Nobel Prize for Physics for 1949 : Prof. H. Yukawa

Abstract

PROF. H. Yukwa, who has been awarded the Nobel Prize physics for 1949, is best known for his theory of nuclear forces which, in 1935, first postulated the existence of a particle a few hundred times heavier than the electron. The nuclear forces would then bear the atom bea same relation to the possible emission and absorption of such a particle as the electromagnetic forces in anr to the emission and absorption of light. The discovery of the meson m cosmic rays appeared to be a confirmation of Yukawa's prediction, but the study of its properties gradually led to the conviction that it could not be identical with the particle required for Yukawa's theory. It was not until 1947 that Powell and his collaborators demonstrated the existence of a second short-lived particle, the π-meson, which is known to be the parent of the cosmic-ray meson, and which is strongly linked to protons and neutrons. This provided a brilliant vindication of Yukawa's idea. The detailed theory of the relation between this particle and the nuclear forces is still in its infancy ; but, whatever the outcome, all thought about nuclear forces for the past decade and for many years to come is entirely dominated by the ideas of Yukawa. Since this first pioneer work, Yukawa has contributed much to other problems in fundamental theory and has built up an important school of theoretical physicists. As the editor of the new journal, Progress of Theoretical Physics, he has helped to provide an outlet for the great wealth of important contributions from his own school, as well as that of his colleagues. This new journal has already found a prominent place in literature on modern fundamental quantum theory.