The question is whether I am naive to suppose that either GR or LQG predicts new universes. I have also posted essentialy the same question (and post) in the Steller Astrophysics forum.(adsbygoogle = window.adsbygoogle || []).push({});

Martin Bojowald has removed the singularities from GR using LQG.

See http://xxx.lanl.gov/abs/gr-qc/0312045. According to Coule, Bojo's model leads to baby universes. (That seems to be his nickname)

Being non-expert in GR, I am intrigued by a recent series of three papers on black holes in which new universes are seemingly predicted on the basis of GR:

http://www.arxiv.org/abs/gr-qc/0411060

Title: The river model of black holes

Authors: Andrew J. S. Hamilton, Jason P. Lisle (JILA, U. Colorado)

http://www.arxiv.org/abs/gr-qc/0411061

Title: Inside charged black holes I. Baryons

Authors: Andrew J. S. Hamilton, Scott E. Pollack (JILA, U. Colorado)

http://www.arxiv.org/abs/gr-qc/0411062

Title: Inside charged black holes II. Baryons plus dark matter

Authors: Andrew J. S. Hamilton, Scott E. Pollack (JILA, U. Colorado)

In the first, space is flowing into the spherical black hole. At the event horizon, space inflow is at the speed of light so light cannot escape. If the black hole does not rotate, the River Flow model predicts, incorrectly as the first paper claims, that space drops through the Cauchy horizon and expands into a new universe. The reader is referred to the second paper for a correct prediction.

In paper two with charged baryonic matter inflow, along with space, the charged baryons either plunge directly into the central singularity if the black hole is uncharged, or if charged they are repelled by the charge on the singularity, become outgoing and pass through the outgoing inner horizon, namely the Cauchy horizon. No mention of a new universe on the other side in this paper. Also no mass inflation so this solution is also presumably incorrect.

The correct solution is found in paper three where the outgoing, repelled baryons encounter an incoming flow of dark matter which leads to exponential mass inflation. The claim is that after mass inflation ceases, the outgoing baryons become ingoing and plunge to the spacelike singularity at zero radius, except when the baryons completely absorb the inflowing dark matter. In that case the baryons pass through the Cauchy horizon (again no mention of a new universe).

Now what intriques me in all this is the prospect of predicting a new universe from GR. Is it correct to assume that whenever the Cauchy horizon is passed through, that a new universe is entered??? And that this may happen whenever counterstreaming ceases?

Now what is even more intriquing is the relationship of these solutions to Bojowald's treatment of the spacelike singularity at zero radius using Loop Quantum Gravity (LQG).

Counterstreaming certainly ceases in the singularity. Perhaps the physics captured by the LQG approximate model is essentially what Hamilton has also found outside the singularity, where GR is applicable.

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# New universe predictions by GR and LQG

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