Karl Schwarzschild (9.10.1873 - 11.05.1916) was a German astronomer and physicist and a member of the Berlin Academy of Sciences (1912). He was born in Frankfurt am Main. He graduated from the University of Munich. In 1901 —09 he was professor at the University of Göttingen and director of the observatory attached to it, in 1909—12 director of the Potsdam Astrophysical Observatory, and from 1912 professor at the University of Berlin.
He laid the foundations of the theory of stellar atmospheres and of the internal structure of stars, and of exact photographic photometry; he developed (1906) the theory of radiative equilibrium of stellar atmospheres and gave (1910—12) the general equations of stellar statistics.
His research in physics was in the field of general relativity, the theory of gravitation, quantum theory, geometrical optics and electrodynamics. He found (1916) the exact solution of Einstein's equation for a static centrally symmetric gravitational field. He predicted gravitational collapse and gave the formula for the gravitational radius (the Schwarzschild radius). Independently of P. Epstein, he developed (1916) the quantum theory of the Stark effect.