Comment by Maxatar
1 day ago
Not sure I follow your comment exactly, perhaps I am misunderstanding it but Hawking radiation doesn't involve anything escaping a black hole.
The radiation never originates from within the event horizon. Furthermore the radiation itself does not encode any information about what fell into the black hole apart from the electric charge, angular momentum, and mass (all of which must remain conserved).
It's been ages since I read it and I am 99% sure I'm remember horribly wrong, but I was thinking it's something like this? Also - your "the only information" is precisely what we can measure of quantum states, so information is still preserved. That's more a limit of what we know?
I think that with Hawking radiation you have quantum entanglement of two pairs. You have a matter-antimatter pair production near the horizon. When the antimatter falls into the blackhole without being destroyed via mutual annihilation, the matter particle at the boundary now "radiates" away. HOWEVER.
The matter inside boundary which the anti-matter DOES interact with is destroyed, and the information of that interaction is is "passed" to the outside via the the anti-matter's entanglement with its co-created pair.
Something like that, isn't it? Please any physicists clarify :)
> I think that with Hawking radiation you have quantum entanglement of two pairs. You have a matter-antimatter pair production near the horizon. When the antimatter falls into the blackhole without being destroyed via mutual annihilation, the matter particle at the boundary now "radiates" away. HOWEVER.
That's not how Hawking radiation actually works. It's just a "lies-to-the-children" explanation. Antiparticles have positive mass, so the black hole would be _growing_ as a result. This mechanism also violates the equivalency principle, as you shouldn't be able to detect the event horizon with only local observations.
Reality is more interesting. In flat space, the ground state of quantum fields is actually non-zero. But black holes "bias" the fields in such a way that their ground state becomes _negative_ from the viewpoint of a remote observer.
This in turn permits it to create new particles from just nothing. This in turn adds _negative_ energy to that space, resulting in the black hole decreasing in mass.
But crucially, the event horizon itself is NOT involved. Particle creation can happen anywhere in the vicinity of the black hole, not just on the event horizon.
The only caveat that I'd ask about is the death of a black hole after it evaporates away too much mass. If that explosion does occur, is that matter/energy that was from inside the singularity itself?
AFAICT nobody has a consistent theory proven by observations. Some theories offer an explosion in which the singularity vanishes, but this has trouble with information / entropy. Some say a microscopic remnant stops radiating because the original assumptions of Hawking radiation mechanism do not apply at near-Planck scale. Some say that as the curvature grows with the diameter shrinking, the black hole pops off from "our" spacetime and forms a parallel universe, without an explosion.
The current age of the Universe is way small compared to the time needed for evaporation, so observing anything like that happening (or not) is hardly possible.
At Planck scale it becomes a big particle, and such particles are known to be unstable and quickly decay.
Indeed All Hawking radiation takes from a black hole is some mass. It's a bit like radiation resulting from annihilation of matter and antimatter: it does not "escape", it "gets born" in the process.
I'm not sure that is a meaningful distinction. All a black hole _is_, is mass. If you take away the mass, you are taking away the black hole.
It's also information / entropy, hence the https://en.wikipedia.org/wiki/Black_hole_information_paradox
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I don't know the slightest about this but... That list looks like it is supposed to be limited but that sounds like infinitely more information than zero?
>> Not sure I follow your comment exactly, perhaps I am misunderstanding it but Hawking radiation doesn't involve anything escaping a black hole.
>> The radiation never originates from within the event horizon. Furthermore the radiation itself does not encode any information about what fell into the black hole apart from the electric charge, angular momentum, and mass (all of which must remain conserved).
> I don't know the slightest about this but... That list looks like it is supposed to be limited but that sounds like infinitely more information than zero?
I don't know about electric charge, but can't you observe mass and angular momentum of a black hole from outside? I think the "no information" thing means the Hawking radiation won't let you tell you if the black hole was made from a dead star or just a really big pile of meat or what's going on inside of it.
IIRC, all Hawking radiation does is provide a mechanism for a black hole to eventually decay.
Hawkings radiation doesn't tell you anything about the contents of the black hole, just that it lost energy/mass. That reduces the event horizon, so there is now a (miniscule) amount of space that has become "visible". It'll be empty space, no extra mass is leaked in that way.
The entire blackhole will eventually evaporate, so yes it is literally escaping from the black hole.
We can play with words all day, but in the sense of a particle entering into the event horizon of a black hole and then at some point in the future exiting from inside of the event horizon, that simply never happens and Hawking radiation does not propose that.