There are many puzzles unsolved in black hole physics. Beyond the issue of information paradox, related to this question we have the nature of the event horizon from a classical (if any!) viewpoint. It is clear from known arguments that the event horizon SINGULARITY is only an apparent one. And though, the event horizon (its position at R=2GM/c²) plays a distinguished role in black hole physics. The event horizon radius fixes the surface gravity that is the analogue of the temperature in thermodynamics. The event horizon position is also relevant in stability and photon sphere calculations. From the pure Schwarzschild solution, the event horizon is stationary and static, as far as I know. However, even when Hawking radiation does NOT origin in the event horizon, the event horizon plays yet a role as ruler. Now, enter quantum mechanics. Position of the event horizon can not BE static or stationary if we include the quantum effects, after all, Hawking radiation makes black holes to loose mass (give up the information paradox at this point). Thus, should we accept that the event horizon is NOT a well defined concept in quantum mechanics? Or at least, it seems that the notion of static and stationary changes in the quantum realm. Since, how can a classical symmetric stationary vacuum solution have a MOVING surface of "stuff"?

  • 2
    $\begingroup$ 1 The event horizon of a black hole is a mathematical surface, it's not a shell of stuff. 2 Please consider breaking that wall of text into paragraphs. $\endgroup$
    – PM 2Ring
    Mar 29, 2018 at 6:08
  • $\begingroup$ What is your question? The title one, or the last one in the text? $\endgroup$ Mar 29, 2018 at 8:42


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