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The usefulness of my Habilitationschrift to physics


Atomic form factor in my Habilitationsschrift
Hans Bethe Scientist
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So you had the atomic form factor generalized to the case where the atom makes a transition from its ground state to an excited state, and you get that generalized form factor and then you multiply it by the initial and final wave function of the atom. And then you have a very much simpler theory. So this was the basis of my paper and having simplified it to that extent it was easy to do the integration, and it was easy then to do more than the... to sum the probability of various... excitations of the atom, to sum over all possible final states of the atom, and get the total cross section or total inelastic cross section of the atom, which comes out very easily. And then I found - and that was very nice - that it became even easier if you took not just the cross section of going from state zero to state n, but multiplied it by the energy difference, energy of state n minus energy of state zero. And if you did that you got a still simpler result, in fact I later found out - much later - that this really was the way in which Kuhn and Reiche had discovered their sum rule for atomic oscillator strengths. And this had been the basis of Heisenberg's Matrix Mechanics, (p*q)-(q*p); that's essentially what I rediscovered, and so I could sum the cross section multiplied by the energy change, and that of course is the energy loss of the integral particle. And so thereby I could calculate in a very simple way the energy loss of any particle going... interacting by electric forces with an atom.

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: atomic form factor, Habilitationschrift

Duration: 2 minutes, 58 seconds

Date story recorded: December 1996

Date story went live: 24 January 2008