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General relativity is the cornerstone of cosmology and astrophysics. It has also provided the conceptual basis for string theory and other attempts to unify all the forces of nature in terms of geometrical structures.

Einstein explained his theory to me every day, and on my arrival I was fully convinced that he understood it.

When general relativity was first put forward in 1915, the math was very unfamiliar to most physicists. Now we teach general relativity to advanced high school students.

The real reason why general relativity is widely accepted is because it made predictions that were borne out by experimental observations.

Einstein wrestled with a problem back before we even knew the universe was expanding, and he was looking for a way to keep the universe from collapsing. And so he discovered, in his theory of gravity, something like this dark energy - he called it a cosmological constant - could play this role, pushing things away.

Our best theory of describing space at a fundamental level is probably string theory.

Gravitation is, so far, not understandable in terms of other phenomena.