Loop Quantum Gravity and the Cyclic Universe

TL;DR

This paper explores how loop quantum gravity modifies the dynamics of a cyclic universe, potentially resolving singularities and altering collision behaviors through quantum effects.

Contribution

It demonstrates that loop quantum effects can significantly change the near-collision dynamics in cyclic universe models, especially during the kinetic-dominated collapse era.

Findings

Loop quantum effects can prevent actual brane collision by freezing the scalar field.

Quantum modifications lead to a bounce instead of a singularity in cyclic scenarios.

Near-collision dynamics are dramatically altered by loop quantum friction.

Abstract

Loop quantum gravity introduces strong non-perturbative modifications to the dynamical equations in the semi-classical regime, which are responsible for various novel effects, including resolution of the classical singularity in a Friedman universe. Here we investigate the modifications for the case of a cyclic universe potential, assuming that we can apply the four-dimensional loop quantum formalism within the effective four-dimensional theory of the cyclic scenario. We find that loop quantum effects can dramatically alter the near-collision dynamics of the cyclic scenario. In the kinetic-dominated collapse era, the scalar field is effectively frozen by loop quantum friction, so that the branes approach collision and bounce back without actual collision.