The Strangest Man Read online

  Notes - Chapter four

  1 Interview with Dirac, AHQP, 6 May 1963, p. 9.

  2 Recollections of Dirac’s first term in the mathematics class are from the testimony of E. G. Armstead in a letter to Richard Dalitz. The lecturer concerned was Horace Todd.

  3 Dirac (1977: 113); interview with Dirac, AHQP, 6 May 1963, p. 10.

  4 Interview with Dirac, AHQP, 1 April 1962, p. 3.

  5 It is likely that Dirac learned this subject from Projective Geometry by G. B. Matthews (1914), published by Longmans, Green and Co. This book apparently meant a lot to him as it was one of the few books from his youth that he kept until his death. His copy is kept in his private library, stored in the Dirac Library, Florida State University.

  6 Dirac studied four courses in pure mathematics: ‘Geometry of Conics; Differential Geometry of Plane Curves’, ‘Algebra and Trigonometry; Differential and Integral Calculus’, ‘Analytical Projective Geometry of Conics’ and ‘Differential Equations, Solid Geometry’. See Bristol University’s prospectus for 1922–3, BRISTU.

  7 Dirac studied four courses in applied mathematics: ‘Elementary Dynamics of a Particle and of Rigid Bodies’, ‘Graphical and Analytical Statics; Hydrostatics’, ‘Dynamics of a Particle and of Rigid Bodies’ and ‘Elementary Theory of Potential with Applications to Electricity and Magnetism’. See Bristol University’s prospectus for 1922–3, BRISTU.

  8 Testimony of Norman Jones (who attended the Merchant Venturers’ School from 1921 to 1925) to Richard Dalitz in the 1980s. Private communication from Dalitz.

  9 Interview with Dirac, AHQP, 1 April 1962, p. 8, and 6 May 1963, p. 10.

  10 The inclusion of the lectures on special relativity can be deduced from the presence of examination questions on the subject. See Dirac Papers, 1/10/15 and 1/10/15A (FSU).

  11 The term ‘non-commuting’ was introduced by Dirac later in the 1920s.

  12 Cahan (1989: 10–24); Farmelo (2002a: 7–12).

  13 Letter from Hassé to Cunningham, 22 March 1923, STJOHN.

  14 Interview with Dirac, AHQP, 6 May 1963, p. 14. During Dirac’s first visit to Cambridge, he had met Cunningham.

  15 Warwick (2003: 466, 467, 468, 493 and 495).

  16 Stanley (2007: 148); see also Cunningham (1970: 70), STJOHN.

  17 Letter from Ebenezer Cunningham to Ronald Hassé, 16 May 1923, and letter from Dirac to James Wordie, 21 July 1923, STJOHN. The grant from the Department of Science and Industrial Research was technically a maintenance allowance for research. Wordie became Dirac’s tutor in his early years in Cambridge. Postcard from Dirac to his parents, 25 October 1926 (DDOCS).

  18 Dirac often spoke to close friends of the significance of this gesture by his father. Among those to attest to this: Kurt Hofer in an interview on 21 February 2004, Leopold Halpern in an interview in February 2006 and Nandor Balázs in an interview

  on 24 July 2002.

  Five

  […] I could behold

  The antechapel where the statue stood

  Of Newton with his prism and silent face,

  The marble index of a mind for ever

  Voyaging through strange seas of Thought, alone.

  WILLIAM WORDSWORTH, The Prelude,

  Book III, ‘Residence at Cambridge’, 1805

  Cambridge has never been the most welcoming place. Visitors who first arrive by rail are often surprised when they realise that the station is almost a mile from the town centre. This rebuffing nudge was quite intentional. Four decades before the station opened in 1845, the authorities had helped to fight off proposals to link the town to London with a canal, but pressure to make Cambridge part of the emerging railway network was irresistible. They did, however, ensure that the station was about twenty minutes’ walk from the nearest college so that students would be less tempted to flit off to London and that outsiders would think twice about invading the town’s privacy. In 1851, the Vice Chancellor of the university complained to the directors of the railway company that ‘they had made arrangements for conveying foreigners and others to Cambridge at such fares as might be likely to tempt persons who, having no regard for Sunday themselves, would inflict their presence on the University on that day of rest’.1

  As soon as Dirac – and every other new, luggage-laden student – emerged from the station, he had to trek to the city centre or join the queue for one of the few buses that took passengers to Senate House Hill. On Monday, 1 October 1923, when he walked through the stone portals of St John’s College to register his arrival, he entered an unfamiliar world of tradition, camaraderie and privilege.2 He would have been greeted by college porters – resplendent in their liveries and silk hats – each of them charged with keeping an eye on the students and with an obligation to report any errant behaviour. The college admitted only men, many of them in jodhpurs and flat caps and talking in voices that advertised their breeding. Dirac’s social standing was given away by his cheap suit – purchased from the Bristol Co-Op – his gauche manners and, on the odd occasion when he spoke, his accent. There was also something out of the ordinary about his appearance. A small and well-tended black moustache lay above his snaggled top teeth, his wan face topped with a thatch of black curly hair and dominated by his assertively pointed nose. Not quite six feet tall and recognisably his father’s son, Dirac had bright eyes, a large forehead that revealed a receding hairline and, already, the slightest of stoops.

  The sense of tradition in the college is most powerfully expressed in its architecture. Some of it was four centuries old, its construction funded by the posthumous largesse of Henry VIII’s bookish paternal grandmother, Lady Margaret Beaufort. The enduring presence of these buildings reminds students that their academic home will remain long after all but the most talented of them have been forgotten. Dirac arrived there with no great ambition, and he was unaware of his academic standing relative to his fellow science students, though he had already decided to do only the most challenging fundamental research. This tradition dates back to Galileo, the founder of modern physics, who took the first steps to cast what he called ‘the book of nature’ in the language of mathematics. He did this at the turn of the seventeenth century, almost a hundred years after the completion of the first buildings of the college. In this sense, St John’s is older than physics.

  College life reflected the origins of British academia. The earliest scholars had been monks, all wearing the same clothes, and all going about their contemplative lives within an agreed set of timetables and rules. In 1923, all the official students of the college and the rest of the university were male, each of them required to wear a gown and mortarboard in public. Any student who went into town incorrectly attired knew he ran the risk of being nabbed by one of the university’s private policemen (proctors or ‘progs’) or their assistants (‘bulldogs’), who roamed the streets after dusk.3 A transgression of the dress code was punished by a fine of 6s 8d, no laughing matter for any young man keen to preserve his spare money, though not nearly as serious as the penalty for being caught with a woman in his room.4

  The students were waited on hand and foot. By 6 a. m., the invariably female bed-makers (‘bedders’) were hanging around the stone staircases, ready to begin their morning’s work. The gyps – man-servants – were available all day to clean, wash up and run errands for the students and for the Fellows (also known as ‘dons’). Such service was not, however, available to young Dirac in his first year. He spent it in a cold and damp shoebox of a room in a four-storey Victorian house, a fifteen-minute walk from St John’s, sharing with two other lodgers. At a cost of almost £15 a term, the landlady Miss Josephine Brown delivered coals and wood for their fires, supplied gas for the lamps that lit their musty little rooms, provided them with crockery and cleaned their boots. Like all the other landladies approved by the university, Miss Brown was obliged to keep a record of any failure of Dirac’s to return home by 10 p.m. Always early to bed, he would not have given her any trouble.5

  Dirac had his first experience
of grand dining in Hall, where he took his meals.6 The room is magnificently appointed, with an elaborately decorated wooden ceiling, Gothic stained-glass windows and dark-wood panels hung with portraits of some of the college’s most distinguished alumni, including William Wordsworth. The formalities began at 7.30 p.m. with the arrival of the procession of Fellows and other senior members of college at their long table, under the calm gaze of Lady Margaret, whose portrait in oils hung above them. The students were already seated in their gowns along the six rows of benches, either side of three long rows of tables, each of them set with crisp white linen tablecloths, the college coat of arms worked into the damask.

  It was expected that every head should be dutifully cocked, every pair of hands solemnly crossed in silence as one of the students read the Latin grace from a tablet. The moment he finished, a hundred conversations surged to fill the hall.

  The menus, written by hand in French, described the three courses in a style that would meet the approval of a Paris gourmet. The meal might begin with scalloped cod or lentil soup, move on to a main course of jugged hare or boiled tongue and end with gooseberry pie and cream or a plate of cheese with cress and radishes, or even sardines on toast.7 Much of this rich food was wasted on Dirac, whose poor digestion made him favour more basic fare, which he ate slowly and in only modest quantities.

  Dirac’s fellow diners consisted mainly of the young men of the Brideshead generation (in Evelyn Waugh’s novel, Charles Rider and Sebastian Flyte were then beginning their final year over in Oxford). Most of them had been privately educated at schools such as Eton, Harrow and Rugby, where they had learned Latin and Greek and the art of discoursing easily about the fashionable topics of the day, such as T. S. Eliot’s modernist poetry, or of passing supercilious judgement on Shaw’s latest provocation. Dirac was ill equipped to join them.

  Every night, alcohol circulated up and down the dinner table in Hall, loosening the students’ tongues, freeing them to shout ever more loudly to make themselves heard over the din. Amid the cacophony, Dirac sat impassively, a teetotaller in the Methodist tradition, silently sipping water from his glass. He had left Bristol never having consumed a cup of tea or coffee, so his first sampling of these drinks was an event for him.8 Neither much appealed to him, though he did have the occasional weak and milky tea, its caffeine dose scarcely exceeding homoeopathic levels. Decades later, he told one of his children that he drank coffee only to give himself courage before giving a presentation.9

  Dirac’s manner at the dinner table became the stuff of legend. He had no interest in small talk, and it was common for him to sit through several courses without saying a word or even acknowledging the students sitting next to him. Too diffident even to ask someone to pass the salt and pepper, he made no demands at all on his fellow diners and felt no obligation to maintain the momentum of any dialogue. Every opening conversational gambit would be met with silence or with a simple yes or no. According to one story still in circulation in St John’s College, Dirac once responded to the comment ‘It’s a bit rainy, isn’t it?’ by walking to the window, returning to his seat, and then stating ‘It is not now raining.’10 Such behaviour quickly persuaded his colleagues that further questioning was both unwelcome and pointless. Yet he did prefer to eat in company and to hear intelligent people talking about serious matters, and it was by listening to such conversations that Dirac slowly learned about llife outside science.

  He was fortunate to go up to Cambridge at this time. The colleges had just seen the departure of the last students in military uniform, which took precedence over academic dress until the students were officially demobilised.11 Now that Britain was under no threat of another international conflict, this was an optimistic time, and the next generation of students was anxious to get back to academic work. Dirac was studying in the university’s largest department, mathematics, famous for its high standards and its competitiveness. Among the students, the highest cachet was reserved for those who both excelled in their studies and who competed successfully in sport, which is why Hassé had thought it relevant to remark in his reference for Dirac that he ‘played no games’. Most students took at least some part in the social life in Cambridge – chatting in the new coffee bars, singing in choirs, slipping out in the evening to the cinema or to see an ancient Greek play.12 None of this interested Dirac. Even by the standards of the most ambitious swot, he was exceptionally focused on his work, though dedication is no guarantee of success, as thousands of students find out every year. He had been consistently top of the class in the academic backwater of Bristol, but he had no idea whether he would be able to compete with the best students in Cambridge. From the moment Dirac and his colleagues arrived, the dons were watching every one of them, always on the lookout for a student of truly exceptional calibre – in Cambridge parlance, ‘a first-rate man’.13

  It did not take long for the extent of Dirac’s talent to become clear to his supervisor, Fowler, who took a brisk interest in his progress, giving him carefully chosen problems to tackle, constantly encouraging him to hone his mathematics. Students who brought Fowler a good piece of work were rewarded with his favourite exclamation, ‘Splendid!’, and, more often than not, a pat on the back. He was an inspirational presence in the department, but sometimes unpopular: by spending much of his time working at home or on trips to the Continental centres of physics, he often frustrated the students who yearned for the succour of his advice. But Dirac was not so dependent; he was content to be lightly supervised, to work alone and to generate many of his own projects. Soon, he realised that he had been lucky to have been allocated the most effective supervisor of theoretical physics in Cambridge.

  Fowler’s manner was unique in the mathematics department. The prevailing culture was intensely formal, and the academics – every one of them male and dressed like a banker – kept their heads down in their offices and college rooms. The use of first names was all but forbidden: even the friendliest of colleagues referred to each other by their surnames and, outside the common room, conversations rarely lasted longer than politeness deemed necessary. Opportunities for them to meet outside the college were minimal as there was no tradition of communal tea and coffee breaks and no programme of seminars. Nor was there any of the staff–student socialising now almost de rigueur in modern university life. Apart from Fowler’s guidance, Dirac was left to his own devices. He soon settled into a private routine that would have rendered him invisible among the thousands of his fellow students. With no room of his own in the department, he worked on problems that Fowler set him, read recommended books and the latest journals and reviewed the notes he had made during the lectures. He relaxed only on Sundays. If the weather was fine, he set off in the morning for a few hours’ walk, dressed in the suit he wore all week, his hands joined behind his back, both feet pointing outwards as he made his way around the countryside in his metronomic stride. One of his colleagues said he looked like ‘the bridegroom in an Italian wedding photograph’.14

  Dirac would put his calculations firmly at the back of his mind, aiming to clear his head so that he could approach his work fresh on Monday morning. Pausing only to eat his packed lunch, he looked every inch the city gent inspecting the local countryside: to the north, there was the winding valley of the river Great Ouse and to the east, the geometrical network of fenland drains and Tudor-style buildings with their Dutch gables.15 He would return in time for dinner at St John’s and then walk back to his digs through the foggy backstreets of Cambridge, most of them unlit. On Monday morning, he was ready for another six days’ uninterrupted study.

  Dirac’s reserve did not prevent him from meeting many of the country’s most famous scientists soon after he arrived. Among them was the man who had introduced him to the technicalities of relativity theory, Arthur Eddington. He was a young-looking forty-year-old, always neatly dressed in his three-piece suit, the knot of his dark tie poised just below the top button of his starched shirt. For someone so eminent, he was surpris
ingly lacking in confidence – he often sat with his arms crossed defensively, weighing his words carefully. His unique strength as a scientist lay in his hybrid skills as a mathematician and astronomer, giving him the ideal qualifications to play a leading role in tests of the general theory of relativity. He was one of the few scientists who could work on the experiments because, as a Quaker, he was registered as a conscientious objector. Unknown to most of his colleagues, Eddington had used his reputation to contrive the media hullabaloo that followed the announcement in November 1919 that the solar eclipse results supported the prediction of Einstein’s theory rather than Newton’s.16

  Dirac attended his lectures and, like most people who first encountered him through his dazzling prose, was disappointed to find that he was an incoherent public speaker who had the habit of abandoning a sentence, as if losing interest, before moving on to the next one.17 But Dirac admired Eddington’s mathematical approach to science, which would become one of the most powerful influences on him. There was no love lost between Eddington and the other great figure of Cambridge science, the New Zealand-born Ernest Rutherford. The two men had sharply contrasting personalities and diametrically opposed approaches to physics. Whereas Eddington was introspective, mild-mannered and fond of mathematical abstraction, Rutherford was outgoing, down to earth, given to volcanic temper tantrums and dismissive of grandiose theorising. ‘Don’t let me catch anyone talking about the universe in my department,’ he growled.18

  Unlike Eddington, Rutherford did not look in the least like an intellectual. 19 By the time Dirac first felt his surprisingly limp handshake, Rutherford was a burly fifty-two-year-old, with a walrus moustache, staring blue eyes and given to filling his pipe with a tobacco so dry that it went off like a volcano when he lit it. Everyone knew when he was in a room as he spoke more loudly than anyone else. To the people who saw him waddling down Trumpington Street, he had the brash, confident air of a man who had done well out of life by running a chain of betting shops. But his appearance was deceptive: he was the most accomplished experimental scientist alive, as he was the first to confirm. His most famous discovery, the atomic nucleus, followed after he suggested to two of his students that they should investigate what happens when they fired subatomic particles at a thin piece of gold foil. After he heard that a few of the particles were deflected backwards, Rutherford imagined his way into the heart of the atom and concluded that the core of every atom is positively charged and occupies only a tiny fraction of its space, ‘like a gnat in the Albert Hall’, as he put it.20 He first identified the existence of atomic nuclei in the summer of 1912, when he was working at the University of Manchester, eight years before he moved to Cambridge to become J. J. Thomson’s successor as Director of the Cavendish Laboratory. Soon after he arrived there, he made one of his bold predictions about atomic nuclei by proposing that most of them are made not only of protons, each positively charged, but also of hitherto-unidentified particles with about the same mass but no electrical charge. Rutherford encouraged his colleagues to hunt for these ‘neutrons’, but their desultory experiments drew a blank.