The Basis of Everything

by Andrew Ramsey

  As she climbed the steep ramp slung from the cruiser, which carried around 750 passengers, Rosa clung tightly to the hands of Michael, aged four, and his two-year-old sister Vivian. Near the lower deck entrance, she turned to find her husband among the many besuited men milling fretfully dockside. ‘I remember going up the gangway of the ship not knowing whether I would ever see him again,’ she later conceded.14

  By the time the Orcades – which two years later was sunk under attack from a German U-boat off the South African coast – had slipped moorings and slid cautiously into the Solent en route to the Channel, Mark Oliphant was on the road, heading back to Birmingham, where urgent work awaited.

  The puzzle of the cavity magnetron had been largely solved, and its production effectively outsourced, but an even greater revelation had materialised in its draught.

  17

  ‘SHOULDN’T SOMEONE KNOW ABOUT THIS?’

  Birmingham, 1939 to 1940

  On 19 September 1939, just over two weeks after war was declared, Adolf Hitler had delivered a triumphant speech in the reclaimed Free City of Danzig (Gdansk). He taunted Britain with the clear threat that ‘soon there could come a time in which we would use a weapon with which we ourselves cannot be attacked’.1

  Some who already feared the power let loose by uranium fission, among them British scientists and politicians, interpreted this as an oblique reference to the Third Reich’s atomic program, or its development of a toxic radioactive gas. Either way, the need to understand and exploit the atom’s destructive power had escalated into a race for survival. Mastery of a uranium fission bomb would surely decide the war.

  Physics laboratories therefore became the front line in the battle of science, and it was at Birmingham’s – under the stewardship of the Poynting Professor, Mark Oliphant – that some of the most decisive blows were landed.

  But while most of the physics department was consumed by the radar task, two members of staff, whom Oliphant had hand-picked during the academic exodus from Europe, were precluded from involvement once war was declared because of their status as ‘enemy aliens’. Instead, they turned their agile minds to the problem that had been occupying physicists until the eruption of fighting.

  * * *

  Even as he was proving the theory of uranium fission, Otto Frisch was planning his escape from Copenhagen. He foresaw that the hate-driven race laws that had forced him to flee his job in Hamburg in 1933 for safety in London would soon arrive in Denmark, with the Nazis already threatening near the border. So when Mark Oliphant, on one of his sojourns in continental Europe, called in to the Bohr Institute to visit its founder early in 1939, Frisch grasped his chance. He approached Oliphant and inquired about a possible return to Britain, in whatever capacity Birmingham University might be able to use him.

  Oliphant’s commitment to continuing Ernest Rutherford’s work was not restricted to science. He had admired the energy and empathy that Rutherford had offered the Academic Assistance Council, whose repatriation role had grown more urgent as war neared, and he met Frisch’s request with unhesitating reassurance. ‘Just come over,’ Oliphant told the thirty-four-year-old Austrian. ‘We’ll find something for you to do.’2

  Oliphant would later recall:

  The exodus of the Jews from Germany became a real river, and in Cambridge [pre-war] we received a large number of German scientists, some of whom worked with me, and I got to know them intimately and their reactions to the regime in Germany . . . I learned a lot from these people, and their reactions to the treatment that they had received.3

  However, as he had learned with his still-unfinished cyclotron, delivering on promises came with greater difficulty than proffering them. As correspondence concerning Frisch’s relocation flowed between his current and prospective employers, Bohr suggested that, rather than seeking a work permit from the outset, Oliphant should offer Frisch a provisional position for several months, ‘to give a few lectures . . . and to assist in your work’.4 That would necessitate only a temporary United Kingdom entry visa, which could be issued immediately. Then, if Frisch made up his mind to remain in Britain, it should prove easier for Oliphant to argue the case for permanent employment with the Home Office.

  Oliphant recognised the pragmatism of Bohr’s suggestion, while acknowledging that any final decision on whether Frisch might be offered a full research fellowship resided with the university’s vice-chancellor. He also noted that Birmingham’s physics laboratory would soon shut down for a few weeks over the 1939 summer vacation. He explained to Bohr in late May 1939:

  In writing to Frisch, I made only a very tentative offer which I thought he might be able to use to avoid the unpleasantness that might come if Denmark were invaded. I had no idea that he would feel that the sum we were able to offer would recompense him for such a change, but we would be very proud to have him here, if that would in any way help him.5

  There was no such equivocation in Frisch’s mind, however. No sooner had he received written confirmation of Oliphant’s earlier informal verbal offer – and even though the details of the role he might fill at Birmingham remained unresolved – he packed two small suitcases and sailed once again for England. He arrived at the height of the Midlands summer, and spent the university break basking under the soft sun in public parks near his bed-and-breakfast lodgings.

  When the students returned from holiday, he took up his notional position as auxiliary lecturer and felt an instant affection for Oliphant, whose quiet authority and cheerful energy proved to be the humanitarian balm Frisch had sought in fleeing Europe’s gathering peril. He also strove to foster the same sense of egalitarian fraternity he had so cherished under Rutherford at the Cavendish.

  ‘Oliphant had impressed me by his aura of confidence and calmness; in his presence you felt that nothing could go wrong and everything necessary would be done without fuss,’ Frisch later observed.6

  Once, as staff milled about, discussing physics during departmental morning tea, Oliphant set aside his cup and announced: ‘we really must have a blackboard in here, you can’t argue without one’.

  Turning to a laboratory assistant, he requested that a surplus blackboard be sourced for the tea room. Upon being told all the blackboards were too large to manoeuvre up the Poynting Building’s narrow, twisting stairway, Oliphant simply countered: ‘never mind, we can get it through the window’.

  As Frisch would remember: ‘He told someone else to find a block and tackle, they went up to the roof, fixed it, hoisted the blackboard out of one window and in by the window of the tea room, and within half an hour we had a blackboard. Elsewhere that would have required days of planning and quite likely some paper work.’7

  It was at the regular tea breaks – religiously observed by Oliphant, whose taste for sickly-sweet, currant-laced Chelsea buns had developed through the Cavendish’s equivalent rituals – that Frisch first came to know another émigré staff member, Rudolf Peierls.

  Born to Jewish parents in Berlin, Peierls was studying theoretical physics under Werner Heisenberg (who became his doctoral advisor) at Leipzig when he first travelled to Cambridge on summer holidays in 1928.

  At first, Peierls found England a curiosity. The run-down accommodation and regimented Cambridge lifestyle, coupled with oddities including bacon-and-egg breakfasts and formal tea parties, made almost as lasting an impression as the brilliant theoretical work led by Ralph Fowler at his father-in-law’s Cavendish Laboratory. Upon earning a year-long Rockefeller Fellowship in 1932, Peierls returned to Cambridge in late spring with his Russian-born wife, Genia. With Hitler’s fanatical regime tightening its grip on Germany, the couple then chose to remain in Britain, where Rutherford welcomed them into the laboratory’s extended family.

  Through the Cavendish’s tight fraternity, Rudolf Peierls became closely acquainted with Mark Oliphant, who, upon gaining the Poynting Chair, asked the German if he might be interested in joining him at Birmingham. Oliphant’s informal proposal suggested that Peierls would b
e his new department’s first academic appointment, in the role of Applied Mathematics (essentially theoretical physics) Professor. ‘The chair did not exist yet; he was trying to persuade the university to establish one and wanted to show that indeed there were suitable candidates about,’ Peierls recalled.8 Oliphant’s ploy worked: the position was advertised in 1937, and Peierls was chosen as the successful applicant.

  Peierls’s unassuming character and utter lack of conceit led Rutherford to assert, long before the German assumed British citizenship in 1940, that he would make a perfect Englishman. (He would also be knighted decades later.) He certainly settled quickly into his professorship and, like Frisch, built a deep rapport with Oliphant, whom he later rated ‘one of the great personalities of world physics’.

  ‘He was a warm, informal and direct person with a great zest for life, a loud voice and a hearty laugh,’ Peierls would say of Oliphant. ‘He was happiest when he could roll up his sleeves and get to work on a piece of equipment. His instrumentation showed the influence of Rutherford’s ‘string and sealing wax’ approach. Because of the developing needs of the experiments, Oliphant’s projects were much more ambitious pieces of engineering than Rutherford would ever have contemplated.’9

  The similarities that Peierls noted between Oliphant and Rutherford were not restricted to their practical talents. ‘Oliphant was perhaps Rutherford’s favourite pupil, and we understand why,’ Peierls opined. ‘The characters of these two men had so much in common in their directness, and in their enthusiasm for the work. Oliphant’s most characteristic quality [is] the fearlessness with which he speaks his mind, no matter whether his thoughts are popular or unpopular, never calculating their effect on his image.’10

  Both Frisch and Peierls found that the teaching duties assigned to them were not overly arduous, which led the diligent pair to seek out additional projects. Oliphant would send students from his first-year physics lectures to Frisch for expert tutelage, while Peierls used his free time to further immerse himself in the theory of nuclear reactions, founded on work published by Bohr.

  As keenly as Frisch and Peierls wanted to add their expertise to the department’s purportedly clandestine radar project, the repercussions for flouting restrictions that applied to their ‘alien’ status were potentially severe. But on many occasions when he found his will blocked by the bureaucratic obstacles of due process – as during the radar project – Oliphant would guilefully find a way around them.

  Eager to engage Peierls’s keen mathematical mind on problems of short-wave radio pulses, Oliphant would approach the German during tea breaks and pose apparently rhetorical questions that both men understood related directly to the highly confidential research.

  ‘If you were faced with the problem of solving Maxwell’s equations for a cavity with conducting walls in the shape of a hemisphere,’ Oliphant would muse, distractedly stirring his tea ‘could you cope with it?’

  To which Peierls, playing his pantomime role as if the query were no more than social small talk, would respond: ‘Well, it’s an interesting problem; I’ll give it some thought.’

  A few days later, as they gathered over more Chelsea buns, Peierls would suddenly recall the earlier conversation and announce: ‘I have a solution to that problem you gave me . . .’

  As Frisch later confirmed:

  Peierls knew that this was connected with the generation of very short electrical waves, such as were needed for radar, and Oliphant knew that Peierls knew, and I think Peierls knew that Oliphant knew that he knew. But neither of them let on; they both pretended that this was purely an academic problem that had occurred to Oliphant out of the blue . . .11

  To keep Frisch and Peierls more productively occupied, Oliphant felt that uranium fission would prove a suitably benign alternative research focus, given that subject was not thought likely to deliver any immediate impact on the war now under way.

  Frisch the experimentalist therefore resumed the work he had abandoned upon fleeing Denmark.

  * * *

  Frisch began by testing Bohr’s proposition that it was not the common uranium-238, but the rare 235 isotope that fissioned when bombarded by slow neutrons. It was work that had previously been started at Birmingham by Philip Moon, whom Rutherford had dubbed ‘Oliphant’s Satellite’ during their research days at Cambridge, but who had found little success in his uranium endeavours.

  In order to try to separate a usable quantity of the 235 isotope, which comprised such a tiny proportion of naturally occurring uranium, Frisch required a greater supply of the metal than Britain’s air ministry had provided for Moon’s earlier research.

  Oliphant, knowing who would be best placed to authorise the release of this highly prized and closely guarded material, wrote to Henry Tizard late in 1939 requesting five hundredweights (around 250 kilograms) of uranium oxide.

  Tizard received Oliphant’s message shortly after entertaining a similar request from James Chadwick at Liverpool University, where experiments on uranium fission had begun within days of the war’s commencement. Knowing that Oliphant’s laboratory was fully engaged in radar research, Tizard inquired as to who at Birmingham would be leading investigations in the sensitive field of nuclear fission.

  ‘I am told you have refugees in your laboratory,’ Tizard wrote, ‘and it just occurs to me that perhaps it is a little hard on the English physicists who are interested in the same problem, but who are now deeply engaged on war work, if the refugees get a good start on them by being in the fortunate position of being able to devote their time to pure science.’

  Oliphant’s retort pulled no punches. He advised Tizard that the work would be undertaken by Otto Frisch who, a year earlier, had worked out the theory of fission in collaboration with his celebrated aunt, Lise Meitner. Then, for good measure, he added: ‘In my opinion, it is much more important that work of this nature should be done than that any question should be raised about whose effort is employed to get the answer.’12

  The uranium oxide was duly delivered, and although the Birmingham laboratory’s already strained resources were devoted foremost to the radar program, Frisch set about making plans to separate the elusive 235 isotope using equipment devised by German physicist Klaus Clusius.

  The Clusius apparatus was a long, vertical glass tube, through which ran a metal wire that could be heated electrically. The tube would then be filled with a gaseous compound of the element to be separated, with the lighter 235 isotopes gathering at the top (where it was hotter) while the heavier ones collected around the cooler base. The immediate difficulty in that process would be procuring the laboratory’s sole glass blower, who fielded almost constant demands from the radar team.

  To ensure that Frisch was not rendered idle while waiting for the apparatus, Oliphant – who had already secured an unused lecture room in which Frisch could conduct his practical work – handed him another task: to prepare an article encapsulating the current state of nuclear physics for the Chemical Society’s 1939 annual report.

  As Frisch would remember:

  I managed to write that article in my bed-sitter where in daytime, with the gas fire going all day, the temperature rose to 42° Fahrenheit (about 6° Centigrade) while at night the water froze in the tumbler by my bedside. What I did was to pull a club chair up close to the gas fire, wear my winter coat and put the typewriter in my lap so as to be protected from all sides; the radiation from the gas fire stimulated the blood supply to my brain . . .13

  In his report, Frisch revisited Bohr’s belief that while a chain reaction of uranium isotopes split by neutrons – with the resultant release of multiple neutrons able to promulgate further fission – was distinctly possible, the likelihood of a violent explosion appeared fanciful. The secondary neutrons released would move too slowly to replicate the cleaving process in the predominant uranium-238 isotope, and only a small fraction of the available uranium-235 atoms would thereby undergo fission.

  It had already been shown that slowing the rel
ease of neutrons through the use of a moderating agent (such as heavy water or graphite) increased the likelihood of achieving fission in uranium-235. However, that process would also quell the speed at which any self-sustaining fission chain reaction might take place. This suggested nuclear fission was potentially useful as a constant energy source, but if employed in a bomb, fission would likely only replicate the sort of energy burst gained from igniting a similarly large stockpile of gunpowder.

  Having submitted his article, which essentially dismissed the notion of an imminent uranium bomb, Frisch returned to isotope separation. Yet his interest was now piqued by the question of how much uranium-235 isotope might be required to sustain such a chain reaction. Given that uranium-235 and uranium-238 shared the same properties and were only distinguishable by mass, they could not be separated by simple chemical methods; that outcome would have to be achieved by physically splitting the lighter (235) isotope from the heavier (238) particles.

  This would require complex mathematics – and the handily available input of Peierls.

  * * *

  From the time Oliphant had united them in the sanctuary of Birmingham, Frisch and Peierls had been drawn closer together by their deep resentment of Nazism. But the bond they shared transcended their cultural pedigrees and recent painful experiences. Frisch would take every opportunity to escape his frigid lodgings and spend evenings with Peierls and his wife, and when the couple moved to larger premises elsewhere in Edgbaston, Frisch gratefully accepted their offer of permanent accommodation.

  The trio would routinely embark on long, exploratory walks through the Midlands, occasionally stopping overnight at village hotels and resuming their trek next morning.

  It was on one of those outings, in May 1940, that the three émigrés walked into a pub on a spring bank holiday Monday to find the clientele within all huddled in grim-faced silence. They were listening intently to the landlord’s radio set, from which the voice of freshly installed prime minister Winston Churchill informed his anxious nation that he had nothing to offer them ‘but blood, toil, tears and sweat’.14 Even though the trio of travellers had been refused overnight accommodation in the village, and the local constable had declined their suggestion they sleep in the otherwise unoccupied police cells, they stayed for the duration of the famous address. ‘Nobody left until Churchill had finished,’ Peierls remembered.15