CHAPTER FOUR

HEISENBERG IN MICHIGAN

(Werner Heisenberg

Sueddeutsche Zeitung Photo / Alamy Stock Photo)

WHEN HEISENBERG TRAVELED TO the United States in the summer of 1939 it was a victory lap of sorts. He had just come through a frightening, yearlong investigation by the Waffen SS, the armed wing of the Nazi Party. After watching the Nazis gut German universities of their best Jewish professors and replace them with second-rate party loyalists and then ban the teachings of Albert Einstein, Heisenberg had felt compelled to speak out. Risking his career and his life, he published articles in the Nazi Party and SS newspapers defending the teachings of Einstein and Niels Bohr, two of the world’s most distinguished theoretical physicists, and both Jewish. Johannes Stark, a German Nobel Laureate and Nazi loyalist, responded with a vitriolic attack in which he labeled Heisenberg, who was a Christian, a “white Jew.” That attack triggered the SS investigation.

Fortunately for Heisenberg, he had friends in high places. His father had taught high school and had been friendly with the father of Heinrich Himmler, commander of the SS. Heisenberg’s mother wrote Himmler’s mother, and, after all the months of investigation during which his home was bugged, Heisenberg finally received a letter from the SS Commander stating, “I take pleasure in being able to inform you . . . there will be no further attacks on your person.” 34 Thanks to a family connection, Heisenberg had dodged a bullet and struck a blow for German science. Himmler imposed one condition, however. Heisenberg could teach the theories of Jewish scientists, but he couldn’t credit them. With Himmler’s backing, Heisenberg’s application to travel and lecture in the United States won immediate approval.

By the time he arrived in the States, hopes of avoiding another world war had all but vanished. The specter of Adolf Hitler armed with an atomic bomb shadowed Heisenberg wherever he went. Yet Heisenberg seemed oblivious. While lecturing to J. Robert Oppenheimer’s Wednesday afternoon seminar at Berkeley, he appeared not to have a care in the world. Afterwards, over tea, he went on at length talking about San Francisco cable cars and the technology that enabled tracks and power lines to cross. 35

To Oppenheimer, Heisenberg’s behavior seemed calculated. To him it was all an act. Writing in 1980 after her husband’s death, Elisabeth Heisenberg insisted it was genuine: “At the time, he still firmly believed in the world community of physicists he spoke about so often.” Long isolated in Nazi Germany, he was happy to be back in that world. “Never having identified himself with the policies of the Nazis,” Elisabeth Heisenberg wrote, “he was of the firm conviction that old friendships could outlast political differences.” 36

That conviction would be tested from coast to coast despite the determination of Heisenberg and his hosts to avoid the discussion of politics. At Berkeley, Robert Oppenheimer warned an associate that Heisenberg “could not be trusted.” 37 Given the treatment of Jews in Germany and the fact that Oppenheimer was Jewish and had relatives there, the distrust was not surprising. But beyond “the smoldering fury” that Oppenheimer felt concerning the treatment of the Jews lay something else. Oppenheimer, it seems, was jealous of Heisenberg. 38

The brilliant young physicist Oppenheimer had met in Göttingen had won a Nobel Prize for his pioneering work in the field of Quantum Mechanics. Nothing short of revolutionary, his work helped develop a new understanding of the atom and the behavior of electrons. Under the old laws of classical physics, electrons were thought to orbit the nucleus just like the earth orbits the sun; their locations were thought to be predictable just like that of the earth, the moon and the stars. Not so, said 25-year-old Heisenberg. The laws of classical physics don’t apply to small objects like electrons. According to his famous “Uncertainty Principle,” it’s impossible to determine both the exact position and velocity of an electron at any given moment. The more precise one measurement, the less precise the other. The best one can do is compute the probability of its being at a specific location or its specific velocity. 39

The world’s most famous physicist, Albert Einstein, disagreed that Quantum Mechanics could be that uncertain. “God doesn’t play dice with the universe,” he argued. 40 Nevertheless, Heisenberg’s “Uncertainty Principle” became a pillar of modern Quantum Mechanics.

Oppenheimer was also brilliant, the West Coast doyen of American theoretical physicists. He had done important work in the fields of nuclear physics, astrophysics and spectroscopy, 41 but his star had not risen to the heights that Heisenberg’s had. He wasn’t a Nobel Laureate and didn’t have the global stature of a Heisenberg. And by all accounts that weighed heavily on him. Oppenheimer did not like being second best.

At Cambridge, where he studied before coming to Göttingen, he became deeply depressed when he did poorly in experimental physics. Conducting laboratory experiments and meticulously recording the results was a “terrible bore,” he wrote a friend. 42 He regained his intellectual footing at Göttingen where he excelled in theoretical physics.

Oppenheimer and Heisenberg met a second time that summer of 1939, at the University of Chicago, where Heisenberg gave a lecture on cosmic rays. The two had competing theories on the subject, and after the lecture Oppenheimer confronted Heisenberg. Heisenberg, like Oppenheimer, had a healthy ego and did not like being challenged. Tempers flared, and they got into a shouting match. The collegiality they had demonstrated at Berkeley had apparently masked their true feelings.

After Chicago, Heisenberg boarded a train for Ann Arbor and the University of Michigan where he was scheduled to give a series of lectures. The University ran an annual summer symposium in theoretical physics and invited top European scientists to attend. The seminars offered American physicists an opportunity to learn from German and other European colleagues. In 1939 the impact of Nazi anti-Semitism, and the flight of Jewish scientists, had not yet fully registered, and Germany was still considered the world leader in physics and chemistry.

The photo from the event shows a smiling Heisenberg, athletic-looking, his linen jacket open, hands thrust casually in his pockets; he exudes an air of confidence. Next to him on his left is Fermi. The two are the same age, 37, but Fermi, standing stiffly, his suit jacket buttoned, his high forehead rimmed by closely cropped dark hair, seems older.

Fermi had time on his hands that summer. His nuclear fission research had stalled for lack of funds. 43 The University of Michigan summer school was always a stimulating and festive gathering, so Fermi was happy to attend.

Samuel Goudsmit, Clarence Yokum, Werner Heisenberg, Enrico Fermi

(Courtesy: AIP Emilio Segrè Visual Archives, Crane-Randall Collection, Goudsmit Collection)

Heisenberg had based his “Uncertainty Principle,” in part, on Fermi’s work. The two had been friends for more than a decade, so Fermi had license to press him on the issue worrying them all. “There is now a real chance that atom bombs may be built,” he told Heisenberg. 44 If war came, would he support the German cause? Would he build Adolf Hitler an atom bomb?

Heisenberg did not answer. Instead, he dodged the question saying, “Atomic developments will be rather slow however hard governments clamor for them; I believe that the war will be over long before the first atom bomb is built.” 45

Standing to the right of Yokum and Heisenberg in that 1939 photo, dapperly attired in a white double-breasted suit, is Heisenberg’s friend Samuel Goudsmit, a Dutch Jew who immigrated to the United States in the late 1920s. Heisenberg had visited Goudsmit at his home in Holland and stayed with him and his family several summers while attending the Michigan conferences. He tried to convince Heisenberg to immigrate to the United States before it was too late.

Everywhere Heisenberg went his American colleagues urged him to bring his family and to accept one of the many university professorships offered him. But Heisenberg, the loyal German, always refused, saying he would be needed at home.

He had made his decision before coming to the United States. In his view, incompetent Nazi bureaucrats were undermining the quality of theoretical physics education in Germany. Faced with a choice of escaping the coming war, or staying to defend his disparaged field, Heisenberg put science and the fatherland first. He bought a cabin for his family in the mountains of southern Germany, hoping they would be safe there during the war, while he stayed behind at the university tending to scientific matters. To him, Nazism was merely a passing storm. He told Goudsmit that the Nazi regime would eventually fail and that he and others like him would then step in. 46 He hoped his American friends would understand.

From Michigan, Heisenberg traveled to New York City where he boarded the near empty ocean liner Europa for the voyage home. In his luggage he carried photographs of his trip, mementos of happier times. The voyage would take four or five days, plenty of time to reflect on the coming war. As he wandered alone on the deck, peering out at the ocean, he wrestled with the question his visit had left hanging. Heisenberg was a patriot. He loved his country, but had only contempt for the Nazis. What would he do? Was he duty bound to build Adolf Hitler an atom bomb? Time to decide was running out.

On September 1, 1939, three weeks after Heisenberg’s return, World War II broke out. And Heisenberg was drafted to work on an atomic bomb.