Some of the other things I was doing I did with great enthusiasm and with the full approval and support of Oppenheimer for which I'm really grateful. Early in the game I brought up a possibility that might make a nuclear explosion work much more effectively than had been predicted. It wouldn't work, we know that, except at a very high temperature. At a high temperature a lot of the energy, and I already said that too, is in radiation and this radiation, as it happens in the stars, can leak out. If it leaks out rapidly enough then the nuclear explosive stays together for a longer time and multiplies better and it would be a great improvement in the yield. This is a point I already brought up in the conference in California in the summer of 1942. In the course of discussion we convinced ourselves, not completely, but we came to the conclusion that that is probably quantitatively not important. But I kept worrying. I wanted to continue to work on it and Oppenheimer said no, but he agreed if I can find a group outside Los Alamos that would do it, let's do it. I found such a group. An excellent theoretical physicist whom I knew well, who later got the Nobel prize, Doctor Maria Mayer, working at Columbia University, seemed to me a very good candidate. With Oppenheimer's permission I went to talk to her. She got her students together, got going. I was not allowed to tell her why I am interested and I did not violate security at all. She did not know why I was doing it but there was one little detail that I could not be silent about. Maria asked me- And please, at what temperature shall we calculate this opacity? I told her. I had to tell her. And at that point her eyebrows went up one tenth of an inch, but she did not ask any further question. Incidentally all this, this remarkable business - how security, so-called security, how secrecy works - it had a little sequel. All this came to the knowledge of the administrative people who called me in and who called in Maria, that we do not let too much information out.