Hawking's bet and ADS theory

  • #1
Heidi
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I read that he admitter having lost his bet with Preskill when he discovered the ADS/CFT equivalence.
I can understand that because CFT is a quantum theory in which evolution is unitary (but there is the problem of measurements). so the black holes can be described with unitary tools.
On another forum somebody tells me that ADS theory is also a quantum theory.
Was it a quantum theory at that moment? in that case ADS was like CFT for unitarity.
 

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  • #2
atyy
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AdS is a classical theory of gravity, and refers to asymptotically AdS spacetimes of Einstein's general relativity.
The AdS/CFT correspondence remains a conjecture, though one that has extremely strong support.
The CFT is a quantum theory, and is thought to be equivalent to a string theory, which is also a quantum theory.
At low energies, the string theory is well described by classical AdS gravity.
 
  • #3
Heidi
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So what was the principal argrument that conviced Hawking?
it seems that it was the equivalent argument. but if gereral relativity (with black holes) was well described at low energy by the quantum symmetry he had the unitarity element in mind. this do not neek the equivalence.
Is it the T duality argument in the equivalence?
Does low energy prevents having black holes?
 
  • #4
Demystifier
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On another forum somebody tells me that ADS theory is also a quantum theory.
Was it a quantum theory at that moment? in that case ADS was like CFT for unitarity.
In this context, AdS refers to string theory on AdS background. String theory is a quantum theory, and it always was.
 
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  • #6
Demystifier
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The AdS/CFT correspondence remains a conjecture, though one that has extremely strong support.
Well, "extremely" may not be the best word. In my opinion, the main problem is the bulk reconstruction problem, namely how to reconstruct the bulk theory from the boundary theory, for which the existing results are not so "extremely" convincing.
 
  • #7
Heidi
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@Demystifier
If it not the T duality which convinced Hawking what was it?
(string theory on Ads space is a quantum theory)
 
  • #8
Demystifier
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If it not the T duality which convinced Hawking what was it?
(string theory on Ads space is a quantum theory)
AdS/CFT duality is what convinced him, but this answer will probably not satisfy you because this duality is just a conjecture. Perhaps you really want to ask why Hawking was convinced that AdS/CFT duality is true. I don't know. Many string theorists are convinced that AdS/CFT duality is true, but Hawking was not exactly a string theorist.
 
  • #9
Heidi
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I would like to understant why this correspondance between two quantum theories with unitary evolution convinced him that black holes may be described with a unitary evolution
He had them before separately. what does this add for him ?
 
  • #10
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I would like to understant why this correspondance between two quantum theories with unitary evolution convinced him that black holes may be described with a unitary evolution
He had them before separately. what does this add for him ?
Here is the logic. The CFT theory is something that is well understood and clearly unitary. Quantum gravity, on the other hand, is something that we don't understand well. Not even Hawking thought that he understands quantum gravity well. Since we don't understand quantum gravity, we cannot tell with certainty whether it is unitary or not. So quantum gravity could be a non-unitary theory, in which case the evolution of black holes could be non-unitary. But AdS/CFT correspondence claims that quantum gravity on AdS background is equivalent to CFT. If that claim is true (which we don't know with certainty), then it implies that black holes on AdS background are in fact unitary. If so, then it seems reasonable to believe that black holes on different backgrounds (not only on the AdS background) are also unitary, even if other backgrounds are even less well understood.
 
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  • #11
Prishon
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So Hawking was wrong. Information isn,t destroyed. Information gets entangled on the boundary of a hole with Hawking radiation. The exactly same matter as seen from an infalling view gets entangled too. The i falling takes a small time while we on the outside see the same matter fall forever (to get frozen on the boundary).
 

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