Sin-Itiro Tomonaga (31.03.1906-8.07.1979) was a Japanese theoretical physicist and a member of the Japan Academy (1951). He was born in Kyoto. He graduated from the University of Kyoto (1929) and worked there in 1929-32. In 1932 —40 he was at the Institute of Physical and Chemical Research. In 1941—69 he was professor at the University of Tokyo, and in 1956 —62 its president. In 1963—69 he was also director of the Institute of Optical Research of the University of Tokyo and president of the Science Council of Japan.
His research concerned quantum electrodynamics, quantum field theory, the theory of mesons, nuclear physics, cosmic-ray physics and the many-body problem. In 1940 he predicted mesic atoms, and in 1942 he was the first to propose a covariant formulation of quantum field theory.
In 1946 he developed the so-called super-many-time formalism, on the basis of which the modern form of quantum electrodynamics arose, making it possible to calculate with great accuracy all the processes of electromagnetic interaction of electrons and photons. In 1955 he developed the theory of collective motions in quantum mechanics. For the creation of modern quantum electrodynamics he was awarded the Nobel Prize in 1965, together with R. Feynman and J. Schwinger.
He was a member of a number of academies of sciences and scientific societies, including a foreign member of the USSR Academy of Sciences (1971). The M. V. Lomonosov Gold Medal (1964).