“When you open your mind to the impossible, sometimes you find the truth.” -Dr. Bishop
In the general theory of relativity, black holes are blobs of space where gravity is so intense not even light can escape its pull. To learn more about these strange phenomenons of physics, see Wikipedia articles on black holes, wormholes, the event horizon.
Carl Sagan on Black Holes and the Bending of Light
Black Hole Simulations
Swallowing a Sun
The Largest Black Holes in the Universe