Bethe:
Well, it went this
way. There was first the experiment of Hahn and Strassmann in Germany, showing a very peculiar
behavior of uranium when bombarded by neutrons, which was then explained by Frisch and Meitner
as indicating that the uranium nucleus splits into two parts. The news of this was brought to
the United States by Niels Bohr in early 1939, and people immediately began thinking what this
may mean. It was very quickly reasoned that in this splitting, in this fission, an enormous
amount of energy would be liberated. That could simply be deduced from the measured masses of
the nuclei involved, and from Energy equal to MC squared, which is a very small, and very
incidental part of the picture. Ah, the, so very soon it was shown that indeed a large amount of
energy is released. And then it was shown also on the basis of previous logical arguments, that
in the fission, neutrons would be liberated. Now if that were so, anybody could conclude if
neutrons are liberated, then there can be a chain reaction. And I believe the idea of a chain
reaction was conceived simultaneously by at least half a dozen people. All of this was discussed
very openly. It was great news. So, in January of '39, we all were aware that a chain reaction
was possible in uranium. Then it was only one more step to put these things together. The chain
reaction would release a lot of energy, and so if you could make it go, you could convert this
energy into power, and make power reactors. And if you were able to make the chain reaction go
very quickly, then you would get an explosion. Intense. The possibility of a powerful explosion,
more powerful than anything we had known before. That was pretty well common knowledge among
physicists in this country, in England, in Denmark, and in Germany. There was a meeting in, I
think it was in March of 1939 in Washington. This was one year of an annual meeting which took
place in Washington, sponsored by the Carnegie Foundation. Carnegie Institution, I think it is
called. This meeting usually was open to the press, but because of the possibility of a nuclear
weapon, the sponsors of the meeting excluded the press from this particular session. And that
particular session, as I said, probably in March of '39, it was generally discussed that this
discovery could lead to a weapon of unbelievable power.