Einstein's Theory of General Relativity

Important thing to remember #1 - GR is a theory of gravity.

The basic idea is that instead of postulating a mysterious, invisible force between masses, GR says that

In this picture, the reason the planets orbit the Sun is not because of a central force, but rather because the planets are tracing out straight lines in curved space.

Michael Bolte
Mon Mar 9 11:01:38 PST 1998