The metric proposed in the paper obviously doesn't exhibit time-symmetry, since the terms in the metric are dependent on the co-ordinate time, e.g. the time-dilation factor is equal to \(1/R(t)\) if we ignore the \(d\Sigma\) term. I don't think this is a very elegant result, but nevertheless, I'm curious to know about the energy-momentum distribution that would give rise to this metric.

(I initially wrote this as a comment, but converted it into a review once I figured that the paper *does *present the metric as something of physical value.)