The Basis of Everything

by Andrew Ramsey

  I am hoping that when you visit us you will bring the latest news from America. We are very interested here in the problem of nuclear fission, a question which has been taken up by the authorities here, in order that there may be no possibility missed that here is a possible source of power, or of explosion.

  I understand . . . that you do not anticipate that the fission process will prove an explosive one, even under the best possible conditions, but it is felt here that the whole possibility must be investigated experimentally. As there are possibilities that the isotopes of uranium may be separated in reasonable quantity in the near future, perhaps this investigation is not so futile as may seem at first.22

  It was the brazen aggression of Nazi Germany, whose troops had already occupied Czechoslovakia amid fears that further conquests were imminent, that underpinned the urgency to explore the prospects of an atomic weapon. But those same ever darker storm clouds gathering over Europe had already set Oliphant on an entirely different, though equally critical, scientific project.

  16

  THE DECISIVE DIFFERENCE

  Birmingham, 1938 to 1940

  As Adolf Hitler’s territorial ambitions had grown, so too had Germany’s military air power increased – to the point where it posed a direct danger to the island nation of Great Britain. As a consequence, from as early as 1935, British scientists and strategists had been exploring an idea that might at least provide them with a fighting chance against Germany’s airborne threat.

  The only public evidence of this project was the network of early warning stations – codenamed Chain Home – that were quietly installed along England’s Europe-facing south coast from the middle of 1938. While the presence of sturdy timber towers reaching almost 100 metres into the sky – and connected by thick webs of electrical wiring – was obvious from miles away, their purpose stayed a tight secret.

  Those privy to the significance of the system knew these towers were capable of detecting incoming aircraft up to 160 kilometres away – roughly the distance from Dover, on Kent’s coast, to the French city of Lille. They were also acutely aware that, while providing up to twenty minutes’ warning of incoming planes, the technology too often proved unreliable.

  As war grew more likely, so too did the urgency to create a system that gave British pilots and observers more detailed information on approaching threats, and thus greater hope of repelling them.

  Like so much of science, the premise that underpinned the desired outcome was infinitely simpler than the means of achieving it. The radio pulses being beamed into the skies and bounced back to earth from naturally reflective sources high in the atmosphere, and from any large objects that intervened between the two, utilised wavelengths of ten metres or more. They effectively acted as floodlights, pointed hopefully into the sky to detect any enemy aircraft that might stray into them.

  If the pulses were to act more like searchlights, able to locate and lock on to imminent dangers, those wavelengths needed to be drastically shrunk. The shorter the wavelengths employed, the more information that could be collected. Under initial experimentation, the desired measure was deemed to be around a metre and a half.

  If the proposed defence system were to be effective against the might of Germany’s Luftwaffe, particularly if they flew missions at night, those short waves would also have to be generated with great power – by a device small enough to fit within the nose cone of a fighter plane.

  * * *

  The men who drew Oliphant into the closed coterie of radar – or radio direction finding (RDF), as it was known in late 1938 – held close ties to the old Cavendish network. One was John Cockcroft, the Oliphants’ great friend from Cambridge. Another was Henry Tizard, scientific advisor to the Air Ministry, and chair of the secret committee charged with improving RDF’s capabilities.

  Tizard had been a long-time colleague and avowed admirer of Ernest Rutherford. It was through Rutherford that Oliphant had first met Tizard at Cambridge, during the Cavendish’s golden period. And by late 1938, Tizard – as head of the Committee for the Scientific Survey of Air Defence – was actively seeking out universities with the capacity and the commitment to pursue short-wave research.

  His approach to Oliphant proved so persuasive that, even as the new Poynting Professor was formulating his ambitious plans for a cyclotron, he was also investigating the problem posed by airborne radio transmission.

  Despite the stringent confidentiality surrounding the RDF program, Oliphant’s belief that the fraternal bond between scientists should transcend security restrictions saw him write immediately to the man who had replaced Rutherford as his principal confidant: Ernest Lawrence – a foreign national. As if that were not risk enough, the unclassified correspondence seeking Lawrence’s input was also sent unwisely via the standard mail service.

  ‘I have received a letter from the Defence Department in England, asking whether I will enquire about the generation of large powers of very short radio waves,’ Oliphant wrote to Lawrence, even before he had returned to Birmingham from his American visit in January 1939. ‘I shall be grateful, if you know this and can pass it on without betraying a confidence, if you will tell me how it is done.’1 The letter set a pattern for Oliphant’s wartime indiscretions.

  Lawrence obliged with information he had gleaned from colleagues at nearby Stanford University, where the klystron – a vacuum tube used to amplify high radio frequencies – had been pioneered. Oliphant then attempted to replicate the device’s capacity to generate short waves. However, given that his only previous experience with radio waves had been using an Adelaide University colleague’s crystal receiver to eavesdrop on Morse code time signals and weather information, he found little success. So he returned his attention to the giant cyclotron nearing completion at Birmingham.

  Tizard and Cockcroft, however, were stepping up their efforts to enlist universities’ expertise as it became increasingly apparent that the policy of appeasement towards Hitler was not going to prevent another war in Europe. Britain stood a very real chance of finding itself under threat of attack. Defence of the British Isles was therefore deemed a high strategic priority. Almost 100 physicists from institutions throughout Britain were drafted and deployed in teams to study the Chain Home technology first-hand, and generate ideas on how it might be improved.

  In August 1939, as one of those recruited into service, Oliphant led his unit of eight researchers to Ventnor on the Isle of Wight’s southern coastline, less than 200 kilometres from France’s Normandy coast.

  Among Oliphant’s troupe was John Randall, who had left manufacturing behemoth General Electric to pursue a Royal Society research fellowship under Birmingham’s new physics professor. The group also included Harry Boot, an eager research student who confided to a newspaper at war’s end that he had marvelled at the team’s ‘free hand to play about with a radar station’. For Oliphant, the chance to clamber across the grassed slopes of Ventnor’s St Boniface Down, to scrutinise the workings of antenna towers, to comb through blueprints, and to examine hitherto unknown electrical circuitry stirred his boyhood passion for hands-on discovery.

  It was while he was at Ventnor that news broke of Hitler’s final act of pre-war brinkmanship. The German aggression that had escalated throughout 1939 exploded into naked hostility on 1 September, when the Nazi military invaded Poland.

  Two days later, Oliphant and his team, housed in an otherwise empty hotel, listened to Neville Chamberlain’s stony address to the nation on BBC Radio. For the second time in a generation, Britain was at war. Only this time, unlike the distant hostilities waged throughout Oliphant’s adolescence, the conflict would be fought on his doorstep. The significance of the Prime Minister’s words was not lost on the new professor.

  The Government have made plans under which it will be possible to carry on the work of the nation in the days of stress and strain that may be ahead. But these plans need your help. It is the evil things that we shall be fighting against – brute force, bad
faith, injustice, oppression and persecution – and against them I am certain that the right will prevail.2

  Oliphant knew that this would not be the boyhood adventure that the First War had seemed to him. He would need to devote all his available resources, both intellectual and physical, to the fight against tyranny. And as he gazed up at the tangle of cables that hung from the scarecrow-like timber towers, he understood that this essential first line of Britain’s defence was where he could make a vital contribution.

  The research at Ventnor completed, he rushed back to his Birmingham laboratory to resume the work already begun on production and detection of very short radio waves – or microwaves, as they would become more widely known.

  * * *

  Within a week of Poland’s occupation, Birmingham’s Edgbaston campus had undergone noticeable change. Barrage balloons flew above the athletics field, student accommodation was given over to medical men and nursing sisters, and a section of basement was hurriedly converted into a public safety shelter.

  Blackout restrictions were enacted across Britain, and in Birmingham it was announced the university day would end at 3.30pm during winter terms to ensure that those with large distances to travel could make it home before darkness. ‘If this is not done, we are likely to have more casualties from traffic accidents than from bombs,’ Vice-Chancellor Raymond Priestley diarised in the war’s first weeks.3 Vehicles were now obliged to have hooded headlamps, which emitted minimal illumination. As a compensatory safety measure, white paint was applied to buffer bars and running boards, and pedestrians took to wearing luminous cards in their hatbands to lessen the chance of collisions on pitch-dark footpaths. As fears of a German land invasion rose, street signs were removed and pillboxes for machine-gunners began appearing at strategic intersections.

  It was also in the early weeks of the war that Oliphant took delivery of a large manila envelope, inside which he found a second envelope stamped boldly in blood-red ink ‘TOP SECRET’. It was from the Admiralty, formally requesting that Oliphant pull together a group at Birmingham to pursue development of a generator able to produce radio waves of ten centimetres in length.

  Unsurprisingly, given that the prestigious wartime contract was so keenly sought by rival laboratories, including the Cavendish, Oliphant found no resistance from his vice-chancellor to the proposal that he should devote time, staff and resources to war work – even if secrecy agreements meant the university’s other top brass were notionally unaware of it.

  Oliphant called a meeting of almost his entire departmental staff, and set out their challenge: to unearth ways whereby vastly shorter wavelengths could be generated and utilised, not only to identify a single aircraft’s approach, but for wider wartime applications such as pinpointing the direction of aerial searchlights, or improving the aim of artillery through the application of gun laying.

  Although some of the groundwork had already been completed, it was abundantly clear to the entire group that the answer they sought was neither close nor simple. Since the start of the RDF research in 1935, waves had been successfully shrunk from ten to around one and a half metres, and the equipment to generate them commensurately reduced to make airborne radar a possibility – at least in theory. Yet those waves still could not be focused into concentrated beams.

  To achieve that outcome, they would need to be narrowed through the use of a concave mirror, and for that apparatus to be fitted into the already cramped cockpit of a fighter aircraft and be of benefit to a pilot, the wavelength would need to be further drastically reduced – to approximately ten centimetres.

  Using the same uncompromising approach he had adopted with fundraising, Oliphant launched himself into the quest to deliver microwave radar. Not only did he channel his practical problem-solving talents into this seemingly daunting project, he successfully transplanted that will and work ethic into the members of his team. His energy stemmed in part from the observation made by Charles (C.S.) Wright, another former Antarctic explorer, now the Admiralty’s director of scientific research. Shortly before Germany’s seizure of Poland, Wright had declared that the next war would be won by the side able to utilise the shortest radio wavelength. Wright was responsible for the development of radio valves on behalf of all Britain’s armed services and, by happy chance, was also married to the sister of his one-time polar exploration colleague and Birmingham’s vice chancellor, Raymond Priestley.

  Oliphant assigned small groups to trial different methods of producing microwaves, and various ways of interpreting reflected signals. His entire laboratory staff was reassigned into groups of two or three, some of which were exploring ways of improving existing technology while others were seeking altogether new ways of solving the problem that circumstances had set them.

  Working with Irish physicist James Sayers, a Cambridge alumnus who was one of the few in the Birmingham laboratory with a background in radio research, Oliphant focused on adapting the klystron technology sourced from Ernest Lawrence. A second team led by Randall trialled magnetrons, high-powered vacuum tubes that used both magnetic and electric fields to generate microwaves, and that pre-dated the klystron.

  The klystron model produced in the United States had yielded microwaves in the desired frequency range, but at a clearly inadequate power output of around ten watts. So while these waves could provide accurate information, they could not be used over anywhere near the distances required. Sayers worked furiously to raise that level to around 400 watts, and also found that the crystal detector – once favoured in radio sets but since regarded as obsolete – made an efficiently sensitive receiver.

  As ever, despite his acknowledged absence of expertise in electrical engineering, Oliphant took a vigorous role in practical work that was not without its perils.

  Britain’s major cities had been provided with barrage balloons, which were attached to steel cables and flown to prevent enemy aircraft from making low-altitude bombing runs. To gauge the klystron’s effectiveness in gathering waves bounced back from a solid source, its sights were to be trained on one of these balloons, which had been provided to Birmingham University at some cost, kindly borne by the institution’s friends within the Admiralty.

  Painstakingly filled overnight with coal gas – a precursor to natural gas in homes and workplaces – and coated with aluminium paint to replicate an aircraft fuselage, the balloon was untethered and moved to the desired testing location by Oliphant, while Sayers operated the klystron. On this breezy morning, however, Oliphant had overestimated the ground force his large frame would exert. As the dirigible caught a sudden gust, Oliphant clung to the mooring rope and was carried almost 100 metres across the university’s grounds, flapping and sweating, before the wind eased and gravity returned him to earth with a thump.4

  To further trial the klystron’s capabilities, Oliphant tapped into his growing network of contacts to procure, on loan, a First World War–issue sound-locator trailer. A contraption rendered obsolete by two decades of innovation, it sported a series of oversized acoustic-amplifying trumpets, lashed to a central rotating shaft that was mounted upon a wheeled chassis. Oliphant’s team stripped the relic of its original parts and fitted a pair of gleaming aluminium dishes to its central mechanism, which could be spun into an array of positions, vertically and horizontally. Its ugly functionality was captured in the name its designers bestowed upon it: ‘the Dog’s Breakfast’.

  The portability of this crude prototype was limited by the need for continuous water flow to cool the vacuum pump, which was therefore prone to freezing in winter. Yet the Dog’s Breakfast proved effective when rolled out for trials at the British naval stronghold of Portsmouth, where its microwaves proved capable of tracking even small vessels on the water, as far as the horizon.

  Having served its purpose, the makeshift equipment was not greatly mourned when it was blown to pieces during one of the German air raids that would land almost 40,000 incendiary and high-explosive devices upon Portsmouth throughout the course of the
war.

  Years after Allied victory was achieved, Oliphant would be contacted by a pair of civil service accountants, demanding that he reconcile the outstanding loan of a ‘valuable piece of government property’, which he quickly established to be the Dog’s Breakfast.

  They were perturbed when I said we no longer had it – that it was dead! I explained that the gigantic ‘ears’ and a multitude of gears and other parts [from the original First World War trailer] were in the cellar. I took them to see the heap of remnants. They wrote busily in their books, and went off without taking the parts away, apparently quite satisfied.5

  * * *

  While Oliphant worked with Sayers’s group, Randall and his partner Harry Boot were researching magnetrons in a confined workspace tucked behind one of the physics department’s lecture theatres. It was there that one of the war’s most crucial developments took shape.

  Randall recognised that the magnetron was currently limited by its negligible power output, barely sufficient to illuminate a handheld torch. He also suspected that the hefty klystron would never be capable of producing sufficient power to fire out pulses that could locate an aircraft 100 or more kilometres away. He then figured that the solution might lie in combining the existing magnetron design with the properties of a resonator, an essential element of high-current devices. In the case of Randall’s innovation, these resonators took the form of six cylindrical cavities drilled equidistantly around a circular block of copper, to control the frequency of the waves. It was the use of these resonators, configured to resemble the familiar cylinder that rotates bullets into the firing chamber of a revolver, that led to its name: the cavity magnetron.