Interesting theory for consideration: Cosmology with torsion: An alternative to cosmic inflation http://arxiv.org/abs/1007.0587 Nikodem J. Poplawski (Submitted on 4 Jul 2010 (v1), last revised 2 Nov 2010 (this version, v2)) In this work, we considered the ECKS theory of gravity which is the closest theory with torsion to general relativity. We used the spin density of matter as the source of torsion, which has a natural physical interpretation in the context of the Poincar´e group and does not introduce additional ﬁelds or coupling constants.... Wikipedia: [the Einstein–Cartan theory, also known as the Einstein–Cartan–Sciama–Kibble theory or the Cartan–Sciama–Kibble theory is a classical theory of gravitation similar togeneral relativity but relaxing the assumption that the metric be torsion-free. Introducing torsion allows greater freedom to couple classical spin angular momentum to the metric.] Avoidance of singularities http://en.wikipedia.org/wiki/Einstein-Cartan_theory#Avoidance_of_singularities Does string theory offer any additional insights as to how particle spin and space-time geometry interact? edit: somewhere I read that including torsion makes the stress energy momentum tensor non symmetric.....Including torsion is what appears to be the source of the high density repulsion.