Steve Hsu has started a conversation that closely parallels discussion in Loop Quantum Cosmology regarding black hole bounce.(adsbygoogle = window.adsbygoogle || []).push({});

http://infoproc.blogspot.com/2006/08/spacetime-topology-change-and-black.html

http://arxiv.org/abs/hep-th/0608175

http://arxiv.org/abs/gr-qc/9908031

http://arxiv.org/abs/hep-th/0103019

In LQC the equation that replaces the classical Friedman or the Wheeler-DeWitt equations has gravity turn out to be repulsive at high densities and many solutions avoid singularity and exhibit a bounce.

Ashtekar has pointed to evidence that in the LQC model gravitational collapse and re-expansion can connect two large classical regions of spacetime.

http://arxiv.org/abs/gr-qc/0509075 (Class. Quant. Grav.)

A black hole can (at least in some circumstances in the LQC model) produce a new region of the universe. The bounce phenomenon is being studied both analytically and by numerical simulations at Penn State.

http://arxiv.org/abs/gr-qc/0604013 (Phys. Rev. D)

It turns out, in other words, that Martin Bojowald, Abhay Ashtekar, and several collaborators have been making adetailed study of a mechanism by which what Steve Hsu is talking about might actually happen: a quantum gravity mechanism by which a new region of space might expand from the pit of a black hole. This is not something that quantum gravitists put into their model by hand. The bounce phenomenon appeared in a 2001 analysis by Bojowald ("Absence of Singularity in Loop Quantum Cosmology") and a number of LQG papers have been published since then, investigating the subject.

Here is a list of 122 papers which cite Bojowald's original "Absence of Singularity in LQC" paper:

http://arxiv.org/cits/gr-qc/0102069

These things seem to fit rather nicely together and it is noteworthy that Stephen Hsu seems to be coming to it from an entirely different direction. So I want in this thread to look at what his message is and at some of the material he gives links to.

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# Steve Hsu and Loop Gravity's black hole bounce

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