Julian Schwinger (born 12.02.1918) is an American theoretical physicist and a member of the National Academy of Sciences (1949). He was born in New York. He graduated from Columbia University (1936). In 1945-75 he worked at Harvard University (professor from 1947), and since 1975 he has been professor at the University of California, Los Angeles.
His work was in the field of nuclear physics, relativistic quantum mechanics, statistical physics, the theory of elementary particles, field theory, many-particle theory, relativistic quantum electrodynamics, of which he is one of the creators (Nobel Prize, 1965), and the quantum theory of gravitation.
In 1941 he constructed the theory of the quadrupole moment of the deuteron and introduced tensor forces. In 1948—49 he developed (independently of others) the method of renormalisation, calculated the anomalous magnetic moment of the electron, explained the “Lamb shift”, and determined the radiative corrections to the processes of electron scattering in a Coulomb field. He suggested (1942) that the vector meson has a greater mass than the pseudoscalar one. He developed the general theory of Green's functions in field theory.
He related (1956) hypercharge to strangeness by the equation Y = S + B. In 1957 he put forward the idea that there are two types of neutrino, associated with the electron and the muon. He advanced the idea of unifying the weak and electromagnetic interactions and developed the model of “global symmetry” (1957). In the formal theory of scattering, together with B. Lippmann he developed computational methods — variational and algebraic — and derived the Lippmann—Schwinger equation. He was the first to point out a specific scattering of neutrons, due to the interaction of the neutron's magnetic moment with the electric field of the nucleus (Schwinger scattering).
In the theory of elementary particles he is the founder of a new direction — chiral dynamics — and is developing a new approach in this field, the theory of sources. He proposed (1969) a magnetic theory of matter, based on a superstrong long-range interaction characterised by a dimensionless constant (the dyon hypothesis). He developed (1967) the method of phenomenological Lagrangians, which makes it possible to reproduce, in the Born approximation, the results of current algebra.
The Prizes of the National Academy of Sciences (1949) and of A. Einstein (1951), the National Medal of Science (1964) and others.