Was Stephen Hawking wrong?

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wolram
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Kea
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Was Hawking wrong?
Wolram, I believe that Hawking conceded defeat on this point (information conservation) some time ago.
 
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marcus
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http://www.sciencedaily.com/releases/2007/02/070227105134.htm

Was Hawking wrong?

This is only part of the article.
Indeed Wolram, I expect he was wrong in some part of his reasoning (in July 2004 when he conceded the famous bet). His talk about BH information paradox at Dublin was not very convincing according to those reporting from the conference. It is OK for famous people to be wrong sometimes.

Here is the article:
http://arxiv.org/abs/gr-qc/0603046
Quantum information cannot be completely hidden in correlations: implications for the black-hole information paradox
Samuel L. Braunstein, Arun K. Pati
Comments: We first obtained this result two years ago

"The black-hole information paradox has fueled a fascinating effort to reconcile the predictions of general relativity and those of quantum mechanics. Gravitational considerations teach us that black holes must trap everything that falls into them. Quantum mechanically the mass of a black hole leaks away as featureless (Hawking) radiation, but if the black hole vanishes, where is the information about the matter that made it? We treat the states of the in-fallen matter quantum mechanically and show that the black-hole information paradox becomes more severe. Our formulation of the paradox rules out one of the most conservative resolutions: that the state of the in-falling matter might be hidden in correlations between semi-classical Hawking radiation and the internal states of the black hole. As a consequence, either unitarity or Hawking's semi-classical predictions must break down. Any resolution of the black-hole information crisis must elucidate one of these possibilities."

Now according to the Uni York press release they have gotten it published in the latest issue of Physical Review Letters. a good publication.

This is not the only paper that has appeared in the past two years indicating that Hawking 2004 attempted resolution of BH info puzzle is wrong.

There was one by Steve Hsu (U. oregon)
there was one by Gambini and Pullin.
I can't remember the others but my impression is a bunch. One by Modesto at U. Bologna, but he is young and hasnt made his reputation yet.

I wouldn't minimize the importance of any of this work. My feeling is Hawking was pretty certainly wrong but WHY hasnt been determined. There are different ways he could be wrong and these different papers are offering different resolutions to the BH info puzzle---which we don't know is the right one.

This is a good find! Thanks Wolram! Post a link if more shows up please.
 
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marcus
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Wolram, I believe that Hawking conceded defeat on this point (information conservation) some time ago.
I think you may be talking about something else, Kea.

He conceded defeat at the GR 17 conference July 2004 in Dublin and talked about giving a baseball encyclopedia.

It is WHAT HE SAID AT DUBLIN that people suspect was wrong.

Various people expressed skepticism at Dublin and the general consensus was to wait until the paper came out. But nothing convincing or new was forthcoming. What he put on archive after several months was roughly same as what he said at Dublin.

Various paper have come out since then implying that the position Hawking took at Dublin was wrong.

He has not yet conceded that what he said July 2004 is wrong. Probably he wont. he is old enough and out of touch enough that the real discussion probably has to go on elsewhere.

I liked what Steve Hsu said. he's world class. It is on arxiv.
 
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marcus
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Steve Hsu has a great blog called Information Processing it is one of my most favorite blogs.
http://infoproc.blogspot.com/

Here is his article about BH info

http://arxiv.org/abs/hep-th/0608175
Spacetime topology change and black hole information
Stephen D.H. Hsu
Comments: 5 pages, 5 figures, published version, to appear in Physics Letters B
Phys.Lett. B644 (2007) 67-71

"Topology change -- the creation of a disconnected baby universe -- due to black hole collapse may resolve the information loss paradox. Evolution from an early time Cauchy surface to a final surface which includes a slice of the disconnected region can be unitary and consistent with conventional quantum mechanics. We discuss the issue of cluster decomposition, showing that any violations thereof are likely to be unobservably small. Topology change is similar to the black hole remnant scenario and only requires assumptions about the behavior of quantum gravity in planckian regimes. It does not require non-locality or any modification of low-energy physics."

His paper was published in Physics Letters this year, and he is the invited speaker about this topic at the Barbados workshop workshop on black holes and quantum information that is now going on.
Here is the program of the Barbados workshop, I'm expect you may recognize some of the other people

Talk titles:
Charlie Bennett: Privacy, Publicity, and Permanence of Information
(Alternate title: Jimmy Hoffa and Sappho's poems)
Don Page: Black hole information (and thermodynamics)
Frédéric Dupuis: Introduction to quantum information theory
Stephen Hsu: Information processing bounds from gravitational collapse
Patrick Hayden: An information theorist's thoughts on black hole evaporation
Paul Alsing: Teleportation in a Non-inertial frame
Possible bonus talk: The Unruh effect in Ion Traps
Debbie Leung: Locking information using quantum mechanics
John Smolin: Information locking in black holes
Ivan Savov: Trapping information in multiple black holes
Jonathan Oppenheim: TBA
 
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wolram
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Wolram, I believe that Hawking conceded defeat on this point (information conservation) some time ago.

Sorry Kea, i am not as well informed as i should be, i just find some things seem wrong to me and try and find info to back it up, i also like history:smile:
 
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marcus
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In case anyone else wants to follow this, it's pretty interesting, here is what Pati and Braunstein say near the end


We now expose the severity of the black-hole information crisis in one specific formulation of the paradox [20].

Suppose one feeds a black hole (with externally entangled states) at the Hawking-emission rate for an arbitrarily long time. Then, Hawking’s semi-classical analysis would predict that such a black hole, of a fixed size, could contain an unbounded amount of entropy, associated with the states of the in-fallen matter.

This unbounded information density is itself tantamount to a loss of unitarity (at least in our universe) [21].


The "at least in our universe" is the escape hatch which Steve Hsu opted for. It appears increasingly likely that the only way to save unitarity is to admit the possibility that time-evolution continues thru the BH pit to form a new fork of the road---a new patch of spacetime.
 
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marcus
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Here are Steve Hsu's conclusions at the end of his recent Physics Letters B paper:

CONCLUSIONS
We discussed a solution of the black hole information paradox which depends entirely on details of Planckian physics – no modifications of low-energy physics, such as non-locality, are required.

The main assumptions are that the interior evolution of large black holes produces topology change, and that the quantum gravitational dynamics of pinching off are strongly coupled. Thus, small perturbations to the ini-
tial state of a black hole lead to different internal state vectors describing the resulting baby universe, even if the semiclassical properties are only slightly changed...
If this scenario is correct, there is no violation of causality or locality at the semiclassical black hole horizon, and no stable Planck mass remnant of black hole evaporation.

Instead, much as Hawking first proposed, information is lost: to a baby universe, from which it may or may not someday emerge via tunneling. If the information emerges again, evolution within the parent universe is
unitary.

If information remains in the baby universe, the parent universe appears to evolve from a pure to mixed state, but the evolution of parent and baby together is unitary. There are no dire consequences, such as energy non-conservation.

ACKNOWLEDGEMENTS
The author thanks T. Jacobson, B. Murray, J. Preskill and A. Strominger for useful comments, and S. Giddings in particular for clarification of the third quantization approach. T. Jacobson provided a number of useful references to earlier work....


If you have been following this on the non-string QG side you can guess as to some of the "useful references to earlier work."
 
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  • #9
jal
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wikipedia has some info http://en.wikipedia.org/wiki/Black_hole_thermodynamics
Classical thermodynamics states as its second principle that entropy is an always increasing function in a closed system—and the universe is an assumed closed system.
Steve Hsu's conclusions
If information remains in the baby universe, the parent universe appears to evolve from a pure to mixed state, but the evolution of parent and baby together is unitary. There are no dire consequences, such as energy non-conservation.
!!!! A NEW DEFINITION OF THE CLOSED SYSTEM (UNIVERSE) !!!!
JAL
 
  • #10
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If the babies have babies and so on to whatever counts as infinity, then isn't the system of however many local universes still open? The idea of a closed universe seems to me to be lost among so many potential babies. Then a black hole is where a universe opens to the inside.

R
 

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