Repulsive gravity at high density in loop quantum cosmology

[marcus]

Here are 109 articles (or books)
http://arxiv.org/cits/gr-qc/0102069?skip=75&db=spires
which all cite Bojowald's landmark paper where he determined that in Loop cosmology gravity REPELS at very high density. Here is the orig:
http://arxiv.org/gr-qc/0102069

the original paper dealt with an isotropic case (the analysis was simplified by making things uniform or symmetric) but since then people have extended the result, assuming less and less, to make it more general.

AFAICS this has no direct connection with the "anti-gravitation" that Sabine H is discussing in her thread of that name. But maybe it is an amusing coincidence.

In any case there is a considerable literature now which takes seriously the possibility that the effect of gravity reverses at very high density, and becomes repellent.
Bojowald, Singh, and others have modeled stellar-size collapse in some detail and Singh has proposed that the model may have an observable signature which can be sought in GRBs.

In any case reversed gravity is a feature of the LQC model, which has the correct classical limit and is currently being studied for observational testing.

 

[hossi]

Hi marcus,

that is indeed interesting! I guess the interest in such behaviour is strongly supported by the cosmological puzzles, in the first line the dark energy/dark matter problems, which indicate that we are really missing something important. That - among other things - is a reason why I think experimental focus will probably shift away from colliders and towards astro/cosmology.

B.

 

[marcus]

Hi marcus,

that is indeed interesting!

I am delighted by your interest. If you ever want to pursue the phenomenology of (loop) quantum gravity stellar collapse, let me know and I will dig up a paper or two by Parampreet Singh or an online seminar talk----something that you might find usable.