Big-bounce cosmology from quantum gravity: The case of a cyclical Bianchi I universe

TL;DR

This paper explores a quantum cosmological model where a Big-Bounce replaces the classical singularity, demonstrating a cyclic universe scenario in Bianchi I and extending insights to Bianchi IX models, with implications for quantum gravity.

Contribution

It introduces a quantum cosmological framework that removes singularities and supports a cyclic universe, linking dust energy density, quantum effects, and polymer discretization.

Findings

Classical singularity is removed with positive dust energy density.

Quantum Big-Bounce connects to universe turning point semiclassically.

Scenario extends to Bianchi IX, suggesting a generic cosmological paradigm.

Abstract

We analyse the classical and quantum dynamics of a Bianchi I model in the presence of a small negative cosmological constant characterizing its evolution in term of the dust-time dualism. We demonstrate that in a canonical metric approach, the cosmological singularity is removed in correspondence to a positive defined value of the dust energy density. Furthermore, the quantum Big-Bounce is connected to the Universe turning point via a well-defined semiclassical limit. Then we can reliably infer that the proposed scenario is compatible with a cyclical Universe picture. We also show how, when the contribution of the dust energy density is sufficiently high, the proposed scenario can be extended to the Bianchi IX cosmology and therefore how it can be regarded as a paradigm for the generic cosmological model. Finally, we investigate the origin of the observed cut-off on the cosmological dynamics, demonstrating how the Big-Bounce evolution can be mimicked by the same semiclassical scenario, where the negative cosmological constant is replaced via a polymer discretization of the Universe volume. A direct proportionality law between such two parameters is then established.