Dark Energy, Dark Matter and Anti-Gravity

The universe is full of matter and the attractive force of gravity pulls all matter together.

The expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. Maybe it was a result of a long-discarded version of Einstein's theory of gravity, one that contained what was called a "cosmological constant." Maybe there was some strange kind of energy-fluid that filled space. Maybe there is something wrong with Einstein's theory of gravity and a ne...