- #1

MTd2

Gold Member

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## Main Question or Discussion Point

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.

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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.

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.

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