born Oct. 9, 1873, Frankfurt am Main, Ger.
died May 11, 1916, Potsdam
German astronomer.
He published his first paper (on celestial orbits) at age 16. In 1901 he became professor and director of the observatory at the University of Göttingen. He gave the first exact solution of gravitation , which led to a description of how mass curves space. He also laid the foundation of the theory of black hole s, using the gravitational equations to show that a body of sufficient mass would have an escape velocity greater than the speed of light and therefore would not be directly observable, since even light rays from it could not escape into space. See also Schwarzschild radius .