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Questions about string theory Black hole entropy results

  1. Jul 8, 2010 #1
    Has these results been extended to non-extremel BH?

    Do they work when the cc is +, (deSitter) and where SUSY is strongly broken (like our world)

    Do they work when the background is strongly varying in time, such as two black holes merging?

    They work for extremel black holes that are rotating, rapidly losing or gaining mass or charge? i.e if they calculate using string theory an extremel black hole entropy, what happens to the entropy as the bh becomes more neutral charge?

    Does it offer precise details of hawking radiation, its spectrum and particle content?

    Roger Penrose in Road to Reality and Lee Smolin in TWOP expressed deep skepticism of string theory's derivation of black hole entropy. "I am quite unconvinced" Penrose states plainly in RTR.
    Are there any reasons to be skeptical of this deviation? i.e are a pile of branes really a black hole? is it true they make these calculations with gravity = 0 and no cosmological constant?

    What is the physical interpretation of these results? The microstates are branes? Is the entropy volume-extensive? What are some qualitative physics in the interior beyond event horizon when GR and QM break down.
  2. jcsd
  3. Jul 8, 2010 #2

    Ben Niehoff

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    I am working on this stuff, but I've only just started, so I can't answer questions very well.

    Yes, so far we do calculations where the gravitational coupling is zero. The hope is that the microstate counting remains roughly the same as the coupling is turned on. I'm not familiar with the details of this yet, so I can't comment on the rigor of this idea.

    It does NOT offer precise details of Hawking radiation (I think).

    In the examples I've seen so far, the microstates are configurations of spacetimes (or configurations of branes, which produce different spacetimes). Large classes of solutions (for BPS black holes) can be found where the spacetime is completely regular, with no horizons or singularities. It is thought perhaps that the horizon is an emergent thermodynamic effect (the fuzzball proposal). For non-BPS black holes, the equations become significantly more difficult to solve, so it is an open question whether the same sort of solutions exist in that case.

    As for supersymmetry, right now I am working on some solutions where most SUSY is broken. I don't know if these solutions are extremal or not. I can tell you more when I finish. :)
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