Oh God, what have we done?

Reasonable men can dream monstrous dreams. It is the lesson of the 20th century: a lesson articulated from various perspectives since Adorno and Horkheimer wrote Dialectic of Enlightenment amid the wreckage of World War Two. Defenders of the Enlightenment can cogently argue (and many have) that Nazi science was a grotesque caricature, that the Holocaust was a betrayal of the Enlightenment rather than a fulfilment of its fatal dialectic. But it is harder to make that case with respect to the development of nuclear weapons. Indeed the subject seems designed to lay bare the contradictions at the core of Enlightenment culture by revealing them at work in the subculture of professional physicists bent to the needs of government power. Few social laboratories could more clearly reveal the tensions between chauvinist impulses and humanist aspirations, or between careerist plotting and disinterested service, or – perhaps most important – between the Enlightenment ideal of intellectual openness and the demands for secrecy made by the national security state.

The history of nuclear weapons began in an atmosphere of creative ferment and international trade in ideas. This was the world of Knaben3physik (‘boy physics’) in the 1920s and 1930s, when young men who had not been shaving for more than a few years were excitedly reading one another’s papers and poring over the results of experiments in Cambridge, Göttingen, Copenhagen and (eventually) Berkeley. This was how Niels Bohr, Werner Heisenberg and others created the foundations of quantum physics. Yet within less than a decade this moment had passed. Olympian conversations were drowned out by fascist chants. Jewish physicists, led by Einstein, fled to America; Heisenberg stayed in Germany; Bohr stayed out of sight in occupied Denmark. The concentration of research effort shifted westwards across the Atlantic. But it was research with a new, pragmatic mission: to build an atomic bomb before Hitler did. Theories conceived in open exchange were harnessed to secret purposes, and illuminating ideas were pressed into the service of mass death. No wonder some of the atomic scientists felt remorse, or at least ambivalence, about their achievement; no wonder some began to glimpse the darker dimensions of Enlightenment when the blinding flash of the first atomic explosion revealed their labours had not been in vain.

J. Robert Oppenheimer, the physicist in charge of the Manhattan Project and hence ‘father of the atomic bomb’, was never openly remorseful. But he was nothing if not ambivalent, as Ray Monk makes clear in his superb biography. When the fireball burst Oppenheimer remembered the words from Vishnu in the Bhagavad Gita: ‘I am become death, destroyer of worlds.’ It was his own idiosyncratic translation, and it became his most famous remark. The next day, though, his mood was anything but sombre as he jumped out of a jeep at Los Alamos base camp. His friend and fellow physicist Isidor Rabi said: ‘I’ll never forget the way he stepped out of the car … his walk was like High Noon … this kind of strut. He had done it.’ His colleague Enrico Fermi ‘seemed shrunken and aged, made of old parchment’ by comparison. Yet his euphoria passed, and he sank into second thoughts, despondent about the calamitous consequences awaiting the Japanese. He walked the corridors mournfully, muttering: ‘I just keep thinking about all those poor little people.’ Racial condescension aside, he meant what he said, and during the days following the test his secretary said he looked as though he were thinking: ‘Oh God, what have we done!’

He was a brilliant physicist, a charismatic leader and a skilful administrator; he was also a deeply reflective and troubled man, sensitive enough to question the conventional wisdom of the powerful even as he struggled to maintain his influence among them. Monk ably captures all these dimensions, in part through sheer accretion of detail. But he does have a central theme, expressed in his title, Inside the Centre. Whatever else Oppenheimer wanted, he always longed to be at the centre of every important theoretical debate and policy discussion he could manage to enter; a child of wealthy and assimilated German Jews on the Upper West Side of Manhattan, he was the quintessential outsider as insider – yet never quite the insider he aimed to be, in part due to his own contrarian instincts. Committed to Enlightenment ideals of open inquiry, he submitted to regimes of suspicion and secrecy though without ever giving up his own doubts.

Oppenheimer alone is a fascinating subject, but Monk provides copious illuminating detail from the historical surround. He sets out difficult controversies in quantum physics with admirable clarity, and deftly reconstructs the history of the discipline from the era of ‘boy physics’ through the start of the nuclear arms race. It is a sad story, on the whole. It would be hard not to see a decline from the intellectual free-for-all of the 1920s and 1930s, when Oppenheimer began his career, to the cramped mid-century years, when Cold War politics dictated the scientific agenda, and Oppenheimer’s career peaked, then quickly plummeted. Judged guilty by association with left-wing politics in the 1930s, he was deprived of his security clearance in 1954 – after spending the previous decade under near constant government surveillance. The trajectory from openness to secrecy could not be more apparent.

Yet in a sense the secrecy was itself a sham, a strategy deployed for political purposes – including the purpose of manufacturing charges of espionage against Oppenheimer. He became used to the surveillance and (most of the time) adjusted his life to the knowledge that he was being followed, watched and listened to. But the most egregious political use of secrecy was believing in the secret that Oppenheimer – in his pursuers’ minds – plotted to pass to the Soviet Union: the secret of how to make an atomic bomb. As Bohr and other physicists (including Oppenheimer) repeatedly pointed out, the secret was that there was no secret – certainly not once the genie was out of the bottle. After the Manhattan Project had shown it could be done, the pieces of the puzzle were available to anyone; it was only a matter of time before they would be properly reassembled. By the time the Soviet Union detonated an atomic explosion in 1949, the furor over atomic espionage was a manufactured fuss over open secrets. Still it was serious enough to damage Oppenheimer, even as it allowed him to embrace a late-life role as a prophetic outsider.

He was born in 1904, the first child of Julius and Ella Friedman Oppenheimer. His father was a successful cloak manufacturer, his mother a patron of the arts who adorned their apartment with her collection – which included a Rembrandt etching, paintings by Renoir and Van Gogh, and a Blue Period Picasso. She was committed to sustaining her home as a retreat from the world and her protectiveness toward Robert intensified when his little brother Lewis died in infancy. A third son, Frank, was born in 1912, too young to be a playmate for the lonely Robert, though they became companions as adults.* Isolated from other children at an early age, Robert developed keen intellectual abilities while his social skills remained stunted.

That became apparent when he was enrolled as a student in the Ethical Culture School, a magnet for German Jews who were distancing themselves from their Jewishness. He had few friends and suffered constantly from shyness, except when he had occasion to exhibit his precocious intelligence. Adolescence made things worse. The low point was an incident at a summer camp on an island in Lake Ontario when he was 14. Taunted by the other boys as ‘cutie’, mocked for reading poetry, he wrote to his parents that he was having a great time, in part because he was learning so much from the other boys about sex. His fretful parents showed up soon afterwards, and when his father demanded that the camp director discipline the boys who were telling dirty stories, the director complied. Soon the boys turned on Robert, the telltale. They dragged him to the ice-house, stripped him, painted his buttocks and genitals green, tied him up and left him alone for hours. Somehow he stuck it out on the island for the rest of the summer. This incident ‘was a – perhaps the – defining moment of his life’, Monk writes. It confirmed his sense of being an outsider and reinforced his grievances against his father. (He adored his mother.)

Herbert Smith, his English teacher, became his mentor. During the summer of 1922, just before Robert started at Harvard, Smith accompanied the boy (at his parents’ request) on a visit to his quintessentially Wasp chum from the Ethical Culture School, Francis Fergusson, who lived in New Mexico. The trip accentuated his anxieties about his Jewishness. He asked if they might travel together under the name Smith, with Robert passing himself off as Herbert’s younger brother. When Smith asked Oppenheimer to help him fold a jacket, Robert snapped: ‘Oh yes, the tailor’s son would know how to do that, wouldn’t he?’ But ultimately he found himself profoundly at home among the gentiles in the South-West. New Mexico, the landscape as well as the people, became a touchstone for him. The choice of Los Alamos as the location of the chief laboratory for the Manhattan Project was rooted in Oppenheimer’s own attachment to that part of the world.

Arriving at Harvard in 1922 amid its president’s campaign to establish Jewish quotas, Oppenheimer was at first determined to be seen as a literary man, but his fiction provoked only withering criticism from Fergusson. Gradually he turned to chemistry and then physics, and also took a seminar (only one other student enrolled) with Alfred North Whitehead on the Principia Mathematica, which Whitehead had written with Bertrand Russell twenty years earlier. However, once Oppenheimer had decided on physics he was champing at the bit to be ‘near the centre’ of the discipline. In the Anglophone world, that meant the Cavendish Laboratory in Cambridge.

The problem was that the Cavendish was the centre of experimental, not theoretical physics and Oppenheimer was theoretically inclined. Aiming high, he applied to work with Ernest Rutherford. Rejected, he turned to Patrick Blackett, a glamorous experimenter whom contemporaries described as ‘a young Oedipus’. Oppenheimer was miserable, near collapse, bedevilled by sexual frustration and academic anxieties. He lacked the practical skills needed for experimental physics, which included everything from carpentry to glassblowing to calculation. At his wits’ end, he left a poisoned apple on Blackett’s desk. What could have been a nasty incident turned out to be a narrow escape. His father, in town on a visit, worked out a deal with the dean. Instead of being sent down (or sent to prison), Oppenheimer was sent to an analyst. Apparently there was at least some meeting of minds. Years later a colleague would say that Oppenheimer practised physics as an avocation and psychoanalysis as a vocation.

By the start of 1926, he was finding his academic feet, becoming intellectually voracious, eager to use experimental physics to get at theoretical issues. He was catching the contagious mood of Knabenphysik. The boys themselves realised they were living in exciting times. And Oppenheimer was beginning to feel as if he might be one of them. When Paul Dirac arrived at Cambridge, Oppenheimer found himself admiring but not worshipping or envying him. Fertile ideas were popping up all over the place in this seedtime of quantum physics. In Paris, in 1923, Louis DeBroglie had put forward the outlandish notion that electrons were both waves and particles. In 1925, Heisenberg began to demonstrate mathematically how this could be possible. By 1926, quantum mechanics, the search for mathematical models that would explain the apparently bizarre movements of electrons and other subatomic particles, was underway. But the most ambitious theorists – Oppenheimer as well as Bohr, Heisenberg and Max Born – still wondered what physical reality was being modelled by the maths. At Cambridge in 1926, Oppenheimer could be sure he was at the centre of things.

That wasn’t the only reason he was feeling better, however. On holiday in Corsica with his Harvard friend John Edsall in spring 1926, he took to reading Proust, and fastened on a passage from A la recherche that released him from his feelings of self-contempt by acknowledging the pervasiveness of human moral frailty – especially the ‘indifference to the sufferings one causes’ as ‘the terrible and permanent form of cruelty’. However badly he might need to cultivate a façade of superiority, Oppenheimer still brooded fitfully about his own indifference to the suffering he caused. (This tendency would increase as the Manhattan Project reached its successful conclusion.) When he and Edsall debated the merits of Tolstoy and Dostoevsky, Oppenheimer chose Dostoevsky, saying ‘he gets to the soul and torment of man.’ He told Edsall that ‘the kind of person that I admire most would be one who becomes extraordinarily good at doing a lot of things but maintains a tear-stained countenance.’ It was a prescient vision of his best self.

Oppenheimer’s first published paper applied quantum mechanics to an understanding of molecules rather than atoms. This ‘quantum chemistry’ was marred by mathematical errors and made only a minor point. But it began the transformation of Oppenheimer, Monk writes, ‘from a failing experimental physicist to an up-and-coming theorist’. In June 1926, Niels Bohr visited Cambridge and then Oppenheimer came into contact with Max Born, who had just provided a definitive solution to the problem of indeterminacy in quantum mechanics with his discovery that identical experiments can have different outcomes. Physical reality is indeterminate at its core, Born argued: we can only know the probability of an electron being in a particular place at a particular time. Einstein disapproved. ‘God does not play dice,’ he announced. Oppenheimer, like other young physicists, headed from Cambridge to Göttingen to work with Born. His emerging self-confidence, Born’s insecurities, and what Monk calls ‘Oppenheimer’s ability to … cast a spell’ – all this combined to make Born miserable. ‘My soul was nearly destroyed by that man,’ he said. Oppenheimer had begun to fashion the armour of self-regard he wore for the rest of his life.

His research during this period, including his PhD thesis, brought quantum mechanics to bear on questions about the fundamental nature of chemical substances: questions that had attracted him to science in the first place. But the real action was taking place in the borderlands between physics and philosophy. In March 1927, Heisenberg announced his Uncertainty Principle: ‘the more precise our determination of the position of a subatomic particle, the less precise will be our determination of its momentum, and vice versa.’ In September, Bohr published his Principle of Complementarity: depending on how we measure light we see it as waves or particles but never both. These two principles made up what became known as the Copenhagen Interpretation. Its emphasis on the importance of observation in the creation of scientific findings led to a rethinking of the very idea of an ‘outside world’. As the old students’ conundrum had it: ‘to what is the external world external?’ This was a movement against determinism, causality and predictability: three pillars of classical physics which still had staunch defenders, including Einstein. At the Fifth Solvay Congress in the autumn of 1927 Bohr and Einstein would address the question: does God play dice or not?

Meanwhile Oppenheimer had returned, homesick, to New Mexico and California, where he took a professorship at Berkeley, spending part of each year at Caltech. His job at Berkeley was to build up an American school of physics, worthy of the best in Europe. One of his partners in this was Ernest Lawrence, whose efforts to split the atom with his cyclotron were attracting a lot of publicity. But by the early 1930s, quantum physicists already knew that the atom could be split with less energy through ‘quantum tunnelling’ – the Russian physicist George Gamow had shown that tunnelling was a direct consequence of the wave-like nature of subatomic particles. Gamow’s account stimulated the work that led to the first splitting of the atom, by John Cockcroft and Ernest Walton at the Cavendish, who discovered that splitting a lithium atom with 125,000 volts released eight million volts for each of two alpha particles. ‘Little wonder, then,’ Monk writes, ‘that people immediately started to wonder how such tremendous energy releases might be used in explosives.’ The trick to sustaining enough energy for an explosion was to find an element that, when split, could set off a chain reaction. The design for an atomic weapon was beginning to take shape.

Oppenheimer was less concerned with such matters than many of his colleagues. In the early 1930s, he began the study of Sanskrit with Arthur Ryder at Berkeley. The Hindu tradition became an important part of his worldview, teaching him that ‘discipline is good for the soul,’ that it can lead to serenity, what Krishna had in mind when he praised ‘freedom from the chains of attachment, even from a selfish attachment to one’s children, wife or home’. This ideal appealed, no doubt, to the monastic isolate in Oppenheimer. His friend Rabi was convinced that Oppenheimer’s turn to Hinduism (rather than Judaism) had calamitous consequences for his career as a theoretical physicist. Hinduism, Rabi said, led Oppenheimer to delight in work for its own sake, to accept certain problems as insoluble, and to cultivate a comparative indifference to results. So he did not achieve what Bohr, Heisenberg, Dirac et al did. But he did, Monk notes, establish an American school of theoretical physics.

Through the 1930s, he continued to do important research in physics, notably on dying stars, which he traced through three stages from white dwarfs to neutron stars to ‘a singularity’ – a collapsing mass of stellar core inside its own gravitational field. This idea anticipated the concept of the black hole, which wasn’t theorised until 1967. It was Oppenheimer’s most brilliant work, and it was met with silence when he published it in 1939. As Monk observes, ‘the question of what happened inside a massive stellar core was of far less interest, and far less import, than the questions of what might be made to happen inside a uranium nucleus and what might become of Europe.’

Oppenheimer too was swept up more and more in political ferment, driven by what he later called his ‘smouldering fury about the treatment of Jews in Germany’, as well as resentment over the impact of the Depression on his students’ prospects and his concern about the fascist uprising in Spain. He found a sense of belonging in left-wing groups, something not much available for him elsewhere. In 1936, he also started an affair with a Communist Party member, Jean Tatlock, who introduced him to her fellow-travelling friends. His brother Frank and sister-in-law Jackie (‘the waitress my brother married’) joined the CP openly. Oppenheimer would never have done that: the ‘pathetic’ meetings, full (as he saw it) of failures, were too off-putting. He was probably a member of a secret communist cell in Berkeley, which was not as serious as it sounds; many professors and other white-collar folk in the Bay Area discreetly gave money to communist causes and occasionally attended informal meetings in friends’ houses. His fellow-travelling leftism, like his German Jewishness, was a part of his identity that he kept largely to himself.

While Oppenheimer was hanging out with communists, the drive toward nuclear fission was accelerating. This was more than a matter of splitting the atom: it was a form of modern alchemy, transforming one element into others and releasing energy in the process. On Christmas Eve 1938, in Sweden, the physicists Lise Meitner, one of the few ‘girls’ among the knaben, and Otto Frisch achieved this for the first time when they bombarded a uranium nucleus with a neutron, making the nucleus wobble, then split into barium and krypton, which together have less mass than uranium. The remaining mass was released as energy. Frisch and Meitner told Bohr, swearing him to secrecy, but he couldn’t contain himself. He spilled the beans to the physicist Léon Rosenfeld while they were both en route to New York; Rosenfeld passed the word to another colleague, John Archibald Wheeler, on the train to Princeton. So it was that in January 1939 the concept of nuclear fission was unveiled to an American audience at a Princeton seminar. By the end of the month, the news hit the West Coast – ‘we didn’t make long-distance phone calls in those days,’ a Berkeley physicist remembered. Oppenheimer was at first sceptical, then brimming with ‘almost feverish excitement’, Monk writes. As the chemist Glenn Seaborg said, ‘I do not recall ever seeing Oppie so stimulated and so full of ideas.’ Realising the possibility of a chain reaction, Oppenheimer predicted that ‘a 10 cm cube of uranium … might very well blow itself to hell.’ The problem was it would have to be U-235, a rare isotope of U-238, present in less than 1 per cent of natural uranium. You could not produce the large amounts of U-235 needed to make a bomb, Bohr said, ‘unless you turn the US into one huge factory’. That, it turned out, was what the US government was prepared to do. The Nazi government meanwhile banned the export of uranium and started a research programme. On 11 October 1939, Roosevelt created the US Advisory Committee on Uranium. The bomb project was born.

Despite his initial excitement, Oppenheimer remained aloof from fission research until the summer of 1940, when Hitler had taken over nearly all of Europe. At about the same time he met Kitty Harrison, whom he married on 1 November 1940, extending his social circle beyond parlour pinks to CP officials and organisers. The FBI opened a file on him on 28 March 1941.

He was still a passionate teacher, but the summer of 1941 marked his decisive shift from creative science to organisation and management. ‘All of a sudden, nobody’s talking to him,’ a colleague in chemistry said – meaning nobody is talking to him about research. ‘He’s out of it.’ Oppenheimer began to distance himself from the CP to make himself more available for war work. For a while he was excluded from the bomb project, now named the S-1 committee, which was set to research four methods of fission, including two that used plutonium as a more fissionable element than U-235. The manufacture of uranium would require building the first nuclear reactor. Oppenheimer haltingly moved from periphery to centre, dogged at every stage by his political beliefs and associations. At the end of 1941, he was asked to head fast-fission research at S-1. In time his security clearance would come; meanwhile his presence energised the project. He revealed his exceptional leadership skills at a meeting of scientific ‘luminaries’ involved with atomic research at Berkeley in July 1942, and when in September General Leslie Groves was chosen to head what was already being called the ‘Manhattan Project’, Groves, who was six feet tall, weighed 250 lbs and possessed a legendary will, fell under Oppenheimer’s spell. Oppenheimer had ‘an unerring sense of what Groves wished to hear’, Monk writes. Things were moving fast. On 2 December Fermi gathered twenty people in the rackets courts at Stagg Field in Chicago to witness the world’s first chain reaction. The theoretical problems were mostly solved. It was time to move from theory to practice: to work with experimentalists and engineers in a central laboratory, which Oppenheimer persuaded Groves should be on a flat mesa in the mountains of northern New Mexico.

Convinced that Oppenheimer was loyal to the United States, and essential to the project’s success, Groves pushed through his security clearance on 20 July 1943. But Lt Col Boris Pash of army intelligence was convinced of his perfidy. He tapped Oppenheimer’s phones, installed hidden microphones in his house, employed intelligence agents as his chauffeurs, and followed him everywhere. Informed of this surveillance by John Lansdale, the Los Alamos security chief, Oppenheimer apparently decided to protect himself, by taking a more active role in turning in old communist acquaintances. One event stands out: just before they left Berkeley for government work in 1942, the Oppenheimers had given a dinner party for Haakon Chevalier, a professor of French literature, and his wife. Chevalier asked Oppenheimer if he could pass on any information about military related research at Lawrence’s Rad Lab to a friend of his, a British Communist called George Eltenton who had contacts at the Soviet consulate. Eager to show his bona fides, Oppenheimer went to Berkeley to warn army intelligence of potential security problems, mentioning Eltenton but not providing any other details. Pash had shown up for this conversation, and he arranged to see Oppenheimer the next day, questioning him more closely about the intermediary, the contacts the intermediary had made, and Eltenton’s own contact at the Soviet embassy. Oppenheimer refused to name Chevalier but inexplicably said the unnamed intermediary had contacted three people. It was, he later admitted, ‘a cock and bull story’; it eventually implicated his brother and dogged Oppenheimer for the rest of his life. Pash’s tape of that conversation would be replayed again and again, behind closed doors and in public congressional hearings. The immediate consequence was that Groves ordered Oppenheimer to reveal the name of the intermediary; Oppenheimer identified Chevalier but instead of admitting that he himself was the contact, named his brother Frank on condition that Groves keep it secret, covering it up by deploying the original cock and bull story in official reports. Eventually, Lansdale informed on Frank. Oppenheimer’s confusing conduct must be explained in part by his desire to stay on the job at Los Alamos, where by all accounts he was performing inspirational work.

For most scientists at Los Alamos, the project began in a beat-the-Germans-to-it frenzy, but soon shifted to an implicit emphasis on the bomb for its own sake. This was when the dialectic of the Enlightenment began to reveal its dark side. Seeing the project through to success became an end in itself. According to James Tuck, a British physicist, Los Alamos was ‘the most exclusive club in the world’, a place where the ‘spirit of Athens, of Plato, of an ideal republic’ prevailed. Oppenheimer, Tuck said, was the source of this spirit. Hans Bethe said that Oppenheimer ‘worked at physics mainly because he found physics the best way to do philosophy.’ Only his sort of vision could prepare the assembled scientists for their impossible task.

The Hiroshima bomb – Little Boy – was a gun assembly bomb made with U-235. Scientists were so confident it would work they didn’t even feel the need to test it. But in late spring 1944, after the failure of Thin Man, a plutonium gun assembly bomb, Oppenheimer reorganised the entire lab to engineer the production of Fat Man, a plutonium implosion bomb that involved assembling a critical mass by bringing together several subcritical mass pieces. This was the bomb dropped on Nagasaki. Oppenheimer’s rapid re-engineering of it, Monk writes, was ‘arguably [his] greatest achievement’.

Monk accepts the standard argument used to justify the bombings: that they would shorten the war by removing the need for invasion. What the argument doesn’t consider is the extent to which the ‘necessity’ of invading a defeated enemy was created by the politically popular but militarily unnecessary doctrine of unconditional surrender. After the successful test, and despite his periodic panics and despondency, Oppenheimer opposed the petition circulated by his colleagues James Franck and Leo Szilard, against the use of the bomb on the Japanese. ‘What do they know about Japanese psychology?’ he asked. ‘How can they judge the way to end the war?’ But after the Hiroshima bombing, Oppenheimer lost heart for more. On the day of the second bombing, he was a ‘nervous wreck’.

As the long-term impact of radiation poisoning became impossible to ignore, remorse spread. Most of the scientists, including Oppenheimer, wanted international control of atomic energy as a barrier against an arms race. There was no secret to the bomb, scientists insisted; Truman and the military insisted there was. Oppenheimer yielded to the president and his generals, supporting the May-Johnson Bill to create an Atomic Energy Commission with much secrecy and military influence. Anxious to remain an insider, he stumbled into a disastrous interview with Truman. Noticing that the ‘father of the atomic bomb’ seemed strangely inarticulate, Truman asked him what was the matter. ‘Mr President, I feel I have blood on my hands,’ Oppenheimer finally said. Disgusted by this ‘cry-baby scientist’, Truman told his aides: ‘I don’t want to see that son-of-a-bitch in this office ever again.’ Oppenheimer’s proposal for international control, like all other proposals, yielded to the Baruch Plan. Bernard Baruch was a crony capitalist with investments in uranium; his ‘Plan’ assumed a continued US nuclear monopoly. As anti-Soviet paranoia intensified, the view that there was no secret about how to make atomic weapons became, in the minds of Cold Warriors, ‘a treasonous plot’. In this political atmosphere, Oppenheimer concluded, physics had become ‘irrelevant’; people who met him now were aghast at this ‘tragic figure’. Yet before long he was back in Washington as a member of the general advisory committee to the Atomic Energy Commission, along with Rabi, Seaborg and the investment banker Lewis Strauss, who was also a trustee of the Institute for Advanced Study in Princeton. Strauss invited Oppenheimer to head the Institute. He would be an insider a little while longer.

Around the same time – in 1946 – J. Edgar Hoover was turning the FBI to a singleminded pursuit of Oppenheimer. Whether because he knew he was being recorded or because he was genuinely frustrated by Russian intransigence in UN debates over atomic weapons, Oppenheimer began expressing more hostility to the Soviet Union. While intellectual life was flourishing at the Institute – Oppenheimer had undertaken a major rejuvenation, bringing in George Kennan, for example – a US-Soviet arms race was building on a foundation of mutual suspicion, paranoia and fear – everything Oppenheimer and his Los Alamos colleagues had warned against.

In June 1949, Oppenheimer was summoned before the House Un-American Activities Committee. At this delicate moment, he seemed determined to alienate as many potential friends and supporters as he could. Treated deferentially by the committee, he informed on Bernard Peters (a younger colleague at the University of Rochester), going beyond what was being requested. When his brother Frank was identified as a communist by the Washington Times-Herald, Frank offered the University of Minnesota a resignation letter ‘just in case’. The university accepted it and a number of prominent physicists protested publicly. His brother was not among them. Oppenheimer was losing his stature with colleagues and his friendship with Frank. And he was making an enemy of Strauss, whom he publicly embarrassed at a meeting of a joint congressional committee on atomic energy by mocking him for his scientific illiteracy.

Another controversy cast Oppenheimer’s loyalty under further suspicion. Since the Manhattan Project, a number of physicists led by Edward Teller had been pushing for the development of a fusion bomb – the so-called ‘Super’ or, later, hydrogen bomb. Oppenheimer, like most of the other Los Alamos scientists, opposed it as a weapon that, if it were technically feasible (which he doubted), would be too destructive ever to be used in war. He maintained this view until tests on Eniwetok Atoll in the South Pacific showed that the bomb worked. What he called its ‘technically sweet’ design outweighed his earlier objections, though they had been moral as well as technical. As at Los Alamos, technological success became its own justification. Yet in Washington circles, Teller insisted that Oppenheimer still opposed the H-bomb, insinuating that some people believed he was acting on ‘direct orders from Moscow’. Teller used this belief cynically in order to promote his campaign for a second nuclear weapons lab (which became Lawrence Livermore Laboratory, in California). Teller’s ambition indirectly reinforced the campaign to blacken Oppenheimer’s reputation – now led by Strauss as well as Hoover. After the Republican victory in the 1952 election, Strauss became Eisenhower’s AEC head. Convinced by now that Oppenheimer had been a Soviet spy at Los Alamos, Strauss pressured Hoover to bring charges against him before the president and on 3 December Eisenhower suspended Oppenheimer’s security clearance.

Oppenheimer, still working as a consultant for the Atomic Energy Commission, refused to resign and agreed to a security hearing before his employers. His attorney, Lloyd Garrison, proved no match for Roger Robb, the tough trial lawyer Strauss had picked to represent the AEC. Robb retraced Oppenheimer’s testimony to Pash, its inconsistencies with respect to the Chevalier conversation, its ambiguities with respect to names and numbers. Garrison called character witnesses, who were undone by Robb’s skilful cross-examinations. The AEC ruled 4-1 that while Oppenheimer was not disloyal, his security clearance should still be withheld. ‘The trouble with Oppenheimer,’ Einstein observed, ‘is that he loves a woman who doesn’t love him – the US government.’

Einstein was right. Oppenheimer was in many ways an unrequited patriot. In the years after his rejection (he had only a decade or so left to live), he began to repair the damage done to his reputation. He embraced a role as a public intellectual, addressing the ultimate questions raised by the arms race he had helped to start. In summer 1959, at a conference held by the Congress for Cultural Freedom, he asked: ‘What are we to make of a civilisation which has always regarded ethics as an essential part of human life… [but] which has not been able to talk about killing almost everybody except in prudential and game-theoretical terms?’ Like his Institute colleague George Kennan, Oppenheimer had become appalled by the bland technocratic jargon used to legitimate strategies of mass extermination – jargon that his colleague John von Neumann had dignified as ‘game theory’. Like Kennan, too, Oppenheimer came round to emphasising (in Monk’s words) ‘recognition and acceptance of the evil in oneself’ as a counterweight to the Cold War demonisation of the Soviet Other. This was his personal dialectic of enlightenment – the confrontation with the evil that his own brilliance, and the brilliance of his colleagues, had released. This was the secret knowledge that official secrecy denied. ‘We most of all should try to be experts on the worst among ourselves,’ he decided towards the end of his life.