General Relativity in Action

Abstract

We explore the famous solutions to the Einstein equation of gravity, using only elementary math and lots of figures. In particular, we show at which angle a light beam bends while passing at the sun. We will see that we really do not only need bending space, but bending space-time, because otherwise we would get only half of the observed angle. We show why the bending space-time forces orbits of the planets around the sun to turn slowly around the sun. We even calculate this so-called perihelion advance, using only elementary reasoning. We show that there can be black holes, and how large and heavy they are. We also apply the Einstein equation of gravity to the universe as a whole, and see why the universe had a big bang. Going to the other extreme, we will see why we do not know how to fit subatomic particles into bended space-time, or how subatomic particles influence bending space-time.