Thread

1. haitchfivee · 1790354524 · focus · HN ↗

   My nitpick is with something the author said in passing about Hawking. Yes, around 1970 Hawking and the scientific community at large still used to believe nothing could escape a black hole, and between 1971 and 1973 Hawking along with Penrose and others expanded their evolving understanding and consequences of of Albert Einstein's breakthrough work.

   But then Hawking argued back the opposite case, which in simple terms means that some things can, indeed, escape an event horizon. In fact, name dropping Hawking just to mention his views as they stood before his 1973 work, and his 1974 model of Hawking radiation seems dangerously incomplete journalistic reporting.

   In 1974 Hawking formulated what we now know as Hawking Radiation, which is the *exact opposite* of what was previously believed about the impossibility of anything coming back from a black hole. Whilst still not conclusively proven as a physical fact, this did win him the Special Fundamental Physics Prize in 2013. specifically for his discovery of Hawking radiation from black holes and his deep contributions to quantum gravity and quantum aspects of the early universe.

   1. Maxatar · 1790356614 · focus · HN ↗

      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).

      1. wormius · 1790362015 · focus · HN ↗

         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 :)

         1. cyberax · 1790373447 · focus · HN ↗

            > 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.

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