Black hole

[Sick]

What is happening in a black hole?

[JohnThorn]

It's not actually a hole. It's a part of space where the density and quantity of matter is so great that light cannot escape its gravity - so it looks black. Once you pass the edge, there is no return...

[danmiller103]

Black holes are regions of space-time where the effect of gravity is so strong that light cannot escape. For theorists and scientists black holes provide natural test cases in which to try to explore the consequences of fitting Einstein's general theory of relativity together with the principles of quantum mechanics. Stephen Hawking showed that quantum effects can allow black holes to radiate, so that they are not entirely black. Hopefully that helps a bit. Dan

[gazzawazza]

This is very simplified but it may help you understand. The larger a planet is, the greater the gravitational pull. Think of the moon, smaller than earth so astronauts need heavy boots to hold them down and counter the effects of weightlessness. Now the way I understand it is that the larger they are, the more matter they attract to themselves, therefore allowing themselves to "grow." If they keep growing then their gravitational pull will increase, attracting more matter and so on, until they get to the point where the gravitational pull is so strong they actually collapse in on themselves. Now where the matter goes I don't know but as has already been mentioned the pull is so strong that even light can't escape making the hole appear black.