Anisotropy due to Brans-Dicke Theory

TL;DR

This paper explores how Brans-Dicke gravity allows for anisotropic universe models with increasing entropy, addressing limitations of Einstein's theory and explaining certain cosmic microwave background anomalies.

Contribution

It demonstrates that Brans-Dicke theory can support anisotropic, thermodynamically consistent cosmological models, unlike Einstein's gravity.

Findings

Anisotropic models satisfy the dominant energy condition.

Entropy growth is possible in Brans-Dicke cosmology.

Model explains low quadrupole anomaly in WMAP data.

Abstract

It is well known that the viscous Bianchi type-I metric of the Kasner form is not able to describe an anisotropic universe, which satisfies the second law of thermodynamics and the dominant energy condition in Einstein's theory of gravity. We investigate this problem in Brans-Dicke theory of gravity using the Bianchi type-I metric with the perfect fluid. We show that it is possible to have the dominant energy condition and the growth of entropy in this model. Also we apply this model to explain the anomaly concerning the low quadrupole amplitude of the angular power spectrum of the temperature anisotropy observed in WMAP data.