Nematic world crystal model of gravity explaining absence of torsion in spacetime

We attribute the gravitational interaction between sources of curvature to the world being a crystal which has undergone a quantum phase transition to a nematic phase by a condensation of dislocations. The model explains why spacetime has no observable torsion and predicts the existence of curvature sources in the form of world sheets, albeit with different high-energy properties than those of string models. (C) 2004 Elsevier B.V. All rights reserved.