Abstract

High-precision cosmological surveys are due to deliver measurements accurate to the percent level. In order to ensure we correctly interpret these data, we need to be sure that our cosmological model is accurate. The current standard model assumes that the Universe is homogeneous and isotropic. These assumptions are often justified by the fact that our Universe is homogeneous and isotropic on large scales, however, we are therefore smoothing over highly nonlinear structures on small scales. This smoothing feeds back onto the large-scale evolution of the Universe in the context of nonlinear General Relativity. In addition, small-scale curvature will affect light propagation, and hence our observations. The effect of this smoothing process, and the extent to which our observations will be affected, can only be fully addressed using numerical relativity. I will describe our simulations using the Einstein Toolkit to evolve cosmological large-scale structure with full numerical relativity. I will present our results of averaging a truly inhomogeneous, anisotropic matter distribution and the effect this has on the large-scale evolution of the Universe.