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Atomic form factor in my Habilitationsschrift


'Bethe is my student. I want him back.'
Hans Bethe Scientist
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I had spent one semester in Stuttgart with Ewald, which was a very happy time, but then Sommerfeld wrote Ewald a postcard, no more, in which he said 'Bethe is my student. I want him back.' So Ewald put me into a package and sent me back to Sommerfeld and I returned to Sommerfeld in the fall of '29. It should be mentioned that Sommerfeld had a sabbatic in the winter semester '28 to '29 in which he traveled all over the globe, among others to India, and had a very good time. When I returned to Sommerfeld and Sommerfeld suggested I should get my Habilitation and I had read the Born paper trying to... to get the inelastic scattering by hydrogen. I think I should mention that the actual calculation was done by Elsasser, which was another paper published. Well, the Born theory for first part approximation says you take the wave function of the system in the initial state and take its complex conjugate and then you take the wave function in the final state and you multiply them and you multiply by the interaction between the atom and the electron which comes in from the outside, e2/r1,2, and you integrate that. Well, Elsasser had done that, by first integrating over the atomic electron wave function, and that's a very hard thing to do and it took him a long time to... to do it. But I noticed that the wave function of the incident particle electron or proton or whatever it may be is much simpler, it's just an exponential, eik.r, and if you multiply two of them, you get eiq.r where q is the change of momentum in the scattering process and to integrate that with the interaction 1/r1,2. It's as easy as can be. Ewald had done it, and it is just taking the fourier transform of the wave function. And that's what people knew as the atomic form factor.

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: Universität Stuttgart, Stuttgart University, Paul Ewald, Arnold Sommerfeld, Walter M Elsasser

Duration: 3 minutes, 39 seconds

Date story recorded: December 1996

Date story went live: 24 January 2008