new Hawking paper out today, online

[Martin]

http://arxiv.org/hep-th/0507171

 

Information Loss in Black Holes

S. W. Hawking

"The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with non-trivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence."

 

Basically it's the talk he gave approx. one year ago in Dublin, that got covered in the media

[Martin]

In case any one's interested here is the text of hawking's talk one year ago in Dublin at the GR17 conference (the 17th international conf. on Gen Rel)

a NY Times reporter transcribed it and it got on the web:

http://pancake.uchicago.edu/%7Ecarroll/hawkingdublin.txt

 

John Baez is known to more than one of us at SFN as a real good reporter and explainer. his website at UC Riverside is a storehouse of FAQ and explanations etc. likewise his This Week's Finds in Mathematical Physics.

Baez was at the GR17 conference and talks about it and the response to hawking's talk

http://math.ucr.edu/home/baez/week207.html

[eon_rider]

John Baez is known to more than one of us at SFN as a real good reporter and explainer.

 

after he (J.B.) explained it for the lay person I understood it better.

 

Very cool paper. Thanks for the link.

[LCD]

that was for the lay person? gosh!

[Martin]

that[/b'] was for the lay person? gosh!

 

yeah, I know

 

thanks to you both for responding, glad someone checked it out

 

I'm a fan of John Baez and would invite anyone to explore his website

but what Hawking has to say about BH information loss paradox must be basically rather obscure. I still dont feel I understand it, maybe a little better now after reading his paper and looking back at what Baez said, but I'm still frustrated and remain in doubt. Maybe this business of information loss in BH is actually not settled yet and Hawking paper is just a step along the way towards getting it resolved.

[[Tycho?]]

http://arxiv.org/hep-th/0507171

 

Information Loss in Black Holes

S. W. Hawking

"The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand' date=' the path integral over metrics with non-trivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence."

 

Basically it's the talk he gave approx. one year ago in Dublin, that got covered in the media[/quote']

 

That bit remindes me of just how little I know about this sort of thing, every third word was something I didn't understand.

[Martin]

'']That bit remindes me of just how little I know about this sort of thing, every third word was something I didn't understand.

 

probably in this case you are in the same boat with people who think they ought to understand H. reasoning but are still in doubt. I dont know if Kip thorne is still holding out, now that H. has conceded the bet. If I were he I'd consider it still unsettled yet and refuse to concede

[Bettina]

The book that is mentioned: "Road to Reality". How "heavy" is it. Could a normal person understand it or would I be wasting my money. Amazon doesn't have it so you can view some pages.

 

And....could you tell be what some good books about the universe are? Something understandable.

 

Geez...no baby universes either

 

Bettina

[Bluenoise]

Well I can understand it or parts of it. Physics really isn't my thing too. I'm a biochemist. He writes it in a way where he points out which parts are easy and which are mindbreakers. He actually uses emoticons to do it. It's kinda funny. I think anyone can get something from it. Even if you just read his history lessons and stories. But a in-depth understanding would take alot of reading. The first 16 chapters kinda cover the math you need for the rest of the book. Good investment I think.

[garyr10000]

I wonder if "trivial topology" of the behavior of information in a black hole is reflective of reality. Asymptotic solutions describe conditions that "exist" inside a black hole. If that is true, we'll never know.

Gary

[Martin]

The book that is mentioned: "Road to Reality". How "heavy" is it. Could a normal person understand it or would I be wasting my money. Amazon doesn't have it so you can view some pages.

 

And....could you tell be what some good books about the universe are? Something understandable.

 

Geez...no baby universes either

 

Bettina

 

Bettina, you ask could a normal person understand Penrose latest book, "Road to Reality". It is a very good book but I think it is for someone who is motivated to learn ON THEIR OWN much of what should be in a college math/physics major. Or for someone who already did a math major and then went into business or statistics and is bored and wished they had studied theoretic physics but they already have a career and family etc.

 

Well what can I say, there really are no normal people. The book is amazingly well written with all kinds of intuitive explanations and examples to make the reader say "Ahah!" And it really can help a wellprepared highly motivated person learn ON THEIR OWN much of what they might have learned in college and even some graduate study.

 

But I think that this book is NOT really for general audience, so in spite of what the reviews and blurbs say i dont think it is for what you might call "normal people".

 

I think you should tell your local public librarian to order it, every public library should have a copy. it is a wonderful book, can even work as a reference for looking up stuff. and it was a best seller. it was in the top 10 of amazon.uk for several weeks and in the top 50 for a few months (in the UK). But I would advise you to read the library copy. not to buy it.

 

(unless maybe if you are planning to be a math major in college or something)

[Martin]

I wonder if "trivial topology" of the behavior of information in a black hole is reflective of reality. Asymptotic solutions describe conditions that "exist" inside a black hole. If that is true' date=' we'll never know.

Gary[/quote']

 

Gary, do you know how to use the arXiv.org library, with its search engine?

In the quantum gravity field (where hawking's "euclidean path integral" or "euclidean QG" is respected as a historical antecedent but has become marginal) Black Hole has become a hot topic with a bunch of recent papers in the past 2 years

 

(it always was a famous subject since circa 1975 with bekenstein and hawking early results: temperature, entropy, radiation, evaporation but i am talking about a fresh spate of work just recently)

 

Some of the authors who have written BH papers from QG perspectives lately

 

Ashtekar

Bojowald

Modesto

Parampreet Singh

Goswami

Viqar Hussain (not sure of spelling)

Renate Loll

Bianca Dittrich

 

all their papers are available free online in the electronic preprint library

and, yes, they are all incomprehensible sorry about that. But hey, so is Hawking and his approach is old and his result in this paper here I do not think will stand. I think quantum models of black holes WILL be constructed and that they WILL get rid of the singularity and replace it by a quantum regime and the evaporation process, if it occurs will be better understood and modeled and that the models WILL MAKE PREDICTIONS AND WILL BE TESTED somehow. But I cannot foresee how. Research is very hard to predict because it is a core creative activity. if you could foresee it then it would already have been done

But even though I cannot predict how this will happen, i am pretty sure that a better quantum gravity understanding of BH is in the works and there will be more detailed models of the insides and they will be testable (somehow)

 

So hawking is sitting off at infinity saying that what dominates is the case where the BH did not even form! (codeword trivial topology) and by a sophistical reasoning talking about double slit experiment saying you cant tell, at infinity, whether it did form or not, and look all the information came thru ( because the case that dominates is where the BH didnt even happen). and then he makes some charming jokes. but no I do not think he scratched the surface of what people will eventually get to know about this

[Martin]

Gary, here are bojowald's papers

http://arxiv.org/find/grp_physics/1/au:+bojowald/0/1/0/all/0/1'>http://arxiv.org/find/grp_physics/1/au:+bojowald/0/1/0/all/0/1

 

they are all free and online

he is a young guy at a place near Berlin, who I think knows more about black holes than anybody else now (from a QG perspective)

 

Look at the titles of his most recent 5 or 6 papers:

 

1. gr-qc/0506128 [abs, ps, pdf, other] :

 

Title: Nonsingular Black Holes and Degrees of Freedom in Quantum Gravity

Authors: Martin Bojowald

Comments: 4 pages

 

2. gr-qc/0505057 [abs, ps, pdf, other] :

 

Title: Elements of Loop Quantum Cosmology

Authors: Martin Bojowald

Comments: 30 pages, 4 figures, Chapter contributed to "100 Years of Relativity - Space-time Structure: Einstein and Beyond", Ed. A. Ashtekar (World Scientific)

 

3. gr-qc/0504100 [abs, ps, pdf, other] :

 

Title: Asymptotic Properties of Difference Equations for Isotropic Loop Quantum Cosmology

Authors: Martin Bojowald, Adam Rej

Comments: 27 pages, 2 figures

Subj-class: General Relativity and Quantum Cosmology; Mathematical Physics

 

4. gr-qc/0504029 [abs, ps, pdf, other] :

 

Title: Black hole evaporation: A paradigm

Authors: Abhay Ashtekar, Martin Bojowald

Comments: 21 pages, 4 figures, v2: new references and discussion of relation to other ideas

 

5. gr-qc/0503041 [abs, ps, pdf, other] :

 

Title: A black hole mass threshold from non-singular quantum gravitational collapse

Authors: Martin Bojowald, Rituparno Goswami, Roy Maartens, Parampreet Singh

Comments: Minor changes to match published version in Physical Review Letters

 

6. gr-qc/0503020 [abs, ps, pdf, other] :

 

Title: The Early Universe in Loop Quantum Cosmology

Authors: Martin Bojowald

Comments: 10 pages, 3 figures, plenary talk at VI Mexican School on Gravitation and Mathematical Physics, Nov 21-27, 2004

 

Bojowald only recently got into studying BH, before that, since about 2001, he has been studying the big bang (again from a quantum gravity perspective)

 

===================

however for a QG take on BH that is different from Bojowald, see the recent paper by Renate Loll and Bianca Dittrich.

 

they are just getting started but they may have eventually even more to say than Bojowald. here is there paper, which will drive anyone crazy however maybe you can get something out of the introduction paragraph

 

http://arxiv.org/abs/gr-qc/0506035'>http://arxiv.org/abs/gr-qc/0506035

 

remember when you take a preprint number like

gr-qc/0506035

 

to turn it into a link you must put this in front

http://arxiv.org/

 

I cant recommend reading any of this, it is all too hard

 

but you might check it out to kind of practice getting to know where the information is

[Martin]

WOW just came across this

http://arxiv.org/abs/gr-qc/0506129

 

I'd forgotten this just came out. This is an incredible paper about

naked singularities. It says when one is trying to form it can explode instead and cause GAMMA RAY BURSTS.

 

so sometimes gravitational collapse will a BH, but, according to these people, there are circumstances where something else can happen!

 

Well this is off topic from Steven Hawking, but just wanted to say that a lot is going on in QG now concerning gravitational collapse, so dont let whatever Hawking says preoccupy you so that you miss getting a look at the larger research picture.

[garyr10000]

Wish I knew more (than I can ever know). Does the "leakiness" of black holes occur because space (and gravity) are not a seamless continuum, being grainy (quantum) at the fundemental level?

GRR

[garyr10000]

I'm just getting back into it. Is a black hole theorized as having 0 diameter?

GRR

[Martin]

I'm just getting back into it. Is a black hole theorized as having 0 diameter?

GRR

 

Gary you should probably start a thread asking for links to where you can learn black hole basics. Or asking people to explain basic stuff about BH.

 

I realize i have been wandering off topic too, but this thread topic is basically about the confusing recent paper of hawking, which is very sketchy and may not be right. It is not about black hole basics but about this odd question of what happens to our ability to reconstruct the past from the present if something falls into a hole and then evaporates.

 

take my advice and dont worry about this question and about hawking paper, for now, just learn BH basics.

 

Andy Hamilton at Univ. Colorado has a website about BH including animations of what you see as you approach and fall in. Great site.

John Baez probably has stuff. Get people to recommend links to you.

[Martin]

Gary, see what you can find in the way of BH links in this thread:

 

http://www.scienceforums.net/forums/showthread.php?t=4133

 

there was a SFN poster named Alexa with a very attractive avatar, you will see what i mean when you go there. For a while she organized a library of links related to astronomy and cosmology. this was in a sticky thread that someone named Radical Edward established so the links would not get lost so easily.

 

If you find some especially good BH links, we can add them to that thread

 

Yes, here is one of Alexa's posts

http://www.scienceforums.net/forums/showthread.php?t=4133&page=3&pp=20

 

and if you scroll down from there you get to post #46 which is this

http://www.scienceforums.net/forums/showpost.php?p=87859&postcount=46

 

I think there is some links about BH there, but maybe there should be more, or different ones. see about finding some we can add to the thread.

-----------------------------------

 

EDITED IN LATER: GARY, I WENT AHEAD AND STARTED A "black hole links" thread. maybe digging around in it will help answer your questions. hope other people add some more sources to it

It's in Astronomy

http://www.scienceforums.net/forums/showthread.php?p=189089#post189089

[garyr10000]

Thanks