This is the simplest solution to the Einstein’s equations. It is a spherically symmetric vacuum solution. It describes the spacetime outside compact gravitating bodies.

The metric can be written as

Note: A metric with a timelikeKilling-Vector is stationary. If in addition there are no dtdx cross terms, the metric is static.

Birkhoff’s Theorem

Now, after solving Einstein’s equations, we obtain the Schwarzschild metric (with G=1)