The falling perspective likewise loses timely access to information about the entire universe as the singularity fills their view.
I don’t see a paradox. Just the strange behavior of time at the limit.
The part that is problematic is that matter that enters the black hole is only returned to the universe as anonymous radiation.
The universe is stateful, and while not all processes in the universe are reversible, matter and energy do encode the states that led to their present state and thus the prior states can be inferred (by a hypothetical, powerful enough computer, for example).
The problem with black holes is that the Hawking radiation from a black hole does not encode any information about its prior state.
Hawking radiation has never actually been observed. It is just something that pops out of the math if, as Sabine rightfully emphasizes in her video, you make certain assumptions. And one of those assumptions is that you have a fully-fledged black hole, i.e. an object that actually contains mass beyond the event horizon. We are used to thinking of this assumption as having actually been confirmed by observation, but it is not actually true. No one has ever actually observed a black hole, notwithstanding that we've ostensibly taken a picture of one. That image was of the radiation emitted by an accretion disk, not the black hole itself. Black holes themselves are, obviously, impossible to image.
So we don't actually know whether black holes actually exist or not. The only thing we've directly observed is their gravitational effects, and the gravitational effects of an actual black hole are indistinguishable from having all of the mass of the hole actually resident just outside the event horizon. What actually happens at the horizon is beyond the reach of our current theories because there both gravity and quantum effects are significant, and we do not yet have a consistent theory of quantum gravity. Everything we think we know about black holes is actually the result of taking GR and QM and framming them together in some ad hoc way by adding simplifying assumptions which may or may not actually be true.
This is the point Sabine was trying to make: the black hole information loss paradox is not a problem with physics, it's a problem with our current theories. We simply don't know how the universe actually behaves in the presence of extreme concentrations of mass/energy. The only thing that the BHILP actually tells us is that either GR or QM -- or both -- are wrong, mere approximations to the actual truth in the same way that Newtonian mechanics turned out to be an approximation to the actual truth (one that happens to work extremely well in weak gravitational fields).
But no one has a clue which one is wrong or how despite 100 years of effort. And one of the reasons for this is that we have no data, and no reasonable prospects for obtaining it. So we may just have to make our peace with not knowing.
What we observe is the "shadow" of the black hole. The expectation is that the flux from the shadow should be consistent with zero. For M87* the observed flux ratio with the ring was ~10:1. See Paper 1:
First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole https://arxiv.org/abs/1906.11238
Unless they produce Hawking radiation. Then by definition they are possible to image. In the original article she mentions that temperature of known black holes is lower than CBR, meaning that they are too cold to be seen agains background of cosmic background radiation.
I personally think that they produce no radiation and do not evaporate, but this is just unscientific philosophical opinion.
Fair point (modulo the practical difficulties of measuring Hawking radiation).
It's like we've come up with two theories of how the universe works but and the universe is like "you guys are like 90% there but here's a case where these don't work.". It's fascinating to think that there's gotta be some one theory that can account for everything in the universe both big and small from black holes to quantum stuff. It's like we've dug ourselves in two very deep holes over the years and maybe we need someone to come along with a new hole that encompasses both things that see the whole picture. Anyways now I'm just speculating.
Actually, there doesn't. The universe is under no obligation to operate according to laws. That the behavior of the universe is so lawful is quite remarkable. It didn't have to be this way. Our universe could be a simulation, and that simulation could have been created by some capricious being who makes all kinds of random shit happen just to fuck with us. That does not appear to be the case, but there is no reason that it could not have been.
Likewise, there is no reason why our brains should have the capacity to be able to figure this out. It may be that the Kolmogorov complexity of the universe is vastly larger than what the human brain is capable of dealing with. Again, this does not appear to be the case. In fact, it appears to be the exact opposite. We can explain 100% of the phenomena within our solar system, and even within most of our galaxy, with theories whose KC is shockingly low, small enough to be grasped by a single human brain. But it didn't have to be that way. And maybe it isn't that way. Maybe we have actually reached the limit of what the human brain is capable of (in terms of figuring out physics). I don't think so, but you can't rule out the possibility on the basis of the evidence we have.
Also, just because a theory is discontinuous at its boundaries doesn't mean we can't have a theory that is on the other edge of that boundary. The unifying theory is supposedly supposed to link both general relativity and quantum mechanics.
Obviously this is just my opinion but I think any system that is sufficiently observable, with enough time can be figured out completely. I don't think it's a matter of if our brains can understand it but if we can have the ability to run experiments on it and enough time.
Is that better?
Dllthomas correctly pointed out that given the two premises that (from the frame of the observer) (1) [matter takes infinite time to transit the horizon] and (2) [due to hawking radiation, black holes have a finite time span], then (2) resolves (1) when the black hole disappears.
To recap, Instead of acknowledging that (2) resolves (1) you proceed to question the existence of hawking radiation and black hole evaporation, which compared to consensus is a radical view and is not warranted. Also the pivot was done in a way that seems to complicate and obfuscate rather than address the point directly (this is a common debate tactic; however I'm not sure if you were conscious of the behavior or if it was more subconscious/rationalization (more likely); you may not have even been aware you were doing it).
It seems like you chose to reject consensus instead of simply accepting that (2) resolves (1), maybe because you seem to have a fixation on not ever conceding a point in a conversation. Sometimes it's ok just so say, "yeah, that's a good point".
(btw if you're rejecting hawking radiation why say anything about black hole theory at all this point because it could all be wrong, no reason to speculate about it)
That is quite the accusation coming from someone whose entry into the conversation was "Wall of text, didn't answer the question." But let's see...
> Dllthomas correctly pointed out...
dllthomas did not "point out" anything, correctly or otherwise. All he did was ask the following question:
"How does that remain true after the black hole has evaporated and there is no longer a horizon?"
This question assumes that black holes evaporate. That assumption may be incorrect. We do not know whether or not black holes actually evaporate. In fact, we do not even know whether or not black holes actually form at all. And therefore:
> (2) resolves (1) when the black hole disappears
That might be true if (2) were true. Even that is arguable, but it is neither here nor there because we do not know whether or not (2) is true
> compared to consensus is a radical view
Yes, of course. The consensus view leads to a paradox, and so we know that the consensus view cannot possibly be correct. We also know that decades of effort have not resolved this paradox, and so it is extremely unlikely that there is a simple straightforward solution that has simply been overlooked. So the correct solution will almost certainly be a radical departure from the current consensus.
If true, I think you can go even further and say no black hole can completely form; the collapsing matter just gets exponentially closer to being fully black until the effect of the Hawking radiation outweighs the gravitation, but it all evaporates before going fully black. No?
(This latter part assumes there's some Hawking radiation or equivalent from pre-black holes as well. And I'm not sure whether that would be unitary or not, so it may not resolve the information paradox anyway).
(Edit: I think the pre-Hawking radiation would be unitary, since the only reason Hawking radiation is not unitary is because BHs don't have information, but pre-black holes are not black holes. So doesn't that solve the info paradox? Without resorting to holographs and whatnot? Where's the error?)
That's how thermodynamics derives indistinguishable macro states from distinguishable micro states. Throw that off and thermodynamics stops working.
Since it has worked well so far they're reluctant to throw it out. Something has to go, and since they already know there's something funny going on where black holes meet quantum mechanics, that's the lowest hanging fruit.
If you read my comment, you will find no mention of the second law of thermodynamics or any violation of said law.
In fact, black holes need to evaporate in this way in order to comply with said law of thermodynamics.
> When you mix water at different temperatures, entropy is irreversibly increased. It's not possible to tell the initial temperatures just from the final state.
It is still water, however. You may not be able to say what temperatures W(a) and W(b) were from W(c), but you could at least say that W(c) may actually be W(ab) i.e. may be the mixture of two bodies of water W(a) and W(b).
Bring the same water to a black hole and you have: W(a) went into a black hole and x came out, where x is some random heat.
If you detect the heat x, what could you say about anything that may have been before?
If W(a), W(b), Chair(a), Xylophone(g), Stone(f), Person(z) or anything went into the black hole, only heat x comes out in the end.
Why is it contradicting that it happens much faster in some places in the universe? It may be surprising but what does it contradict? I’m asking sincerely.
Regarding the water thought, if you recite a poem inside a chamber, it turns into heat. If you are outside and can only measure that the room slightly increases its temperature you also can’t recover the poem.
But whether something with higher entropy than "black-hole matter" exists is a more refined question than if black-holes erase the entropy of what fallen into it. And Quantum Mechanics has a problem with erasing entropy, even if it's into a larger amount.
Have we proved the Hawking radiation is without information (or enough of it), or is it just 'encrypted' at a level we can't distinguish from noise?
"[Hawking] radiation is thermal which means it’s random except for its temperature, and the temperature is inversely proportional to the mass of the black hole. This means two things. First, there’s no new information which comes out in the Hawking radiation..."
Its mass is one of the few things we know from the outside.
Instead, Hawking radiation is a prediction of a mathematical model. In that model, Hakwing radiation is purely random.
If I remember correctly, Hawking radiation is postulated to arise because of fluctuations in the vacuum giving rise to virtual particle pairs. Normally, these would annihiliate back almost instantly. But, when such an event happens near the event horizon, one of them may fall into the black hole, leaving the other one to "escape", and appear as if the event horizon is emitting radiation. Since this radiation is caused by random fluctuations in the void outside the event horizon, it can't be correlated with anything past the even horizon, so it can't carry information about that.
Or do you believe quantum mechanics is equivalent to relativistic mechanins?
Either would unwrite a century of physics.
This is talking about quantum states and how they describe the world. Each state corresponds to physical (quantum) reality, conforming to the laws of physics. So it’s not like you can just twiddle bits to make new representations.
I think this is an area where appealing to the lay reader’s intuition is counterproductive. If you haven’t solved the Schrodinger equation before then you definitely shouldn’t be trying to intuit things about quantum systems; they are just weird and kind of irreducibly complex from the mathematical representation.
Let me attempt to go against my advice above and give you some intuition for why encryption doesn’t parse here. It would be like you have a program with some static types, some classes, and then say “what if we just encrypt the memory location for this object on the heap and run the program”. The program is the thing that is running (laws of physics), the variables on the stack/heap are the state for the current execution, and it has no concept of decryption, so it would just produce garbage and crash. In the same way, the quantum physics description of a system has superposed states that are all valid configurations of the physical system, and no notion of “encryption”. So there is nowhere in the model of physical reality (and therefore unless we are missing some new Physics, nowhere in the reality that is modeled) for this information to “hide”.
Or taking a different tack, “thermal entropy” means it’s just a bunch of gas buzzing around randomly at the same temperature - there is no physical place for structure to be “encrypted”. Where is the “key” in your model of the world? It’s just a cloud of gas. What physical process performed the encryption? That would require a complex structure, yet we are talking about a cloud of particles emitted when one half of a particle-antiparticle pair is captured by the black hole’s event horizon. There is no place in a workable physical model of the world for an entity that performs encryption on the quantum states (whatever that might mean).
All this just points to why you can’t encrypt states in this way, not why the black hole information paradox is a problem. For that you really do need the maths; eg see https://www.cs.umd.edu/class/fall2018/cmsc657/projects/group... for the Physics here; while that requires graduate-level understanding of QM, hopefully the intro will be useful.
Heh heh, define "solved"... If I remember my QM class correctly, we "solved" the Schrodinger equation for the hydrogen atom; the book achieved this by observing "... which gives us <equation>, and, hey! look at this! it turns out that FamousLastName polynomials--which you've never heard of--turn out to solve this equation, here's their definition, and... problem solved!" (If I remember correctly they were Legendre Polynomials, but maybe that was some other equation. And to be fair to the book, it was a pretty good book.) After having "solved" the equation for one isolated, most-basic atom, they went on to say, "basically we have no idea if there is an analytic solution for anything more complex".
If manipulating bra and ket vectors symbolically around an equals sign counts, we did a lot of that, although it did not develop in me the least intuition about QM. But then, I never really understood what those bra and kets were doing, and my grades steadily dropped (fortunately for my GPA there were only three courses). So it's possible I might have developed some intuition had I understood what was going on.
Not a quantum information theorist, but am a scientist. We actually do have (conjectured) low-complexity one way functions, so this by itself is not necessarily true. I do agree that it's a fairly unlikely to be the case that natural processes execute this algorithm, though.
If information leaks out they'll have to figure out why the No Hair Theorem is wrong.