From: g.scholten@nospam.gmx.de   
      
   stargene  wrote:   
      
   > Hi Mark - - Thanks for the response.  I already saw SH's blog page,   
   > and I didn't find it helpful.  Her take on 'true' virtual pair   
   > production near the event horizon is quite different from, say,   
   > Leonard Susskind's, who explicitly writes and lectures about such   
   > virtual pairs popping in and out, within several Planck lengths   
   > (~10^-35 m) of the event horizon itself, for one thing.  I used the   
   > "virtual pair" pedagogy approach, which we usually see, mostly because   
   > I can intuit it more easily than other interpretations.  I also know   
   > that there is still a split between theorists who claim the actual   
   > physicality of virtual particles and theorists who insist that the   
   > presence of 'virtual pairs' in QFT's calculations just reflects an   
   > artifact of the particular mathematical machinery which QFT uses.   
      
   It is very important to note that this "split" is NOT about virtual   
   particles occuring in quantum vacuum, Unruh effect or Hawking radiation,   
   but about something completely different, namely virtual particles as   
   parts of Feynman diagrams that describe interaction processes, e.g.   
   Bhabha-scattering, where an electron and a positron are scattered due to   
   the electromagnetic interaction what is depicted by a virtual photon   
   exchanged between electron and positron in the corresponding Feynman   
   diagram.   
      
   Virtual particles that occur in interaction processes are in fact part   
   of serious physics, more precisely speaking a part of perturbation   
   theory which is an approximation to quantum field theory, focused on   
   scattering processes (the "particular mathematical machinery" you   
   mentioned). Virtual particles in quantum vacuum that are related to   
   Unruh effect and Hawking radiation, on the other hand, can only be found   
   in pop-science descriptions.   
      
      
   > 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??   
      
   As already pointed out in my parallel post, Hawking radiation originates   
   from processes that take place while the collpsar is collapsing. So, one   
   can assume that the first particles of Hawking radiation are already   
   created before the collapsar's surface deceeds the Schwarzschild radius.   
   However, detailed calculations are only known for the Hawking radiation   
   observed in region J+ in this diagram:   
      
   https://picload.org/view/rcacailw/poesselhawkingradiation.png.html   
      
   An observer in this region surely will consider the black hole as   
   already formed.   
      
   --- SoupGate-Win32 v1.05   
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