Robert Green Sachs (born 4.05.1916) — American theoretical physicist, a member of the National Academy of Sciences (1971). Born in Hagerstown. Graduated from Johns Hopkins University (1939). In 1939-41 he worked at George Washington University, in 1941—43 at Purdue University. In 1945-47, 1964-68 and 1973 — 79 he was at the Argonne National Laboratory (director from 1973), in 1948—64 a professor at the University of Wisconsin, and from 1964 at the University of Chicago (in 1968 — 73 director of the Enrico Fermi Institute for Nuclear Studies).
His work was in high-energy physics, field theory, nuclear physics, general relativity, the theory of gravitation, astrophysics and cosmology. Studying the structure of the nucleon, he established (1952) the so-called mirror theorem, which relates the magnetic moments of the neutron and the proton, and developed a phenomenological theory of nucleon structure. He gave (1954) an explanation of the mass difference between the proton and the neutron. In 1953 he put forward the idea of the charge independence of strong interactions, and in 1962 introduced the concepts of the electric and magnetic form factors of nucleons.