The Strangest Man

by Graham Farmelo

  The Diracs’ daughter Betty was as timid as her brothers. Most such girls of her generation began a menial job straight after leaving junior school, but Charles and Flo wanted her to continue her education at the nearby Redlands Girls’ School, where she studied without special enthusiasm or achievement. It was convenient for her father to accompany her to school after 1919, when his school relocated to Cotham Lawn Road, ten minutes’ walk from the Diracs’ home. The move was unpopular with its teachers, though it was made palatable for Charles by a sweetener – promotion to the more lucrative post of Associate University Lecturer. His colleagues in the staffroom respected him as one of the most effective teachers in Bristol, though many regarded him as odd. He did nothing to shed this reputation when he told one of them that he had been trepanned: presumably a surgeon had drilled a tiny hole into his head, intending to let out evil spirits.18

  To some of Charles’s fellow teachers, there was a whiff of fraudulence about him: they found out that the letters B. ès. L. (Baccalauréat-ès-Lettres) that he almost always put after his name signified only that the University of Geneva had pronounced him able to embark on higher education. He had spent only a year at the university, as an auditeur, taking notes but not a degree. One of his colleagues later chuckled as he recounted the minor staffroom scandal involving Charles: as he was not eligible to wear the full academic dress, he bought a gown and asked his wife to make him a hood in red, white and blue. She knew nothing of the deception and only found out about it several years later.19

  In the spring of 1919, for reasons that are not clear, Charles Dirac sought British nationality for the first time. He wrote urgently to the Swiss authorities, saying that after teaching in the UK for thirty years, ‘professional reasons’ made it essential that he renounce his Swiss nationality.20 When he submitted his application to the British authorities, he said he wanted the right to vote after the government had withdrawn it, following the recent amendment to the Aliens Registration Act, which also denied Flo – as the wife of a ‘foreign national’ – the right to vote in future general elections (she had voted for the first time six months before, in common with other British women over thirty years of age). Perhaps, too, he wanted his daughter and elder son to be eligible for the scholarships available only to British citizens? Whatever his motivation, Charles swore allegiance to George V in front of a justice of the peace in Bristol on 22 October 1919.21 On that day, his children also became Britons, having previously been classed as Swiss, a status that, according to Betty’s later recollections, caused her to be teased in the playground for being ‘one of those Europeans’.22 Paul Dirac was no longer a foreigner, but, to many British eyes, he would always have the air of one.

  In the early summer of 1919, when Paul’s first-year results confirmed his potential as a top-flight student, Felix became the first person in his extended family to be awarded a degree, though only with third-class honours. The disparity between the brothers’ academic talents had never been so stark, so it is probably no coincidence that the relationship between them became seriously troubled at about this time. In the pained and elliptical comments Dirac made later about Felix, he remarked they would often ‘get into a row’, though he gives no details of the arguments.23 One possibility is that they were seeded by Felix’s jealousy and sense of inferiority, nourished by Paul’s lack of empathy with his brother and by his inability to muster tactful words that were sorely needed to preserve Felix’s sense of self-worth. Among his colleagues in his later career, Paul Dirac was famous for not understanding the feelings of others and for his lack of tact. It is unlikely that he was any different when he was a young man.

  After Felix had taken his degree, he left home and moved two hundred miles away to Rugby, which was rapidly changing from one of the East Midlands’ sleepy market towns into a booming centre of the new electrical technology. Felix took a three-year student apprenticeship at the British Thomson-Houston Company, on a starting wage of a pound a week, giving him a measure of financial independence. Meanwhile, his penniless brother continued to study engineering – while moonlighting in physics – at the Merchant Venturers’ College. As he had already chomped his way through the mathematics part of the course, he seemed destined to spend the remaining two years of his engineering degree fumbling his way through his laboratory exercises and listening to his lecturers drone their way through the syllabus. Having cast around for a challenge, he amused himself in the library by hunting down the longest German words in the technical dictionaries (hyphens barred) and reading about the subject that most interested him, physics.24 His scientific imagination was ripe for a challenge, and, a few weeks after he began his second year at university, it arrived.

  No event in Dirac’s working life ever affected him as deeply as the moment when relativity ‘burst upon the world, with a tremendous impact’, as he remembered nearly sixty years later.25 Einstein became a media figure on Friday, 7 November 1919, when The Times in London published what appeared to be just another post-war edition, including the news that the King supported the proposal of an Australian journalist for two minutes’ commemorative silence on the anniversary of Armistice Day. On page 12, the sixth column featured a 900-word article that most readers probably passed over, unless the headline, ‘Revolution in Science’, captured their attention. Yet this was a momentous piece of journalism, and it helped to propel Einstein from relative obscurity in Berlin to international celebrity; soon, his moustachioed face and frizzled mane of black hair were familiar to newspaper readers all over the world. The unsigned article reported the apparent verification of a theory by Einstein that ‘would completely revolutionize the accepted fundamental physics’ and thereby overturn the ideas of Isaac Newton that had held sway for over two centuries.26 The observations were made by two teams of British astronomers who had found that the deflection by the Sun of distant starlight during the recent solar eclipse was consistent with Einstein’s theory but not Newton’s. When he was an old man, Dirac remembered this as a time of special excitement: ‘Suddenly Einstein was on everyone’s lips […] [E] veryone was sick and tired of the war. Everyone wanted to forget it. And then relativity came along as a wonderful idea leading to a new domain of thought.’27

  Dirac, Charlie Wiltshire and their fellow students were fascinated by Einstein’s new theory and tried to find out what the fuss was about. This was not an easy task. Their teachers, like most academics in the UK, were no more knowledgeable than their students about this alleged scientific revolution. Apart from occasional articles in scientific journals such as Nature, the primary sources of knowledge about the new theory of relativity were newspapers and magazines, whose editors gave commentators thousands of column inches to speculate – usually facetiously – about the new theory and its apparent defiance of common sense. On 20 January 1920, Punch featured an anti-Semitic poem that exemplified popular puzzlement with the theory that had originated behind the lines of the UK’s bitter enemy:

  Euclid is gone, dethroned,

  By dominies disowned,

  And modern physicists, Judaeo-Teuton,

  Finding strange kinks in space,

  Swerves in light’s arrowy race,

  Make havoc of the theories of Newton.

  The pages of the newspapers and magazines were replete with advertisements for scores of half-baked accounts of Einstein’s work churned out only months after the theory came to public attention.28 At that time, there were no science journalists, so Dirac and his friend Wiltshire had to rely on popular articles written by scientists, notably Arthur Eddington, the Quaker astronomer and mathematician at the University of Cambridge and the only person in Britain to have mastered the theory. He had even got his hands dirty in one of the eclipse expeditions that produced crucial support for the theory.

  In a stream of entertaining articles and books, Eddington deployed witty, down-to-earth analogies that made even the most complex abstract ideas accessible and arresting. His skill is exemplified in the account he gav
e in 1918 of Einstein’s famous equation E = mc2. Other authors could only crank out a dreary and barely comprehensible explanation of the equation’s neat connection between the energy E equivalent to a mass m, and the speed of light in a vacuum (symbolised by the letter c). Eddington knew better. In his explanation, he used the equation to do a calculation that he knew would interest his readers: he worked out the total mass of the light that the Sun shines onto the Earth and then used the result to comment on the controversial question of whether to keep daylight-saving time:

  the cost of light supplied by gas and electricity companies works out at something like £10,000,000 an ounce. This points the moral of Daylight Saving: the Sun showers down on us 160 tons of this valuable stuff every day; and yet we often neglect this free gift and prefer to pay £10,000,000 an ounce for [light of] a much inferior quality.29

  Eddington and other writers fuelled Dirac’s interest in understanding how the material universe works. But he spent most of his time studying for his engineering degree, struggling to concentrate in lectures, mastering the theoretical concepts, doing experiments and writing them up in immaculate accounts that feature scarcely a single crossing-out. To the modern eye, they almost look as if they had been printed by machine in a special typeface that successfully mimics ordinary human handwriting, with every repeated letter reproduced identically.30

  Charlie Wiltshire was one of the very few people who glimpsed the human side of Dirac. To most people, he looked like a cold-hearted solipsist, uninterested in human contact, engaged only by mathematics, physics and engineering. Even in those repressed times, Dirac appeared to be exceptionally narrow-minded and inhibited.31

  Soon after his eighteenth birthday, Dirac had to spend time away from his sheltered environment for the first time. He travelled to Rugby, where his brother Felix was one of the small army of young apprentices in the local factories, to spend the summer as a trainee engineer, and, perhaps, to see whether he was suited to factory work. By the end of his month-long stay, the answer was clear.

  Dirac worked in the British Thomson-Houston electrical goods factory, located on a ninety-acre site next to the railway station. The factory dominated the town. It was said that everyone who lived in Rugby either worked there or knew someone who did. Certainly, everyone in the town was familiar with the saw-tooth profile of the factory’s roofs, one of them bearing the sign ‘Electrical Machinery’. And everyone, wherever they stood, could see the smoke billowing from two chimneys that pointed to the sky like a pair of smouldering lances.

  Dirac arrived in Rugby sporting a new wristwatch, a device that had a decade before been regarded as effeminate for men (and outré for women) but had become respectable after soldiers in the war had found them useful.32 He lodged above a draper’s shop on a street corner, precisely midway between the factory’s two entrances, a few minutes’ walk away. Dirac was one of about a hundred vacation students who provided menial labour, mainly in the relatively quiet testing laboratories well away from the turbine-construction area, when many of the workers were on holiday. It was a slow-news summer, enlivened only by the dramatic lockout of the Electrical Trades Union and by a local polo match in which one of the players was the Secretary of State for War, Winston Churchill.33

  Flo regularly wrote to Paul, the first of several hundred letters that she sent him between then and her death. It seems that he kept all of them. These first letters were warm and newsy, telling him of Betty’s new dog, how ‘Daddy missed you when he had all the grass to cut’ and of the new overcoat she was going to have done up for him (‘I showed it to Pa & he wants it for himself’). Flo repeatedly complained that he was not telling the family enough about what he was doing. ‘Do you ever come across Felix?’ she asked.34 The answer was that the two brothers did pass each other on the streets of Rugby, but they did not exchange a word.35 Their relationship had deteriorated into a state of cold hostility; Paul apparently offered his brother the same expressionless stare that he gave almost everyone else. Either their mother did not know of her sons’ falling out, it seems, or she was too blinkered to notice.

  Dirac’s employers in Rugby gave him the only poor report he would receive in his entire life. David Robertson later showed him the damning comments and disclosed that he was the only vacation student from Bristol ever to receive an unfavourable report. It judged Dirac to be ‘a positive menace in the Electrical Test Department’, to ‘lack keenness’ and to be ‘slovenly’, making it clear between the lines that Dirac would be unwise to seek a future on the factory floor.36

  In late September 1920, Dirac returned to Bristol to prepare for his final undergraduate year, when he specialised in electrical engineering. His passion, however, was the theory of relativity. One of his frustrations was that he could not find an accessible technical account of the theory that would explain, step by step, how Einstein had developed his ideas. Of the academic disciplines that contributed the reams of piffle Dirac read about relativity, none was more prolific than philosophy. One commentator wrote: ‘A philosopher who regards ignorance of a scientific theory as insufficient reason for not writing about it cannot be accused of complete lack of originality.’37 The writer of those words was one of the most talented young philosophers working in Britain, Charlie Broad. Having originally wanted to be an engineer, he trained in both philosophy and science at Cambridge and acquired more expertise in relativity theory than the great majority of physicists, many of whom knew next to nothing about Einstein and his work. In the autumn of 1920, soon after Broad was appointed as the Professor of Philosophy at the University of Bristol, he gave a series of lectures for final-year science students on scientific thought, billed to include a description of Einstein’s theory.38 Dirac and several other engineering students sat in on these lectures, though few of them were sitting alongside Dirac to the end, as the going quickly became tough and the material had little to do with engineering. For Dirac, the course was a memorable experience, as it was for Broad, who wrote thirty years later in his autobiography:

  there came to these lectures one whose shoe-laces I was not worthy to unloose. This was Dirac, then a very young student, whose budding genius had been recognized by the department of engineering and was in the process of being fostered by the department of mathematics.39

  Broad was a wonderfully idiosyncratic lecturer. He always appeared with a carefully prepared script, and he read every sentence twice, except for the jokes, which he delivered three times. Although he spoke drearily, his content was compelling, jargon-free and spiked with witty references to Charles Dickens, Conan Doyle, Oscar Wilde and other literary figures. Trenchancy was one of his strongest suits. During a warning about the snake oil of most popular accounts of relativity, he counselled that ‘popular expositions of the Theory are either definitely wrong, or so loosely expressed as to be dangerously misleading; and all pamphlets against it – even when issued by eminent Oxford tutors – are based on elementary misunderstandings.’40

  Broad’s treatment of relativity in his course was unconventional to the point of quirkiness. He taught Einstein’s first theory and his more general version together, taking a unified approach and concentrating on the basic ideas rather than on the mathematics. Broad’s aim was to make it clear that the theories give ‘a radically new way of looking at Nature’.41 The first of Einstein’s theories is usually dubbed the ‘special theory’ because it deals only with observers who move in straight lines at constant speeds with respect to one another; for example, passengers on two trains moving smoothly on parallel tracks. Einstein based his theory on just two simple assumptions: first, that when each of the observers measures the speed of light in a vacuum, they will always find the same value, regardless of their speed; and, second, that measurements made by the observers will lead them to agree on all the laws of physics. Einstein’s great insight was to see that if these assumptions were followed to their logical conclusion, a new understanding of space, time, energy and matter emerged.

  A casual
ty of Einstein’s theory was the widely accepted belief that the universe is pervaded by an ether, which Broad argued had become superfluous:

  there was supposed to be a peculiar kind of matter, called Ether, that filled all Space. On these theories the Ether was supposed to produce all kinds of effects on ordinary matter, and it became a sort of family pet with certain physicists. As physics has advanced, less and less has been found for the Ether to do.42

  Contrary to the theory, the existence of such a substance would imply that there is a uniquely privileged frame of reference, so relativity implies that the ether is an unnecessary assumption and may well not exist, unless experiments say otherwise. Einstein also noted that measurements of space and time are not, as almost everyone else thought, independent but are inextricably linked, leading to the idea of a unified space-time, a concept introduced by his former teacher Hermann Minkowski, a German mathematician. Finally, Einstein showed that an inevitable consequence of this new way of thinking was his equation E = mc2, implying that the mass of a small coin is equivalent to the vast energy needed to run a city for days or indeed to raze it. An apocalyptic vision of this power had already been presented by H. G. Wells, shortly before the outbreak of the First World War, in his novel The World Set Free.