i know what 'dark matter' is (Score 1)

no one has figured out that massive bodies indent spacetime. imagine a planet rotating around it's sun and creating a nice indented ring in spacetime. It's curve trails the planent but eventually fades away - never creating a full ring. imagine a big sun, sort of indenting a large hole in spacetime that will exist after the sun dies. or the massive and deep pits left by black holes. affecting spacetime long after the black hole.