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Hawking IMO is one of the most readable of the great Physicists. As a summer assignment for our 11 year old we had him read most of "A Theory of Everything" and answer some basic questions about each chapter.
I especially enjoyed reading some of his theories applying Quantum Mechanics (specifically Uncertainty) to explain how information could escape black holes (empirical measurements have been taken that are consistant with the existance of this phenemona).
To put together some of the info here that seemed a bit disjointed:
X-rays are emitted by matter spiralling into a black hole... this energy is emitted BEFORE the matter crosses the event horizon, because if it was emitted after... it wouldn't escape either.
A Neutron Star is a star that was massive enough to go supernova but not massive enough to collapse into a black hole. It does collapse under it's own gravity, but that gravity is only strong enough to force the electrons and protons to form into neutrons. The term "singularity" does not apply to Neutron Stars since they have size (they don't reduce to a single point in space)
White Dwarfs are formed by stars too small to go supernova (like our sun)
One cool theory - for supermassive black holes it's entirely possible that a person crossing the event horizon wouldn't even know it. The event horizon for these beasts is a LONG way away from the singularity, and the gravitational gradiant at that point would be fairly low.
[ 11-25-2002, 02:05 PM: Message edited by: Thoran ]
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