Yakov Borisovich Zeldovich (born 8.03.1914) was a Soviet physicist and an academician (1958; corresponding member 1946). He was born in Minsk. In 1931 he began work at the Institute of Chemical Physics of the USSR Academy of Sciences. From 1964 he worked at the Institute of Applied Mathematics of the USSR Academy of Sciences, and from 1966 he was also professor at Moscow University.
His work concerned chemical physics, the theory of combustion, the physics of shock waves and detonation, physical chemistry, the physics of the nucleus and of elementary particles, astrophysics and cosmology. He is one of the founders of macroscopic kinetics. In the theory of combustion he found the connection between the speed at which a flame spreads and the kinetics of the chemical reactions within it, and solved such important problems as the ignition of a mixture by a heated surface, the determination of the front of a spreading flame and others. He created the physical foundations of the internal ballistics of solid-propellant rocket motors. In the theory of detonation he justified the Chapman–Jouguet hypothesis, was the first to explain the phenomenon of the detonation limit, solved the problem of a high-speed impact on the surface of a medium, and others.
In 1939 — 40, together with Yu. B. Khariton, he gave a calculation of the nuclear chain process in uranium, studied the effect whereby neutrons escape below the fission threshold through scattering, developed the theory of a homogeneous thermal-neutron reactor and the theory of the resonance absorption of neutrons by uranium-238 nuclei, examined the kinetics of a reactor and pointed out the fundamental part played by delayed neutrons in controlling its operation. As one of I. V. Kurchatov's closest collaborators, he took a direct part in solving the problem of the use of nuclear energy.
He predicted the possibility of confining ultracold neutrons in a vessel with reflecting walls, and muon catalysis (1953), whose theory he also developed. He pointed out the possible existence of nuclei with a large excess of neutrons (*He). He introduced the concepts of lepton charges (1952 — 53), predicted the beta decay of charged pions (1954) and, together with S. S. Gershtein, the conservation of the vector current (1955). He pointed out the existence of new electromagnetic characteristics of particles which arise when parity is violated, and was the first (1958 — 60) to draw attention to the existence of a charge form factor of the neutrino and to the violation of the parity of atomic states through the weak interaction of an electron with the nucleus. In 1958 he proposed a method of detecting short-lived particles by measuring the distribution of the number of events over the effective mass of the decay products, which became one of the main methods in the search for and the study of resonances.
From the beginning of the 1960s Zeldovich's interests were concentrated mainly in the field of astrophysics and cosmology. He developed the theory of the structure of supermassive bodies with masses from hundreds of thousands to billions of solar masses, gave a complete qualitative picture of the last stages of the evolution of ordinary stars of various masses, and studied the properties of “black holes” and the processes which may help to discover their existence. He obtained fundamental results in the theory of the processes in the “hot” Universe: he constructed the theory of the interaction between the hot plasma of the expanding Universe and radiation, examined the processes by which the spectrum of the cosmic microwave background radiation is distorted and small-scale fluctuations in the intensity of the radiation arise, developed the theory of the growth of perturbations in the “hot” Universe, and studied the last stage of the formation of galaxies.
He founded a school of relativistic astrophysics. Three times Hero of Socialist Labour (1949, 1953, 1956), winner of the Lenin Prize (1957) and of four USSR State Prizes (1943, 1949, 1951, 1953). The I. V. Kurchatov Gold Medal (1977). A member of a number of foreign academies of sciences.