Her frustration with the priorities of theoretical physics probably is justified, but in this case I disagree with @skdh. Her claim is that any solution for the BHIP cannot be falsified, and that strikes me as too pessimistic for two reasons. First, look at the results of pushing the theory harder with respect to spinning black holes. Many predictions of Kerr's theory have been observed, even if the ring singularity at the center hasn't. Second, we're observing new black hole phenomena every day, and if black holes really do explode at the end of evaporation, then maybe that is also observable. Sure, Hawking radiation is normally too small to be directly observed, but the theory can be driven into a place where it can make a testable prediction.
The Black Hole information loss problem is unsolvable
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Re: The Black Hole information loss problem is unsolvable
#72As a non-physicist, I've always been hung up on a much simpler paradox: how does radiation escape from a black hole? I thought even light could not escape? Is there an explanation to that?
I suggest reading
https://www.forbes.com/sites/startswithabang/2018/11/03/ask-...
Most importantly, he argues that Hawking's own popular explanation (often repeated across the media, about the particle-antiparticle pair) is too simple to be correct:
"It's not right, though, in a number of ways. First off, this visualization is not for real particles, but virtual ones. We are trying to describe the quantum vacuum, but these are not actual particles that you can scoop up or collide with. The particle-antiparticle pairs from quantum field theory are calculational tools only, not physically observable entities. Second, the Hawking radiation that leaves a black hole is almost exclusively photons, not matter or antimatter particles. And third, most of the Hawking radiation doesn't come from the edge of the event horizon, but from a very large region surrounding the black hole."
Additionally, the article also writes enough to explain the whole context and gives enough details for those who are interested to learn more.
Re: The Black Hole information loss problem is unsolvable
#73Earlier quoted context omitted.
People who believe that past experience is a good predictor of the future will make decent predictions as a result; people who believe that past experience has nothing to do with the future ("anti-inductivists") will make wrong predictions again and again. The inductivists will therefore outcompete the anti-inductivists. On the other hand, as a friend of mine pointed out, for the anti-inductivists that manage to exis…
> The inductivists will therefore outcompete the anti-inductivists. You have no deductive or a priori reason to know this, rhetoric about "epistemically traps" aside.
So is this survivorship bias or something else? I don't understand your point. I have a white wall in front of me. If I take a brush and red paint and paint a big red circle on the wall, are you saying that the big red circle "just happens to be there" with no relationship to the brush, red paint and my actions?
Re: The Black Hole information loss problem is unsolvable
#74Earlier quoted context omitted.
> The information isn't gone, its right -there- in the black hole No, it isn't; it hits the singularity inside of the hole and gets destroyed. At least, that's what Hawking's original model, the one he used to predict that black holes evaporate, says. One way of seeing why Hawking's model had to say this is to combine the following facts about the evaporating black hole and the Hawking radiation in Hawking's model: (…
> The hole itself cannot contain any information other than its mass, charge, and spin... which is far too little information Maybe the information gets encoded in digits of value of mass expressed in some unit. There is enough digits to store any finite number of bits.
> Maybe the information gets encoded in digits of value of mass expressed in some unit.
No, it can't, not all the information. Two objects of the same mass but different internal composition would add the same mass to the hole, but would be described by different information. So the hole can't store in the value of its mass which of the two objects fell in.
More generally, a hole of, say, ten Solar masses could have gotten that mass by an infinite number of possible combinations of things falling in. The mass itself can't distinguish between any of those possibilities; all it can tell you is that ten Solar masses total of stuff fell in.
Re: The Black Hole information loss problem is unsolvable
#75Earlier quoted context omitted.
> The hole itself cannot contain any information other than its mass, charge, and spin... which is far too little information Maybe the information gets encoded in digits of value of mass expressed in some unit. There is enough digits to store any finite number of bits.
Sure, and the point of this video is that while that may be _mathematically and theoretically_ sound, there's no way you can realistically make any measurements or any observations to confirm or deny your particular idea. What we have a lot of these ideas, with no way to discern between theories which accurately represent nature and theories which are merely mathematically correct.
> while that may be _mathematically and theoretically_ sound
The particular idea suggested in the GP actually isn't. See my post upthread.
Re: The Black Hole information loss problem is unsolvable
#76> And without data, the question is not which solution to the problem is correct, but which one you like best. I think this is correct to some extent, ultimately unavoidable, and some assumptions can be "inferred" as more reasonable than others, even in the absence of falsification. By Sabine's stance, the problem of induction [0] hasn't been "solved" because we actually have no reason to assume that past events are…
> By Sabine's stance, the problem of induction [0] hasn't been "solved" The "problem" of induction is a different kind of problem from the black hole information loss problem. Induction can't be tested against experimental data. Induction isn't a testable hypothesis; it's a strategy we have no choice but to adopt if we want to plan for the future at all. So there is no "problem" of induction at all: it's just somethi…
The problem if induction attacks the idea of experiments leading to anything meaningful.
Re: The Black Hole information loss problem is unsolvable
#77Earlier quoted context omitted.
> The information isn't gone, its right -there- in the black hole No, it isn't; it hits the singularity inside of the hole and gets destroyed. At least, that's what Hawking's original model, the one he used to predict that black holes evaporate, says. One way of seeing why Hawking's model had to say this is to combine the following facts about the evaporating black hole and the Hawking radiation in Hawking's model: (…
> The hole itself cannot contain any information other than its mass, charge, and spin... which is far too little information Maybe the information gets encoded in digits of value of mass expressed in some unit. There is enough digits to store any finite number of bits.
Imagine a 2t object falls into the hole and then a 3t object. Can that be differentiated than what would have happened had there been only one 5t object using mass alone?
Only if mass conservation is broken, and current theory does not predict this (where does the extra mass go to?). Same applies for the other 'no-hair' theorem properties - spin and charge.
Re: The Black Hole information loss problem is unsolvable
#78> And without data, the question is not which solution to the problem is correct, but which one you like best. I think this is correct to some extent, ultimately unavoidable, and some assumptions can be "inferred" as more reasonable than others, even in the absence of falsification. By Sabine's stance, the problem of induction [0] hasn't been "solved" because we actually have no reason to assume that past events are…
> By Sabine's stance, the problem of induction [0] hasn't been "solved" The "problem" of induction is a different kind of problem from the black hole information loss problem. Induction can't be tested against experimental data. Induction isn't a testable hypothesis; it's a strategy we have no choice but to adopt if we want to plan for the future at all. So there is no "problem" of induction at all: it's just somethi…
My point is that there are always going to be equally possible alternative theories which make any problem "unsolvable".
I could make a theory that says that gravity works exactly as we think it does, except in about 1000 years will cease to function entirely - and that theory would be equally consistent with observation. I would be equally correct in saying that we do not yet posses the technology (time travel) to falsify this theory.
We have to rely on some sort of proxy for the simplicity or elegance of the theory in order to preclude hypotheses like the above. If we find an elegant solution to the BHIP that uses existing QM + GR (which are empirically verified), then that seems like a pretty good resolution even if it can't be observationally verified directly at a black hole yet.
Re: The Black Hole information loss problem is unsolvable
#79The most recent podcast for Star Talk Radio ( https://www.startalkradio.net ) which, admittingly is much more of a layman's level than deep science, was about black holes.
One of the topics covered in https://www.startalkradio.net/show/cosmic-queries-black-hole... was about the debate on the black hole information loss problem.
Re: The Black Hole information loss problem is unsolvable
#80Original result discussed on Sean Carroll's podcast, Mindscape:
https://www.preposterousuniverse.com/podcast/2020/09/21/115-...
He seems a little non-committal if not skeptical.
One telling exchange near the end regarding the gravitational path integral they used:
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"1:18:41 SC: And there is this trick that you can introduce, ’cause what you’re supposed to do is say, well, integrate up all of the spacetimes that match on to this particular wave function you’re looking at. But the trick is, instead of integrating all the four-dimensional spacetimes that match on to this condition you’re looking at, you can just say, well, I’m going to integrate over all four dimensional spaces, so I’m going to forget about spacetime. I’m just going to do what we call the Euclidean path integral because Euclid just talked about space, not time. And…
1:19:13 NE: Oh, you went there. [laughter]
1:19:15 SC: I did, I did. This is where I’m going. And so it was sort of like you could justify… It’s a trick. It’s a mathematical trick. And it’s very rigorously justifiable in certain simple cases in quantum mechanics, and it certainly has the smell of being correct in certain more subtle cases in quantum field theory. In quantum gravity, what they were doing with it, it just seemed to be a trick so they could get a finite answer at the end of the day, and it was very unclear why it had anything to do with the real world, but they suggested it did. Maybe they were right. And since then, I think we’ve become a little more comfortable with the idea that we can use this trick of calculating quantum gravity wave functions by integrating over the Euclidean path integral, the set of all the spaces that end up looking like what we want, instead of all the spacetimes that look like what we want.
1:20:05 NE: Yes.
1:20:05 SC: And that’s what you’re doing, isn’t it? That’s the kind of wormholes that you’re invoking.
1:20:09 NE: Yes, right. That’s what I was trying to sweep under the rug.
1:20:11 SC: I know. [laughter] And you were right to do so, but I just like to live dangerously here.
[chuckle]
1:20:18 SC: So Lenny and Juan have wormholes that are literally good old in spacetime wormholes, and you have wormholes that are in these fake Euclidean spaces that you used to calculate the entropy.
1:20:29 NE: That’s exactly right. Yeah, that’s exactly right. And these fake Euclidean spacetimes have more boundaries. There are more edges than our original spacetime, which means that these wormholes are connecting these… More edges than we have in our original spacetime, and therefore, it’s difficult to make sense of them in terms of the original spacetime that we’ve started with."
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