The first to think seriously of such a nuclear chain reaction was the Hungarian physicist Leo Szilard (1898-1964). He was working in Germany in 1933 when Adolf Hitler came to power and, since he was Jewish, he felt it would be wise to leave Germany. He went to Great Britain and there, in 1934, he considered certain new types of nuclear reactions that had been discovered. In these, it sometimes happened that a fast neutron might strike a nucleus with sufficient energy to cause it to emit 2 neutrons. In that way the nucleus, absorbing 1 neutron and emitting 2, would become a lighter isotope of the same element. But what would happen if each of the 2 neutrons that emerged from the original target nucleus struck new nuclei and forced the emission of a pair of neutrons from each. There would now be a total of 4 neutrons flying about and if each struck new nuclei there would next be 8 neutrons and so on. From the initial investment of a single neutron there might soon be countless billions initiating nuclear reactions. Szilard, fearing the inevitability of war and fearing further that the brutal leaders of Germany might seek and use such a nuclear chain reaction as a weapon in warfare, secretly applied for a patent on a device intending to make use of such a nuclear chain reaction. He hoped to turn it over to the British Government, which might then use its possession as a way of restraining the Nazis and keeping the peace. However, it wouldn’t have worked. It took the impact of a very energetic neutron to bring about the emission of 2 neutrons. The neutrons that then emerged from the nucleus simply didn’t have enough energy to keep things going. (It was like trying to make wet wood catch fire.) But what about uranium fission? Uranium fission was initiated by slow neutrons. What if uranium fission also produced neutrons as well as being initiated by a neutron? Would not the neutrons produced serve to initiate new fissions that would produce new neutrons and so on endlessly? It seemed very likely that fission produced neutrons and indeed, Fermi, at the conference where fission was first discussed, suggested it at once. Massive nuclei possessed more neutrons per proton than less massive ones did. If a massive nucleus was broken up into 2 considerably less massive ones, there would be a surplus of neutrons. Suppose, for instance, uranium-238 broke down into barium-138 and krypton-86. Barium-138 contains 82 neutrons and krypton-86 50 neutrons for a total of 132. The uranium-238 nucleus, however, contains 146 neutrons. The uranium fission process was studied at once to see if neutrons were actually given off and a number of different physicists, including Szilard, found that they were.