Inside the Centre: The Life of J. Robert Oppenheimer

by Ray Monk

  Apart from these very brief mentions of Sanskrit literature, Oppenheimer’s only other allusion to Hinduism in his correspondence comes in yet another letter to Frank, in which he tells him that he has called his third and latest car ‘Garuda’, after, he says, ‘the mechanical bird which the carpenter made for his friend the weaver who loved a princess’ – a description that shows a knowledge of the collection of fables known as the Panchatantra, rather than of the Upanishads scriptures, or the epic poem the Mahabharata, in both of which Garuda is depicted quite differently as a minor deity who carries the supreme god, Vishnu.

  Though detailed discussion of his reading is absent, one can see the influence of Hinduism in much of what Oppenheimer writes to his brother. For example, in a letter to Frank, undated but probably written in January 1932, he speaks of ‘that delectatio contemplationis which is the reward and reason of our way of life’ and says that, though such things are not to be expected, nevertheless ‘we try to do everything to invite them, cultivate a little leisure, and a certain detached solitariness, and a quiet discipline which uses but transcends the discipline of our duties’.

  In some ways, these remarks carry echoes of some of Felix Adler’s maxims, but, in their emphasis on detachment, separateness and transcendence they seem closer to the Bhagavad Gita than to the Ethical Culture movement, with its encouragement to engage politically and socially so as to improve the lives of others. Even more clearly indebted to Hindu ideas is the extended disquisition on the notion of discipline that Oppenheimer included in a letter to Frank two months later. The view Oppenheimer puts forward there is that discipline is to be valued independently from, and more than, ‘its earthly fruit’. ‘Discipline is good for the soul’, as Oppenheimer puts it, and it is not good because it leads to good results, or because it enables us to do things. That discipline is good for the soul ‘is more fundamental than any of the grounds given for its goodness’. It is, as it were, good in itself. What Oppenheimer writes about discipline to Frank is worth quoting at length, because it offers, I think, some valuable clues about the way he looked at life, and how that enabled him to do the things he did.

  I believe that through discipline, though not through discipline alone, we can achieve serenity, and a certain small but precious measure of freedom from the accidents of incarnation, and charity, and that detachment which preserves the world which it renounces. I believe that through discipline we learn to preserve what is essential to our happiness in more and more adverse circumstances, and to abandon with simplicity what would else have seemed to us indispensable; that we come a little to see the world without the gross distortion of personal desire, and in seeing it so, accept more easily our earthly privation and its earthly horror – But because I believe that the reward of discipline is greater than its immediate objective, I would not have you think that discipline without objective is possible: in its nature discipline involves the subjection of the soul to some perhaps minor end; and that end must be real, if the discipline is not to be factitious. Therefore I think that all things which evoke discipline: study, and our duties to men and to the commonwealth, war, and personal hardship, and even the need for subsistence, ought to be greeted by us with profound gratitude; for only through them can we attain the least detachment, and only so can we know peace.

  These thoughts carry direct echoes of the Bhagavad Gita, which begins on the battlefield with the great warrior Prince Arjuna despairing at the suffering of war and coming to doubt that there is any glory in killing the ‘teachers, fathers and sons’ who face him. He therefore wants no more part in the ‘evil of destruction’. The god Krishna, however, tells him that his concern for the deaths of his kinsmen and enemies is misplaced, since the spirit does not perish with the body and it is the spirit alone that is of value. Arjuna must fight, Krishna urges, not because of what fighting will accomplish, but rather because it is his duty to fight. ‘Set thy heart upon thy work,’ Krishna says, ‘but never on its reward. Work not for a reward; but never cease to do thy work.’ Towards the end of the book Krishna preaches ‘freedom from the chains of attachment, even from a selfish attachment to one’s children, wife or home’, a freedom achievable by ‘retiring to solitary places, and avoiding the noisy multitude’, Krishna continues: ‘A constant yearning to know the inner Spirit, and a vision of Truth which gives liberation: this is true wisdom leading to vision.’ He then speaks of Sattva, Rajas and Tamas – light, fire and darkness – and says: ‘Any work when it is well done bears the pure harmony of Sattva’ and ‘From Sattva arises wisdom.’

  According to Isidor Rabi, Oppenheimer ‘would have been a much better physicist if he had studied the Talmud rather than Sanskrit . . . it would have given him a greater sense of himself.’ Rabi was inclined to link Oppenheimer’s interest in Sanskrit texts with his expertise in French literature; both, he thought, were part of Oppenheimer’s attempt to persuade himself and others that he was not Jewish. If he had mastered the literature of his own tradition, rather than those of others, Rabi thought, Oppenheimer would not have had the problems that come with denying one’s own background. ‘The Jewish tradition,’ Rabi thought, ‘even if you don’t know it in detail, is so strong that you renounce it at your own peril. Doesn’t mean you have to be orthodox, or even practise it, but if you turn your back on it, having been born into it, you’re in trouble.’

  As we have seen, the sense in which Oppenheimer was ‘born into’ the Jewish tradition is elusive, perhaps too elusive for Rabi’s point to be persuasive, because there is no clear way in which we can see Oppenheimer turning his back on his own tradition. In his family, as in many of the German Jewish families that made up Oppenheimer’s cultural background, the back-turning had been done a generation or two earlier. In the introduction he wrote to the published collection of speeches given at Oppenheimer’s memorial, Rabi offered another reason for thinking that the influence of Hinduism on Oppenheimer’s physics had been for the worse, this time in an effort to explain ‘why men of Oppenheimer’s gifts do not discover everything worth discovering’. The answer, he suggests, is that ‘in some respects Oppenheimer was over-educated in those fields which lie outside the scientific tradition, such as his interest in religion, in the Hindu religion in particular, which resulted in a feeling for the mystery of the universe that surrounded him almost like a fog. He saw physics clearly, looking toward what had already been done, but at the border he tended to feel that there was much more of the mysterious and novel than there actually was.’

  He was insufficiently confident of the power of the intellectual tools he already possessed and did not drive his thought to the very end because he felt instinctively that new ideas and new methods were necessary to go further than he and his students had already gone. Some may call it a lack of faith, but in my opinion it was more a turning away from the hard, crude methods of theoretical physics into a mystical realm of broad intuition.

  It is difficult to know whether the work that Oppenheimer did in the period after 1932 exemplifies or refutes Rabi’s remarks. On the one hand, this was one of Oppenheimer’s most impressively concentrated periods of work, during which he worked on the most fundamental, and difficult, problems that theoretical physics had to face at that time. Addressing these problems took all of the very considerable talents and energy at Oppenheimer’s disposal. Or, anyway, most of them; it is true that he combined his work in physics with, for example, learning Sanskrit and reading ancient Greek – things that most of us would regard as significant achievements in their own right – but, for the most part, he approached physics at this time with something of the attitude recommended by Krishna in the Bhagavad Gita: freedom from attachments, seclusion from the ‘noisy multitude’ and, above all perhaps, a ‘constant yearning to know’. If he showed some interest in things of beauty, such as the literature he read, he showed almost none in the social and political upheavals that were happening at that time. Whether one thinks of this as a good or a bad thing, it is certainly hard to see
that it hindered his progress in physics, and hard too to regard it as anything but an application of the outlook he had acquired from Hinduism.

  On the other hand, despite his extremely hard work and his utter absorption in physics at this time, it is true that he did not accomplish anything remotely comparable to the achievements of Bohr, Heisenberg, Dirac et al. And the reason for that may have something to do with his Hindu-influenced attitudes. Regarding work as being valuable for its own sake, regardless of its results, may have inspired in him a devotion to work that others lacked, but it may also, as Rabi suspected, have made him less single-minded than the very best physicists with regard to solving problems, and more accepting of the idea that some problems were simply insoluble. Someone like James Chadwick or Ernest Lawrence, or even Paul Dirac, worked at a problem in order to solve it; Oppenheimer took pleasure in the work itself.

  And yet, if Oppenheimer approached physics from the point of view of someone who saw in it ‘truth, goodness and beauty’, he also had at least one practical result in mind – namely, the development and growth of the peculiarly American school of theoretical physics that he had set out to create. In contrast to Paul Dirac, say, who had very few graduate students and spent very little time with those he had, Oppenheimer did almost everything, including his own research, with his students.

  For both Oppenheimer and his students, the research agenda was set by the remarkable discoveries of 1932, as Oppenheimer spelled out in his letter to Frank in the autumn of that year. He begins his report with the very distinction that forms the heart of the Bhagavad Gita view of work: ‘The work is fine: not in the fruits but the doing.’ He goes on:

  There are lots of eager students, and we are busy studying nuclei and neutrons and disintegrations; trying to make some peace between the inadequate theory and the absurd revolutionary experiments . . . We have been running a nuclear seminar, in addition to the usual ones, trying to make some order out of the great chaos, not getting very far with that. We are supplementing the paper I wrote last summer [the one he published with Frank Carlson on ‘magnetic neutrons’] with a study of the radiation in electron–electron impacts, and worrying about the neutron and Anderson’s positively charged electrons, and cleaning up a few residual problems in atomic physics. I take it that there will be a lull in the theory for a time; and that when the theory advances, it will be very wild and very wonderful indeed.

  During the year 1932–3, Frank Carlson, having received his PhD in April 1932, was Oppenheimer’s research associate, Melba Phillips was in the final year of her PhD studies, and Leo Nedelsky, who, like Carlson, had completed his PhD in 1932, was still in Berkeley, having had no success in finding an appointment. Harvey Hall, meanwhile, had found a job at Columbia as an instructor in physics. Oppenheimer, perhaps thinking he was helping out, asked Nedelsky to lecture for him during the weeks he left Berkeley to go to Caltech. ‘It won’t be any trouble,’ Oppenheimer told him, ‘it’s all in a book.’ The book, however, turned out to be in Dutch. When Nedelsky reported that this would be a problem, Oppenheimer airily replied: ‘But it’s such easy Dutch.’

  In 1932, these graduate students were joined by some postdoctoral students, holders of the coveted National Research Fellowship, who, now that Oppenheimer was there, regarded Berkeley as a serious rival to Cambridge, Copenhagen and Göttingen as a place in which to pursue postdoctoral research. In 1932–3, Oppenheimer worked with two of these NRF postdoctoral students. The first was Wendell Furry, a Methodist minister’s son from Indiana, who had taken his PhD at the University of Illinois. Furry had attended the Ann Arbor summer school in 1931 and had been deeply impressed at seeing Oppenheimer, the only American invited to share the platform with the galaxy of European stars on display, standing up to none other than Wolfgang Pauli. When he went to Berkeley, however (to begin with at any rate), Furry felt hopelessly out of his depth, finding that when he attended Oppenheimer’s lectures he did not understand a word of them. It took him a year to regain his confidence.

  In the meantime, Oppenheimer began to work closely with Milton Plesset, his second National Research Fellow, though he had arrived not at Berkeley but at Caltech, initially hoping to work with Paul Epstein, the Russian physicist who had been there since 1921. Plesset had done his PhD at Yale on a subject close to Oppenheimer’s heart, Dirac’s theory of the electron, and so it was natural that Oppenheimer would take some interest in his work and that they should start working together. After all, people who understood Dirac’s quantum electrodynamics were few and far between. As Plesset later recalled: ‘The state of theoretical physics in this country at that time was not very advanced, except for Oppenheimer.’ When Oppenheimer arrived in Pasadena, Plesset remembers, ‘things really started to move’. He and Oppenheimer got interested in what Plesset describes as ‘a problem with the Dirac electron’ and together they wrote a short paper that ‘put a new light on the Dirac theory’.

  That paper, entitled ‘On the Production of the Positive Electron’, was published as a letter to the editor in the Physical Review in the summer of 1933 and is the first of a series of papers in which Oppenheimer, usually together with one of his students, attempted to address what he saw as the problems in Dirac’s theory of the electron. This had been an ongoing preoccupation of his since Dirac had first shown him the theory in 1928, but, after the discovery of the positron in 1932, this preoccupation took on a rather different form. He could no longer, as he had before, point to the negative energy states in the theory as evidence of a problem; these states were filled, as Dirac had predicted, with positively charged particles. Indeed, the paper jointly written by Oppenheimer and Plesset begins with the following acknowledgement: ‘The experimental discovery of the positive electron gives us a striking confirmation of Dirac’s theory of the electron.’ It had quickly been confirmed that positrons could be created not only by the impact of cosmic rays, but also in the laboratory. In their paper, Oppenheimer and Plesset discuss, in particular, the experiments at Caltech conducted by Carl Anderson and his colleague Seth Neddermeyer, in which they showed that pairs of electrons and positrons are created when the very energetic gamma radiation from thorium C" passes through lead. From Dirac’s theory, they point out, one can make predictions about the frequency of pair production that are confirmed by the experimental evidence, but only – and this is where Oppenheimer thought major changes in the theory were needed and where his interest really lay – up to energies of a certain limit. Beyond that limit, Oppenheimer and Plesset claim, the theory fails.

  In the penultimate paragraph of their short paper, Oppenheimer and Plesset make what Abraham Pais has described as a ‘fundamental observation’, namely that ‘fast electrons and positives [positrons] . . . will themselves tend to produce further pairs’ – a prescient anticipation of the phenomenon of showering that would later be studied intensely by physicists, including Oppenheimer himself. Pais is less complimentary about the mathematics in the paper, pointing out: ‘Their final formula was wrong, as usual, as others rapidly noted.’

  These two aspects of Oppenheimer’s work – his originality and his mathematical carelessness – are neatly captured in a recommendation that Ralph Fowler wrote to Edwin Kemble of Harvard, when Harvard expressed an interest in trying to lure Oppenheimer away from California. Kemble knew Oppenheimer himself, of course, but he also knew that Fowler had seen him on many occasions during his rise to prominence, the latest of which was a visit Fowler made to Berkeley in the autumn of 1932. Dated 30 November 1933, Fowler’s report reads:

  I fancy he is not a very good lecturer and his work is still apt to be full of mistakes due to lack of care, but it is work of the highest originality and he has an extremely stimulating influence in a theoretical school as I had ample opportunities of learning last fall.

  Nevertheless, despite his unreliable mathematics, Oppenheimer was successfully putting both Berkeley and Caltech on the international map. When distinguished physicists came to California, the man who made t
he most impression on them was usually Oppenheimer. This was certainly the case when God himself, Niels Bohr, came to Pasadena in the summer of 1933. This was the only opportunity Oppenheimer had had to discuss physics with his greatest scientific idol since their initial meeting at Cambridge in 1926, and it seems to have been remembered by both as a pleasant and instructive occasion. At the very end of their 1933 paper, Oppenheimer and Plesset extend their ‘profound thanks’ to Niels Bohr, ‘who has helped us to understand the essential consistency of the theory which we have here applied’. For his part, Bohr was very pleased to be able to discuss physics with Oppenheimer, his meeting with whom seems to have been the highlight of his visit. He was much less enchanted with Millikan, but nevertheless agreed to meet the trustees of Caltech to tell them how well the school of physics was doing. On 14 June 1933, Oppenheimer wrote to Bohr to thank him for his visit, and to send him a copy of the paper he had written with Plesset, who was about to leave Pasadena to spend a year at Bohr’s institute.

  Plesset remembers that Bohr’s institute that summer was ‘swarming’ with refugees from Nazi Germany, mostly Jewish scientists. Shortly after Plesset’s arrival, the institute held its annual seminar, which for a number of reasons is remembered as a melancholy occasion. Dirac, Heisenberg and Ehrenfest were among the attendees, and Plesset recalls ‘a lot of discussion over the validity of Dirac’s theory. People were groping still.’

  In especially poor spirits at Bohr’s seminar was Paul Ehrenfest, who was described as looking ‘pudgy-faced and overweight’ and ‘losing his grip on physics’. When the time came to leave, Dirac, who had grown close to Ehrenfest, saw him waiting for a taxi, looking flustered and unhappy, and thanked him for his contributions to the discussions. This elicited from Ehrenfest an extreme and, for Dirac, extremely worrying, reaction: ‘What you have said, coming from a young man like you, means very much to me because, maybe, a man such as I feels he has no force to live.’ A few days later, the dreadful news came that Ehrenfest had shot himself, prompting Dirac to write a four-page letter to Bohr describing in detail his last moments with Ehrenfest and telling him that he could not help blaming himself for what had happened.