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Continuing work on solid state physics


Explaining neutron bombardment and resonance theory
Hans Bethe Scientist
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As part of my first article in the Reviews of Modern Physics I tried to figure that and found that the number of resonance's would increase exponentially with the energy of the neutron and the energy of the neutron when... of a slow neutron when entering the nucleus is some 7 or 8 million electron volts, because that's what it would be bound by when it finally is captured. And at such an excitation energy you get a very high density of levels. Then very soon, Weisskopf introduced the concept of entropy, and said 'Well, the number of levels is es where s is the entropy', and in my first article I calculate the entropy as a function of excitation energy and atomic number. I also made a mistake in that but I think it's not important to dwell on that. In fact, one thing I should mention, I sent that paper to Peierls to look at, and Peierls was horrified by the sloppiness I had... I had used, and wrote me back a letter which went, taking off from the Dreigroschenoper in Germany; 'Erst komt das denken, dann das Integral.' First think and then carry out an integral.

The late German-American physicist Hans Bethe once described himself as the H-bomb's midwife. He left Nazi Germany in 1933, after which he helped develop the first atomic bomb, won the Nobel Prize in Physics in 1967 for his contribution to the theory of nuclear reactions, advocated tighter controls over nuclear weapons and campaigned vigorously for the peaceful use of nuclear energy.

Listeners: Sam Schweber

Silvan Sam Schweber is the Koret Professor of the History of Ideas and Professor of Physics at Brandeis University, and a Faculty Associate in the Department of the History of Science at Harvard University. He is the author of a history of the development of quantum electro mechanics, "QED and the men who made it", and has recently completed a biography of Hans Bethe and the history of nuclear weapons development, "In the Shadow of the Bomb: Oppenheimer, Bethe, and the Moral Responsibility of the Scientist" (Princeton University Press, 2000).

Tags: Reviews of Modern Physics, Rudi Peierls, Victor Weiskopff

Duration: 2 minutes, 14 seconds

Date story recorded: December 1996

Date story went live: 24 January 2008