When referring to Hawking radiation I often see the example of a particle-antiparticle pair which become separated by the event horizon boundary with one half of the pair remaining outside and the other being part of the black hole. I began to wonder what happens to the particle which remains "inside" the black hole. Since we cannot make any observations how do we form ideas about these kind of things?

  • $\begingroup$ @safesphere - Right. So if a pair separates at the event horizon we can then only ever speak about the "observable" one since the fate of the other actually becomes "unknowable"? $\endgroup$ – Wookie Dec 4 '19 at 11:24
  • $\begingroup$ @safesphere - Thank you - "in our view of the world nothing ever crosses the horizon" - I can accept that and even that a black hole can grow if matter becomes smeared across the horizon. I was a little confused because I only understand General Relativity in terms of reference frames. So I was imagining that even though for us the particle becomes frozen in time, in its own frame of reference time passes "normally". BUT if the only phenomena inside the BH are those left from the time of it's creation that is a new perspective for me and one I will work with. $\endgroup$ – Wookie Dec 5 '19 at 10:59
  • $\begingroup$ @safesphere - so that is the apparent paradox about matter falling into black holes - to the outside observer measuring time the result is "infinite". May I please ask though ... since you write "If things do cross (a big "if")" what is your definition of the fate of matter coming too close to a black hole? (P.S. I am going to edit the question now so it does make a little more sense hopefully) $\endgroup$ – Wookie Dec 7 '19 at 17:55
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    $\begingroup$ The logic of rossing the horizon is not rigorous and can be shown to be flawed. Still it is the mainstream view repeated in most relativity textbooks, so I won't debunk it in a comment. The important part is that that this makes no difference to any observers outside the horizon. All of them see all fallen matter frozen forever at the horizon. Please note that "see" and "frozen" here are just figures of speech. In reality, the fallen matter practically disappears and becomes virtually undetectable other than by the total mass, charge, and spin. $\endgroup$ – safesphere Dec 7 '19 at 18:28

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