Bouncing scalar field cosmology in the polymeric minisuperspace picture

TL;DR

This paper explores a classical polymerization approach applied to scalar field cosmology, demonstrating that it produces a bouncing universe model that avoids the big bang singularity, thus mimicking quantum cosmological effects.

Contribution

It introduces a formalism for polymerizing classical variables in cosmology, showing equivalence between operator and symplectic methods, and demonstrates a bouncing universe solution.

Findings

The scale factor exhibits a bounce from contraction to expansion.

Polymerization replaces the big bang singularity with a bounce.

The formalism mimics quantum cosmological signals.

Abstract

We study a cosmological setup consisting of a FRW metric as the background geometry with a massless scalar field in the framework of classical polymerization of a given dynamical system. To do this, we first introduce the polymeric representation of the quantum operators. We then extend the corresponding process to reach a transformation which maps any classical variable to its polymeric counterpart. It is shown that such a formalism has also an analogue in terms of the symplectic structure, i.e., instead of applying polymerization to the classical Hamiltonian to arrive its polymeric form, one can use a new set of variables in terms of which Hamiltonian retains its form but now the corresponding symplectic structure gets a new deformed functional form. We show that these two methods are equivalent and by applying of them to the scalar field FRW cosmology see that the resulting scale factor exhibits a bouncing behavior from a contraction phase to an expanding era. Since the replacing of the big bang singularity by a bouncing behavior is one of the most important predictions of the quantum cosmological theories, we may claim that our polymerized classical model brings with itself some signals from quantum theory.