Carl von Weizsäcker

Carl von Weizsäcker

Carl von Weizsäcker was born in Kiel in 1912. He studied physics at Leipzig and in 1938 he proposed the theory for stellar evolution that explained the production of ironizing and particulate radiation by stars.

In 1940 Weizsäcker joined the German atomic bomb research team led by Werner Heisenberg. In April, 1945, Allied forces arrested Weizsäcker and Heisenberg as well as other German scientists such as Otto Hahn, Max von Laue, Karl Wirtz, and Walter Gerlach. These men were now taken to England where they were questioned to see if they had discovered how to make atomic weapons.

After the war Weizsäcker returned to Germany where he became director of a department in the Max Planck Institute of Physics in Gottingen. He was also professor of philosophy at Hamburg (1957-69).

Primary Sources

(1) Just before the outbreak of the Second World War Carl von Weizsacker commented to a friend on Nazi Germany.

People whose political judgment I respect, my own father chief and foremost among them, do not believe that Hitler has the least chance of winning the war. My father has always looked upon Hitler as a fool and a criminal who is bound to come to a bad end, and he has never wavered in this belief. But if that is the whole truth, how can we possibly explain Hitler's successes so far? Hitler's liberal and conservative critics have completely failed to grasp one decisive factor: his hold over the minds of the masses. I don't understand it myself, but I can certainly feel it. He has often enough confounded all his critics with his success, and - who knows - perhaps he will do it again.

(2) Carl von Weizsacker had a long discussion with Werner Heisenberg in 1939 about the morality of scientific research.

We must make a clear distinction between the discoverer and the inventor. As a rule, the former cannot predict the practical consequences of his contribution before he actually makes it, the less so as many years may go by before it can be exploited. Thus Galvani and Volta could have had no conception of the subsequent course of electrical engineering, nor can the slightest responsibility be attached to them for the uses and abuses of subsequent developments. Inventors seem to be in quite a different position. They have a definite, practical goal in view, and ought to be able to judge its merits. Hence we can apparently hold them answerable to their contributions. Yet it is precisely the inventor who can be seen not to act mot so much on his own behalf as for society at large. The inventor of the telephone, for instance, knew that society was anxious to speed up communication. In much the same way the inventor of firearms may be said to have acted on the orders of a society desirous of increasing its military strength.

(3) While in England the captured German scientists were secretly taped to discover how much they knew about atomic weapons. This included Weizsäcker, Otto Hahn, Werner Heisenberg, Max von Laue and Karl Wirtz.

Otto Hahn: If the Americans have a uranium bomb then you're all second-raters.

Werner Heisenberg: Did they use the word uranium in connection with this atomic bomb?

Otto Hahn: No.

Werner Heisenberg: Then it's got nothing to do with atoms, but the equivalent of 20,000 tons of high explosive is terrific. All I can suggest, is that some dilettante in America knows it has the equivalent of 20,000 tons of high explosive and in reality, it doesn't work at all.

Otto Hahn: At any rate Heisenberg, you're just second-raters, and you may as well pack up.

Werner Heisenberg: I quite agree. I am willing to believe that it is a high pressure bomb and I don't believe that it has anything to do with uranium but that it is a chemical thing where they have enormously increased the whole explosion.

Karl Witz: I'm glad we didn't have it.

Carl von Weizsacker: I think it's dreadful of the Americans to have done it. I think it is madness on their part.

Werner Heisenberg: One can't say that. One could equally well say, "That's the quickest way of ending the war."

Otto Hahn: That's what consoles me.

Werner Heisenberg: I believe the reason we didn't do it was because all the physicists didn't want to do it, on principle. If we had all wanted Germany to win the war we could have succeeded.

Otto Hahn: I don't believe that, but I am thankful we didn't succeed.