Quantum Isotropization of the Universe

TL;DR

This paper investigates how quantum effects in minisuperspace models with Bianchi I geometries can lead to non-singular, isotropic phases in the universe's evolution, despite classical singularities and anisotropies.

Contribution

It demonstrates that quantum gravitational effects can produce non-singular, isotropic cosmological trajectories in Bianchi I models, even from anisotropic initial conditions.

Findings

Quantum states can lead to non-singular bohmian trajectories.

Quantum effects induce large isotropic phases in anisotropic models.

Results hold even without scalar field presence.

Abstract

We consider minisuperspace models constituted of Bianchi I geometries with a free massless scalar field. The classical solutions are always singular (with the trivial exception of flat space-time), and always anisotropic once they begin anisotropic. When quantizing the system, we obtain the Wheeler-DeWitt equation as a four-dimensional massless Klein-Gordon equation. We show that there are plenty of quantum states whose corresponding bohmian trajectories may be non-singular and/or presenting large isotropic phases, even if they begin anisotropic, due to quantum gravitational effects. As a specific example, we exhibit field plots of bohmian trajectories for the case of gaussian superpositions of plane wave solutions of the Wheeler-DeWitt equation which have those properties. These conclusions are valid even in the absence of the scalar field.