On Bianchi type VI$_0$ spacetimes with orthogonal perfect fluid matter

We study the asymptotic behaviour of Bianchi type VI$_0$ spacetimes with orthogonal perfect fluid matter satisfying Einstein's equations. In particular, we prove a conjecture due to Wainwright about the initial singularity of such spacetimes. Using the expansion-normalized variables of Wainwright-Hsu, we demonstrate that for a generic solution the initial singularity is vacuum dominated, anisotropic and silent. In addition, by employing known results on Bianchi backgrounds, we obtain convergence results on the asymptotics of solutions to the Klein-Gordon equation on all backgrounds of this type, except for one specific case.