by Chris Peterson » Tue Apr 06, 2010 2:48 pm
mark swain wrote:Professor Stephan hawking, has argued for thirty years that matter inside a black hole just disappears?
That's not quite what he has argued. AFAIK, pretty much everybody agrees that when matter crosses into a black hole, it "disappears" in the sense that it is not recoverable. It doesn't
really disappear, since some of its fundamental properties- mass, magnetic field, electrical field, angular momentum- are conserved in the black hole's properties.
Why did he change his mind?
He didn't change his mind about mass "disappearing". The issue is about what happens to the full quantum state description of matter that crosses into a black hole. QM argues that this state must be conserved, but simple black hole models don't allow for any mechanism to ever recover this information. Hawking originally stated that the information isn't conserved, but changed his mind about that.
In reality, calling this a "paradox" is a little inaccurate. The fact is, we have no well developed theory about what happens to material inside a black hole, so while the information problem is an interesting one, it doesn't rise to the level of "paradox".
[quote="mark swain"]Professor Stephan hawking, has argued for thirty years that matter inside a black hole just disappears?[/quote]
That's not quite what he has argued. AFAIK, pretty much everybody agrees that when matter crosses into a black hole, it "disappears" in the sense that it is not recoverable. It doesn't [i]really[/i] disappear, since some of its fundamental properties- mass, magnetic field, electrical field, angular momentum- are conserved in the black hole's properties.
[quote]Why did he change his mind?[/quote]
He didn't change his mind about mass "disappearing". The issue is about what happens to the full quantum state description of matter that crosses into a black hole. QM argues that this state must be conserved, but simple black hole models don't allow for any mechanism to ever recover this information. Hawking originally stated that the information isn't conserved, but changed his mind about that.
In reality, calling this a "paradox" is a little inaccurate. The fact is, we have no well developed theory about what happens to material inside a black hole, so while the information problem is an interesting one, it doesn't rise to the level of "paradox".