My Dear Li: Correspondence, 1937–1946

Werner Heisenberg and Elisabeth Heisenberg; ed. Anna Maria Hirsch-Heisenberg, transl. Irene Heisenberg. Yale University Press: 2016.

9780300196931

Credit: Illustration by Eoin Ryan

Werner Heisenberg is a conundrum. He won the 1932 Nobel Prize in Physics for creating the foundations of quantum mechanics and his uncertainty principle, which describes how it is impossible to know a particle's location and its momentum simultaneously. During the Second World War, directed by the Nazi government, he headed Germany's unsuccessful efforts to create an atomic bomb. Why didn't he succeed? Why did he try?

There are no unambiguous answers here, although clarifying Heisenberg's motives is one reason that his daughter, Anna Maria Hirsch-Heisenberg, gives for publishing the letters between him and her mother. What the letters do illustrate is Hirsch-Heisenberg's other reason for publishing (in German in 2011, and now in English for the first time): how a couple much in love lives through a war.

Werner begins his letters with “My dear Li”. Li is Elisabeth, née Schumacher; they met in 1937 at a musical evening. The two talked — a conversation, Werner wrote, that seemed to have begun so long ago that continuing it for the rest of their lives felt natural. Two weeks later, they were engaged; four months later, they began a 40-year marriage. But Heisenberg had to travel for research and was rarely at home, thus the letters. This collection spans the tumultuous years from 1937 to 1946.

The letters, necessarily discreet about politics and the military, contain mostly the quotidian — frighteningly so, this being Germany during that war. By 1939, Werner lives in Leipzig and Li has moved to their safe country house in southern Germany. Li has had twins; she will have four more children in the next five years. The war has started. “I get caught up pondering the dark picture everybody is painting,” Li writes, “how fortunate that the children ... are so unencumbered and jolly.” Werner makes a long lecture trip to the United States, where he finds the audiences receptive and the students bright. He tells his US colleagues who offer him jobs that he needs to stay in Germany “so that I might also be here afterward and help”; as he writes to Li, “we are just not at home here”.

Over the next few years, Werner alternates between Berlin, where “it is quite striking these days how everybody becomes thinner”, and Leipzig, where newspapers carry obituaries of young people dying. “I myself am often so sad and downcast,” he writes to Li, “without you I would not quite be able to cope”. Food is scarce; Werner preserves cherries from his Berlin garden. His work, directing research on nuclear fission, “makes no sense”.

In 1945, between air raids, Werner advises Li that as the front moves closer to southern Germany, she should watch for attack planes and the children should practise throwing themselves to the ground near a wall. Li makes her own yeast and worries about getting enough flour for bread. They tell each other that they are thinner and more exhausted. “Love,” he writes, “stay well and prepare for the more difficult times.”

Near the war's end, Heisenberg and other German nuclear scientists are arrested by the Allies. They are held for six months in England; few letters are allowed. For lack of food, Li puts two of the children into a home. She cares for Heisenberg's dying mother and cuts their firewood. He's released in January 1946. “I want to build a containing wall around you from all the love I have in my heart,” writes Li. The letters end that June, with the family reunited and living in Göttingen; in 1950, they have a seventh child.

Hirsch-Heisenberg writes that the letters were chosen and edited for relevance and concision. We cannot know what other filters, if any, children apply to the publication of their parents' letters. Hirsch-Heisenberg gives no sources, but makes the case that her father's motives for working on a German atomic bomb were to control atomic research and to convert it to peaceful uses, but that building an actual bomb was “out of the question”. Judging from these letters, Heisenberg was doing what it took to wait out the dreadful storm so that he could get on with his life with physics and Li.