Beta Decay Redux, Slow Neutrons, Bohr and his Realm

A large conference on nuclear physics was held in London and Cambridge from October 1–6, 1934. Six German refugee physicists were present, but Werner Heisenberg was not. Czech theoretical physicists Guido Beck and Kurt Sitte had proposed a theory of beta decay that challenged Fermi’s, which Beck presented but apparently gained no support for. On October 22, Fermi serendipitously discovered the efficaciousness of slow neutrons in producing nuclear reactions. Niels Bohr would be the greatest beneficiary of Fermi’s discovery. In 1935 Bohr, with the assistance of refugee Otto Robert Frisch, began to develop experimental nuclear physics at his institute, which after its inauguration in 1920 became a mecca for young physicists. On September 29, 1943, Bohr and his family were among the 7220 Danish and other Jews who were transported to Sweden in the greatest mass rescue operation of the war.

Otto Robert Frisch, 1 October 1904 - 22 September 1979

O. R. Frisch brought to physics the approach of a craftsman. He enjoyed, above all, doing experiments with his own hands, preferably on apparatus of his own design, aimed at simple basic questions. This approach required the ability to think about the important problems of physics simply, but deeply, an ability underlying the two contributions for which he was best known: his share in the explanation of the fission process and that in the recognition of the feasibility of an atomic weapon. The craftsman was also something of an artist, not only in his love for music and his skill and taste as a pianist and a violinist, but in the use of language, which made him an outstanding expositor. There were many problems, in physics and elsewhere, which he regarded as interesting, and these he pursued persistently, in depth, until he saw convincing answers in simple terms, and he evidently enjoyed himself in doing so. He equally firmly refused to become involved with matters other than those which he had decided were of interest to him.