Sergei Ivanovitch Vavilov (1891-1951) was an outstanding Russian physicist and President of the USSR Academy of Sciences. His life is of interest not only for the history of physics but also for the history of Soviet Society. He conducted fundamental research in physical optics and luminescence. His most famous results were his discoveries of the non-linear optical effect in 1926, and of the Vavilov-Cerenkov radiation in 1934. In 1932 he was appointed Head of Research at the State Optics Institute (GOI) in Leningrad. In 1934 he became the founder and first director of the Lebedev Institute of Physics (FIAN) in Moscow.S.I.Vavilov made colossal contribution to the progress of research and to the growth of both institutes. GOI was instrumental in the emergence of an advanced optics industry in Russia, where no optical engineering had ever existed. Under S.Vavilov's leadership, FIAN grew out of a small laboratory to become the multidisciplinary institution, which is today. S.Vavilov made great contribution to the development of nuclear and cosmic ray physics. In July 1945 S.I.Vavilov was elected President of the USSR Academy of Sciences. While he was president, until 1951, he accomplished much to foster science in Russia: the laboratories were better supplied with equipment, the salaries of the researchers were much increased, the number of the scientific publications was multiplied tremendously. Vavilov was also concerned with the general issues of national science administration, the development of higher education, practical applications of the knowledge gained from fundamental research, and the broad cultural progress of the nation. Unfortunately his heavy administrative responsibilities did not leave him enough time to pursue his own research objectives. Vavilov could not behave otherwise, though: he was a man of integrity, and his own interests were never his primary concern. Acting as President of the Academy under the brutal dictatorial regime of Stalin was the source of an appalling stress. With his Eldest brother (the biologist Nikolai Vavilov ) having been murdered by this regime, Vavilov's health was seriously damaged, and he died two months before his sixtieth birthday. The talk will review S.I.Vavilov's very rich life and presents the still poorly known history of the discovery of the Cerenkov effect.
