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. pixl97 · 1790356895 · focus · HN ↗

         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?

         1. nine_k · 1790358170 · focus · HN ↗

            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.

            1. GoblinSlayer · 1790415383 · focus · HN ↗

               At Planck scale it becomes a big particle, and such particles are known to be unstable and quickly decay.

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