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Hans Bethe - Accelerating shocks in supernovae (137/158)

829 views · Published 26 June 2017 · 2:59 · Indexed 25 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: This is not the reason why the shock accelerates. It is much simpler than that, namely once the shock reaches something like 300 kilometers from the center, then the gravity has decreased sufficiently that just the distribution of gravitational force, the decrease of gravitational force at larger distance, that is enough to accelerate the shock in the way I indicated from a few thousand to 10 or 20,000 kilometers per second. That I found out only during the last year, I'm still working on it, and I am still writing papers on it. I am now at paper number eight which I just finished writing and which is presently being typed. I believe that I have now understood the mechanism, namely neutrinos are emitted from the core which has accumulated gravitational energy; the neutrinos give energy to matter between the gain point and wherever the shock is; the gain point usually is around 100 kilometers from the center and I can calculate that you use about 10% of the neutrino energy and give 10% to the matter out there, and then these 10% serve to expel the outside of... of the star. Now that you see, the expulsion of the outside of the star and of course it gives you big fireworks, tremendous luminosity, very high temperature at the surface which then gradually declines. And we had the great good fortune that in 1987 there was a supernova, not in the galaxy, but in the neighboring galaxy, in the so-called Large Magellanic Cloud.

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