Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Black Hole information loss problem is unsolvable

backreaction.blogspot.com

Post reply on HN
Print view View original

21–30 of 143 posts

Re: The Black Hole information loss problem is unsolvable

#21

Post by whimsicalism »

pjungwir wrote: post #18

As 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?

Basically.. and this is somewhat lay: in quantum mechanics, there is fundamental randomness. Part of that randomness means that in space, virtual pairs of particles can be formed right at the barrier between being able to escape and not escape.

Normally, these particles annihilate each other - however if one crosses the threshold and is not able to escape, it can't annihilate the other particle and that escapes as radiation.

Re: The Black Hole information loss problem is unsolvable

#23

Post by colejohnson66 »

whimsicalism wrote: post #21
pjungwir wrote: post #18

As 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?

Basically.. and this is somewhat lay: in quantum mechanics, there is fundamental randomness. Part of that randomness means that in space, virtual pairs of particles can be formed right at the barrier between being able to escape and not escape. Normally, these particles annihilate each other - however if one crosses the threshold and is not able to escape, it can't annihilate the other particle and that escapes as ra…

So similar to “anti particles”?

Re: The Black Hole information loss problem is unsolvable

#24

Post by adzm »

pjungwir wrote: post #18

As 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?

This is Hawking radiation, which I'm sure wikipedia can explain better than me: https://en.wikipedia.org/wiki/Hawking_radiation

> A pair of virtual waves/particles arises just beyond the event horizon due to ordinary quantum effects. Very close to the event horizon, these always manifest as a pair of photons. It may happen that one of these photons passes beyond the event horizon, while the other escapes into the wider universe ("to infinity"). A close analysis shows that the exponential redshifting effect of extreme gravity very close to the event horizon almost tears the escaping photon apart, and in addition very slightly amplifies it. The amplification gives rise to a "partner wave", which carries negative energy and passes through the event horizon, where it remains trapped, reducing the total energy of the black hole. The escaping photon adds an equal amount of positive energy to the wider universe outside the black hole. In this way, no matter or energy ever actually leaves the black hole itself. A conservation law exists for the partner wave, which in theory shows that the emissions comprise an exact black body spectrum, bearing no information about the interior conditions.

Re: The Black Hole information loss problem is unsolvable

#25

Post by saiya-jin »

pjungwir wrote: post #18

As 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?

Yes its about matter-antimatter (or different spin?) particles forming spontaneously from energy on the edge of event horizon, one falling in and another escaping.

At least that's my super-layman recollection, a lot of space to be wrong in that 1 sentence.

Re: The Black Hole information loss problem is unsolvable

#26

Post by BobbyJo »

pjungwir wrote: post #18

As 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?

It kind of doesn't. Stuff doesn't actually 'escape' a black hole to form Hawking radiation, rather, negative stuff goes in.

Photon pairs form in the vacuum all the time. When a pair forms at the event horizon of a black hole, it rips the pair apart. Half falls in, and half shoots out into space. The half the falls in, through the effect that rips the pair apart, winds up with negative energy, lowering the energy level of the black hole.

Re: The Black Hole information loss problem is unsolvable

#27

Post by c1ccccc1 »

So this new result is derived semiclassically, right? Which means it was derived using more or less the same assumptions Hawking used to derive Hawking radiation. So couldn't the same objection be made about the claim that black holes evaporate at all? After all, we also have no empirical data about that, and likely won't have such data for a long long time.

Re: The Black Hole information loss problem is unsolvable

#28

Post by sterlind »

Not a physicist, but Hossenfelder didn't clarify well that, unlike previous proposed solutions, this one only relies on standard quantum mechanics and general relativity, not strings or LQG. Similar in spirit to Hawking's original approach, which she did mention.

She seems to have a beef with extrapolating (even well-accepted) math, rather than doing experiments. But this kind of work clarifies where the theories clash and break down, how they can work together, maybe even testable predictions.

I wonder if she would have been critical of the Casimir effect, back when it was thought to be untestable.

Re: The Black Hole information loss problem is unsolvable

#29

Post by pontus »

I think this approach is a bit disingenuous. Her claim is that since we can't directly observe black hole evaporation, we can't know which mathematical model is "correct" in describing the phenomenon and that we're therefore just left with picking the explanation that we personally like the best.

This same argument can be made about a ton of things. For example, we have yet to observe free quarks directly (due to confinement in QCD), but I don't think people are saying that the quarks model is just the one that we happen to find most pleasing. The reason we are confident in the quarks model is because it makes all sort of other predictions that we can confirm.

Who is to say that the various ways of resolving the BH information paradox are indistinguishable simply because we can't observe the evaporation directly? Maybe they make other predictions as well.

Generally, I think that we need to be skeptical of various speculative ideas and in many ways we have strayed off course for a while in theoretical physics, but I don't think the answer is to just explore topics and theories that are completely grounded in observations and experiments.

Re: The Black Hole information loss problem is unsolvable

#30

Post by db48x »

colejohnson66 wrote: post #23
whimsicalism wrote: post #21

Earlier quoted context omitted.

Basically.. and this is somewhat lay: in quantum mechanics, there is fundamental randomness. Part of that randomness means that in space, virtual pairs of particles can be formed right at the barrier between being able to escape and not escape. Normally, these particles annihilate each other - however if one crosses the threshold and is not able to escape, it can't annihilate the other particle and that escapes as ra…

So similar to “anti particles”?

No, even anti-matter particles have positive mass. Thus they make a black hole larger when they are absorbed.
Post reply on HN