The Jewish Nucleus of the Second World War's Atomic Drama

How a group of Jewish physicists helped the United States beat Nazi Germany in the race for nuclear weapons.

September 17, 2021 | Alex Gordon
About the author: Alex Gordon is a professor of physics at Haifa University and the author of eight books and roughly 500 scholarly articles published in Russian, Hebrew, English, and German.

Physicists, some Jewish, at a nuclear-weapons colloquium at the Los Alamos Laboratory in April 1946. Wikimedia.

The Marxist philosopher György Lukács disliked the West and Western civilization. He liked to ask: “Who will save us from Western civilization?” But in an amusing, roundabout way, one he was unaware of, he contributed to the salvation of Western civilization. How? By helping to set in motion a chain of events that would lead to the creation of the atomic bomb and the subsequent Allied victory in World War II.

Lukács fomented anti-Semitism with his active participation in the government of the Communist Hungarian Soviet Republic; as people’s commissar he pursued a policy later known as “cultural terror” for its brutal overturning of cultural norms and mores. The Hungarian Soviet Republic—which, like many in those days, was stocked with Jews, including Bela Kun, its leader—lasted 133 days in early 1919. After its overturning, the country plunged into an abyss of ultranationalist “white terror.” The population perceived the HSR to be a Jewish-run organization, and so the uprising against the Communists had a violent and bloody anti-Semitic character as Hungarians took revenge on ordinary Jews who had nothing to do with the revolutionary events. Many Jews fled for America, including, most notably for our purposes, a group of prominent Jewish physicists from wealthy families—Eugene Wigner, John von Neumann, Leo Szillard, and Edward Teller. (Wigner and von Neumann went to the same Lutheran grammar school as Lukács.) Many years later, the Nobel Prize-winning Wigner told me—then a young physicist wearing the uniform of the Israeli army and armed with a machine gun while on leave from university—that the United States owed Bela Kun and the HSR its success in developing nuclear weapons. For without their revolutionary activities and the ensuing pogroms, he said, Hungarian Jews would not have come to the United States and would not have persuaded Einstein to sign the letter of August 2, 1939 to President Roosevelt that led to the creation of the nuclear project at Los Alamos.

Wigner was right. Central and East European Jews were the impetus behind the American nuclear endeavor. The Jews who worked on the project described in this essay sought to prevent the continuation of the Shoah. The “Protocols” of these atomic “Elders” are not written on paper, but in action.


During World War II, the U.S. dropped two atomic bombs on Japan. The bombs were supposed to be dropped on Germany, but that front of the war ended before the bombs were made. The closing of that front was marked not only by the making of American nuclear bombs but also by the Nazis not making nuclear bombs. Had the Germans succeeded in their military nuclear project, Hitler would have continued to dominate Germany and Europe. But Germany, which had many outstanding nuclear physicists, led by Werner Heisenberg during the war, never managed to complete its project.

In 1933, at the age of thirty-two, Heisenberg became the world’s youngest Nobel Prize winner, for the formulation of the uncertainty principle and for his great contribution to quantum mechanics. Yet a decade later, during the war, the great Heisenberg made a great mistake by incorrectly calculating the critical mass of nuclear fuel. He had estimated it to be fifteen tons, whereas it was about 1,000 times less; the Hiroshima bomb weighed just 123 pounds. After the war, Heisenberg denied in public for a while that he had made such critical-mass calculations, fearing the backlash that would come. His confession first came in private in August 1945, after the bombing of Hiroshima, in a conversation with the discoverer of nuclear fission, the German chemist and Nobel laureate Otto Hahn, while the two were interned in England—a conversation recorded on an eavesdropping device belonging to British intelligence.


On May 8, 1924, two German Nobel laureates in physics, Philipp Lenard and Johann Stark, endorsed Hitler’s NSDAP program in a German newspaper. Lenard and Stark were members of a group of 30 physicists who put forward the concept of “German physics.” They argued that the correct approach to explaining physical phenomena had to be based on classical physics, which was being overshadowed by the theories of relativity and quantum mechanics, which thought irrelevant to reality and called “false” and “the world’s Jewish bluff.” The inventors of “German physics” did not have enough intelligence to comprehend and properly understand what they criticized. They heard from most of their world-renowned non-Jewish colleagues about the tremendous successes of the new theories without fully understanding their meaning, and were outraged at the enormous role played in their creation by theoretical physicists of Jewish origin. Thus, they attributed their misunderstanding of the new physics to the malign influence of their Jewish colleagues. They further believed that such a “correct classical” understanding of physics was given only to Aryans and called themselves “national researchers.”

The mainstream of the German physics world, full of intelligent Jewish rationalists, paid no attention to the nationalist screamers. They believed that absurdity could not win. But, of course, it did: the irrational Nazis seized power over reason, and kicked out the Jewish physicists. After the dismissal of the Jews from one university, the following incident occurred there involving the famous mathematician David Hilbert. The Austrian Jewish journalist Robert Jungk describes it in his 1958 book Brighter than a Thousand Suns: A Personal History of the Atomic Scientists:

The scientists who remained in Göttingen, among them outstanding researchers, were not able to continue scientific work during the Third Reich at the same high level they did during the twenties. The elderly mathematician Hilbert felt this decline the most. About a year after the “purge” in Göttingen, Hilbert was sitting in the seat of honor next to the new minister of education, Rust, at one of the official celebrations. Rust carelessly asked the old scholar, “Is it true, Herr Professor, that great harm has been done to your institute since the Jews left?” Sharp of tongue and as outspoken as ever, Hilbert replied, “Much harm? No harm has been done to the institute, Mr. Minister; it simply no longer exists!


In July 1937, Johann Stark published an article entitled “White Jews in Physics” in the newspaper Black Corps, the official organ of the SS, that continued to press the distinction between Jewish (theoretical) and Aryan (experimental) physics and labeled the former “erroneous” and the latter “correct.” On such grounds Stark cast a suspicious eye on none other than Werner Heisenberg. Heisenberg, he pointed out, had not joined the National Socialist Party, had refused to sign a manifesto of scientists drawn up by Stark in support of Hitler, and, worst of all, had continued to promote Einstein’s theory of relativity. Stark wrote: “In 1933 Heisenberg, along with Einstein’s disciples [Erwin] Schrödinger and [Paul] Dirac, received the Nobel Prize. This decision was made demonstratively by the Jewish-influenced Nobel Committee, a direct challenge to National Socialist Germany. Heisenberg belongs to the viceroys of Jewry in the life of the German spirit. These men must disappear as well as the Jews themselves.”

Heisenberg was extremely disturbed by the article and wrote a letter to Reichsführer SS Heinrich Himmler to justify himself. In response he was summoned for interrogation at the Berlin Gestapo office on Prinz-Albrecht-Strasse. The investigation lasted almost a year. All charges were dropped. Heisenberg soon received prestigious appointments: he was head of the Kaiser Wilhelm Society Institute of Physics and became a professor at Berlin University. He was free to travel around occupied Europe. In the summer of 1939, he was allowed to visit the United States. Then he was put in charge of the German nuclear project. Everything indicated that he enjoyed the extraordinary trust of the Nazi leadership.


After World War II, physics became more than a science. The use of the nuclear bomb in 1945 instantly gave its practitioners the most favored status given to people who know how to kill. But in 1941, theirs was still one of those fields of knowledge that could excite only a small number with its problems. Some at the time did understand the enormous destructive power lurking in the nuclei of atoms, though they didn’t yet know for sure whether a nuclear bomb could be created. The technological challenge of the lethal use of nuclear energy was daunting.

That summer, in July 1941 a Stockholm newspaper published news of an American experiment to build a nuclear bomb. “According to reports from London,” Stockholms Tidningen wrote, “experiments are being conducted in the United States to build a new bomb. The material used in the bomb is uranium. Using the energy contained in this chemical element, it is possible to produce an explosion of unprecedented power. A bomb weighing 5 kilograms would leave a crater one kilometer deep and 40 kilometers in radius. All structures at a distance of 150 kilometers would be destroyed.”


In September of that year, Werner Heisenberg traveled to occupied Copenhagen to meet with Niels Bohr, his old teacher and a principal collaborator in the creation of quantum mechanics. Why did Heisenberg go? He could not fail to understand that his arrival would not please his teacher—he was now a representative of the occupiers and in their service, and Bohr was half-Jewish. So, what was the purpose of Heisenberg’s mission? Was he disturbed by the Swedish report and driven by a desire to find out the truth about the U.S. project? Did he want to find out if Bohr was in contact with his British and American colleagues to design the bomb? Did he suspect Bohr had invented a way to build a nuclear bomb that he didn’t know about? Did he want to get Bohr to collaborate on the German atomic project? And what actually happened when the two met?

Not all the answers to these questions are clear, but one thing is: after the meeting ended, nothing remained of the friendship between Bohr and Heisenberg.


Jungk presents Heisenberg’s post-war version of the meeting as follows, in relatively uncritical fashion:

Much to his regret, the important conversation between Heisenberg and Bohr was unfortunate from the beginning. Bohr became aware that at a recent reception held in honor of Heisenberg, Heisenberg defended the German occupation of Poland. Indeed, to conceal his point of view, Heisenberg was in the habit of publicly presenting a different position, and he usually did so abroad. But the fanatically truthful Niels Bohr refused to play this two-faced game imposed by totalitarian power. From the moment Heisenberg came to visit Bohr, the latter received his former favorite student warily and even coolly. . . .

At first Heisenberg tried to explain to him the coercive situation imposed on German physicists, and gradually he began to speak cautiously about the atomic bomb. But, unfortunately, he did not say frankly that he and his group would do everything in their power to prevent the manufacture of this weapon, and it would be good if the opposing side behaved the same way. With excessive caution, the two interlocutors tested each other and missed the main point. Asked by Heisenberg if he believed in the possibility of building such a bomb, Bohr confidently replied, “No!” because since April 1940 he had heard nothing about the progress of nuclear research in England and the USA, as their achievements had been kept secret. Heisenberg tried to convince him that, according to his information, it was possible to manufacture these weapons, and even in the near future, if the matter is taken up vigorously.

Bohr read Jungk’s book after it was published but remained silent.

There have been numerous interpretations of what happened during the 1941 meeting and its impact on the development of the German atomic project. In 1998, Copenhagen, a play by the English writer Michael Frayn, was staged in London. In it the author tries to capture the mysterious meeting. In it, Heisenberg’s version is presented relatively uncritically once more. It includes a denial of the fact that he had calculated critical mass and a proposal he supposedly made to create an international alliance of physicists against the creation of nuclear weapons. To be fair, Frayn does not insist on this version of the meeting, and there is another possible interpretation available in his text, but, still, at best, the account is left artfully vague. The success of the play was enormous; it received a prestigious award for the best theatrical work in English. Its influence was so great that Bohr’s children felt compelled to publish drafts of letters written but never sent by their father to Heisenberg in 1958. The letters were kept in Bohr’s copy of Jungk’s book. Thus, 40 years after Bohr’s death and 26 years after Heisenberg’s death in 1976, a bit more light was finally shed on the mysterious conversation.

“Dear Heisenberg!” Bohr begins.

I have read Robert Jungk’s book Brighter than a Thousand Suns. . . . And I think I have to tell you how deeply surprised I am by how much your memory fails you. . . . I personally remember every word of our conversations, which took place against a background of deep sadness and tension for all of us here in Denmark. In particular, it left a strong impression on me and Margret [Bohr’s wife], and everyone at the institute with whom you and Weizsäcker [a famous German physicist who traveled with Heisenberg in Copenhagen at the time] spoke, that you were absolutely convinced that Germany would win and that it would therefore be foolish for us to hope for a different outcome of the war and to be reticent about German offers of cooperation. I also distinctly remember our conversation in my office at the institute, during which you spoke in vague terms in a manner which gave me no reason to doubt: under your leadership, Germany was doing everything possible to build an atomic bomb. . . . I listened silently, because it was an important problem for all mankind, in which, despite our friendship, we should be seen as representatives of two opposing sides of a mortal battle.

In 1961, while in Moscow, Bohr said, “I understood him perfectly. He suggested that I cooperate with the Nazis.”


After the war, the legend was born that Heisenberg went to Bohr for advice on whether it was permissible for physicists to participate in the development of lethal weapons. According to Heisenberg, Bohr said that the use of nuclear energy for military purposes was inevitable and justified. Over the years Heisenberg transformed this story and turned it into an attempt to organize an international conspiracy of physicists against the creation of nuclear weapons. He spread the legend of German physicists’ resistance to Hitler, which he retold to Jungk, who again portrayed it as the real truth. “[Heisenberg] and scientists close to him sought to control the atomic project by taking over the Kaiser Wilhelm Institute, because they feared that other physicists with low moral character would take over the atomic project for Hitler,” Jungk wrote. “On the contrary, these physicists successfully diverted power away from such inhuman weapons.” Here Jungk quotes Heisenberg: “Only by pretending to be an employee can real resistance be made.” But after the release of Brighter than a Thousand Suns, Jungk changed his mind and called the version about the passive resistance of German physicists to the Nazis a “myth.”

David Cassidy, Heisenberg’s American biographer, writes: “Heisenberg’s views during this period were no different from those of other patriotic Germans of non-Jewish background in artistic, academic, or military circles. These social groups fervently supported German policy in the name of the German nation. As the German army marched victoriously across Europe in the early years of the war, these circles welcomed reports of victories on the fronts.”

It is possible that Heisenberg believed that if the war dragged on, it could only be won with a nuclear bomb. This is the interpretation put forward by Bohr’s son Aage, himself a Nobel physics winner, in his retelling of the Heisenberg-Bohr meeting:

In a private conversation with my father, Heisenberg raised the question of the military use of atomic energy. My father was very reticent and expressed his skepticism, given the enormous technical difficulties that had to be overcome. But he was left with the impression that Heisenberg believed that the new possibilities could hasten the ending of the war if it dragged on.

One of Bohr’s close collaborators, Stefan Rosenthal, a Polish Jew and nuclear scientist who worked at the Bohr Institute during Heisenberg’s visit, recalled: “I only remember that Bohr was in great agitation after the conversation and that he quoted Heisenberg approximately as saying, ‘You must understand that if I take part in the project, it is because I am strongly convinced of its reality.’” Heisenberg’s wife Elisabeth wrote in her memoirs that her husband “constantly tormented himself” with the idea that the better-resourced Allies could build a bomb and use it against Germany.


In 1943, the German nuclear-bomb institute moved out of Berlin and disappeared from the sight of American and British intelligence. No one knew what Heisenberg and his collaborators were doing or where they were. It was not until May 1944 that American intelligence learned that Heisenberg’s new laboratory was located near Hechingen in southern Germany and its neighboring town of Haigerloch, on the edge of the Black Forest, and that the German uranium project had been funded to build a 200-million volt cyclotron, a device to enable isotope separation and to produce the uranium-235 needed for the bomb. This finding makes me think of another possible reason for the meeting between Heisenberg and Bohr at the time.

In 1941, there were only two cyclotrons in Europe. One was at Paris-Saclay University, under the leadership of Jean Frédéric Joliot-Curie, a Nobel laureate in chemistry; the other was at the Bohr Institute in Copenhagen. The Germans did not have a cyclotron. Not only did they desperately need one but they also needed to keep their work in the strictest confidence. In Paris, Heisenberg could expect neither cooperation nor secrecy from Joliot-Curie. But his closest friend Niels Bohr was working in Copenhagen; perhaps he could be counted on to lend his cyclotron. Either way, it was worth finding out. But Heisenberg was wrong not only in the calculation of critical mass; he was, in his assessment of his friend’s unbreakable anti-Nazi stance, also wrong about Bohr. His underestimation of Bohr not only led to the crisis between the two old friends but delayed the Nazi nuclear project at a crucial moment.


Heisenberg was not the only one on the German team who was wrong at such a point. Hitler and his advisors simply did not grasp the significance of nuclear weapons for the outcome of the war. Hitler was instead fascinated and delighted by the new German V1 and V2 rockets the Nazis were firing on London, even though the damage caused to the British capital by the German rockets was incomparably less than that caused by the British bombardment of German cities. In focusing on the wrong weapon, the Führer made a mistake perhaps equal in importance to one that Napoleon may have made during war with England. As the possibly apocryphal story goes, in the early 1800s a young American inventor came to the emperor of France and volunteered to build a steam-powered fleet with which Napoleon could land in England, despite unstable weather. Ships without sails? This seemed unbelievable to the emperor, and he banished the inventor. Thus, England was saved; the history of the 19th century might have unfolded differently had it not been for Napoleon’s shortsightedness. Apocryphal or not, an account of this historical episode apparently helped convince Franklin Delano Roosevelt to embark on the nuclear project.


In his play on the nuclear engineers, Michael Frayn noted one moral paradox: starting in 1943, the anti-fascist Bohr took part in the Manhattan nuclear project that led to the deaths of 120,000 people in Hiroshima and Nagasaki, while the German patriot Heisenberg, who worked for the Nazi war machine, didn’t accomplish anything that would lead to the death of even one person. This says approximately nothing about the moral weight of either man. Heisenberg tried to make a bomb to use in a war of aggression and failed. As for Bohr and his colleagues on the Manhattan project, they were fighting for their lives. One of the creators of quantum mechanics, the Nobel Prize-winning physicist Max Born, a German Jew, later wrote: “Exiled physicists knew that there would be no escape if the Germans were the first to succeed in building the atomic bomb. Even Einstein, who had been a pacifist all his life, shared this fear and let himself be persuaded by several young Hungarian physicists who asked to warn President Roosevelt.”


After the war, many scientists shunned Heisenberg. Bohr never again agreed to cooperate with his beloved pupil, colleague, and friend.

Shocked that the clearly laggard Americans had managed to produce the atomic bomb, Heisenberg did not think about the role of the Jews. He did not realize that, humiliated, deprived of home and work, persecuted and expelled by their countrymen from occupied Europe, and bereft of their families lost in Nazi death camps, Jewish scientists had become the ferment force behind the American nuclear project. Heisenberg underestimated the importance of the critical mass of Jewish physicists who fled Nazi persecution in the United States and worked against their own (and Heisenberg’s) country. He underestimated the power of the “Jewish physics” denounced by his German colleagues. Famous European Jewish physicists L. Szillard, A. Einstein, E. Wigner, E. Teller, J. Frank, S.A. Goudsmit, J. von Neumann, Sir Rudolf Peierls, O.R. Frisch, V.F. Weisskopf, D. Bohm, F. Bloch, the “half-Jews” N. Bohr and H. Bethe contributed greatly to the success of the project, not to mention American Jewish participants in the project like J.R. Oppenheimer and R. Feynman. Among them were seven Nobel laureates. The German Aryan physicists were convinced that they were far superior to the Americans in developing the nuclear weapons project. They underestimated the “Jewish danger.”

Laura, the Jewish wife of Enrico Fermi, one of the chief scientific advisors to the American nuclear project, observed in her book Atoms in the Family (1954) that it was Jewish immigrants from Europe, not native-born Americans, who initiated it: “That is why the first warning to President Roosevelt came from people like Einstein, Szillard, Wigner, and Teller, while physicists born and brought up in America continued to sit in their ‘ivory tower.’ These foreigners knew both what a military state and the concentration of power in one hand meant, while Americans lived only by their notions of democracy and free initiative.”

Special consideration goes to Leo Szillard, who was the first to act. His letter, signed by Einstein, was the most important link in the effort to convince Roosevelt to organize the nuclear project. (Szillard was likewise the first to write a letter against the use of nuclear weapons in 1945.) Thus, “Aryan physics” was defeated. The Nazi leaders did include real physicists and not only racist physicists in their nuclear project. But that was not enough. Their zoological hatred of the Jews boomeranged back to them. In the work of the Manhattan Project, perhaps the only real Jewish conspiracy in history took shape, a conspiracy of Jews against the Nazis who had made them aliens in their own country.