Petrov type I silent universes with G3 isometry group: the uniqueness result recovered

TL;DR

This paper revisits the classification of silent universes, confirming that Petrov type I silent universes with a G3 isometry group are uniquely the orthogonally spatially homogeneous Bianchi I models, correcting previous proof errors.

Contribution

The authors provide a new proof confirming the uniqueness of Petrov type I silent universes with G3 isometry, addressing and correcting a conceptual mistake in earlier work.

Findings

Confirmed the uniqueness of Bianchi I models among Petrov type I silent universes with G3 symmetry

Provided a new proof method for the silent universe conjecture in this context

Clarified the conditions under which silent universes are spatially homogeneous

Abstract

The \emph{silent universe conjecture} (Sopuerta 1997, van Elst et al. 1997) states that the only algebraically general silent universes are the orthogonally spatially homogeneous Bianchi I models. In the same paper by Sopuerta this was confirmed for the subcase where the spacetime also admits a group G3 of isometries. However the proof contains a conceptual mistake. We recover the result in a different way.