consider a more deadly implication of relativity: the vast reservoir of energy trapped in the heart of matter.
In their memo, Frisch and Peierls described in detail how a bomb could be built using a sphere of uranium ‘made in two (or more) parts which are brought together first when the explosion is wanted’.20 In the bomb dropped on Hiroshima, the uranium was brought to explosive criticality by firing a piece of uranium-235 into a subcritical mass of the isotope. Frisch also explained how uranium-235 could be separated by a thermal diffusion method using gaseous uranium hexafluoride, producing 1 gram a day.
They made plain the enormous explosive power of a uranium bomb, and also highlighted ‘the effects of… radiation on human beings’. Describing for the first time in a scientific paper the effects of fallout, Frisch and Peierls noted that ‘it is difficult to tell what will happen to the radioactive material after the explosion. Most of it will probably be blown into the air and carried away by the wind. This cloud of radioactive material will kill everybody within a strip estimated to be several miles long.’ In a passage which anticipated the lethally radioactive black rain that fell after the Hiroshima bomb, they predicted that ‘if it rained the danger would be even worse because active material would be carried down to the ground and stick to it, and persons entering the contaminated area would be subjected to dangerous radiation even after days’. The scientists also warned that, because its effects could not be contained or predicted, ‘the bomb could probably not be used without killing large numbers of civilians, and this may make it unsuitable as a weapon for use by this country’.21
The atomic bomb, said Frisch and Peierls, would be ‘practically irresistible’. They predicted that ‘effective protection is hardly possible’ against such ‘super-explosions’. Only ‘deep cellars or tunnels’ might offer some protection, b
ut only if air could be supplied from an uncontaminated area. As no shelter could offer protection against the bomb, and as ‘Germany is, or will be, in the possession of this weapon’, they argued that the only practical policy was ‘counter-threat with a similar bomb’. For this reason they advised the speedy development of an atomic bomb. In the meantime they recommended that ‘detection squads’ be set up to monitor radioactivity levels in the event of surprise attacks.22 The following year, Frisch saw James Chadwick armed with a Geiger counter checking bomb craters in Liverpool, afraid that German planes might already be dropping radiological, or ‘dirty’, bombs.
By late summer 1941, the scientists had convinced the British Government that an atomic bomb could be made. At the end of August, Winston Churchill approved the proposal to develop a bomb. ‘Although personally I am quite content with the existing explosives,’ he wrote, ‘I feel we must not stand in the path of improvement’.23
As Churchill was giving the go-ahead to the British atomic bomb (innocuously code-named ‘Tube Alloys’), Mark Oliphant was on his way to the United States to find out why his American colleagues had not yet responded to the British scientists’ report. The bluff Australian was not impressed with what he found on the other side of the Atlantic. The attitude of Lyman Briggs, a former soil scientist now nearing retirement, typified for Oliphant the lack of urgency among his American allies. Briggs showed Oliphant the Frisch–Peierls memo, together with other British reports on the atomic bomb, locked away in a safe in his office. ‘No one had read them,’ said the exasperated Oliphant. ‘I don’t believe that mild-mannered old gentleman had read them! Not one of them knew what I was talking about.’24
‘Amazed and distressed’, Oliphant voiced his concerns in a typically robust manner to everyone he met.25 He made a deep impression on cyclotron-builder Ernest O. Lawrence at Berkeley. ‘The waste of time is criminal,’ Lawrence agreed.26 He immediately arranged for Oliphant to see Vannevar Bush and James Conant. Bush, an engineer by training, headed up the newly created Office of Scientific Research and Development (OSRD), an organization which oversaw the mobilization of American science for military purposes. Conant was the Chairman of the National Defense Research Committee (NDRC), a subsidiary of the OSRD, which had absorbed Briggs’s Uranium Committee the year before.
Unknown to Oliphant, a secret copy of the British report had reached Bush and Conant – despite appearances, the atomic bomb was quite definitely on the agenda. Gradually, Oliphant’s brusque lobbying won the two men round. When Bush officially received the report, he took it personally to the President on 9 October 1941. Slowly but surely, the machinery of American bureaucracy was gearing up to build the most terrible weapon the world had yet seen.
On Saturday 6 December 1941, a cold and crisp Washington morning, James Conant convened a meeting of the key players in the Uranium Committee. He had important news for his colleagues: FDR had authorized an ‘all-out’ project with the ultimate aim of building an atomic superbomb.27 The newly reorganized project was to be known as S-1, Section 1 of the OSRD. Conant told them that Harold Urey was to continue his promising work on isotope separation by diffusion at Columbia, while Lawrence would work on electromagnetic separation at Berkeley. In Chicago, Arthur Holly Compton would pursue theoretical studies and bomb design. He was also to investigate the new element plutonium and its possible use in a bomb. Two years after Einstein and Szilard wrote to Roosevelt, America was finally set on a course to build the atomic bomb. The next day, Pearl Harbor was attacked without warning by Japanese planes, killing 2,403 American soldiers and civilians. The United States of America was at war.
In November 1940, for the first time in a decade, Leo Szilard began receiving a salary. It was paid by James Conant’s NDRC. Together with Enrico Fermi, Szilard was developing a graphite-moderated reactor at Columbia. As ever, he was reluctant to get his hands dirty handling the graphite. With his new income he hired two assistants for that – Bernard Feld and John Marshall, Jr. When he heard this, Edward Teller couldn’t resist nicknaming his Hungarian friend Feld-marschall – ‘field marshal’. At least it was a step up from Director General.
Before the President finally gave the go-ahead for the atomic bomb project, Szilard had been growing increasingly impatient with the US Government. Like Frisch and Peierls in Britain, he was still classed as an enemy alien by the authorities. Ironically, the very scientists who knew most about the atomic bomb were deemed untrustworthy by the Allies. As a result, neither Szilard nor Fermi were told about the new low estimates for the critical mass of a bomb. Neither did they know that Harold Urey had made considerable progress by the end of 1941 in separating uranium-235. ‘Urey’s contract specified that he was not supposed to discuss his results with Fermi and me, who were not cleared,’ said Szilard. ‘Therefore we were not able to put two and two together and come out with the simple statement that bombs could be made out of reasonable quantities of uranium-235.’28
Leo Szilard credited Mark Oliphant with kick-starting the Manhattan Project. Oliphant disregarded ‘international etiquette’ and told ‘all those who were willing to listen what he thought of us’, wrote Szilard later:
Considerations other than those of military security prevent me from revealing the exact expressions he used. If Congress knew the true history of the atomic energy project, I have no doubt but that it would create a special medal to be given to meddling foreigners for distinguished services, and Dr Oliphant would be the first to receive one.29
As a result, by the start of 1942 there was a new sense of urgency about the atomic bomb. Szilard and the other ‘meddling foreigners’ were delighted. In January, Szilard moved to Chicago. Compton had insisted that Szilard and Fermi relocate to the city. Compton now had a clear plan of action. It was a tight schedule: they were aiming for a chain reaction by January 1943 and a functional bomb by January 1945.
Moving to Chicago annoyed Leo Szilard. He was happy in New York where he had established a network of scientific and business contacts. His brother Bela was there, as was Trude, who was now working at a New York hospital. It was the first sign that the physicists were losing control of the project. According to the historian of the atomic bomb Richard Rhodes, from the outset of the American atomic energy programme
scientists were summarily denied a voice in deciding the political and military uses of the weapons they were proposing to build… A scientist could choose to help or not to help build nuclear weapons. That was his only choice. The surrender of any further authority in the matter was the price of admission to what would grow to be a separate, secret state with separate sovereignty linked to the public state through the person and by the sole authority of the President.30
Despite his irritation at being forced to move to Chicago, Szilard soon felt at home living on the campus, with its late-nineteenth-century, grey-stone neo-Gothic buildings. It reminded him of Oxford, but it was not that different from leafy Dahlem either. Rather than living in a hotel, he rented a room with maid service in the comfortable Quadrangle Club, and settled down to work on his brainchild.
As far as the Manhattan Project was concerned, the University of Chicago was known by the code name of the Metallurgical Laboratory, shortened to Met Lab. Szilard eventually became the Met Lab’s chief physicist. The physicists worked first in the three-storey Eckhart Hall. Their objective was to achieve what Szilard had first visualized back in Russell Square in 1933 – a self-sustaining chain reaction with neutrons. Inside what was essentially a nuclear reactor, the storm of neutrons released from the fissioning uranium would transmute the uranium-238 into the new element, plutonium. With this element, the scientists hoped to be able to build atomic bombs without the need for the difficult process of separating uranium-235 from uranium-238. Although Szilard never worked on the design of bombs, Met Lab’s work was crucial to the success of the whole bomb project. The military importance of Met Lab was apparent when armed guards were posted at Eckhart Hall to check passes.
Szilard
never liked being surrounded by armed guards. He hated bureaucracy even more, and as the federal government became ever more involved in the project, so this steadily increased. During 1942, he subjected the leaders of the project to a stream of complaints about slow progress and the growing threat from Germany. On 26 May 1942 he wrote to Vannevar Bush: ‘Nobody can tell now whether we shall be ready before German bombs wipe out American cities.’31
Fourth-anniversary reunion of CP-1 scientists on the steps of Eckhart Hall, Chicago, 2 December 1946. Front row, from left to right: Enrico Fermi, Walter Zinn, Albert Wattenberg and Herbert Anderson. Leona Woods Marshall is in the middle row, and next to her in the raincoat is Leo Szilard.
The implication behind all these complaints was of poor management. Szilard always believed he should have been in charge of the atomic bomb project. After all, no one had invested more time, energy and brainpower in atomic energy – its science, engineering and political implications – than Leo Szilard. Now he could only stand by and watch as his brainchild was gradually taken over by other people. ‘If the project could have been built on ideas alone,’ said Wigner later, ‘Szilard alone could have done it.’32 Although he bore the brunt of Szilard’s incessant kvetching, Compton respected the troublesome Hungarian. He reassured his irate boss, Bush, by saying that Szilard was ‘one of the most valuable members of our organization’.33 But he couldn’t halt the complaints.
As Teller ruefully acknowledged, Szilard’s name means ‘doggedly determined, or to put it less politely, rather stubborn’.34 In September 1942, Szilard prepared a memo for the project with the provocative title ‘What Is Wrong With Us?’ In it he admitted that ‘I am, as a rule, rather outspoken, and if I do not call a spade a spade I find it rather difficult to find a suitable name for it.’35 Again he complained about delays, as well as an increasing tendency to force scientists to concentrate on a very specific area of research. This ‘compartmentalization’ of knowledge was a security measure imposed by Washington to prevent the spread of classified information. Soon every aspect of the project was on a need-to-know basis. But, as Szilard later put it, ‘compartmentalization of information poisons the discussion’.36 Scientific progress depends on the free flow of information, and that, in Szilard’s view, was not happening. It was ironic that this complaint came from the man who had done more than anyone to introduce secrecy into the science of atomic energy.
