Paul Ewald (born 23.01.1888) - German physicist. Born in Berlin. He studied at the universities of Cambridge, Göttingen and Munich. In 1921—37 he was professor at the Polytechnic School in Stuttgart, in 1937 — 39 he worked at the University of Cambridge, in 1939 — 49 at the Queen's University in Belfast, and in 1949 — 59 he was professor at the Brooklyn Polytechnic Institute.
His main research was in the physics of crystals and X-rays. In 1912 he constructed the theory of the polarisation of dielectric crystals, and in 1916 the dynamical theory of the interference of X-rays. He proposed (1921) a method of calculating the Madelung constant (the Ewald method).
A member of a number of academies of sciences and scientific societies. In 1960—63 he was president of the International Union of Crystallography. The M. Planck Medal (1978).