The information paradox for black holes

GuanYin

The Euclidean path integral over all topologically trivial metrics can be done by time slicing and so is unitary when analytically continued to the Lorentzian. On the other hand, the path integral over all topologically non-trivial metrics is asymptotically independent of the initial state. Thus the total path integral is unitary and information is not lost in the formation and evaporation of black holes. The way the information gets out seems to be that a true event horizon never forms, just an apparent horizon.
Stephen Hawking - Abstract at 17th International Conference on General Relativity and Gravitation, RDS, Dublin, Ireland

Anyone catch this today or does anyone have a link to the gist of his presentation?

Its a pretty big thing for Ireland to host and I'm really surprised there hasnt been a hell of a lot more publicity on it.

mr_angry

I was beginning to wonder if there'd be any publicity, were it not for Hawkings latest theory. I'd imagine the full transcript probably wont appear for another month or so, until the conference proceedings are published. Unless some kind soul at the conference goes to the trouble of transcribing it for us.

With a bit of luck, it'll make RTE Six-One News tonight.

GuanYin

Yeah, I've been watching it for a while. I would have gone only I'm flying out to my own conference tomorrow morning.

I was hooing someone else would post about it .... *sigh*

Can anyone explain to me what exactly he's likely to say?

dudara

There was an article in the Irish times on this conference and Stephen Hawking's presentation yesterday (20/07/04). He has apparently solved a mystery that has baffled scientists since the 1970's.

Now I've had a friend who did a PhD in this kind of stuff, and I just can't handle it at all. It's far too remote and abstract for me.

davej

Lot's of news articles about the conference on the web:

http://story.news.yahoo.com/news?tmpl=story&cid=624&ncid=753&e=1&u=/ap/20040721/ap_on_sc/black_holes

davej

dudara

That Yahoo article gives a good explanation. Now the question that I have is that, since some black holes must have been created and died since the existence of the universe, should we not be able to detect the matter that excapes them once they die?

Or is there an infinitestimably small probability of being able to do this?

ecksor

meep, I could probably give you the gist of it after four years of maths.

Gurgle

Whoooooooooooooosssssshhhhhhhhhhhhh
Did something just go over my head ?

So the whole silly big bang theory is a load of cobblers ?
Just a dying black hole spitting out what it had swallowed in previous eons.

Makes more sense than 'first there was nothing, which exploded' anyway.

uberwolf

the current new scientist has a page long article - on the topic but no details really.


"Hawkings black holes, unlike classic black holes, do not have a well-defined event horizon that hides everything within them from the outside world. In essence, his new black holesnow never quite become the kind that gobble up everything. INstead, they keep emitting radiation for a long time, and eventually open up to reveal the information within" - is the crux of the explanation given therein based on a seminar Hawkings gave in Cambridge

Woden

couple of my mates have been are at it today, they've come up for the conference which has been on since monday i think.

another mate of mine went up to the door today and was told it was €90 in to it.

one of the lads that was there is dropping over tonight so i should get the gist of it, but probably not just looking at that abstract

John

This conference is news to me!

Originally posted by Gurgle
So the whole silly big bang theory is a load of cobblers ?
Just a dying black hole spitting out what it had swallowed in previous eons.

Makes more sense than 'first there was nothing, which exploded' anyway.

I'm not a physicist but from what I got from A Brief History of Time was that the universe might consist of cycles of expansion and contraction (ie big bang: universe is formed follwed by contraction into "nothing" and followed by big bang and so on and so on). Basically what he has just described about black holes just makes them sound like "little bangs", a miniature version of the familiar big bang.

Someone more knowledgable on the subject might be able to shed more light on the subject.

Civilian_Target

I'm not surprised that there's so little publicity, look at the abstract!

I'm doing a Physics degree and the words "Euclidean path integral over all topologically trivial metrics" make me shudder, because I know that's going to be a huge amount of maths, and that's nothing to what joe average sees, all he gets are a lot of words with more than 10 letters!

Although i would like to see them read that on RTE news...

dudara

My question is (and I'm doing a physi phd) what is a trivial and non-trivial metric?

Oh and, WTF is a Riemann manifold?

planck2

Basically the gist of the theory is that all though a black hole evaporates what is called Hawking Radiation, initially thought to be thermal radiation, but know one believed it to be entirely thermal.

This evaporation meant that all the information in the black hole was evaporated away and thus unretrievable. People involved in theoretical physics from a general relativity point of view liked this outlook.

However those in quantum mechanics didn't, they liked the idea that no information from a black hole.

Hawking has supposedly shown today that information is not in fact lost, but that information that is eaten by a black is in fact retrievable, but that it is in a very different form than the form it was in before it was eaten by the black hole.

Dont worry about the maths you need a phd in theoretical physic in general relativity and more to understand it.

planck2

oh yeah i am one of data's mates

planck2

One of the lines should read quantum mechanics believe that no information from a black hole is lost

Civilian_Target

Saw it again in the news yesterday evening, but they didn't read the abstract (shich was a shame) and focused on talking about the bet instead.

It always amazes me that it takes the smartest people out there 14 years of school and at least another 7 at college to even understand what Hawking is talking about....

John

Originally posted by Civilian_Target
It always amazes me that it takes the smartest people out there 14 years of school and at least another 7 at college to even understand what Hawking is talking about....

And even then he comes out with a humdinger that sends everyone into a tizzy.

dudara

I think that what he did was to bring black hole theory into line with quantum mechanics.

planck2

yeah, basically its that information is not lost because because we're not a 100% certain the black hole is there and the uncertainty principle places limits on the area of the black hole, i.e. there are quantum fluctuations in the area of the black hole which i think means it never evaporates completely

redspider

Its is interesting that Hawking and his team have come up with yet another way of using exotic mathematical constructs that can predict/model of yet another version of what a black-hole can and cant do. The subject matter is interesting as it uses very complex maths for astro-physics, so it can be discussed on a few forums here. Hawking is a celebrity for bringing Physics into the mainstream, and it is ironic that it took someone that was so badly crippled to get the imagination of the mainstream populace, media and press.

One interesting aspect is that Hawking and his team are showing that what they said before is wrong. So how do we know what they are saying now is right? The beauty of theoretical physics is that we probably dont know!

I have a masters in mathematics but find the details of the maths very difficult to follow, as do most of the academics. I sort of get uncomfortable when they start using "infinities" in their equations and using them to cancel each other out. But overall, Hawking and his kind are trying to find elegant equations that can describe and predict astro events at microscopic (strings) and macroscopic (galaxy super clusters, universe(s?)), levels, etc.

Quantum mechanics makes the Universe a very strange place. Thats how black holes can radiate, by two particles (a real and an anti) suddenly appearing out of "nowhere", one being sucked into the blackhole due to gravity and the other continuing outwards.

The latest black-hole theory stating that information is not lost but will come out in some shape or form, does not have any impact on the origins of the Universe, the big-bang and if we are in an oscillating universe or not. That is a different discussion I would have thought. Of course I could be wrong, but you will need to show me the mathematical proof of that without using anything Lorentzian!

planck2

I'm afraid a non lorentzian proof is out of the question as all the local laws of physics which are the same across the universe are described by a lorentzian symmetry, that is to say the laws are invariant under lorentz transformations.

Woden

does the current theory explain why there has been no been no detection of the evaporation/explosion of primiodial black holes?

is that based on the uncertainty principle as well?

planck2

Hello Data.

It may indeed at some deepr level explain why there has been no detection of the evaporation of primordial black holes, and I would say that it is probably tied into the uncertainty principle on some level.

stevenmu

Hi All,

Apologies in advance for my explanation, I think I've remembered the principle ok but I don't have much of a memory for the proper terminology.

Basically (I think) what they're saying now is that all sub-atomic particles are made up of a whatsit (can't remember the proper word for these) and an anti-whatsit. Due to some principal or other in quantam physics only one of these gets sucked into a black hole, the other goes off at a right angle to it and I believe becomes what's known as Hawking radiation. This other whatsit supposedly also carries mass away from the black hole which will reduce in size to the point where it no longer has sufficient mass to remain a black hole, at which stage "information" will begin to escape from it again.

As someone mentioned before this is really an attempt to incorporate quantam principles, which I'm not a big fan off, into it. I may be totally wrong on all this, I'll try and look it up again later to find out.

John

I think a whatsit = neutrino?