Vavilov, Sergei Ivanovich

Born Mar. 12 (24), 1891, in Moscow; died Jan. 25, 1951, in Moscow. Soviet physicist, political and public figure; academician of the Academy of Sciences of the USSR (1932; corresponding member, 1931). Brother of N. I. Vavilov. Graduated from Moscow University in 1914. From 1914 to 1918 he was in the military service. From 1918 to 1932 he taught physics at Moscow State University (he became a professor in 1929). From 1918 to 1930 he directed the division of physical optics at the Institute of Physics and Biophysics of the People’s Commissariat of Health. In 1932 he became the director of the Institute of Physics of the Academy of Sciences of the USSR. From 1932 to 1945 he was scientific director of the State Optical Institute. In 1945 he was elected president of the Academy of Sciences of the USSR. He was chairman of the Council for the Coordination of Activities of the Academies of Sciences of the Union Republics.

Vavilov’s main scientific work was devoted to problems of physical optics, especially to the study of the nature of luminescence. The concept of luminescence yield introduced by him has proved extremely fruitful for the development of a theory of luminescence. Vavilov deduced a law generalizing and correcting the famous Stokes’ law. In studies devoted to a definition of the absolute value of luminescence yield, he proved that more than 70 percent of the absorbed energy in strongly fluorescent substances is transformed into the light of luminescence. Studying the causes of the decrease in luminescence yield and of other processes, Vavilov developed the theory of migration of the energy of excitation in solutions, which qualitatively explained a broad range of phenomena. He studied the problem of the polarization of luminescent light, owing to which he succeeded in approaching the problem of the nature of elementary radiators. He presented the general sytematics of the phenomena of luminescence. Problems associated with the practical applications of luminescence, in particular the development of the technology for the production of sunlamps, were solved under his direction. Vavilov contributed to the development of luminescence analysis. The research cycle of Vavilov and his coworkers devoted to a visual method of observing the quantum fluctuations of light is of great importance for the theory of light and for physiological optics. In 1934, under Vavilov’s direction, P. A. Cherenkov discovered the luminescence of pure liquids under the influence of gamma and beta radiation of radioactive materials. Vavilov immediately pointed out that this luminescence was not ordinary luminescence but was associated with the movement of free electrons (so-called Cherenkov-Vavilov radiation).

In his book The Microstructure of Light (1950), Vavilov generalized the results of his work and laid the foundations for a new trend in optics, which he called microoptics. The quantum properties of light, the nature of elementary radiators, and the interaction between radiating and absorbing molecules at distances comparable to the wavelengths of light were reviewed by Vavilov in this book from the single perspective of microoptics. Vavilov was one of the founders of nonlinear optics, and he founded a large school of physicists.

Vavilov devoted a great deal of attention to problems of the philosophy of natural science and the history of science. He headed the Commission on History of the Academy of Sciences of the USSR. His studies on the history of atomism are also of great interest. The popularization of scientific knowledge occupied an important place in Vavilov’s activity. In 1933 he became the director of the Commission of the Academy of Sciences of the USSR on the Publication of Popular Scientific Literature and of the series Results and Problems of Contemporary Science. He was one of the initiators of the All-Union Society for the Dissemination of Political and Scientific Knowledge (now the Znanie Society) and was the first chairman of this society (1947). Beginning in 1945, Vavilov was chairman of the Editorial-Publication Council of the Academy of Sciences of the USSR, a member of the editorial staffs of many journals, and one of the directors of encyclopedia work in the USSR: he was a member of the editorial staff of the Technical Encyclopedia, the first edition of the Great Soviet Encyclopedia and, beginning in 1949, the editor in chief of the second edition of the Great Soviet Encyclopedia.

In 1938, Vavilov was elected deputy to the Supreme Soviet of the RSFSR and, in 1946 and 1950, deputy to the Supreme Soviet of the USSR. During the Great Patriotic War he was a plenipotentiary of the State Committee for the Defense of the USSR. New devices for the armament of the Soviet Army and Navy were developed under his direction. Vavilov was awarded two Orders of Lenin, the Order of the Red Banner of Labor, and the State Prize of the USSR (1943, 1946, and, posthumously, 1951). His name was conferred on the Institute for Physical Problems of the Academy of Sciences of the USSR in Moscow and on the State Optical Institute in Leningrad. In 1951 a Vavilov gold medal was established, to be awarded yearly for outstanding work in the areas of physics.