Herbert Fröhlich who died in Liverpool on 23 January 1991, at the age of 85, was one of the group of theoretical physicists who started research just after the new quantum mechanics was formulated, and subsequently spent their lives in applying it to outstanding problems of physics and chemistry, and in Fröhlich’s case also to biology. This group included such figures as Hans Bethe, Rudolf Peierls, Eugene Wigner and Edward Teller, as well as the author of this article; most of them came from Central Europe and, with the rise of Hitler, made their careers in England or the United States, with very positive effects on the development of science in both these countries. Fröhlich, apart from a short stay in the Soviet Union and some months in Leiden, spent his whole career after the rise of Hitler based in Bristol and then in Liverpool; he made extended visits to Germany, Japan and America. His interests were unusually wide. As early as 1936 he published (in German) the first book to be devoted to the application of quantum mechanics to electrons in metals (i)*. In Bristol, already before and during the war, he developed a theory of dielectric behaviour, and in particular dielectric breakdown, which attracted much interest in the electrical industry, and financial support. At the same time he worked with Kemmer and Heitler on a problem of particle physics, a subject in which he maintained a deep interest throughout his life. Later, in Liverpool, he turned his attention to the unsolved problem of superconductivity. Here he pointed out that electron-phonon interaction could produce a weak attraction between the electrons. Although a proof that the resultant pairing lead to superconductivity had to await the Nobel prizewinning work of Bardeen, Cooper and Schrieffer a few years later, Fröhlich was confident that the origin of superconductivity lay in this attractive force, and predicted that the strength of this force, and hence the transition temperature, would depend on the vibrational frequency of the phonons and therefore on the isotopic mass. This was a turning point in our understanding, as most physicists realized. During the later years of his active career, which lasted until a few weeks before his death, he created an important new subject, applying concepts developed in his work on superconductivity to certain problems of biology.
Eugene Wigner, Pupil of a legendary School
