Hans Bethe on trying to understand what makes stars shine.

Bethe:

Now, in 38 Gamow and Teller decided that they would have something new, that they would have a new conference on stellar energy. In this they brought together some of the best astrophysicists, for instance, Strömgren, with the theoretical physicists who had normally attended these meetings. It seemed very exciting because apparently the astrophysicists were at a loss as to what to do. 0ne of the participants was Weizsäcker at that time, and Weizsäcker reported on some of the attempts which he was making to explain energy production. I think nobody at the conference had any question but that the energy production must somehow be due to nuclear reactions. This of course was very different from the original ideas of Eddington several years earlier—ten years earlier or so. Eddington thought to use annihilation of matter to produce the energy. But nuclear reactions were well established by this time and gave a good, large amount of energy, and anybody could calculate for himself that nuclear reactions with abundant elements were sufficient to keep the sun shining for the past life of the universe and of course many billions of years thereafter. So this was more or less unwritten common background.

Weiner:

Was this articulated and discussed or was it just felt by everyone?

Bethe:

I think this was probably discussed even. Well, I don't think it was discussed in detail because it was assumed as so obvious. People probably referred to it and said, "Well, of course, there are nuclear reactions but now what? What are these nuclear reactions?" I was otherwise impressed by the total ignorance which pervaded everybody at the meeting. People really were at a loss as to what to do and what reactions to consider. Weizsäcker in particular tried to do two things at the same time—namely, to build up the elements and simultaneously generate energy. And to build up the elements he wanted neutrons on the basis that neutrons easily enter the nucleus. And so he was discussing at the meeting various ways how you could get neutrons. The main step which I took was to get away from this, to get away from the coupling between building up the elements and generating energy. But that of course came later.