# Schwarzschild black hole

A solution of Einstein's equations found by Karl Schwarzschild in 1916, which corresponds to a model universe that contains a single, spherically symmetric black hole.

More precisely, the Schwarzschild solution is a whole *family*
of solutions: Schwarzschild's formulae contain a free parameter m
corresponding to the mass of the black hole. To each concrete value of
m corresponds one specific solution to Einstein's equations, a
space-time containing a spherically symmetric black hole of mass m.

The Schwarzschild solution is of practical importance as the outlying regions of the corresponding model universe describe the space-time distortion around all kinds of objects that are spherically symmetric, or nearly so, such as the sun or the earth (cf. Birkhoff's theorem).

### Variants

- Schwarzschild solution