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Self-dual Black Holes in LQG: Theory and Phenomenology: (title of the article)

  1. May 21, 2009 #1

    MTd2

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    http://arxiv.org/abs/0905.3170

    In this paper we have recalled the semiclassical metric obtained from a classical analysis of the loop quantum black hole (LQBH). We show that the regular Reissner-Nordstrom-like metric is self-dual in the sense of T-duality: the form of the metric obtained in Loop quantum Gravity (LQG) is invariant under the exchange "r <-> a0/r" where "a0" is proportional to the minimum area in LQG and "r" is the standard Schwarzschild radial coordinate at asymptotic infinity. Of particular interest, the symmetry imposes that if an observer at "r" close to infinity sees a black hole of mass "m" an observer in the other asymptotic infinity beyond the horizon (at "r" close to "0") sees a dual mass "mp/m" ("mp" is the Planck mass). We then show that small LQBH are stable and could be a component of dark matter. Ultra-light LQBHs created shortly after the Big Bang would now have a mass of approximately "10^(-5) mp" and emit radiation with a typical energy of about 10^(13) - 10^(14) eV but they would also emit cosmic rays of much higher energies, albeit few of them. If these small LQBHs form a majority of the dark matter of the Milky Way's Halo, the production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultra light black holes would be compatible with the observed rate of the Auger detector.

    *******


    This is arguably the best phenomenological LQG article I've ever seen. It brings in extremely bold predictions for LQG, specialy when it comes to Black Hole remains from the big bang, and the dark matter. In fact in this case, these black holes are stable particles, whose size depends on the ambient temperature, in general, the CMB. This is interesting because this is the 1st time that I see particles emerge from gravity.

    Also, it seems the first time that I see the possibility of particles in general emerging from LQG, and also, interstingly, they are duals to black hole. It seems LQG is finally showing signs of carrying other fields, and suprisigly, it seems related to the old programme of geometrodynamics.
     
    Last edited: May 21, 2009
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  3. May 21, 2009 #2
    These micro-blackholes as WIMP's sounds like geons in geometrodynamics.

    What would happen if these LQBH collide?
     
    Last edited: May 21, 2009
  4. May 21, 2009 #3

    MTd2

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    If they are slow, they will probably coalesce, emit some energy, and go to the same value of an usual on CMB... I guess.

    But when it comes for geons, I guess you can say that section II.B offers a better perspective on the whole thing.
     
  5. May 21, 2009 #4
    I like the "minimal" idea of 4D + SM (NO SUSY) WIMP = LQBH

    If they coalese, and they then meet normal matter, would that be absorbed as well as classical BH do?
     
  6. May 21, 2009 #5

    MTd2

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    Yes, I was thinking about that yesterday. I guess so, but they would enter in equilibrium as soon as possible. I guess a better picture of these black holes it is that they behave like a rubber balloon with holes, in which the bigger it is the imput the matter/energy, the bigger they get, but also they expel more.

    Heh, this thing makes me think about Louise Riofrio's idea that every major celestial body has a little blackhole inside. I never took that seriously, but now...

    And where is Marcus, damn it!

    BTW, I like the idea of just space with no fields. Just gravity + quantum mechanics, with some odd gravitational obstructions, yielding fields at a low energy limit.
     
  7. May 21, 2009 #6
    Classical BH are just that classical and obey no-hair theorem.

    I wonder if "quantum" BH follows quantum rules like heisenberg uncertainty principle, Pauli exclusion principle, perhaps conservation of baryon number, etc.

    Neutrons, after all, don't stick to one another even though they, unlike 2 protons, have no repulsive electrical charge.
     
  8. May 21, 2009 #7

    MTd2

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    Notice that this is just a limit from LQG that showed this kind of duality. But I would love to see that they can indeed emulate quantum fields.
     
  9. May 22, 2009 #8

    marcus

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    I've been watching the video of Modesto's January 2009 Perimeter seminar talk about the LQ black hole.
    http://pirsa.org/09010024/

    Thanks for spotlighting the paper. If it stands up to review, it could be important because of the high energy cosmic ray phenomenology and above all because it provides another interesting (possibly testable) idea about the makeup of dark matter.
     
    Last edited: May 23, 2009
  10. May 22, 2009 #9

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    Marcus, this is not what made me excited about the paper. I would like if you to say something about section II.B. It seems to me that LQG can be used as a TOE.
     
  11. May 22, 2009 #10
    What makes this approach more promising than the earlier Bilson Sundance preon braiding promoted several years prior?
     
  12. May 22, 2009 #11

    MTd2

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    I don't think there is any approach yet, but just an indication that there might be something very deep happening in there, that is, because since you've got particles, maybe fields or something else will come later.

    But I've been thinking on what would happen if you braided connections... like they were preons. Or at least, strings made of correlated points, that is, a "phonon" in LQG would be like braids.
     
  13. May 23, 2009 #12
    Personally I"m skeptical that a "twisting" of spin networks on the planck scale could give rise to particles at 100gev scale.
     
  14. May 23, 2009 #13

    MTd2

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    I wasnt thinking about spin networks or dark matter, but any kind of particle from LQG quantum correlation. More specifcaly, I was thinking that aproximating LGG by a lattice would eventualy lead to braids in the form of strings, pretty much like phonons arise.
     
  15. May 23, 2009 #14

    marcus

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    Just want to remind folks of the context
    The main content of the paper regarding quantum black hole structure was already presented in that January talk, given to a mixed crowd of string and non-string QG people.

    Everybody here probably knows of Herman Verlinde (Princeton, string) and Sami Mathur (Ohio, string). They were both asking LM a lot of questions. Also Raphael Sorkin, Lee Smolin, Laurent Freidel took part in the discussion.

    The workshop ("Black Holes and Quantum Physics") was organized by Verlinde and two Perimeter string-practitioners: Robert Myers and Jaume Gomis. It went on for several days in January.

    Also in the audience was Premont-Schwarz who subsequently joined in and co-authored the May 2009 paper that we are discussing.
    ==================

    If you want something to compare your own impressions of the paper with, I don't know of anything better than watching and listening how LM presents the fundamental (and extremely new) ideas, and how the mixed stringer and quantum graviter audience reacts. What questions they ask, what the response is, and so forth.

    Here are the videos from the whole workshop:
    http://pirsa.org/C09002
    BTW I see that Bee Hossenfelder gave a talk at the workshop. It was about the black hole paper that she just co-authored with Lee Smolin.
    http://arxiv.org/abs/0901.3156
    Conservative solutions to the black hole information problem
    I don't see that it bears on the Modesto/Premont-Schwarz paper we are discussing, so I just mention it in passing.
     
    Last edited: May 24, 2009
  16. May 29, 2009 #15

    MTd2

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    I must see that, I will think about it.
     
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