The Strangest Man Page 12

  of the nickname: when discussing his work with Rutherford, Kapitza was always afraid of having his head bitten off. (Chadwick papers, II 2/1 CHURCHILL). Chadwick dismissed other explanations (e.g. Boag et al. 1990:11).

  30 Letter from Keynes to his wife Lydia, 31 October 1925, Keynes archive, JMK/PP/45/ 190/3/14 to JMK/PP/45/190/3/16 (KING’S © 2008).

  31 Spruch (1979: 37–8); Gardiner (1988: 240). See also The Cambridge Review, 7 March 1942; Boag et al. (1990: 30–7).

  32 Parry (1968: 113).

  33 Letter from Kapitza to V. M. Molotov, 7 May 1935, translated in Boag et al. (1990: 322).

  34 See Hughes (2003), Section 1.

  35 Childs, W., Scotland Yard, to Chief Constable, Cambridge, 18 May 1923, KV 2/777, UKNATARCHI.

  36 Werskey (1978: 92); Brown (2005: 26, 40).

  37 I am grateful to Maurice Goldhaber for his recollections of the meetings of the Kapitza Club, moderated by Kapitza, in 1933 and the first two terms of 1934.

  38 Blackett (1955).

  39 Postcard from Dirac, 16 August 1925 (DDOCS).

  40 See, for example, letters to Dirac from his mother, 26 October and 16 November 1925, 2 June 1926, 7 April 1927: Dirac Papers, 1/3/5 and 1/3/6 (FSU).

  41 Ramsay MacDonald’s Labour Government was a minority one, whose survival depended on support from at least one of the other two parties. This partly explains

  the Government’s moderate agenda.

  42 Letter to Dirac from his mother, 9 February 1924, Dirac Papers, 1/3/3 (FSU).

  43 In one letter, c. 1924, Felix requests a weekly wage of £2 10s 0d. Dirac Papers, 1/6/3 (FSU).

  44 The spelling of the Reverend’s name is not completely clear. His letters to Felix, including one dated 25 September 1923 and another dated 21 September, are in

  Dirac Papers, 1/6/6 (FSU). I am grateful to Peter Harvey for his advice on the theosophy

  of Felix’s correspondent and to Russell Webb for pointing out the tone of the

  Reverend’s letters, from the point of view of a follower of Eastern philosophy.

  45 Interview with Dirac, AHQP, 1 April 1962, pp. 5–6.

  46 Cunningham (1970: 65–6).

  47 Description of Compton is from the article ‘Compton Sees a New Epoch in Science’, New York Times, 13 March 1932.

  48 Einstein (1949), in Schilpp (1949: 47).

  49 Hodge (1956: 53). Details of Dirac’s early mathematical and scientific influences in Cambridge are in the final section of Darrigol (1992).

  50 Cunningham, E., ‘Obituary of Henry Baker’, The Eagle, 57: 81. Dirac (1977: 115–16).

  51 Edinburgh Mathematical Notes, 41, May 1957.

  52 Quoted in Darrigol (1992: 299–300).

  53 Moore (1903: 201); Baldwin (1990: 129–30). Moore’s conception of the role of art in relation to morality is prefigured in Hegel and thence by his successors. Moore

  adapts this position to the utilitarian scheme that he took over from the Victorian

  thinker Henry Sidgwick. John Stuart Mill anticipates Moore through the conception

  of the great value of the ‘higher’ pleasures.

  54 As Budd describes Kant’s conception of the experience of beauty, it was ‘the facilitated play of imagination and understanding, mutually quickened (and so made

  pleasurable) by their reciprocal harmony’ (2002: 32).

  55 Boag et al. (1990: 133).

  56 Letter from Einstein to Heinrich Zangger, 26 November 1915.

  57 This, and all of Dirac’s publications until the end of 1948, is reproduced in Dalitz (1995).

  58 Interview with Dirac, AHQP, 7 May 1963, p. 7.

  59 Orwell (1946: 10).

  Six

  My grief lies all within,

  And these external manners of lament

  Are merely shadows to the unseen grief

  That swells with silence in the tortured soul.

  WILLIAM SHAKESPEARE, Richard II,

  Act IV, Scene 1

  Towards the end of Dirac’s graduate research, Ebenezer Cunningham described him as ‘quite the most original student I have met in the subject of mathematical physics’ and ‘a natural researcher’.1 By the time he returned to Bristol for Christmas in 1924, he had every reason to be pleased with himself: he had written five good papers – well above the average for even a strong graduate student – with little help from Fowler or any other senior colleague. He was certain to get his Ph. D. But Dirac knew that his work had so far involved mainly tidying up loose ends in other people’s projects and that he had not done nearly enough to deserve a place with Bohr and Einstein at the forefront of theoretical physics. For the moment, Dirac was biding his time in the green room, awaiting inspiration, before he could step out on the international stage.

  Throughout the preceding year, Dirac may have noticed that his mother’s letters indicated her deepening unhappiness and that she was manoeuvring him into the position of a confidant. Early in the summer, she had complained of having little money of her own, a theme that was to become a leitmotif of her correspondence with him. Charles earned a respectable salary and supplemented it by giving private tuition but was always worried about money and had – like many a husband at that time – no compunction about giving his wife only enough to run the house. With virtually no money of her own and too proud to turn to her siblings, she was reduced to asking Paul for money: ‘[Pa] is grousing about the bills just now especially the grocer’s, so I am wondering if you will be able to spare a few shillings a week next time you are home?’2 Though Dirac does not appear to have responded in writing, it is reasonable to suppose that he was disturbed by it as he was living frugally on his grant and had no additional income from teaching. To give his mother money would reduce him to penury.

  In June, he had moved out of his digs into one of the grandest buildings in the college, the neo-classical New Court, built in the early nineteenth century.3 In his rooms in the west wing of the building, he had for the first time the benefits of being able to work in complete private, disturbed only by the cleaner and bed-maker. Many well-off students put their individual stamp on their own patch of the college by bringing their own furniture, oriental rugs, paintings and trinkets. Dirac’s room was as bare as a jail cell, but the accommodation gave him all he needed: peace and quiet, regular meals and warmth. The only irritation for him was the regular ringing of the chapel bell: a few years later, he told a friend that it ‘gets on my nerves sometimes’ – so much so that ‘I am a little afraid of [it]’.4 But his mother knew that he was happier in Cambridge than he was in Bristol, and she feared that he would no longer be content in the modest and ill-kept family home now that he had gone up in the world. Shortly before he returned to Bristol for the Christmas vacation, she prepared his bedroom, beating the carpet and scrubbing the floor, ‘the best I can do to such a shabby room’.5

  Felix had settled in Birmingham, living in lodgings in the south-west of the city and working in the machine-testing laboratory of a factory. With no sign that his career was about to move up a gear, it may have been hard for him to hear his parents talk about the successes of his younger brother in Cambridge. Felix had good reason to be envious: he was still tethered to a stool in a drawing office, plying a trade that brought him little money and, it seems, little satisfaction. Still regretting that his father had refused to let him study medicine, Felix volunteered for the Ambulance Corps, evening work that gave him glimpses of the doctor’s life he had longed for. He was sharing none of this with his brother – they lived separate lives, all fraternal affection spent.

  Early in the cold and dreary January of 1925, Felix snapped. He left his job, though he took care to remain on good terms with his employer, the technical manager in the Testing Machine Department, who certified that he always found Felix ‘to be obliging, courteous, and painstaking in his work’.6 He stopped writing to his parents and sister and did not tell either them or his landlady what he had done or that he was living off his savings. He pretended still to be at wor
k, leaving his digs in the morning and returning for his evening meal, sometimes attending classes at the nearby Midland Institute.

  By the end of winter, his savings ran out. His landlady did not suspect that anything was wrong until the first Thursday evening in March, when he did not return for dinner.7

  The chilly, overcast morning of 10 March began like any other term-time Tuesday for Paul Dirac. There was a hint of spring in the air. As usual, before beginning his day’s work, he walked across the stone courts of St John’s to the Porter’s Lodge to see if there was any mail in his pigeonhole. He found a tiny envelope – small enough to fit in the palm of his hand – postmarked in Bristol late on the previous night, though it was not the weekly note from his mother. He opened the folded letter and saw that it was from his mother’s sister Nell. She began uneasily, asking him to bear up for the news that she was about to convey because his ‘parents are so greatly upset’. Felix was dead.8

  His body had been discovered four days before under a holly bush on the edge of a field two miles south of the Shropshire village of Much Wenlock. Smartly dressed in a suit and bow tie, Felix had a spanner in one of his pockets and was still wearing his bicycle clips, though his cycle was nowhere to be seen. The people who found him assumed that he had killed himself by taking poison, as an empty glass bottle lay next to his corpse. He carried no identifying papers and left no final message; the only clue to his identity was the case of his glasses, which bore the name of an optician in Wolverhampton.9

  Not so long ago, Dirac had loved his brother and looked up to him, shared the same bedroom and the same handed-down comics, ran with him on the Bristol Downs and followed him to university. They had been split by arguments, resentments and jealousies, all of them now rendered pathetically insignificant by grief. Now, the act of suicide had made reconciliation impossible.

  Dirac’s feelings about all this are not known, as there is no documentary evidence of his reactions. If he behaved according to type, he will have received the news with the calm of a statue and told no one in Cambridge about it, apart, perhaps, from Fowler. But it is possible to speculate on his emotions from the testimonies of the few close family members with whom he shared his pain decades later, if only for a few moments.10 If we extrapolate the feelings he showed then back to 1925, it is reasonable to conclude that the passing of Felix left his brother with a tapeworm of anger, sadness and guilt gnawing inside him.

  The news of Felix’s death had been all over Bristol late on the Monday afternoon: the Evening News announced the death in a front-page article under the headline ‘Dead in a Field’.11 A report on the following day noted that Felix’s death had caused ‘a profoundly painful sensation in the city’, hinting that the tragedy was all the more incomprehensible because the deceased was ‘the son of one of the most respected gentlemen connected with education in this city’.12 Charles and Flo did not read the report when it was published as they were in Shropshire to identify their son’s body and attend the first stage of the inquest. Dirac had just received his aunt’s letter and may have wondered why his parents had not wired him as soon as they heard the news. Did they really believe that he would not want to be among the first to hear of his brother’s death? Four decades later, Dirac told friends that he was shocked by his parents’ distress. The death of his brother was ‘a turning point’ for him: ‘My parents were terribly distressed. I didn’t know they cared so much. […] I never knew that parents ought to care for their children, but from then on I knew.’13

  If these and his other recollections of his early family life are accurate, they indicate the extent of his emotional detachment. He appears to have been unaware of many of the experiences that do most to shape the lives of children – the fondness of their parents, the importance of family rituals, the day-to-day entanglements of family life. Nor does he ever even allude to the possibility that the coldness of the Dirac household could have been due at least in part to his own insensitivity. These are among the strongest clues that he suffered from what amounted to a kind of emotional blindness.

  From Dirac’s portrayals of his father’s cold-hearted tyranny and his mother’s overweening maternalism, it would be natural to expect that the suicide of Felix would have hurt his mother much more than his father. But it was the other way round. Charles was poleaxed. This was no ordinary grief: his doctor advised him to rest for a year; his family feared for his sanity and even worried that he might take his own life.14 Flo, by contrast, took it all in her stride, though she was distressed that she had misunderstood Felix and had not seen the disaster as it approached. In a memorial poem to him she wrote thirteen years later, she wrote, ‘He had dropped the mask.’15

  On a bitterly cold Sunday, two weeks after Charles and Flo first heard of their son’s death, they attended a memorial service for him at a nearby church. When Flo returned home, she wrote to Dirac with a mother’s firmness: ‘Mind you meet Pa on Thursday & stick to him all the time after the inquest, there’s a dear boy, & bring him home safely whatever he may hear.’16 Dirac did as she requested: a few days later, he travelled to the enquiry, held within a mile of the hills where Felix had been found, a part of the country finely etched into the English imagination by Housman’s bitter, nostalgic poetry. At the enquiry, Dirac and his heartbroken father sat next to each other when they listened to the coroner read his report. He began by noting that the body had been found on Friday 6 March. The corpse was of a man about twenty-five years old, five feet nine inches tall, with thin features, dark hair, a slight moustache and good teeth. Felix had taken his life, the coroner concluded, by ‘taking cyanide of potassium whilst of unsound mind’.17

  Witnessing Charles Dirac’s grief taught his son a lesson: no matter how painful life might become, he would never commit suicide, because the price paid by his family would be too great.18 Betty was no less affected: in her later life, she never spoke about the circumstances of Felix’s suicide, though she once remarked to her children that he had been killed in a car accident.19

  It appears that Dirac kept working to his usual routine. Fowler had gone on sabbatical in Copenhagen to work with Bohr, leaving Dirac in the care of the young astrophysicist Edward Milne. He set Dirac the task of investigating the processes going on at surfaces of stars such as the Sun, a problem that Dirac solved efficiently, though once again he did not come up with any eye-catching conclusions.20 For several months, Dirac’s productivity plummeted. He never explained why, but it is reasonable to speculate that he was slowed down by grief and, possibly, that he was turning his attention from tackling readily solvable problems to looking for a truly fundamental research problem. Dirac had yet to show that he had the ability to identify such a challenge, the hallmark of a great scientist. But it is clear that he was developing the talent: he returned to the unexplained question of understanding black-body radiation, which had first led Planck to the idea of energy quanta.

  Dirac investigated a daring new idea first introduced by a twenty-six-year-old French student, Louis de Broglie, in his Ph. D. thesis. De Broglie used special relativity to argue with startling boldness and originality that every subatomic particle – including electrons – should have an associated wave of a nature yet to be understood.21 Dirac was inured to thinking of the electron as a particle, for example, in orbit around an atomic nucleus, so de Broglie’s notion of a wave-like electron seemed to be a mathematical fiction of no importance to physicists.22 He carried out some initial calculations but put the work aside after concluding that he had done nothing worth publishing. Having sniffed the scent of an important problem, he had then lost it; but he would soon return.

  In early May, almost two months after the death of Felix, Dirac was looking forward to the visit of Niels Bohr, widely regarded as the world’s leading atomic scientist (he had won the Nobel Prize for physics two years before). Then approaching his fortieth birthday, he was an imposing figure: tall, charismatic and good-natured, with a huge head and a heavily built body that still bore traces
of youthful athleticism.23 His sprawling hands had once helped him to become a top Danish goalkeeper, narrowly missing selection for his country’s soccer team in the 1908 Olympics. Those hands now spent much of the time relighting his pipe or cigarettes; like his fellow chain-smoker Rutherford, Bohr was a serial cadger of matches. The two men had worked together in Manchester for three months in the early summer of 1912, and Bohr had come to regard Rutherford as a ‘fatherly presence’. It was an improbable friendship. Both were profound, intuitive thinkers and impatient with mathematical thinking, but their modes of expression were entirely different: Rutherford was a straight talker whose bluntness could make a navvy blush, whereas Bohr – an inveterate mumbler – was almost always polite and struggled to articulate the tortuous debate going on inside his head. His words were well worth hearing, however, and his audiences sat in silence, straining to hear his every word.24

  Bohr gave his talk, ‘Problems of Quantum Theory’, on 13 May and spoke again at the Kapitza Club three days later. He underlined his view that the current atomic theory was only provisional and that a better-founded one was sorely needed. Bohr was also unhappy with the need to describe light sometimes as particles and at other times as waves. Shortly before, he had failed to resolve the dichotomy, and he was now gloomy about the state of quantum physics. Such confusion intimidates mediocre thinkers, but for the most able ones it signals an opportunity to make their name. One student who was bright enough, in Bohr’s estimation, to solve the problems of quantum theory was the German prodigy Werner Heisenberg, based in Göttingen but soon to visit Cambridge.25 He was very different to Dirac: widely cultured and with a fondness for conversation and patriotic songs which had been nurtured around campfires during his years in the German Youth Movement. Heisenberg would declare over a glass of beer that ‘physics is fun’, a phrase that would not have entered the heads of the serious men who had founded the subject eighty years before.26