How Mass Creates Gravity

Abstract

How does mass bend space-time? That is to say: how does mass create gravity? The answer is the famous Einstein equation of gravity. We explain it in plain language. This is possible, because nature has chosen the law of gravity to be as simple as possible. We will see that gravity basically tends to shrink volumes. We explain in detail exactly how this fits in with the theory of special relativity. However, mass does not only create gravity, via the Einstein equation of gravity: at the same time the same mass also reacts to gravity, via the equivalence principle. We will see that both laws of nature fit neatly together. This explanation reveals that this theory of general relativity is the simplest theory of gravity we could imagine.