When history turns back to look at me, I only hope its judgement isn’t determined solely by an unsent letter from one of my colleagues. That’s the predicament of Werner Heisenberg‘s legacy. His Uncertainty Principle still weighs more on the books, but dig a little deeper and there’s a raging debate about Heisenberg, Niels Bohr, Nazi Germany and the atom bomb.

Much like the principle he’s famous for, it’s impossible for us to be certain of the full details regarding Heisenberg’s intent while working on a nuclear weapon for the Nazis.

Heisenberg himself worked behind-the-scenes to secure a place for science in Hitler’s regime. Despite his upper-middle class upbringing in the Weimar elite, Heisenberg had detractors that referred to him as a pacifist “White Jew” who belonged in a concentration camp. He was originally suspect because he hadn’t made a political stance at the beginning of the Third Reich. After some cunning maneuvering (Heinrich Himmler was a family friend) and interrogations by the Gestapo, Heisenberg was made director of Germany’s nuclear-fission research project. Was Heisenberg a failed engineer that didn’t understand bomb physics? Or had he purposefully misled the Nazis to save millions of lives?

His sympathizers argue that Heisenberg’s team deliberately slowed their pace to keep the atom bomb out of Hitler’s hands. Journalist Thomas Powers holds this position in his 1993 book “Heisenberg’s War,” writing that Heisenberg killed the bomb project, withheld knowledge from the Nazis and even tried to pass information onto the Allies.

The Uncertainty of Heisenberg's Nazi Bomb Motivations
Copenhagen Conference, 1930. The front row of this picture shows Christian Klein (1849-1925), Niels Bohr (1885-1962) & Werner Heisenberg (1901- 1976). © Science & Society Picture Library/Getty.

Why then did Heisenberg stay in Germany when he had multiple opportunities to escape to the United States? He stated himself that he felt a national obligation to try to save Germany from within. In addition, he didn’t want to build a nuclear bomb for the U.S. any more than he did for Hitler. Both could threaten his homeland and family. However, certain researchers of Germany’s atomic program have found this excuse wanting.

Two moments fuel their doubts. First, in the summer and fall of 1945 Heisenberg was interned at an English manor called Farm Hall. The transcripts of his discussions there seem to reveal his complete ignorance on how to develop an atom bomb, with sloppy math and not enough Uranium-235. Heisenberg later realigned his calculations once he had more information about how the Hiroshima bomb was designed, but it appears that regardless of his feelings toward Nazism, he simply didn’t understand how to create the bomb they wanted him to.

The second moment that questions Heisenberg’s authenticity is a trip he took to Copehhagen in September of 1941 to meet with his friend, fellow physicist and former mentor, Niels Bohr. Heisenberg said the meeting was a diplomatic mission disguising his attempt to let Bohrs know he was sabotaging the German nuclear effort. Powers takes it so far as to claim that Heisenberg betrayed Germany and was passing classified information to Bohr, in the form of a secret sketch of a German nuclear weapon.

Did Bohr misunderstand Heisenberg’s intent? Or was Heisenberg lying? We’ll never truly know.

If scientists like Heisenberg really were slowing their own progress for political and humanitarian reasons, you have to wonder if similar “lethargy” happens today, when most United States federal funding for research is done for the Department of Defense. Are today’s scientists apolitical? Or are they purposefully holding back their results because they disagree with the government that sponsors them? Even letters from the future can’t answer these questions.

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