Origin of a classical space in guantum cosmologies

TL;DR

This paper investigates how vector fields influence the emergence of classical space in quantum cosmologies, showing that they can eliminate the initial compactification stage in multidimensional models.

Contribution

It demonstrates that vector fields significantly affect the classical-quantum transition and compactification in multidimensional quantum cosmological models, using the Bianchi-I framework.

Findings

Classical space emerges when horizon size reaches a characteristic scale.

Vector fields remove the initial compactification stage in multidimensional models.

Features of classical-quantum transition are captured within the Bianchi-I model.

Abstract

The influence of vector fields on the origin of a classical space in quantum cosmologies and on the possible compactification process in multidimensional gravity is investigated. It is shown that all general features of the transition between classical and quantum regimes of the evolution can be obtained within the simplest Bianchi-I model for arbitrary number of dimensions. It is shown that the classical space appears when the horizon size reaches the smallest of characteristic scales (the characteristic scale of inhomogeneity or a scale associated with vector fields). In multidimensional case the presence of vector fields completely removes the initial stage of the compactification process which takes place in the case of vacuum models.