Loop quantum cosmology and singularities
Abstract
Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of socalled loop quantum cosmology which concerns symmetryreduced models of quantum gravity. In this paper, the problem of singularities is analysed in the context of the Bohmian formulation of loop quantum cosmology. In this formulation there is an actual metric in addition to the wave function, which evolves stochastically (rather than deterministically as the case of the particle evolution in nonrelativistic Bohmian mechanics). Thus a singularity occurs whenever this actual metric is singular. It is shown that in the loop quantum cosmology for a homogeneous and isotropic FriedmannLemaîtreRobertsonWalker spacetime with arbitrary constant spatial curvature and cosmological constant, coupled to a massless homogeneous scalar field, a big bang or big crunch singularity is never obtained. This should be contrasted with the fact that in the Bohmian formulation of the WheelerDeWitt theory singularities may exist.
 Publication:

Scientific Reports
 Pub Date:
 August 2017
 DOI:
 10.1038/s4159801706616y
 arXiv:
 arXiv:1703.10274
 Bibcode:
 2017NatSR...7.8161S
 Keywords:

 General Relativity and Quantum Cosmology;
 Quantum Physics
 EPrint:
 17 pages, no figures, LaTeX