The development of the atomic bomb by the Allies during the Second World War was one of the critical events in human history. The world today would be unimaginable if the Nazis had developed the bomb first and then used it on London.

The fact that history did not follow this dark and horrifying course has been the subject of a great deal of study. Before World War II, German science, especially physics, was preeminent. The Allies knew that Werner Heisenberg, one of the great scientific minds of the twentith century, was the head of the German nuclear effort. During the war, those working on the Manhattan project, many of whom had known Heisenberg and his colleagues before the war, were convinced that they were in a close race with the Germans to develop an atomic bomb. As the Allies advanced on Germany, the Alsos Mission, whose scientific director was Samuel Goudsmit, was sent to Europe to gain information about the progress of the German nuclear efforts. In France, at the University of Strasbourg, Goudsmit was able to examine the papers left behind by one of Heisenberg's colleagues, Carl Friedrich Von Wezsacker. Goudsmit discovered that the Germans had made little progress toward the construction of an atomic bomb. In fact, as it turned out, the Germans had made little progress obtaining a fission chain reaction and they never constructed a working nuclear reactor, which is the first step to producing plutonium for nuclear weapons.

Why, when the Germans seemed to have such a head start, did they make so little progress toward an atomic bomb? After the war, Von Wezsacker, who took a position at the Max Planck Institute, claimed that the German nuclear project made so little progress because their heart was not in it. They did not want Hitler to have the bomb. In fact, Von Wezsacker condemed the allies for constructing such a horrible weapon, when the Germans were, he claimed, only working on a nuclear reactor for power generation.

In Thomas Powers' 1993 book Heisenberg's War: The Secret History of the German Bomb, Powers makes a similar argument about Heisenberg's motivations. According to Powers' account, although Heisenberg was offered prestigious research positions in the United States, he chose to stay in Germany and share the "German fate". But he never really wanted Nazi Germany to have the atomic bomb.

After the Nazi defeat, ten physicists, including Heisenber, Von Weizsacker and Otto Hahn (who later won the Nobel prize as the co-discoverer of nuclear fission) were interned for six months at an English estate known as Farm Hall, located near Cambridge. By collecting the major players in German nuclear physics, the British and Americans kept them out of the hands of the Russians. They also made sure that until the atomic bomb was used, atomic information would be kept largely in American hands. While at Farm Hall the German scientists were well treated and probably ate better than their families back in Germany.

At Farm Hall each of them was assigned a prisoner-of-war batman to look after his needs. There was a tennis court and a piano for Heisenberg. the bedrooms were paneled and the food was good. What none of them seem to have realized, at least initially, was that the estate had been wired to record conversations.

Selected conversations were transcribed and circulated to British and American officials, including General Leslie Groves, who headed the Manhattan project. Although the existence of the Farm Hall transcripts had been known of for some time, it was not until early 1992 that they were finally made available to the public. In Hitler's Uranium Club Jeremy Bernstein provides an edited and annotated version of these transcripts. Bernstein also provides a detailed prologue, which discusses the history of the German bomb and his interpretation of the transcripts.

The Farm Hall transcripts, taken in conjunction with captured German documents, paints a very different picture than the one put forth by Von Weizacker and in Powers' Heisenber's War. The leading scientists in Germany had the opportinity to accept positions in America, before America entered the war. Those who remained in Germany fell into one of three catagories: they were Nazis, like Nobel Prize winner Johannes Stark, they could not leave, for what ever reason, or they were selectively blind to the regime around them and its implications. This did not mean that they were ignorant of Nazi terror and murder.

Heisenberg: During the war I had five calls for help in cases where people were murdered by our people. One was Soloman, Hoffman's son-in law. I could do nothing in his case as he had already been killed when I got the letter. The second one was Cousyns the Belgian cosmic ray man; he disappeared in a Gestapo camp and I couldn't even find out through Himmler's staff whether he was alive or dead. I presume he is dead too. Then there was the mathematician Cammaille; I tried to do something about him through Sethel but it was no good he was shot. Then from among the Polish professors there was a logistician with a Jewish name --- and then with the other Poles the following happened: his name was Schouder, a mathematician. He had written to me and I had put out feelers in order to see what could be done. I wrote to Scholz who had something to do with Poland. [...] I heard nothing more about Schouder and I have now been told that he was murdered.

The evidence of the Farm Hall transcripts is morally damning. Heisenberg and his colleagues knew about the murder going on around them, but they still worked on the German nuclear program. They did not build a nuclear weapon because they did not know how. Although Heisenberg was a gifted theoretical physicist, it was widely known at the time that he was a poor experimentalist and he had no experience with large scale scientific projects. Heisenberg and his colleagues also made several critical mistakes early in the project. For example, they tried using graphite as a nuclear moderator. However, the graphite was impure and absorbed neutrons, rather than slowing them down, which is necessary for the controlled nuclear fission in a reactor. Heisenberg also insisted on using reactor designs that worked well on the chalk board, but were experimentally a disaster. The Farm Hill transcripts and related documents do not point to any evidence that Heisenberg and his colleagues knew how to build a working reactor and but chose not to for moral reasons.

The American nuclear program consumed two billion dollars, which at that time was a vast sum of money. Tens of thousands of people worked on the design and manufacture of the first nuclear weapons, although a much smaller number actually know what they were building. In contrast the German effort was miniscule. In part this was because until the German army started to bog down on the Easter Front, they thought that the war was won. No "super weapons" were needed. Later in the war, the German scientists told officials that the construction of a nuclear bomb could not be completed in the near term. This was not because they were misleading their Nazi masters, but because this was what they actually believed. After the bomb was dropped on Hiroshima and it became clear that the Americans were far ahead of the Germans, Heisenberg and his colleagues were shocked.

Bernstein is one of the best popular science writers and I have enjoyed several of his books. He is a professor of physics at the Stevens Institute of Technology and he does a good job of explaining the technical problems encountered constructing a nuclear weapon. For the general reader, the most interesting part of Hitler's Uranium Club will be Bernstein's prologue. Although Bernstein has annotated and classified the Farm Hall transcripts, I found that they make tedious reading, and skimmed them. But for the serious student this book will be an important resource.

Ian Kaplan - 4/96

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