Semiclassical gravitation and quantization for the Bianchi type I universe with large anisotropy

TL;DR

This paper investigates quantum effects on the early universe's anisotropy using semiclassical gravity and quantization, revealing that large anisotropy is less probable and may influence early universe dynamics.

Contribution

It introduces a perturbative approach with zeta-regularization for quantum corrections in anisotropic spacetime and analyzes the impact on early universe evolution.

Findings

Quantum corrections reduce anisotropy over time.

Large anisotropy has lower probability in initial conditions.

Quantum effects influence early universe dynamics.

Abstract

We use a perturbative method to evaluate the effective action of a free scalar field propagating in the Bianchi type I spacetime with large space anisotropy. The zeta- function regularization method is used to evaluate the action to the second order in the Schwinger perturbative formula. As the quantum corrections contain fourth derivative in the metric we apply the method of iterative reduction to reduce it to the second-order form to obtain the self-consistent solution of the semiclassical gravity theory, The reduced Einstein equation shows that the space anisotropy, which will be smoothed out during the evolution of universe, may play an important role in the dynamics of early universe. We quantize the corresponding minisuperspace model to investigate the behavior of the space anisotropy in the initial epoch. From the wavefunction of the Wheeler-DeWitt equation we see that the probability for the Bianchi type I spacetime with large anisotropy is less then that with a small anisotropy.