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Hans Bethe - Edwin Salpeter's work in astrophysics (76/158)

1,780 views · Published 27 June 2017 · 2:52 · Indexed 18 October 2026

Channel: Web of Stories - Life Stories of Remarkable People · 2017 · Science & Technology

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German-born theoretical physicist Hans Bethe (1906-2005) was one of the first scientists to join the Manhattan Project, later strongly advocating nuclear disarmament. In 1967, he was awarded the Nobel Prize in Physics for his theory of stellar nucleosynthesis. [Listener: Sam Schweber; date recorded: 1996]

TRANSCRIPT: Now, the great question, how do you build up elements? How do you get beyond helium? And there Edward Salpeter came in, who was a graduate student with Rudi Peierls in Birmingham and then was recommended by Peierls to me as a postdoc. So whenever Peierls recommended somebody as a postdoc I eagerly took him, and vice versa, and so Salpeter came here and very soon he became interested in astrophysics. He came here, I think, in '48, but it took until '52 as far as I remember before he went to Cal Tech on a visit, being interested in astrophysics. He talked to Willy Fowler there and Fowler suggested to him 'Well, there's this problem. How are the elements built up?' And so Salpeter very soon found that indeed, if you had high temperature you could get from helium to carbon, namely two helium's can get together and make a beryllium-8. And if you have high temperature and high density, you have some probability of this beryllium-8 staying together, or maybe for one-billionth of a second, and that's enough to have a chance for another helium to get there while the beryllium-8 is there, and making... combining to make the stable nucleus, carbon-12. And he wrote that down and correctly calculated the temperature to be something of the order of a 100 million degrees instead of 20 [million degrees], and so at a 100 million degrees you would get this reaction and you would build up carbon.

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