John Archibald Wheeler (born 9.07.1911)-an American theoretical physicist, member of the National Academy of Sciences (1952). Born in Jacksonville (Florida). He graduated from Johns Hopkins University (1933). In 1933-35 he worked in Copenhagen with N. Bohr, in 1935 — 38 at the University of North Carolina, and in 1938 — 76 at Princeton (from 1947 as professor, and in 1951—53 as director of the Matterhorn stellarator project). Since 1976 he has been professor at the University of Texas. His work was in nuclear physics, the problem of thermonuclear fusion, special and general relativity, unified field theory, the theory of gravitation and astrophysics. Independently of W. Heisenberg he introduced (1937) the scattering matrix for describing interactions (the S-matrix). In 1939, together with N. Bohr, he developed the theory of the fission of the atomic nucleus, proved that it is the rare isotope uranium-235 that undergoes fission under the action of thermal neutrons, mathematically substantiated (1939), independently of others, the possibility of a nuclear fission chain reaction in uranium, was the first to explain the negative effect of the fission products (xenon) on the course of a nuclear chain reaction, and developed methods of controlling a nuclear reactor. Independently of others he put forward (1948—49) the idea of the universality of the Fermi interaction, with D. Hill developed (1953) the collective model of the nucleus, and predicted (1947) the existence of mesic atoms. In 1949 he postulated the possibility of two ways of fission of uranium by stopped muons: the capture of a μ--meson and radiationless transitions in muonic atoms. Recently he has worked chiefly in the field of gravitation and relativistic astrophysics. He is one of the creators of geometrodynamics, which studies the structure of space-time on extremely small scales. In particular, he developed the so-called geometrodynamic models of mass and charge — the model of “mass without mass” (Wheeler geons) and the model of “charge without charge” (Wheeler “handles”) — and the theory of superspace. His research was also devoted to the quantisation of gravitation, gravitational collapse, and the structure of matter of extremely high density and temperature. He developed the theory of neutron stars. President of the American Physical Society (1966). A. Einstein Medal (1965), E. Fermi Medal (1968), B. Franklin Medal (1969), National Medal of Science (1971) and others. He founded a school of physicists.