The Basis of Everything

by Andrew Ramsey

  Then, within two months of Oliphant’s report to the council, the university was advised by another automotive entrepreneur, Lord Nuffield, in a covering letter of ‘barely five words’,7 that he would make available a grant of £60,000: the precise figure Oliphant had named. As the grateful professor wrote in a Birmingham newspaper in the days that followed, the gift represented ‘an expression of his knowledge of the great role played by physical science in industry today’.8

  The irony that the first Viscount Nuffield – born William Morris and founder of the eponymous motor vehicle manufacturer – had come to his rescue only heightened Oliphant’s sense of triumph. It was a victory he felt most keenly when he climbed behind the wheel of the decrepit car he had previously considered a liability, for his daily fifteen-kilometre drive to the university. There, after seeing off bids from envious colleagues to have Lord Nuffield’s gift spread across all science disciplines, the new professor began enacting his vision.

  * * *

  Oliphant had already announced his intention to build Britain’s most powerful particle accelerator, which would shade the technology he had helped deliver to the Cavendish as well as the ongoing efforts under Chadwick at Liverpool. He also knew where a blueprint for that accelerator would be most readily found.

  He duly submitted his idea to the university’s newly appointed vice-chancellor, Raymond Priestley. Priestley had been the registrar at Cambridge when Oliphant first arrived there, and he was a former Antarctic exploration colleague of another Adelaidean, Sir Douglas Mawson. Oliphant received the go-ahead for a fact-finding visit to his friend Ernest Lawrence at California University’s Berkeley campus near San Francisco. The sabbatical would forge a friendship that was ultimately crucial to the birth of the bomb.

  Oliphant had previously met Lawrence only briefly, when the tall, almost puritanical American delivered an address at Cambridge on his way home from the 1933 Solvay Conference in Brussels. Lawrence’s self-assured challenges to accepted thinking at the Solvay, a periodic gathering of the foremost international names in physics and chemistry, saw him labelled brash and impatient, qualities that had led Rutherford to observe: ‘He is just like I was at his age.’9

  From the moment that Oliphant set foot on campus at Berkeley, having sailed to America in late 1938, he was dazzled – not only by the striking similarities in character and competence between ‘The Two Ernests’, as he would label his memoir of working with Lawrence and Rutherford, but also by the equally impressive research environment the former had cultivated.

  Like Rutherford, Lawrence had been raised in a small, isolated community, though in South Dakota rather than the southern hemisphere. Both his parents were schoolteachers, and in adolescence Lawrence showed a mastery of mechanical equipment – motor cars, radios – and a fascination with the way the world around him worked. When he was appointed as an associate professor at Berkeley in 1928, he decided that his research focus would be the atomic nucleus. As a child of the machine age, just two months older than Oliphant, he differed fundamentally from Rutherford in his belief that answers lay in the construction of bigger, more powerful technology.

  Oliphant would later write a lengthy essay comparing his two most enduring influences.

  Neither was a good speaker or lecturer, yet each influenced and inspired more colleagues and students than any other of his generation. Both built great schools of physics which became peopled with other great men, and Nobel prizes went naturally to members of their laboratories. Each was most generous in giving credit to his junior colleagues, creating thereby extraordinary loyalties.

  Rutherford and Lawrence were self-confident, assertive and at times over-bearing, but their stature was such that they could behave in this way with justice, and each was quick to express contrition if he was shown to be wrong.

  Both Rutherford and Lawrence could be devastatingly blunt and uncompromising when faced with evidence of lack of integrity, or gullibility, in scientific work. But there was one great difference. Rutherford enjoyed what has been called smoking room humour. Although his own memory for such stories was not good, his great roar of booming laughter was to be heard after dinner as he savoured the subtlety of some lewd tale.10

  Lawrence, by contrast, never uttered a swear word and would have balked at even a suggestion of ribald humour.

  His pivotal partnership with Mark Oliphant was struck over dinner in late 1938, at Lawrence’s favourite restaurant, the Hawaiian-themed Trader Vic’s. The pair’s animated discussions then continued at the site of Lawrence’s giant cyclotron at Berkeley, and in his office, where Oliphant first met the aloof Robert Oppenheimer. It was through this succession of meetings that Oliphant saw the future, in terms of both the infrastructure he would introduce to Britain, and the experimental team he would seek to assemble.

  Lawrence had been drawn to exploration of the atomic nucleus as a result of Rutherford’s pioneering work at the Cavendish. In turn, the American added superior engineering acumen to the late professor’s canny intuition. The science behind the cyclotron – with its beams of particles harnessed by enormous magnetic forces, accelerating at increasing velocities around a curved track before being fired at targets, like stones from a slingshot – accordingly made Oliphant’s eyes dance in delight.

  Initially, Lawrence’s machine had used an eighty-ton magnet to boost hydrogen ions, within an accelerating chamber five inches (12.7 centimetres) in diameter, to an energy level of 80,000 electron volts. More powerful magnets and more sophisticated apparatus increased the track’s size to eleven inches (28 centimetres) and capability to 1 million volts. By the time Oliphant visited, Lawrence was gaining results from his thirty-seven-inch (ninety-four-centimetre) cyclotron that could accelerate alpha particles to 16 million electron volts – around four times the energy generated by alpha particles emanating from radioactive uranium. It was a precursor to the Large Hadron Collider in Switzerland, which pushes particles close to the speed of light through a subterranean ring twenty-seven kilometres long.

  Oliphant sailed back to Birmingham in early 1939, as inspired by prospects of the possible as he had been after Rutherford’s Adelaide visit – but this time with resources at his fingertips, and resolve born of proven achievements. This was reflected in the excited letter he wrote to Lawrence upon his return, recounting his experiences at Berkeley.

  I know of no laboratory in the world at the present time that has so fine a spirit or so grand a tradition of hard work. While there I seemed to feel again the spirit of the old Cavendish, and to find in you those qualities of a combined camaraderie and leadership which endeared Rutherford to all who worked with him.11

  He had decided he would use the Nuffield grant to build a sixty-inch (1.5-metre) cyclotron at Birmingham, like nothing that existed in Britain. ‘Many things about the cyclotron are now clear, which were formerly hazy,’ Oliphant declared elsewhere in that same letter to Lawrence. ‘I return with a greater confidence and a greater belief in the cyclotron, in physics and in mankind’.12

  That was despite the major modifications needed to the Berkeley blueprint to transplant it to Birmingham, and the unwillingness of heavy manufacturing businesses in the British Midlands to lend support through donating funds, raw materials or engineering expertise for the ambitious project. Oliphant, however, showed how relentless he could be with a mission in mind, and slowly the ‘giant atom-splitting machine’, as the press dubbed it, took shape.

  The single-level Nuffield Building housed a pit almost five metres deep, lined with lead and surrounded by water tanks, ‘so that workers in the vicinity won’t be killed by the terrific radiations emitted from it’, one local newspaper reported.13 Around fifty tons of copper wire were wound into coils for the massive electromagnet, which measured almost two metres in diameter, and weighed around 300 tons. The same tonnage of plate steel was shipped from Glasgow for the magnet frame, though work stopped when a five-metre sheet fell on two research workers helping build the monster apparatus,
breaking both legs of both men.

  The vast copper-coil ‘pancakes’ that made up the magnet, so heavy they caused sections of wooden floor to give way, needed to fit together so snugly that even the smallest positioning supports proved too intrusive. Instead, the copper was lowered into place upon a layer of dry ice, which would then evaporate as the massive plates gently settled.

  By May 1939, Oliphant forecast that the cyclotron would be operational by year’s end. Speculation grew as to the fantastic possibilities that might emerge from its reputed power to transform every known element. ‘In fact it may be practicable to change one pound of matter so that it will produce the equivalent energy of the burning of something like five million tons of coal,’ a journalist enthused. ‘An illustration of this possibility is that it might be possible to carry enough fuel to drive the Queen Mary across the Atlantic in the captain’s waistcoat pocket.’14

  * * *

  The reason why Oliphant’s atom-smashing machine was being touted as a source of unimaginable energy was the result of a discovery made in Germany six months earlier.

  Rutherford’s former McGill student Otto Hahn had been performing experiments at Berlin’s Kaiser Wilhelm Institute in which uranium was bombarded with neutrons fired at slower speeds than those generated by powerful particle accelerators.

  The results puzzled him, so he wrote to his friend and former collaborator Lise Meitner, an Austrian of Jewish heritage and the aunt of Otto Frisch, who had been at Rutherford and Oliphant’s Royal Institution discourse years earlier. Like her nephew, who had previously fled to England by freighter in 1933, Meitner had escaped following Hitler’s Anschluss of Austria in 1938 and taken up a research position at Stockholm’s Nobel Physics Institute. She was similarly perplexed by the issue that had puzzled Hahn – namely, how disintegration of uranium (atomic number 92) could yield traces of barium (56), a metal so far removed from uranium on the periodic table. While transmutation was by now standard practice for nuclear physicists, it was expected that the fragments chipped off elements would reveal similar atomic properties to their source.

  The exiled Meitner travelled to Kungälv, near the Swedish port city of Gothenburg, for Christmas in 1938 with family. This included her nephew, who had by now returned to Europe and the supposed safety of Niels Bohr’s institute in Copenhagen. Frisch and his aunt spent the morning of Christmas Eve hiking through deep snow – Frisch wearing cross-country skis, while Meitner, who often walked more than ten kilometres per day, kept pace unaided. They would stop occasionally to rest and discuss the likely reasons for Hahn’s confounding results.

  It was in that postcard Yuletide setting, while they were seated upon a toppled log, that the answer dropped with the startling clarity of a fresh snow flurry.

  The pair tried applying the liquid-drop model of the atom that Bohr had devised, which proposed that the nucleus of an atom resembled a water droplet held together by forces of attraction. Therefore, Bohr argued, the atom might be capable of absorbing a colliding neutral particle that carried the appropriate level of energy.

  Meitner and Frisch hypothesised that Hahn’s uranium atoms had done precisely that – and in so doing, had split into two roughly equivalent parts, which, because of their altered structure and the accompanying release of the particles’ binding energy, instantly repelled each other with huge force.

  Frisch returned to Copenhagen, where he confirmed Hahn’s experimental findings. He chose the term ‘fission’ for this stunning process, in which one atom was transformed into two. He would later calculate that the energy released when each uranium atom split was around 200 million electron volts – enough to make a grain of sand visibly jump when a solitary uranium nucleus popped. He also noted that a single gram of uranium contained something like 2.5 x 1021 atoms – a number written as twenty-five followed by a further twenty zeroes.15

  Frisch wrote of this find to his concert pianist mother Auguste, Meitner’s sister, and conceded that when he hit upon this discovery he ‘felt like someone who has caught an elephant in the jungle by the tail and did not know what to do with it. But he knew it was an elephant.’16

  Barely a decade had passed since Ernest Rutherford stood before a meeting of the British Association for the Advancement of Science in Liverpool and dismissed suggestions that new sources of power might become available through the sudden release of energy stored in atoms. Elsewhere, Rutherford had acknowledged that, if the disintegration of heavy atoms including uranium could be somehow speeded up, so that the rate of radioactive decay could be condensed into a few days rather than millions of years, then nuclear power might be feasible. ‘Unfortunately,’ he had concluded ‘although many experiments have been tried, there is no evidence that the rate of disintegration can be altered in the slightest degree by the most powerful laboratory agencies.’17

  Come the end of 1938, that was palpably no longer true.

  When Frisch revealed the theory to Bohr in Copenhagen, the Dane slapped a hand to his forehead before exclaiming: ‘Oh what idiots we have all been.’18 He was about to sail to the United States for a conference in Washington, DC, and when he arrived, news of the discovery roared through America’s science community like a contagion.

  In Berkeley, physicist Luis Alvarez was reading a newspaper in a barber’s chair when he saw the headline proclaiming the splitting of the uranium atom, and bolted so quickly back to Lawrence’s laboratory his barber feared his cut-throat razor had slipped. Alvarez burst in on a seminar to deliver the news to Robert Oppenheimer, who countered: ‘that’s impossible’.19 Mark Oliphant first learned of the breakthrough when Nature magazine arrived on his desk at Birmingham in mid-January 1939.

  More startling revelations had quickly followed. It was known that uranium, a metal that looks rather like lead and is softer than iron, existed as two isotopes. The more predominant of those, which had an atomic weight of 238, was found to be 140 times more abundant than uranium-235, which accounts for around 0.7 per cent of the naturally occurring element. It was Bohr who realised, while still in the United States in early 1939, that only the rare 235 isotope underwent fission when bombarded with slow neutrons.

  This explained why the element remained present in the earth’s primitive rocks, as well as in seawater – even though both isotopes continually emitted mild radioactivity as uranium transmuted itself to lead over billions of years. The fact that the fissionable uranium-235 existed in such minute quantities meant it was never available in sufficient concentration to promulgate violent fission and spontaneously explode.

  A more sobering observation was initially made by physicist Leo Szilard, who had left his native Hungary for the United States in the aftermath of the First World War. It was at the height of the Cavendish’s fame, as Chadwick discovered the neutron and Cockcroft and Walton artificially split the atom, that Szilard saw the possibility of a self-sustaining nuclear chain reaction.

  If an environment could be created whereby a nucleus, split by a neutron, spat out other neutrons from the resultant disintegration, then those released neutrons could, in turn, repeat the effect as they collided. One split atom triggers another two, then four, and so on. With the right concentration of source materials to sustain that sequence, the result would be an exponential spike in atomic explosions, all taking place within millionths of a second. Each one would release vast energy in an instant, making it uncontrollable. And unthinkable.

  When Szilard learned of Otto Hahn’s discovery, he understood that the dystopian vision he had grimly foreseen was now at the door.

  ‘Hahn found that uranium breaks into two parts when it absorbs a neutron,’ Szilard recounted. ‘When I heard this I immediately saw that these fragments, being heavier than corresponds to their charge, must emit neutrons and if enough neutrons are emitted . . . then it should be, of course, possible to sustain a chain reaction.’20 Szilard was among the first to calculate that the average number of neutrons released when a uranium atom split was 2.5.

  With
in a year, more than 100 scientific papers exploring uranium fission were published. Many of them touted the theoretical prospect that if sufficient quantities of the difficult to isolate uranium-235 isotope could be produced, then a bomb of cataclysmic magnitude would technically be possible. However, the consensus among those scientists postulating this macabre scenario was that such a huge volume of fissionable uranium would be needed to sustain the chain reaction – more than 100 tons, by most calculations – that a device of such size could not be delivered by any means other than a boat or train. This would rather limit its potential impact as a strike weapon. Bohr also maintained that separating such an amount of the rare uranium isotope would drain the resources of an entire nation.

  Not that those likely limitations prevented newspapers and magazines from prophesying anthropogenic Armageddon. A New York Times headline of 29 April 1939 warned: ‘Scientists Say Bit of Uranium Could Wreck New York’. A day later, across the Atlantic, Britain’s Sunday Express trilled: ‘A Whole Country Might Be Wiped Out in One Second’. This dire prognostication was followed by details of the ‘first news’ regarding the uranium atom split, which noted that ‘if the experiments succeed, one pound of the metal will produce as much power as 20 million tons of coal do now. The new potential power was described . . . by one of the scientists who are investigating it as “too great to trust humanity with”.’21

  * * *

  Mark Oliphant was among those to express early fascination with the prospect of a fission bomb. Although immersed fully in the construction of his new cyclotron, Oliphant invited Niels Bohr to attend Birmingham’s degree ceremony in July 1939. Bohr had recently returned from the United States and, as Oliphant spelled out in a letter to his friend, he was eager to glean the latest developments – especially amid the worrying political storm brewing in Germany.