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How the Black Hole Firewall Paradox Was Resolved
Stephen Hawking's recent comments about the nature of black holes have bred uncertainty about physics concepts that were relatively well understood. This article from astrophysicist Ethan Siegel explains that yes, black holes still exist, and how a group of three academic papers answered the black hole 'firewall' paradox. Quoting:
"... And so what these three papers, in tandem, have done, is demonstrate that there is no firewall and that the resolution to the firewall paradox is that the first assumption, that Hawking radiation is in a pure state, is the one that's flawed. You won't read about this in the popular write-ups because it doesn't have a catchy headline, it's complex, and it's not work by someone that's already very famous for other work. But it's right. Hawking radiation is not in a pure state, and without that pure state, there's no firewall, and no paradox. There is still an incredible amount to learn and understand about black holes, event horizons, and the behavior of quantum systems in strongly curved spacetime, to be sure, and there's lots of very interesting research ahead. These findings arguably raise more questions than they answer, although at least we know that black holes won't fry you when you fall in; it will still be death by spaghettification, not by incineration!"
"death by spaghettification" Perhaps this is the ultimate end for a 'Flying Sphaghetti Monster' fearing Pastafarian? Ramen!
"it will still be death by spaghettification, not by incineration!" +1 for Pastafarians
PlanetVulkan.com
... at least we know that black holes won't fry you when you fall in; it will still be death by spaghettification, not by incineration!
Well, that's a load off my mind. I'll be sleeping much better - thanks.
Although, now I have a hankering for some fried spaghetti.
It must have been something you assimilated. . . .
No, this is all still highly theoretical and you cannot state that this hypothesis is absolutely, definitely correct. It may be correct, it may well be the best theory we have and all that, but it's still a theory.
The problem with that is that black holes need the mass they suck in to exist.
The mass cannot both be in the black hole and shot out the other side into a new universe.
So unless you can come up with a theory that has black holes creating mass out of nothing, that is simply impossible.
Troll is not a replacement for I disagree.
nonsense, it's the nature of the work. every famous theorectical physicist you ever heard of has produced provably false and bad models, disproved models, models in need of more refining, models they discard themselves. From the time of the Greeks to Newton to Einstein and onward.
There is a simple proof to the contrary but the /. comment system is too small a space in which to contain it. There are many, many hours of Susskind videos on Youtube, primarily and most recently "ER=EPR|Leonard Susskind", which deal with exactly this.
Ever notice that Cobra Commander sounds an awful lot like Star scream?
But what if you reconfigure the main deflector to emit a tachyon pulse
No it isn't. A cosmological model is a foliation of maximally-symmetric spacelike hypersurfaces. A black hole is not maximally-symmetric. A black hole is a non-evolving system -- it possesses at least one timelike Killing vector -- and a cosmological system is the exact opposite, an evolving system that has no timelike Killing vector. The only real similarity is that a black hole (as you're doubtless meaning it; a Schwarzschild solution) is spherically symmetric, and the spacelike slices in a cosmological spacetime are also spherically symmetric. But so is flat Minkowski space, and so are Tolman-Bondi spaces.
So instead of educating you choose to belittle and trash others. You want more erudite folks? Teach.
It all depends where you're observing from.
If you're alice, falling through the black hole horizon, you see no horizon, and no firewall. It's a harmless point of no return. In a particularly large black hole say with a horizon the size of the solar system (this would have to be a super-galactic beastie) you could potentially live out your life in there before getting crushed by tidal forces.
If you're bob on the outside, it looks like alice slows down and gets increasingly red shifted. Alice moves asymptotically towards the horizon but never quite reaches it. Just getting slower and redder. Of course the reverse is also true, if alice looked back at bob she'd see him all sped up like keystone cops.
Because the light coming to you from the regime around alice is so red shifted, you conclude that it must be incredibly high energy/frequency down where alice is (the firewall)
The funny part is, if you send photons at alice hoping to reflect them back to yourself (to see if she's alright) - the photons have to be so energetic to make the return trip that you end up vapourising alice just as the firewall would have done.
This is the impression I get from reading Leonard Susskind's stuff, broadly taken to be black hole complementarity. Neither view is objectively more 'correct' than the other. We've accepted wave/particle duality so I don't really see how we can't have two pictures of what happens in a black hole.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
There is some debate exactly what happens when you get enough mass together to tie space-time into knots. The most important part of a black hole is really the event horizon, which is the point X distance from the center of mass of a black hole where the gravitational pull is so strong that nothing can escape. The original idea was that is was a very static place, a perfect circle.
There is a bunch of different problems with this. Because in this universe we have the idea that mass, energy, and information cannot be lost. Something cannot just go into a black box and all knowledge of it is lost, because then information would then of been lost.
Stephen hawking's has just come forward with the idea that it is a far more stormy area with fluctuating gravity. Which would allow this information to escape. Previously the idea was Hawking radiation, which would allow things to escape from the black whole even without fluctuation gravity.
One of the problems of with the horizon, that someone just proposed, was that it would be so tumultuous at the edge that everything would be burned beyond recognition,. This article is about how stuff entering a BH would NOT in fact be burned beyond recognition.
Troll is not a replacement for I disagree.
You fall into a black hole and you will heated up from friction to the point that you become atomized.
The most generous interpretation of this is that you're talking about the accretion disk. Yes if your trajectory takes you into the accretion disk (assuming there is one, there doesn't have to be) you'll be atomised. No reason you can't come in from an angle that doesn't take you into the disk though. In those instances you certainly won't be atomised; black holes are very very cold. So cold in fact that the vacuum in the universe won't be colder than any stellar-mass black hole for the very distant future.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Hawking made a proposition. It's not a theory, it's a proposition. His note (two page paper) shouldn't be taken to imply that it is anything more than a proposition. Once it has been fleshed out with equations it will be a hypothesis, if the math works out it will be a theory, and if it agrees with observations better than any other theory it will be accepted.
Not a sentence!
(I do have a doctorate in cosmology and I've a contention with what you've said: a black hole is not a singularity, whether by definition or otherwise. A "black hole" is simply a region in vacuum shrouded by an event horizon, and this situation occurs when a body is compressed enough that it lies entirely within its event horizon. In classical GR there are a few ways to get to this situation, with perhaps the most common being the collapse of a supermassive star. In classical GR there is also a singularity at the centre of the black hole, but a quantum theory of gravity would be expected to smear this out. What this does not imply is that a quantum theory of gravity would destroy the concept of a black hole entirely -- instead it seems very likely that in a quantum theory of gravity we would retain an event horizon, merely a somewhat "smeared" and non-absolute form of one (a distinction that would seem heartlessly academic to any poor sod falling into a hole). Hawking's conjecture, which is eerily similar to an equally unproven conjecture he advanced a few years back to "prove" that the information paradox was solved, is that ultimately there are no "black holes" because they are not an infinite state -- eventually they will dissipate, which immediately implies that their "event horizons" are actually apparent horizons. So far as this goes, it strikes me as eminently non-controversial.
Anyway, the concept of a singularity and a black hole are therefore rather distinct.)
AFAIK it is however conjectured that naked singularities cannot actually form (what is AFAIR definitely proved is that you cannot turn a black hole into a naked singularity).
There are singularities all over physics, even in something as simple as the velocity field of a classical vortex (v ~ 1/r). The world doesn't go all goofy at them-- the universe tends to take care of them in relatively convenient and pedestrian ways, like by sending the density to zero where the velocity goes to infinity. It's all fun to be a theorist talking about naked singularities (probably as close to naked anything as many of them get...) but if someone figures out a way to actually observe what's going on there, it will probably be interesting but probably won't be anything particularly magical.
"However, I'd like to point out that nothing in your analysis validates wisnoskij's contention that the mass of a black hole has to be considered as existing entirely within this universe, therefore preventing it from acting as a "wormhole" to another one."
A fair comment - I put my entire reply in parantheses because it was meant to pick at one of your statements, rather than the entire post, something I should have made a lot clearer.
With the wormhole thing, the idea basically comes from a maximal extension of a black hole. You can split the spacetime of a black hole into four sections: section I is our universe, asymptotically flat. (So, evidently, not actually our unvierse but let's ignore that for now.) Section II is the future inside the black hole, section III is the past inside the black hole, and section IV is another asymptotically flat region on the "other side" of the black hole. (See here.) This then obviously raises questions about what that other region is and how to get there -- perfectly valid questions, the answer to which is commonly called a wormhole.
Unfortunately it does have to be pointed out that this has arisen because we've maximally-extended the spacetime. In reality, we can already guarantee that section III does not exist, because the extension into the past cannot be made -- the black hole has not existed for all time. This basically screw us, and the realistic situation is more like this.
Of course, this isn't the only way we can envisage getting a wormhole out of GR, but it's one of the best studied.
And also, of course, the singularity does render any speculations -- even using GR -- nothing more than speculations. We simply can't say what goes on there. I know that in loop quantum gravity the singularity issue is rather lessened but I don't actually know what happens there, since it's very much not my field.
You're totally right that Hawking's more recent statements have been conceptual arguments rather than mathematical models. That was the case when he talked about the information paradox, and it's the case now talking about the firewall. That doesn't mean the arguments are not worth listening to, but it does mean there's no reason to think that the issues are finished just because Hawking's deigned to talk about them.