On the Stability of Jordan-Brans-Dicke Static Universe

TL;DR

This paper investigates the stability of the Jordan-Brans-Dicke static universe, finding it can be stable under certain perturbations, which has implications for the universe's initial conditions and early evolution.

Contribution

It extends previous stability analyses of the JBD static universe by including anisotropic perturbations and more general fluids, revealing potential stability unlike in general relativity.

Findings

JBD static universe can be stable against isotropic perturbations

Stability persists with anisotropic Bianchi IX modes

Results suggest a possible stable initial universe state

Abstract

In this work we study the stability of the Jordan-Brans-Dicke (JBD) static universe. This is motivated by the possibility that the universe might have started out in an asymptotically JBD static state, in the context of the so called emergent universe scenario. We extent our previous results on stability of JBD static universe by considering spatially homogeneous Bianchi type IX anisotropic perturbation modes and by including more general perfect fluids. Contrary to general relativity, we have found that the JBD static universe, dominated by a standard perfect fluid, could be stable against isotropic and anisotropic perturbations. The implications of these results for the initial state of the universe and its pre-inflationary evolution are discussed.