Schwarzschild, Karl
(from Encyclopedia Brittanica on-line)
(b. Oct. 9, 1873, Frankfurt am Main, Ger.--d. May 11, 1916,
Potsdam), German astronomer whose contributions, both practical and
theoretical, were of primary importance in the development of
20th-century astronomy.
Schwarzschild's exceptional ability in science became evident at the age
of 16, when his paper on the theory of celestial orbits was published. In
1901 he became professor and director of the observatory at the
University of Göttingen, and eight years later he was appointed director
of the Astrophysical Observatory at Potsdam.
While at Göttingen, Schwarzschild introduced precise methods in
photographic photometry. The results of his studies clearly demonstrated
the relationship between the spectral type and colour of a star. He
pioneered in the use of a coarse grating (for example, a glass plate with
closely spaced parallel lines etched into it) in the course of measurement
of the separation of double stars; the technique has found widespread use
in determining stellar magnitude and colour. He also developed certain
basic methods for the analysis of solar spectra obtained during eclipses.
Schwarzschild enunciated the principle of radiative equilibrium and was
the first to recognize clearly the role of radiative processes in the
transport of heat in stellar atmospheres. His hypothesis of stellar motion is
one of the most important results to come out of his fundamental work in
modern statistical methods in astronomy. He also made theoretical
studies of the pressure exerted on small, solid particles by radiation.
Schwarzschild made fundamental contributions to theoretical physics
and to relativity. He was one of the great pioneers in developing the
theory of atomic spectra proposed by Niels Bohr. Independently of
Arnold Sommerfeld, Schwarzschild developed the general rules of
quantization, gave the complete theory of the Stark effect (the effect of an
electric field on light), and initiated the quantum theory of molecular
spectra.
Schwarzschild gave the first exact solution of Albert Einstein's general
gravitational equations, which led to a description of the geometry of
space in the neighbourhood of a mass point. He also laid the foundation
of the theory of black holes by using the general equations to
demonstrate that bodies of sufficient mass would have an escape velocity
exceeding the speed of light and, therefore, would not be directly
observable.
While serving in the imperial German army during World War I,
Schwarzschild contracted a fatal illness.