Stephen Hawking offers new resolution of black hole paradox

[Garth]

Would information be preserved through a 'Big Crunch' of a cyclical universe?

If so the entropy problem reappears.

Garth

 

[Ben Niehoff]

The conference participants have all sat down together to do a Reddit AMA. Might be entertaining to read:

https://www.reddit.com/r/IAmA/comments/3iuf6c/we_are_the_international_group_of_theoretical/

 

[marcus]

The conference participants have all sat down together to do a Reddit AMA. Might be entertaining to read:

https://www.reddit.com/r/IAmA/comments/3iuf6c/we_are_the_international_group_of_theoretical/

Great! Thanks for posting the link!
Here's a brief sample of discussion
https://www.reddit.com/r/IAmA/comments/3iuf6c/we_are_the_international_group_of_theoretical/cujq1qu
Francesca was active in Physicsforums for several years, and still occasionally drops in. She gave a talk at the the Stockholm conference and also participated in the Reddit later.
https://www.reddit.com/r/IAmA/comments/3iuf6c/we_are_the_international_group_of_theoretical/cujq8hr
Here's a very brief thread where both Carlo Rovelli and Malcolm Perry replied to a question about "super translations"
https://www.reddit.com/r/IAmA/comments/3iuf6c/we_are_the_international_group_of_theoretical/cujporr

==sample quote from Carlo and Malcolm==
CarloRovelli 12 points 2 days ago

Here is a zero-level version of what a "super translation" means. Take a big sphere and imagine many clocks on it, say all beating at the same time. Now make one of the cocks miss a bit. So now that particular clock is a bit later than all the others. Well, this change is (an elementary version of) a "super translation". It is a "translation" because it is like "translating in time". But it is a "super" translation because it does not translate all the clocks (like normal time translation would), but only some of them. Now it turns out out, or at least so suggest Malcolm and Stephen, that the "super translations" might code the information about how things fall in a black hole... but Malcolm can certainly explain this part better...

• permalink
• parent

MalcolmJPerryPHYSICIST 14 points 2 days ago

The original idea of a super translation relates to how to detect gravitational radiation. Imagine a collection of satellites orbiting the earth. As you look into the sky, these satellites will formake a fixed pattern. Now suppose that a burst of gravitational radiation passes through the system. The pattern the satellites makes will change. The mathematical description for this change is called a super translation. What is new is the discovery that can extend the idea of a super translation to the horizon of a black hole. Then the super translation will give information about what has fallen into a black hole. In this way, one can determine what goes to make up the black hole and hence resolve (or perhaps help to resolve) the black hole information paradox

• permalink
• parent

load more comments (4 replies)...
==endquote==

 

[marcus]

Would information be preserved through a 'Big Crunch' of a cyclical universe?

If so the entropy problem reappears.

Garth

I'm not sure that bounce cosmologies have an entropy problem, Garth, because entropy is observer-dependent. The observer's coarse grain map of what matters--what makes a difference and what doesn't. We depend on the fact that according to our coarse-graining map the entropy was very low at the bounce, or start of expansion.

But in a bounce cosmology, at the bounce itself there are no observers, so entropy is simply not definable. The observers are partitioned into two groups, those before and those after.

I don't speculate about "cyclic". That is a further topic of conversation. Just a simple one-bounce model cosmology as in the paper by Ed Wilson-Ewing and Yi-Fu Cai

 

[Ben Niehoff]

Here is Malcolm's talk, and I suspect Nordita has put up everyone else's talk as well:

 

[marcus]

Ben, I suspect Nordita will post the other talks as you suggest. At http://www.nordita.org/video/index.php
they have batches of talks from other events like this conference, and they have added an icon for this conference on that page.
So far when you click on it you get a menu with only 1 talk, Malcolm Perry's:
http://www.nordita.org/video/index.php?ev=hrad2015

But it is clearly set up to have videos of the other talks from the event added to the menu. We can check the menu later in the week and see what they have added to it.

 

[Ben Niehoff]

By the way, I'm impressed at the production value of Nordita's talk videos (at least Malcolm's above). Three different camera angles! I don't think most conferences do this. I only remember seeing one camera in the room at any conference I've attended.

 

[marcus]

Hawking now has a 3 page paper on arxiv covering his talk and giving references
http://arxiv.org/abs/1509.01147
The Information Paradox for Black Holes
S. W. Hawking
(Submitted on 3 Sep 2015)
I propose that the information loss paradox can be resolved by considering the supertranslation of the horizon caused by the ingoing particles. Information can be recovered in principle, but it is lost for all practical purposes.
3 pages. Talk given on 28 August 2015 at Hawking Radiation, a conference held at KTH Royal Institute of Technology, Stockholm

It's quite brief, the abstract (which you see here) plus 1 and 1/2 page of text, plus half a page of references.
I think basically just a verbatim transcript of the talk, which we have recorded on video. But it's nice to see specific references.

 

[0-fmg]

Inside a black hole there is gravity, matter and energy. The event horizon of a black hole is the limit between the black hole and the space. When the matter reaches the event horizon it turns into energy. E=mc2.

 

[anorlunda]

Hawking now has a 3 page paper on arxiv covering his talk and giving references
http://arxiv.org/abs/1509.01147
The Information Paradox for Black Holes
S. W. Hawking
(Submitted on 3 Sep 2015)
I propose that the information loss paradox can be resolved by considering the supertranslation of the horizon caused by the ingoing particles. Information can be recovered in principle, but it is lost for all practical purposes.
3 pages. Talk given on 28 August 2015 at Hawking Radiation, a conference held at KTH Royal Institute of Technology, Stockholm

It's quite brief, the abstract (which you see here) plus 1 and 1/2 page of text, plus half a page of references.
I think basically just a verbatim transcript of the talk, which we have recorded on video. But it's nice to see specific references.l

I read that paper, but I don't understand the premise. Hawking's approach is to analyze what happens when a particle falls in through the EH. But that does not address the information paradox with respect to mass trapped inside the BH as the star collapsed and which, therefore, never did pass through the EH.

My understanding of information conservation is that it is strict. Unless the paradox is resolved for every last particle, it remains a paradox.
Is that correct?