I find this black hole information debate akin to medieval ramblings on amount of angels dancing on diamond pin head. Can we please move on a little and come back when we have new angle?
Exactly. I call it exploitation of the unknown. You can generate lots of "theories" by just combining a couple of mysterious things into one. For example, something that hasn't been tried yet afaict, is a theory that black holes are a gateway between the physical world and human consciousness (or self-awareness).
Black hole (as singularities that may have formed without collapsing stars) played a central role in early universe by swallowing matter and anti matter and radiating energy by hawking radiation which then fueled energy decay into standard matter, and that may explain the current imbalance between matter and anti matter or it may be mad internet rambling.
Your theory is so important that it will get evaluated no matter what. And today it is vague and baseless, a speculation. We're seeing a lot of speculations around black holes, most of them obviously turn out wrong.
Your theory doesn't make much sense. There's really nothing special about "normal" matter vs antimatter. You could as easily call the matter I'm made of antimatter and reverse the names and the physics is the same for both.
You've set up a strawman. The GP doesn't claim that there's anything special about antimatter. He simply provides a wacky explanation for the unsolved problem of baryon asymmetry.
There is actually a reason to care about black holes and information loss: no information loss is a consequence of assumptions baked in to how we do a lot of physics, so if information truly is lost that has consequences beyond just "how a black hole works".
Basing this on personal hunch instead of any theoretical hard standing whatsoever I think black holes are really just the event horizon, there's nothing 'inside' the event horizon.
I believe that the collapse into a 'black hole' 'stops' at the moment that space-time curvature creates a sphere of space-time that geometrically appears to us 'outsiders' as the surface of a sphere or a shell - ergo the event horizon.
That is, I believe that there is _nothing_ inside the event horizon (literally nothing, no space-time, no anything), the event horizon is just the region of space-time occupying the surface of a shell inside which there is NOTHING.
I don't believe you fall 'through' the event horizon, I think that the matter that would otherwise make up the singularity at the centre of the black hole is smeared over this surface/event-horizon region.
There are problems with this idea, but those are somewhat related to the fact we believe matter becomes infinitely dense (why wouldn't material on the surface of the sphere collapse to smaller spheres/event-horizons of their own) But infinite density is clearly not a 'proven' theory, however widely it's postulated - so we clearly don't understand if that is even a physical possibility.
I've not seen anything concrete that says you can't model a black-hole as a shell of mass. As I understand it, to an outside observer a shell behaves gravitationally identically to a point mass at the centre of such a shell would.
Of course, I'm no doubt very wrong, but whenever I've mentioned this to anyone, no one has really come up with anything to say it absolutely isn't possible, not without holding on to other things we 'think' we know like matter 'should' continue to collapse to infinite density once past some arbitrary point. Something I'm not convinced is true.
> I've not seen anything concrete that says you can't model a black-hole as a shell of mass. As I understand it, to an outside observer a shell behaves gravitationally identically to a point mass at the centre of such a shell would.
> Of course, I'm no doubt very wrong, but whenever I've mentioned this to anyone, no one has really come up with anything to say it absolutely isn't possible, not without holding on to other things we 'think' we know like matter 'should' continue to collapse to infinite density once past some arbitrary point. Something I'm not convinced is true.
Sure, you can model the external gravitational field as a shell of mass (interior to the event horizon), but they you have to explain why the mass is in a shell, rather than collapsing in on itself. If black holes form as the remnant of the cores of massive stars, then there's no shell configuration to start out with, so now you also have to explain why a shell forms in addition to it is maintained. So, while the shell model may be consistent with the external gravitational field, it seems to be constructed in an ad hoc fashion.
Also, not everyone thinks matter should collapse to infinite density, e.g., [0]. I don't have enough domain knowledge to say how reasonable that particular model is. But "collapsing to infinite density" is a simple explanation for non-experts, but I don't think physicists are comfortable with it as an actual interpretation. The more common interpretation is that the laws of physics we have do not apply in such situations, and we need an understanding of quantum gravity to say what happens at the center of a black hole.
> but then you have to explain why the mass is in a shell, rather than collapsing in on itself.
That is an easy one. It is the only "stable" configuration given two pieces of information:
1) The force of (and therefor effects of) gravity of a sphere is maximum on the surface and tapers to zero at the center.
2) Time (and therefor motion) all but stops at when the force of gravity reaches black-hole proportions.
So the center becomes an unstable region of low density and rapid time/motion, and the surface becomes a stable region of treacle-time. A hollow sphere would be the result.
That said it is almost certainly wrong because it is sufficiently simple that every pop-culture astrophysicist would have written about it, and none have.
The net force on a particle due to gravity tapers towards the center but the pull of gravity on the surrounding particles accumulates into pressure preventing any lower density from forming on the interior unless there is another force like fusion providing outward pressure. Since black holes form after gravitational collapse that is no longer possible.
The only natural equivalent I can think of would be rotational vorteces (tornadoes) but the "shell" would be two dimensional and such a system requires two fluids with different properties, which couldn't exist in the black hole.
> the pull of gravity on the surrounding particles accumulates into pressure preventing any lower density from forming on the interior unless there is another force ... providing outward pressure.
(Keep in mind I don't believe this, it is just fun to argue cute ideas from basic principles.)
In this case the secondary force would be time dilation. Assuming that black holes have finite density, there must be a second event horizon inside the body. Just as a particle can't escape the surface going upwards, particles inside the black hole would not be able to escape downwards, if between the two horizons. While the force of gravity would still pull particles towards the center and away from the interior horizon, any brownian motion away from the center is self-reinforcing since the particle moves towards a region of greater time dilation.
There would be an intermediary unstable stage like a nut rattling around inside a shell, but the slightest instability would start the core oscillating, and each time it brushes the shell it loses a bit more mass. When matter approaches an event horizon it tends to release a lot of energy, repeatedly breaking up (or boiling off) the core and launching bits of it into the shell. This provides a another source of outward pressure.
Reiterating: this is likely complete poppycock.
edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass.
>> edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass.
Exactly. The relationship between mass, space, and time is complicated but there is a causal link going (roughly) in the direction of mass -> space -> time. The presence of mass warps space which dilates time (ignoring special relativity and quantum gravity which makes it weirder). The combined effects of the gravitational force (pressure) necessitates an increase in density, which further warps space, which further dilates time around the singularity.
Time dilation isn't "fighting" the force of gravity and the warping of space, it is an observational effect that is only meaningful outside of the reference frame of the singularity. All other forces and phenomenon are already dependent on time so if the laws of nature do exist inside of a singularity, the existence of other effects like brownian motion will be entirely dependent on the mass/gravitational forces (aka they likely wouldn't be relevant due to the overwhelming effect of compressing matter and energy to such a small volume).
A few comments. I doubt that many or even any serious physicist imagine something of infinite density inside a black hole, infinities are just the way our theories tell us that we don't understand things well enough and got the math wrong. The event horizon can be a very ordinary place with almost flat space and no strong gravitational forces. You can probably cross the event horizon of a large black hole without even noticing what you just did and that you are doomed. So imagining that the event horizon is kind of a wall with nothing behind the wall most likely does not work. Lastly the singularity is not a place but a time, the common pictures of black holes are highly inadequate to think about black holes.
Event horizon is an ordinary place that happens to be bombarded by high energy particles coming from the whole galaxy in great numbers. I think you'll note.
Black holes are not active all the time, after cleaning out the surrounding space they can go through extended periods in which they are not aggregating more mass. I am not even sure if you should expect particles with high energy rushing in. Why not gas clouds with densities of a few atoms per cubic meter drifting into the black hole with modest velocity? If I remember correctly you can even be inside the event horizon before the black hole actually formed, I would definitely not expect high energy particles in such an scenario.
When you approach event horizon you witness the galaxy age and die, and also get multiple billion year load of heavy particles, possibly even blueshifted thermal photons.
Nothing special happens when you approach or cross the event horizon. If you look back, even from inside the event horizon, everything looks normal to you, at least until you are close enough to the singularity so that the curvature becomes significant. Only observers outside of the black hole see the event horizon as a special place. For a pretty accessible introduction including a discussion of falling into a black hole see for example [1].
I've come to same conclusions and even got a minimal model. Imagine two Planck singularities falling toward each other. For an external observer, they'll stop eventually due to time dilution. What's between them now?
Why wouldn't the "filling" of that black hole shell be the pressure of the so-called dark energy that's inflating the universe itself? Maybe it's the leakage of these additional sources of dark energy that's fueling the increasing expansion of space-time.
Armchair physics here, but it's fascinating to ponder.
That's precisely the bit that is at issue. The boundary of a black hole seems to be asymmetric regarding information and the arrow of time. Not reversible, which would be a new thing.
Stupid question: is this any differen from the "everyday" problem of information loss? That is, we know phase space is conserved, and yet, if you burn a piece of paper and mix up the ashes, you can't practically recover what was written on it.
Is there information loss (per the claim in the dispute) in a stronger sense for black holes? Is it a case where multiple start states map to the same final state, or just another case of in-practice irreversibility like in the burning paper example?
I am not a physicist but I believe it is similar in a superficial way. With a piece of parchment, the information is encoded based on the relative positions of molecules of ink and paper and if you use thermodynamically irreversible processes to decompose the constituent molecules you by definition lose any information encoded in higher layers of abstraction.
The most fundamental piece of information is the identity of individual clumps of energy (subatomic particles). The reason black holes destroy information is that they are such an extreme environment that this identity no longer holds. Any energy, whether it is a photon or gluons making up a proton, that enters a black hole becomes a faceless part of the entire mass.
Even if Hawking is correct and blackholes can radiate energy, anything they radiate will be made up of the same energy as the particles absorbed by the singularity but any information about what energy was before is entirely lost, as is any information stored in higher level patterns of that energy.
The article is saying that when an object is sucked into a black hole, all state information is squeezed back out in the form of vibrations.
The brick wall analogy is very bad. It is more like flushing an object down a toilet: information about what it was is represented in variatons in the sound of the flush.
While from a human perspective information seems to be being destroyed, really it's just being obfuscated beyond our means of recovery.
If you were to pause time, with enough analysis and knowledge of the present state of your burning parchment you could recover the state from a split-second prior to that.
No-hair theory says that the event horizon of a black hole is different. One moment the information exists, the next moment it's just gone.
This is a key point: recovery of the information requires some knowledge of time. If you were handed a pile of ashes (assuming ideal combustion of every molecule) you have zero chance of recovering any information but if you watched it burn, you can theoretically recover the initial state.
Thats where the analogy breaks down with black holes: when a singularity absorbs a particle not only is any information about its identity lost, but also where it was in time.
If you were to mix a bunch of ashes after watching several different documents burn you could still recover the initial state of each one but because of the extreme conditions in a singularity, even this basic axiom of cause and effect is no longer valid.
So black holes really do shrink phase space, and it's not simply a matter of it being too computationally expensive to extract out "what went inside it" given the microstate of the black hole radiation?
Yep. The big unanswered question as far as I know (from a layman's perspective) is whether the matter/energy in the singularity at the center of a black hole even follows the laws of nature as we have observe them or if all of that is out of the window past the event horizon. If you don't know the laws of nature describing what happens inside (and you can't study them due to the destructive nature of those forces), no amount of computation will be able to help.
> handed a pile of ashes... you have zero chance...
I think I may disagree with you on the parchment, and think I agree with you on the singularity... but it's hard to tell for sure because we're all throwing half-cooked analogies around and it's been a long day.
>you can't practically recover what was written on it.
Keyword: Practically. In theory, the information is in the mixed up ashes though. Thus, the information is not lost, just scattered and made inconvenient.
If you dropped the ashes in the black hole, the ashes would go into the same state as if you dropped ashes of a paper with different text on it - in other words, it's literally unrecoverable.
it appears that what the physicists
mean is just that two systems that
start different will forever remain
different.
So, maybe the thought is,
otherwise, when the two systems
became the same, could just
reverse time back to where they
should split into
two different systems and would
get a contradiction, that is,
not know how to make the split.
The thing to remember is that space isn't flat. Gravity warps it, like a bowling ball warps a flat bed sheet, but in 3 (technically, 4) dimensions. A black hole is a warping where instead of a gradual dip in the sheet, there is a cone that plummets down seemingly infinitely. But the principle of relativity means we don't really know what's on the other side; just that anything that goes over the edge of the quasi-spheroid line (the event horizon) can't ever go fast enough to come back.
40 comments
[ 3.3 ms ] story [ 85.5 ms ] threadBlack hole (as singularities that may have formed without collapsing stars) played a central role in early universe by swallowing matter and anti matter and radiating energy by hawking radiation which then fueled energy decay into standard matter, and that may explain the current imbalance between matter and anti matter or it may be mad internet rambling.
Still medium worthy?
But still, that's a perfectly valid oppinion. It may well be that entropy decreases as matter gets into a black hole. People just expect otherwise.
It's about ongoing explorations of the Electric Universe theory.
I believe that the collapse into a 'black hole' 'stops' at the moment that space-time curvature creates a sphere of space-time that geometrically appears to us 'outsiders' as the surface of a sphere or a shell - ergo the event horizon.
That is, I believe that there is _nothing_ inside the event horizon (literally nothing, no space-time, no anything), the event horizon is just the region of space-time occupying the surface of a shell inside which there is NOTHING.
I don't believe you fall 'through' the event horizon, I think that the matter that would otherwise make up the singularity at the centre of the black hole is smeared over this surface/event-horizon region.
There are problems with this idea, but those are somewhat related to the fact we believe matter becomes infinitely dense (why wouldn't material on the surface of the sphere collapse to smaller spheres/event-horizons of their own) But infinite density is clearly not a 'proven' theory, however widely it's postulated - so we clearly don't understand if that is even a physical possibility.
I've not seen anything concrete that says you can't model a black-hole as a shell of mass. As I understand it, to an outside observer a shell behaves gravitationally identically to a point mass at the centre of such a shell would.
Of course, I'm no doubt very wrong, but whenever I've mentioned this to anyone, no one has really come up with anything to say it absolutely isn't possible, not without holding on to other things we 'think' we know like matter 'should' continue to collapse to infinite density once past some arbitrary point. Something I'm not convinced is true.
> Of course, I'm no doubt very wrong, but whenever I've mentioned this to anyone, no one has really come up with anything to say it absolutely isn't possible, not without holding on to other things we 'think' we know like matter 'should' continue to collapse to infinite density once past some arbitrary point. Something I'm not convinced is true.
Sure, you can model the external gravitational field as a shell of mass (interior to the event horizon), but they you have to explain why the mass is in a shell, rather than collapsing in on itself. If black holes form as the remnant of the cores of massive stars, then there's no shell configuration to start out with, so now you also have to explain why a shell forms in addition to it is maintained. So, while the shell model may be consistent with the external gravitational field, it seems to be constructed in an ad hoc fashion.
Also, not everyone thinks matter should collapse to infinite density, e.g., [0]. I don't have enough domain knowledge to say how reasonable that particular model is. But "collapsing to infinite density" is a simple explanation for non-experts, but I don't think physicists are comfortable with it as an actual interpretation. The more common interpretation is that the laws of physics we have do not apply in such situations, and we need an understanding of quantum gravity to say what happens at the center of a black hole.
[0] http://arxiv.org/abs/gr-qc/0506111
That is an easy one. It is the only "stable" configuration given two pieces of information:
1) The force of (and therefor effects of) gravity of a sphere is maximum on the surface and tapers to zero at the center.
2) Time (and therefor motion) all but stops at when the force of gravity reaches black-hole proportions.
So the center becomes an unstable region of low density and rapid time/motion, and the surface becomes a stable region of treacle-time. A hollow sphere would be the result.
That said it is almost certainly wrong because it is sufficiently simple that every pop-culture astrophysicist would have written about it, and none have.
The only natural equivalent I can think of would be rotational vorteces (tornadoes) but the "shell" would be two dimensional and such a system requires two fluids with different properties, which couldn't exist in the black hole.
(Keep in mind I don't believe this, it is just fun to argue cute ideas from basic principles.)
In this case the secondary force would be time dilation. Assuming that black holes have finite density, there must be a second event horizon inside the body. Just as a particle can't escape the surface going upwards, particles inside the black hole would not be able to escape downwards, if between the two horizons. While the force of gravity would still pull particles towards the center and away from the interior horizon, any brownian motion away from the center is self-reinforcing since the particle moves towards a region of greater time dilation.
There would be an intermediary unstable stage like a nut rattling around inside a shell, but the slightest instability would start the core oscillating, and each time it brushes the shell it loses a bit more mass. When matter approaches an event horizon it tends to release a lot of energy, repeatedly breaking up (or boiling off) the core and launching bits of it into the shell. This provides a another source of outward pressure.
Reiterating: this is likely complete poppycock.
edit: Ah, I see the snag. There isn't a second event horizon inside the black hole. Just because opposing gravitational forces cancel each other out in the center (and space is flat there) does not mean time is any less distorted by all the surrounding mass.
Exactly. The relationship between mass, space, and time is complicated but there is a causal link going (roughly) in the direction of mass -> space -> time. The presence of mass warps space which dilates time (ignoring special relativity and quantum gravity which makes it weirder). The combined effects of the gravitational force (pressure) necessitates an increase in density, which further warps space, which further dilates time around the singularity.
Time dilation isn't "fighting" the force of gravity and the warping of space, it is an observational effect that is only meaningful outside of the reference frame of the singularity. All other forces and phenomenon are already dependent on time so if the laws of nature do exist inside of a singularity, the existence of other effects like brownian motion will be entirely dependent on the mass/gravitational forces (aka they likely wouldn't be relevant due to the overwhelming effect of compressing matter and energy to such a small volume).
[1] http://theoreticalminimum.com/courses/general-relativity/201...
Armchair physics here, but it's fascinating to ponder.
Is there information loss (per the claim in the dispute) in a stronger sense for black holes? Is it a case where multiple start states map to the same final state, or just another case of in-practice irreversibility like in the burning paper example?
The most fundamental piece of information is the identity of individual clumps of energy (subatomic particles). The reason black holes destroy information is that they are such an extreme environment that this identity no longer holds. Any energy, whether it is a photon or gluons making up a proton, that enters a black hole becomes a faceless part of the entire mass.
Even if Hawking is correct and blackholes can radiate energy, anything they radiate will be made up of the same energy as the particles absorbed by the singularity but any information about what energy was before is entirely lost, as is any information stored in higher level patterns of that energy.
The brick wall analogy is very bad. It is more like flushing an object down a toilet: information about what it was is represented in variatons in the sound of the flush.
If you were to pause time, with enough analysis and knowledge of the present state of your burning parchment you could recover the state from a split-second prior to that.
No-hair theory says that the event horizon of a black hole is different. One moment the information exists, the next moment it's just gone.
Thats where the analogy breaks down with black holes: when a singularity absorbs a particle not only is any information about its identity lost, but also where it was in time.
If you were to mix a bunch of ashes after watching several different documents burn you could still recover the initial state of each one but because of the extreme conditions in a singularity, even this basic axiom of cause and effect is no longer valid.
I think I may disagree with you on the parchment, and think I agree with you on the singularity... but it's hard to tell for sure because we're all throwing half-cooked analogies around and it's been a long day.
(disclaimer: I am a physicist)
Keyword: Practically. In theory, the information is in the mixed up ashes though. Thus, the information is not lost, just scattered and made inconvenient.
If you dropped the ashes in the black hole, the ashes would go into the same state as if you dropped ashes of a paper with different text on it - in other words, it's literally unrecoverable.
http://www.worldsciencefestival.com/programs/holographic_wor...
it appears that what the physicists mean is just that two systems that start different will forever remain different.
So, maybe the thought is, otherwise, when the two systems became the same, could just reverse time back to where they should split into two different systems and would get a contradiction, that is, not know how to make the split.
Maybe.