# Dictionary

## 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 spacetime 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 spacetime distortion around all kinds of objects that are spherically symmetric, or nearly so, such as the sun or the earth (cf. Birkhoff’s theorem).