There was no time to delay. On the basis of the startling new knowledge unleashed by the Frisch–Peierls Memorandum, a British wartime committee of scientists known as the Military Application of Uranium Detonation (MAUD) Committee was established in April 1940 out of the broader but short-lived committee called the Scientific Survey of Air Warfare. (It quickly became the Maud Committee and there are several theories why the upper case acronym was dropped, one being in reference to Maud Ray, a governess to the children of the pioneering quantum mechanics theorist Niels Bohr while he visited the UK.) The Maud Committee developed the ideas sketched out in the Frisch–Peierls Memorandum into a practical plan to build an atomic bomb. The committee had as members some of the leaders of British physics at that time, including Mark Oliphant and the later Nobel Laureate John Cockcroft. The authors of the famous memorandum were not allowed to be members, though, because of their German background and continuing connections with some German physicists. These connections were, most notably, via Frisch’s eminent aunt, Austrian-born Lise Meitner, who maintained links to colleagues in Germany even though she had fled to Sweden. Nevertheless, the pair was consulted regularly by the committee. Because so many of the most important thinkers in this field were from Germany, over time the Maud Committee accepted several exiled Germans as members, although never Frisch or Peierls. The pair did become members of a technical sub-committee later, though, where their input continued.
The Maud Committee, which met at the Royal Society in London and was chaired by Professor George Thomson, oversaw a secret experimental program carried out at four main British universities: Liverpool, Birmingham, Oxford and Cambridge. Physicists from the eminent London universities had been evacuated to Liverpool during the Blitz. In an astonishingly short time and for negligible expense, this highly targeted team made huge progress. They quickly filled in the gaps of the theoretical musings of Frisch and Peierls around concentrating uranium-235 with new understanding and practical strategies. According to Gowing, despite the fact that this work was carried out in open laboratories at the universities, the physicists managed to keep what they were doing secret, largely through an ingenious system of codenames, including tube alloys, which soon took on considerable significance. While the exact reasons why many of the British atomic codenames were chosen are usually unclear, the pattern does seem to be obfuscation, often combined with British whimsy.
In these early, pioneering days secrecy was not difficult to achieve. By the end of 1940, as Nazi bombs rained down on Britain during the Blitz, the Maud Committee delivered its verdict – uranium-235 could be created in the right quantities and therefore a fission ‘super-bomb’ was feasible. Experimental and theoretical hints emerged of new, unnatural radioactive elements too, created in a reactor by irradiating uranium with neutrons. These new theorised substances were named to conform to the planetary origins of the name uranium. One was neptunium. The other was plutonium.
To create a nuclear bomb, the physical properties of the radioactive substance at its heart have to be awakened in a precise and technically challenging way. A fission reaction occurs when a substance such as uranium-235 is bombarded with a controlled cascade of neutrons, unleashing tremendous energy. However, this reaction is fraught with difficulty since bombardment on its own is insufficient. Generally neutrons fired at uranium arrive too fast and are dispersed without causing fission reactions. The neutrons have to be slowed down and better directed to ensure a chain reaction. Adding hydrogen as a moderator, generally in the form of so-called heavy water, can slow neutrons.
Heavy water is made up of hydrogen and oxygen, like normal water, but the hydrogen is a particular isotope called deuterium that contains neutrons. The neutrons make this kind of water about 11 per cent denser than normal water. The particular properties of heavy water enable it to slow down incoming neutrons. By a combination of luck and good management, 26 cans of heavy water produced in France as the war began were spirited away to the UK when Paris fell. Initially stored at Wormwood Scrubs prison, and later shifted to Windsor Castle, the heavy water proved to be an invaluable resource as scientists attempted to understand how to moderate the influx of neutrons. Slowing down the reactions in uranium posed significant problems, and the first bombs could not have been developed so quickly without heavy water. As it happens, plutonium is ruthlessly efficient in creating a chain reaction using fast neutrons, thus removing the technical constraints on slowing neutrons down. Ultimately, plutonium became the material of choice in nuclear bombs, including those tested in Australia.
By March 1941, the Maud Committee had incontrovertible proof that the bomb was feasible and could be created from just 8 kilograms of uranium-235. They finalised their report in July 1941. Bluntly titled ‘Use of Uranium for a Bomb’, it laid out a blueprint for a workable bomb. The committee also produced a report on atomic energy, ‘Use of Uranium as a Source of Power’. The two new uses of uranium were laid bare, and the committee never met again.
At the time, Britain was in the middle of the Blitz, which lasted from September 1940 until May 1941, so it was not a safe place to develop the bomb. They needed to find somewhere else.
The Maud Report on the atomic bomb was sent up the chain of command to the highest levels of the British Government. Several months later a new entity was created: the Directorate of Tube Alloys, housed within the Department of Scientific and Industrial Research. Tube Alloys was Britain’s new A-bomb establishment, the forerunner to the organisation that later tested bombs in Australia. The name was marvellously enigmatic – indeed, as Gowing described it, ‘meaningless and unintelligible’ – and most likely to be associated in the casual observer’s mind with aeroplane or tank parts. Such a simple strategy was remarkably successful and provided excellent cover.
While the Maud Committee stage-managed the realisation of the dangerous Frisch–Peierls idea, the US was working on its own top-secret physics separately. The Americans had not yet been party to the Frisch–Peierls Memorandum; if they had, their work might by then have been further advanced than the British. But at this point, Britain was well in front. For the idea of the bomb to be made real, though, it would have to shift across the Atlantic.
Some insiders in Britain wanted the bomb-building infrastructure to be established in Canada, a close and trusted member of the Commonwealth and the main supplier at that stage of uranium oxide, but in the end the better equipped US had to be the choice. After a slow start, American atomic bomb research was accelerating. A summary of the activities of the Maud Committee was transmitted to the US in July 1941, although the Maud Report itself did not arrive until October. News about the Maud scientists and the contents of the Frisch–Peierls Memorandum (so far unseen in the US) had an instant effect. Mark Oliphant was among the insiders who took this knowledge to America in 1941, speaking to US military officials and fellow physicists. He found an attentive reception. Such visits led to a chain reaction of information, and the physics world in America lit up. The American physicists, now in possession of the work by the Maud scientists as well as their own escalating research, understood immediately what could be unleashed.
In December 1941, just after the Japanese attack on Pearl Harbor brought the US into the war, the US Government established the Office of Scientific Research and Development to pursue atomic weapons science. This organisation began collaborating with the new Directorate of Tube Alloys, intensifying the information flow across the Atlantic for a short while. In the US, Glenn Seaborg pioneered research on the chemistry of plutonium at Berkeley in California that proved essential to bomb development. In the Metallurgical Laboratories in Chicago sufficient quantities of plutonium were created for the first time. The Americans, in remarkably quick time, did not actually need the British any more, and increasingly UK physicists were shut out. Political tussles erupted between the two allies over who would take the lead.
By early 1942 there was no doubt. The US was unstoppable. After considerable wrangling, Roosevelt and Bri
tain’s prime minister Winston Churchill struck the Quebec Agreement, a painstaking negotiation that set the ground rules for engagement between the two countries and established a joint project to find and buy uranium. The rules limited British access to the project, which meant that British scientists developed expertise only in certain areas. The Americans would not agree to continuing British involvement on any other terms. The Quebec Agreement allowed British scientists to travel to the US to continue fulfilling the promise of the Frisch–Peierls Memorandum, and atomic bomb building activities in the UK were effectively closed down. All efforts were focused on America. The full implications of the Quebec Agreement were felt later when the US pushed them away completely and the British found themselves only partially equipped to build their own atomic weapon.
The Manhattan Project had its beginnings in 1939 when Roosevelt established the Advisory Committee on Uranium. It became a military and political priority in August 1942 when it was transferred to the control of the US Army. The project was named after New York’s Manhattan Island, where a group of engineers had been recruited to construct some of the required infrastructure. A new top-secret laboratory, built on a desert mesa at remote Los Alamos in New Mexico, was set up to build the bomb. Many British scientists went there to brave the desert winds and fight against time to build a weapon never seen before. Other laboratories around the country, notably the Lawrence Livermore National Laboratory in California and Oak Ridge, built on a farm in Tennessee, joined the effort as well. In all, around half a million people ended up working on the Manhattan Project.
From 1942, General Leslie Groves, a gung-ho US Army officer, led the atomic bomb project. Groves chose a young American physicist, J Robert Oppenheimer, to head the weapons laboratory. It was a surprising choice because Oppenheimer was open about his leftist leanings – some even thought he was a communist – and throughout the entire time he worked on the project he was enthusiastically investigated by the notoriously paranoid Federal Bureau of Investigation headed by J Edgar Hoover.
Groves and Oppenheimer gathered together a team of physics brainpower the likes of which had never worked together before. Hundreds of thousands of physicists, chemists and technicians joined the effort between 1941 and 1945, including some of the greatest contemporary thinkers. Many were European scientists who had fled the rise of Nazism. Once the political differences between America and Britain were sorted out, largely through the 1943 Quebec Agreement, a significant number of scientists joined the Manhattan Project from the UK as part of the British mission, including William Penney and Ernest Titterton, later pivotal in the Maralinga story. Klaus Fuchs – another pivotal scientist for a different reason – also joined the effort.
Physics had always been an open science, where an international community of theorists and experimentalists shared their hypotheses and observations. The Manhattan Project, of necessity, could not operate like that. Its activities were totally secret. The results of the speeded-up experimental work could not be published in the scholarly literature; the work could not be discussed at international conferences; other laboratories couldn’t attempt to replicate the findings of researchers unless they were inside the tent. This secrecy rankled many scientists, and some refused to accept it. The more extreme became atomic spies. Others, such as Ernest Titterton, went the other way. Titterton relished secret work, as his later behaviour in Australia abundantly demonstrated.
Professor William Penney, another Manhattan Project physicist, was likewise comfortable with secrecy. His extensive background in secret wartime explosives and atomic weapons research equipped him to head the British nuclear tests in Australia. Penney was part of the small team who selected the targets for the Manhattan bombs, surely an onerous responsibility for a donnish mathematical physicist. He also visited Hiroshima after the bomb was dropped and conducted numerous scientific measurements on the ground.
In short, the Manhattan Project trained the men who later made the British bomb and brought it to the Australian desert. The huge covert project also taught them to keep their knowledge close. This ability to keep atomic secrets meant going against their scientific training. However, there is no reason to believe that these men (they were overwhelmingly men) were not sincere in their belief that the future safety of the world depended upon their ability to quietly and methodically change the nature of warfare.
The Trinity test of 16 July 1945 at Alamogordo in the New Mexico desert was a bittersweet moment for the science of physics. On the one hand, the brilliance of the thinkers engaged by the knotty problems presented by the bomb project prevailed. These were among the best minds of their generation, and, collectively, they moved nuclear physics and technology to a new realm. On the other hand, they unleashed a monster, and no-one was better placed than they were to understand this brute fact. While harnessing fundamental physical forces had undoubtedly given the whole enterprise a feeling of great adventure, the sobering reality hit when they saw the tangible evidence of their success in the form of a billowing mushroom-shaped cloud.
Oppenheimer, who had a literary bent, is said to have drawn inspiration from a John Donne poem to name the test Trinity. The plutonium bomb, nicknamed the gadget, and fundamentally the same as the weapon dropped a few weeks later on Nagasaki, produced the explosive force of 20 kilotonnes of conventional TNT. A select group of observers, including Oppenheimer and General Groves, were positioned about 32 kilometres from the device for the 6 am test. While some feared the device would fizzle (bets were taken on the outcome and fizzle was an option), instead it rose dazzlingly from the desert plain to create an awe-inspiring mushroom cloud that climbed upwards over 12 kilometres. A thump on the earth was felt by an oblivious civilian population in a 160-kilometre radius of the test site. Oppenheimer spoke his famous lines quoting Vishnu, destroyer of worlds, and recalled later in a haunting recorded interview, ‘We knew the world would not be the same. A few people laughed, a few people cried. Most people were silent’. The atmosphere of the protective bunker is almost palpable in these words.
A few weeks later, on 6 August, people died in their tens of thousands because of this great leap forwards in nuclear physics. President Harry Truman said in his statement to a stunned American population immediately after the world’s first A-bomb was dropped, ‘It is an atomic bomb. It is a harnessing of the basic power of the Universe’. He continued, ‘We have spent two billion dollars on the greatest scientific gamble in history – and won’.
The bomb dropped on Hiroshima was a crude nuclear weapon, codenamed Little Boy, based upon uranium-235 and using a technique known as gun technology that quickly became obsolete. It involved driving a cylinder of uranium-235 into the centre of another cylinder of the same substance with a hole in it. The bomb dropped on Nagasaki was nicknamed Fat Man and operated quite differently using plutonium. The basic idea of Fat Man (and indeed of the gadget) was to jam two half-spheres of plutonium together by detonating high explosives in a small space, initiating a chain reaction in which neutrons split the atoms and released energy. Fat Man was superior to Little Boy in design but had some drawbacks. In particular the weight of the conventional explosive needed to initiate the reaction made the bomb much bigger than Little Boy – hence ‘Fat Man’ – which presented logistical difficulties. The aircraft that dropped the Hiroshima bomb, Enola Gay, could not drop Fat Man. Instead, a specially modified B-29 called Bockscar was used for the task.
Some Manhattan scientists, notably the American Ernest Lawrence, argued for an eye-opening but non-lethal ‘demonstration’ of the weapon to the Japanese, rather than using it on human targets. The idea was dismissed. Washington agreed with the Scientific Advisory Committee: the shock value would be lost if the weapon was not used for real. Arguments about the ethics of that decision continue today.
In the final months leading up to the Trinity test, Winston Churchill wanted to ensure that the collaboration would continue after the war ended. Now that the idea of a fission bomb was becoming re
ality, with crucial input from both sides of the Atlantic, such a collaboration seemed both likely and desirable. The Hyde Park Agreement struck between Churchill and Roosevelt on 19 September 1944 said in part, ‘Full collaboration between the United States and the British Government in developing tube alloys for military and commercial purposes should continue after the defeat of Japan unless and until terminated by joint agreement’. In fact, soon after the defeat of Japan, the Americans changed their minds.
After Hiroshima and Nagasaki, the world collectively took a deep breath. Atomic bomb research stopped abruptly, and bomb-making expertise dispersed for a short time as the Manhattan Project scientists and technologists went back to where they came from. While Little Boy and Fat Man had worked as they were designed to do, they were not well-developed bombs, and nuclear weapons needed more research, testing and refinement. But for a moment, everyone involved stopped to take stock, while the shock waves from the war in general, and the atomic weapons in particular, ebbed away. What had been wrought was so world-changing that for a while those involved did not know what to do. The genie was out of the bottle. During this time, both the UK and the US held talks with the United Nations (established in October 1945) to try to formulate a way that nuclear weaponry and energy could be harnessed without sparking an unstoppable nuclear arms race. The talks were unsuccessful and an arms race soon began.
The US gathered its thoughts on the existential issue of nuclear warfare and pondered the consequences of rapid atomic weapons development. One of its first postwar actions was to drive its atomic weapons allies away. The McMahon Act (known officially in the US as the Atomic Energy Act) was the result of this period of postwar reflection. This new American law, which banned collaboration on nuclear weapons development, took Britain by surprise and created a range of problems that the nation had not seen coming. Indeed, Britain saw the McMahon Act as a betrayal by the Americans, after Britain had handed over so much expertise during the war. Suspicions arose that the McMahon Act was a commercial decision, attempting to corner a lucrative new market in weaponry and energy. British know-how, combined with that of British-based European refugees who had escaped from the Nazis, made the atomic bomb possible. Suddenly Britain was elbowed out of the nuclear game. The country was displeased and wrong-footed.
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