In the preface to In the Shadow of the Bomb, the physicist and historian of science Sylvan S. Schweber tells us that ten years ago Hans Bethe asked him to write Bethe’s “intellectual biography.” This turned out to be a monumental task since Bethe, who is now in his early nineties and still very active, has in the last seven decades made profound contributions to almost all branches of physics. Schweber realized that it would take several volumes to describe Bethe’s work and that in the end it might not have much interest for nonspecialist readers.

Hence he decided to condense his account to a more manageable size. In fact, the present relatively short book—186 pages of text and some 70 pages of notes and bibliography—began as a chapter before Schweber decided to make it a book in its own right. In effect he has written a dual biography of Bethe and J. Robert Oppenheimer, concentrating on the time when they both worked on the atom bomb and tried to deal with its consequences. There is much in it to be admired, but much that I found disappointing.

He describes part of the difficulty when he writes, “…I know so much more about Bethe’s life than about Oppenheimer’s, and Bethe’s story continues to unfold.” This works against his project in two ways. The obvious one is that his portrait of Oppenheimer lacks sufficient detail and does not bring us close to Oppenheimer’s complex personality. The less obvious one is that the presence of the living Bethe, whom, and with good reason, Schweber admires enormously, inhibits a frank account of his life. For example, Schweber tells us that in the 1970s, Bethe’s activities in pure science—as opposed to government and industrial consulting—were not “outstanding.” He notes that part of the reason had to do with “crises within the home.”

We are given no clue to what this refers to. If a writer does not want to explain such matters, then why mention them at all? Furthermore, the accounts of both Bethe and Oppenheimer are encumbered with material which only gets in the way of the story. These digressions might be overlooked in a long book, but in a short one they crowd out material that is genuinely important.

Oppenheimer, who was born in New York in 1904, came from a well-to-do German-Jewish family and was educated at the Ethical Culture School in New York. This leads Schweber to devote several pages to a somewhat tedious digression into the ideas of Felix Adler, who founded the school. What any of this had to do with Oppenheimer is not entirely clear. What is clear is that Oppenheimer had considerable difficulty in dealing with the fact that he was Jewish, and rather pointedly avoided involvement with Jewish culture and traditions. Schweber does not say enough about this or its possible sources in his early years, or about the anti-Semitism Oppenheimer encountered in the 1920s.

Schweber, for example, quotes from a letter of recommendation that Oppenheimer’s great teacher at Harvard, Percy Bridgman, had written in 1925 to Ernest Rutherford, suggesting that Oppenheimer come to work with him in Cambridge. However, the part of the letter that he does not quote is the most interesting. In it Bridgman writes, “As appears from his name, Oppenheimer is a Jew, but entirely without the usual qualifications of his race. He is a tall, well set-up young man, with a rather engaging diffidence of manner, and I think you need have no hesitation whatever for any reason of this sort in considering his application.”1

Bridgman was in no way an anti-Semite. He was simply trying to help Oppenheimer. Jews with a strong emotional center of gravity were able to deal with such condescension, sometimes by finding strength in their heritage. One of Oppenheimer’s oldest friends, the physicist I.I. Rabi, told me that Oppenheimer reminded him of a man he knew who could not decide if he wanted to be a member of the B’nai B’rith or the Knights of Columbus. He joked that if Oppenheimer had learned Yiddish rather than Sanskrit he might have become one of the best physicists who ever lived.

I have often wondered if some deep sense of insecurity contributed to the indiscretion that Oppenheimer sometimes showed in conversation and that I witnessed firsthand. In the fall of 1957 I had just driven across the country to Princeton to take up a postdoctoral appointment at the Institute for Advanced Study, of which Oppenheimer was the director. I was told that Oppenheimer wanted to see me. Disheveled as I was, I went to his office to find him impeccably dressed, as usual, in one of his suits from Langrocks, the local tailor to the fashionable. He studied me with his remarkable blue eyes and asked, “What is new and firm in physics?” The “and firm” impressed me.


Before I could try to answer, the phone rang. I got up to leave, assuming he would want to speak in private. He motioned to me to remain seated and had a brief, apparently intimate, conversation. When he hung up he said to me, “It was Kitty,” referring to his wife, whom I had never met. “She has been drinking again.” That he would say this to a perfect stranger left an impression I have never gotten over. As thoughtless as it was, it was not likely to have any repercussions. But some of Oppenheimer’s indiscretions did have repercussions, and here Professor Schweber provides a telling example from Oppenheimer’s relations with the physicist Bernard Peters.

Peters, who had been born in what was then the German city of Posen in 1910, had moved to Munich to study electrical engineering in 1932. When Hitler came to power, Peters, who was never a Communist, took part, along with some Communists, in anti-Hitler demonstrations. He was arrested and sent to Dachau, from which he miraculously escaped. He managed to bicycle by night to Italy to join the woman whom he later married. After further travels they ended up in the San Francisco Bay area, where she obtained a research position in the Stanford Medical School, while he worked as a longshoreman. He met Oppenheimer at the house of friends and somehow Oppenheimer recognized his abilities and suggested that he come to Berkeley to study physics. After Peters took one undergraduate course, Oppenheimer decided that he was so gifted that he should be admitted to the graduate program. He was later invited to come to Los Alamos but decided to remain in Berkeley at the Radiation Laboratory.

The scene now shifts to 1944 when Oppenheimer was the director of Los Alamos. For reasons not entirely clear, Peer De Silva, who was in charge of security, brought up with Oppenheimer the names of four of his former students, among them Peters. He asked which of them was most likely to be the most “dangerous.” In a moment of monumental indiscretion, Oppenheimer named Peters, who by then was teaching at the University of Rochester. In a report that De Silva later filed with the House Committee on Un-American Activities, which was leaked in 1949 to the Rochester Times-Union, Oppenheimer was alleged to have said that Peters’s background “was filled with incidents which indicated his tendency towards directaction”—such as taking part in an anti-Fascist demonstration in Germany—and that he was “quite red.” In those days such descriptions could ruin someone’s life.

When Oppenheimer’s colleagues, among them Bethe, read the newspaper account, they were, Schweber tells us, outraged not only that it had been leaked but that Oppenheimer could have made such statements, especially when on several occasions he had spoken highly of Peters. When Peters finally had a chance to confront him, Oppenheimer could not deny that he had made the statements, and insisted that they had been a “dreadful mistake.” He called the university and received assurances that Peters’s position there was not in jeopardy. He even wrote a letter to the newspaper, which did more harm than good.

Although Peters did not lose his job, the US government restricted his travel abroad. In 1951, he took a position in India, then in Copenhagen. When he died in 1993, he was recognized as one of the most significant contributors to his field—cosmic rays. I could not help wondering if the same impulse that led Oppenheimer to tell me that his wife was an alcoholic was somehow involved when he told De Silva that Peters was the most dangerous student he’d had. In both cases, Oppenheimer seemed both insecure and self-wounding in saying damaging things about others.

No one could call Hans Bethe “insecure.” He sometimes reminds me of a large, unstoppable ocean liner. This is quite remarkable considering the forces that were at work that could have fragmented Bethe’s psyche. Bethe was born in Strasbourg in 1906. His mother was Jewish by birth but had become a Lutheran before she married his Protestant father. They were divorced when Bethe was young and he grew up in a strained family atmosphere.

The turmoil of the post-World War I period in Germany also affected him. I don’t think that Schweber—who has much to say about the murky influence of German metaphysics on Bethe—does justice to this concrete experience. During the nearly two years I spent interviewing Bethe for a New Yorker profile I was struck again and again by the echoes of the postwar period in Bethe’s life. Bethe’s recollections of the post-World War I monetary inflation were as vivid as if it had happened yesterday. He described being sent early in the morning to buy food before the currency devalued to the point where, later in the day, it became nearly worthless. He was persuaded that this could happen in the United States and he told me he was protecting himself by investing in rare postage stamps and other things that he hoped would retain their value.


As if all of this was not enough, in 1933 Bethe was summarily dismissed from his university post because of his Jewish grandparents. He was struck by the fact that he had no sympathy from his German colleagues.

It is clear that from the beginning Bethe knew how good he was at what he wanted to do—theoretical physics. He would, I think, have found some of Oppenheimer’s diversions, such as writing poetry—he published a poem in Hound and Horn—rather remote from the main task of doing physics during a revolutionary period in the history of science. 2 Bethe is able to take almost any problem in physics and turn it into a sensible subject for research.3 Since many physicists lose themselves in abstract problems for a lifetime with limited success, Bethe’s ability to solve problems was recognized early in his career. He was able to quickly find a post in England, but no permanent job was available there and he accepted an offer from Cornell, where he has been ever since, despite numerous attempts by other universities to lure him away.

I do not think that he knew Oppenheimer at all well before the war. They were on different coasts and worked on entirely different problems. Just before the war Oppenheimer and his students presented the first modern theory of what later came to be called “black holes.” While this was interesting, it must have seemed to many physicists as irrelevant to their work as his poem in Hound and Horn. These ideas, however, much expanded, are now in the forefront of contemporary research. Bethe, on the other hand, had immersed himself in nuclear physics. In 1938, he identified the set of nuclear reactions—the so-called “carbon cycle”—that provides the energy emitted by many stars. He won the Nobel Prize for this in 1967. He had also written a long, influential review article on developments in nuclear physics that came to be known as “Bethe’s bible.”

The choice of Oppenheimer as the director of the Los Alamos Laboratory in 1942 struck most of his colleagues as almost incomprehensible. In the first place Oppenheimer was not a nuclear physicist. He was not even an experimental physicist; his early attempts to carry out experiments had been disastrous. He was not an engineer and had never run a large engineering project. He was notorious for getting arithmetic factors wrong. To add to all of this, he carried a burden of left-wing associations. His brother had been a member of the Communist Party and his wife had been married to a Communist. Some of his students had flirtations with the Party, and Oppenheimer himself—while certainly never a member of the Party—had associations with organizations that had Communist front associations. It is unlikely that he could have been cleared to work on radar, which in the beginning of the war was the most important super-secret military project. Nonetheless, General Leslie Groves, who was in charge of the nuclear weapons program, chose him.

Without Oppenheimer the atomic bomb would probably have been built sooner or later, although perhaps not in this country. Once weapons of mass destruction are shown to be possible in principle, human beings do not seem to have the gift of restraint. Whether the use of the weapons can be restrained is an open question. But the bomb would probably not have been built by the summer of 1945 were it not for Oppenheimer.

What made him so effective? Among other things, he had an almost instantaneous comprehension of every facet of the science and engineering needed for the bomb. One must read the technical accounts of the Manhattan Project to understand what this meant. Everything was new. For example, plutonium is not found naturally. It had to be manufactured in reactors, which were also new. Its properties had to be studied initially in milligram samples. But then it turned out that the plutonium from the reactors was contaminated with an unwanted and unavoidable isotope which fissioned spontaneously, potentially making plutonium useless in a bomb. Thus a new method of detonation—implosion—had to be used. This created an entire new engineering science of shaped explosions whose properties—when they could be computed—had to be computed more or less by hand. Electronic computers were still over the horizon.

Oppenheimer was able to understand such problems as they arose and suggest how they could be tackled. He had no difficulty in consulting others and accepting their advice. He also had a quiet élan, a way of intimating, without saying so, that he was a leader of an entirely special group. It is a talent very difficult to capture in words but one that was palpably evident when I was at the Institute for Advanced Study. He also seemed to have there the same instantaneous comprehension that was evident to his colleagues at Los Alamos, although I was never sure how deep it went. His Delphic comments were often impenetrable. But at the institute nothing much was at stake. If you are trying to design an atomic bomb your comments have to make sense; and during the war he became one of the greatest laboratory directors who ever lived.

Once, when we talked for an hour during a train ride from Princeton to New York, he seemed to reveal something about himself. In fact he did most of the talking, in part about what he referred to as “my case,” that is, the hearings of the Atomic Energy Commission in 1953 at which Oppenheimer lost his security clearance. What struck me was his apparent detachment when he spoke of the hearings. It was as if the inquisition had not happened to him, but to someone else. Schweber describes Oppenheimer’s defense at the hearings as “apathetic” and attributes this in part to Oppenheimer’s need to do “penance”—presumably for his role in creating the atomic bomb.

I am not sure that this is right. I think his attitude was more like disbelief, disbelief that after having performed what he regarded as a patriotic wartime service, he was being tried for things of which he had been cleared several times over during the war. I wondered later whether he understood the real reason for the hearings—which was to discredit him in such a way that he would lose his public voice. If the Atomic Energy Commission no longer wanted his advice, it could simply decide not to renew his consulting contract. But this would have left him as a highly visible opponent of the new reliance of the military, above all the air force, on nuclear weapons, including the hydrogen bomb. Once he was publicly disgraced, he was effectively silenced. People like Bethe and Rabi, who knew Oppenheimer well before the hearings, told me that he became a much-diminished man after the verdict against him was announced.

Oppenheimer also told me that he was thinking of writing a play. I don’t know how seriously he meant it. T.S. Eliot had been at the institute in the fall of 1948 and had been writing The Cocktail Party—which I gather Oppenheimer did not much like—and that may have been on his mind. In any event, he told me that his play was going to be called The Day that Roosevelt Died. He felt that Roosevelt’s death put an end to the possibility of cooperation with the Russians and worldwide control of the bomb.

I don’t think that he appreciated the determination of the Russians to have a bomb of their own. Truman seems to have had a more realistic intuition about this than Oppenheimer. The one time Oppenheimer tried to discuss these matters with Truman was a disaster. He began by telling Truman that he, Oppenheimer, had “blood on his hands” for creating the weapon. Truman was furious since he was the one who had ordered its use. He stopped the conversation as soon as he could and told Dean Acheson, who had arranged the meeting, never to arrange another.

We now know from reading the memoirs of people like Andrei Sakharov that nothing would have stopped Stalin from trying to make a bomb. Because of the espionage of Klaus Fuchs and others, the Russians knew, well before Hiroshima, that the bomb had been successfully tested and how it had been designed. Even Sakharov, who later became one of the outspoken opponents of the testing of nuclear weapons, to say nothing of their use, worked willingly to create them since he felt that they protected his country.

Bethe’s association with nuclear weapons goes back to the summer of 1942 when he was invited by Oppenheimer to join a small group in Berkeley. He stopped off in Chicago and saw that Enrico Fermi’s project of making the first nuclear reactor was well underway there. This, Schweber writes, convinced Bethe that nuclear weapons were a real possibility. He was joined by Edward Teller and during the rest of the journey they discussed Teller’s nascent ideas of trying to make a hydrogen bomb using an atomic bomb—whose design had not yet been made—as the fuse.

Bethe was working at the Radiation Laboratory at MIT, which was developing radar. But Oppenheimer persuaded him to come to Los Alamos, which he did in March of 1943. Oppenheimer chose Bethe over Teller to head the theoretical division, which caused a great deal of resentment. Perhaps this helps to explain Teller’s destructive testimony against Oppenheimer at his security hearings. Among Bethe’s assistants in the division was the very young Richard Feynman. Their monumental daily arguments over technical matters, which Bethe enjoyed immensely, could be heard throughout the division. After the war Feynman came to Cornell with Bethe and it was there that he did his great work on quantum electrodynamics. Bethe collected a group of brilliant students, among them Freeman Dyson, who never bothered to get a Ph.D. He was made a professor at the Institute for Advanced Study without one.

Both Bethe and Oppenheimer became very active after the war in trying to educate the general public—as well as the government—about the situation that had been created by the advent of nuclear weapons. Until his security clearance was removed, Oppenheimer was deep inside the government. He had been chairman of the General Advisory Committee (GAC) of the Atomic Energy Commission—the most powerful civilian body involved with nuclear energy—as well as numerous Pentagon committees. He testified from time to time before Congress. When one watches films of these sessions, Oppenheimer looks like a somewhat disdainful professor trying to lecture a not very bright class.

Behind the scenes the GAC was wrestling with the question of whether the US should embark on a crash program to build the hydrogen bomb. In October of 1949, the GAC recommended against such a program although a majority of its members, including Oppenheimer, favored continuing research on the possibilities of constructing such a bomb. One of the things that came up in Oppenheimer’s security hearings was that he had dragged his feet over the hydrogen bomb and that this had influenced people like Bethe against getting involved with it—at least initially. In fairness, the entire GAC had, with good reason—no one knew how to make such a bomb—dragged its feet. But the Russians had detonated their first nuclear weapon—Joe 1—in August of 1949. Klaus Fuchs was arrested the next January. This convinced Truman to order a hydrogen bomb crash program on January 30. After that, public discussion of the weapon by people inside the government, such as members of the GAC, was forbidden.

Bethe, although he was a consultant at Los Alamos, was not inside the government and was therefore free to speak out against the hydrogen bomb, which he did. Here Schweber’s account is particularly informative. Bethe, he writes, at first saw the hydrogen bomb not as a weapon of war but as an instrument of genocide; but he did not oppose a research project into the costs and effects of such a weapon. Still, in February of 1950 he wrote Norris Bradbury, the director of Los Alamos, that he would not, on his visits, discuss the “super”—the name for the design of the hydrogen bomb which was then being talked about and which, in fact, did not work.

Things changed radically in the spring of 1951, when the Polish-born mathematician Stanislaw Ulam suggested a new design which was then sketched out in detail by Teller. The essential idea was to use the radiation pressure created by the explosion of a conventional nuclear weapon to rapidly compress and heat a collection of light nuclei, which would then fuse, releasing energy. In stars this compression is provided by the force of gravity and the process is a slow one. It soon became clear that this design might well work and, as is usual in these matters, once this was realized, the pressure to build a bomb based on it was insurmountable. Bethe himself succumbed and became what he called the “midwife” of the bomb—Teller being the “mother” and Ulam the “father.” It was successfully tested in the fall of 1952.

Bethe has regretted his role in the affair ever since. He feels, as Schweber makes clear, that the hydrogen bomb should never have been built. He began a campaign to eliminate all nuclear testing and this partially succeeded in July of 1963 when, after Bethe had supplied essential technical advice about the detection of underground explosions, a treaty was signed with the Soviet Union banning atmospheric testing. One curious consequence has been that the present generation of experts who work on nuclear weapons have never seen a nuclear explosion. While this is certainly good for the environment, one wonders about its other effects. No one who has seen an actual nuclear explosion can think the same way about them afterward.4

Oppenheimer died in 1967 at the age of sixty-three. He never wrote an autobiography, and by now there are few people left who knew him well, so we may never have an adequate biography. Nothing I have read fully captures the fascination and complexity of the man. I remember inviting him to a small party for a young Austrian physicist who was visiting Princeton and whom Oppenheimer admired. Remarkably, he showed up. Even more remarkable, he was wearing a jacket with leather elbow patches that looked as if the moths had been at it. Perhaps he thought that one of his Langrocks suits would look out of place. We were all wearing our best and it was Oppenheimer who looked out of place; but perhaps he knew very well that this would be the case.

This Issue

May 11, 2000