One of the great puzzles of the Second World War is that the Germans failed to make the atomic bomb. While much has been written about this there has always been a missing piece: the explanation of the Germans themselves. Such German testimony that we have had was written well after the fact and could have been self-serving. But it has been known for nearly fifty years that ten of the leading German nuclear scientists were interned in England in the summer and fall of 1945 and their conversations were recorded. The transcripts of these recordings were classified by the British government as “TOP SECRET” and were not available to the public until January of this year. They make up an extremely dramatic and revealing historical document. What follows is an edited version of part of the transcripts, which deals with the reaction of the Germans when they learned about Hiroshima, to which I have added my own commentary. To make the significance of the transcripts clear, some historical introduction is needed.
In the autumn of 1943 an intelligence gathering unit named the Alsos Mission was created by General Leslie Groves, who was in charge of the American atomic bomb project. With the Allied forces advancing in Europe, he decided that a small group, partly scientific and partly military, would follow just behind the armies and try to find out in detail the real status of the German atomic bomb project of which we had only hints, many of them disquieting. It was known, for example, that the Germans were accumulating heavy water—water in which ordinary hydrogen is replaced by heavy hydrogen, which has an additional neutron. The only use anyone could think of for this material was to cause a uranium chain reaction.
Groves appointed Colonel Boris Pash as the mission’s military and administrative leader and the physicist Samuel Goudsmit as its senior scientist. Goudsmit was an excellent choice. He had been born in Holland, knew many of the German scientists personally, and spoke several European languages. (His parents had been killed in a German concentration camp and he learned the details of how they died while traveling with the Allied intelligence unit.) Furthermore, he was not a nuclear physicist and did not have any firsthand knowledge of the US program. Before the mission he had been given a limited briefing, making it possible for him to ask the captured Germans questions without giving anything away. He was ordered not to tell the Germans anything about the US atom bomb project.
The Allied scientists had good reasons—apart from the evidence about heavy water—to worry that the German nuclear bomb program was ahead of ours. Nuclear fission had been discovered as a result of experiments by Otto Hahn and Fritz Strassmann in Germany in December of 1938. They had been bombarding natural uranium with slow neutrons. They expected to see some nuclear transmutations in which the products should have been elements close in the periodic …