1212.4697 (Andrzej Krasiński et al.)

Drift of Light Rays Induced by Nonsymmetric Cosmic Flow: an
observational test of homogeneity of the Universe + a few general comments on
inhomogeneous models    [PDF]

Andrzej Krasiński, Krzysztof Bolejko

Investigation of null geodesic equations in the Szekeres models shows that observers in favourable positions would see galaxies drift across the sky at a rate of up to $10^{-6}$ arc seconds per year. Such a drift would be possible to measure using devices that are under construction; the required time of monitoring would be $\approx10$ years. This effect is zero in the FLRW models, so it provides a measure of inhomogeneity of the Universe. In the Szekeres models, the condition for zero drift is zero shear. But in the shearfree normal models, the condition for zero drift is that, in the comoving coordinates, the time dependence of the metric completely factors out. In the second part of the article, the real-time cosmology program is briefly described, and a few widespread misconceptions about the cosmological models are pointed out and corrected.

View original: http://arxiv.org/abs/1212.4697