Starship Asterisk*

Information paradox

Easy, something comes from nothing, it should go back to nothing. Where is, the ''universe's'' nothing?


Professor Stephan hawking, has argued for thirty years that matter inside a black hole just disappears?

Why did he change his mind?

http://www.youtube.com/watch?v=pF63fxXMKTM

http://en.wikipedia.org/wiki/Black_hole ... on_paradox

Mind blowing.

Mark

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".

Chris Peterson wrote: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".

Oh, right. When I watched the horizon program, the thing that through me was the part where the top scientists on black holes, said " when you fall into a black hole, you would not experience anything substantially like what the person watching you fall in would describe". I can not imagine what it would be like, to be dead and alive at the same time.

Chris Peterson wrote:

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.

Did you watch the horizon program I posted?

Chris Peterson wrote:

mark swain wrote: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.

So I guess he changed his mind then. Bit of a big jump huh. Isn't the conservation of information one of the fundamental rules?

Mark

mark swain wrote:Oh, right. When I watched the horizon program, the thing that through me was the part where the top scientists on black holes, said " when you fall into a black hole, you would not experience anything substantially like what the person watching you fall in would describe". I can not imagine what it would be like, to be dead and alive at the same time.

Well, it isn't at the same time. It's just that the flow of time as you perceive it while falling into the black hole is different from the flow of time as seen by an outside observer. It's similar to the different time flows experienced by observers traveling at different velocities with respect to each other. This is well supported by experiment, but that doesn't necessarily make it easier to grasp intuitively.

So I guess he changed his mind then. Bit of a big jump huh. Isn't the conservation of information one of the fundamental rules?

What's "fundamental"? It isn't as well supported as conservation of energy. But it seems to be an important property predicted by QM, which is why, I think, Hawking finally changed his mind about the matter.

Chris Peterson wrote:

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".

Why it turns into a white hole and creates a new universe of course.... . Black holes are recycling centres, taking mass and creating new universes with it via wormholes.

Paul

wonderboy wrote:Why it turns into a white hole and creates a new universe of course.... :P. Black holes are recycling centres, taking mass and creating new universes with it via wormholes.

I believe I'll reserve judgment on that idea, for the time being.

Chris Peterson wrote:

wonderboy wrote:Why it turns into a white hole and creates a new universe of course.... . Black holes are recycling centres, taking mass and creating new universes with it via wormholes.

I believe I'll reserve judgment on that idea, for the time being.

Ahh, so you are not discounting it out of hand, hmm.

Need a chin scratching icon

bystander wrote:Ahh, so you are not discounting it out of hand, hmm.

I only discount ideas once they are proven wrong. The whole issue of white holes I consider nearly non-scientific, because it is so speculative, and nobody has developed anything that comes close to rising to the level of testable theory. This is just playing around with math; it isn't really physics.

I think green holes inhabited by unicorns are about as likely, but I don't know they don't exist, either <g>.

green holes ... they would be the ones at the other end of the red holes ...