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Writing a paper with Enrico Fermi


Energy loss: bridging classical and quantum formula
Hans Bethe Scientist
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[Q] The problem of energy loss had been a famous problem that Bohr had worked on and...

Yes, in fact the old theory of energy loss was initiated by Bohr about the same time as he found the old quantum theory and it's a beautiful paper, Bohr's paper, and his formula differs from mine in a just a very slight extent. But Bohr was very intrigued by that and he asked Felix Bloch to look into this: Why is it different? And Bloch then succeeded in making the connection between the classical formula of Bohr and my quantum formula and he found that for very slow electric particles, especially those of high charge, the old classical theory is right; and then for fast particles, my quantum theory is right, and Bloch succeeded in getting the... in bridging the two.

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: Niels Bohr, Felix Bloch

Duration: 1 minute, 22 seconds

Date story recorded: December 1996

Date story went live: 24 January 2008