From: carlip@physics.ucdavis.edu   
      
   On 2/24/17 4:12 AM, stargene wrote:   
      
   [...]   
   > Regardless of any particular interpretation of the mechanism of   
   > Hawking's well-known radiation at the actual event horizon, my question   
   > still stands (at least for me!)   
      
   > Ie: Can there be a sort of poor man's version of HR, however weak,   
   > simply due to the extremely steep potential gradient, which would exist   
   > at a tiny distance r=10^-7 m, say, from the collapsar's surface, even   
   > before it's surface precisely matches the r_s or Schwarzschild radius   
   > for that given mass M, a fraction of a second later??   
      
   This question, or at least something like it, is addressed by Barcelo   
   et al., arxiv.org/abs/1011.5593, or for an earlier variation with   
   condensed matter analogs, arxiv.org/abs/gr-qc/0607008.  The answer   
   (if I'm understanding the question right) is that you don't need a   
   horizon to form in order to have Hawking radiation, but you do need   
   exponential "peeling" of geodesics, which basically requires an   
   exponentially large blue shift as a light ray approaches the surface.   
      
   Steve Carlip   
      
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