The aim of this set of lectures is a systematic presentation of a 1+ 3 covariant approach to
studying the geometry, dynamics, and observational properties of relativistic cosmological …

No. In a number of papers, Green and Wald argue that the standard FLRW model
approximates our Universe extremely well on all scales, except close to strong-field …

We discuss the physics of backreaction-driven accelerated expansion. Using the exact
equations for the behaviour of averages in dust universes, we explain how large-scale …

Cosmological models typically neglect the complicated nature of the spacetime mani-fold at
small scales in order to hypothesize idealized general relativistic solutions for describing the …

We derive the relationship of the redshift and the angular diameter distance to the average
expansion rate for universes which are statistically homogeneous and isotropic and where …

We argue that “effective” superluminal travel, potentially caused by the tipping over of light
cones in Einstein gravity, is always associated with violations of the null energy condition …

We construct the first exact statistically homogeneous and isotropic cosmological solution in
which inhomogeneity has a significant effect on the expansion rate. The universe is …

We evaluate the average expansion rate of a universe which contains a realistic evolving
ensemble of non-linear structures. We use the peak model of structure formation to obtain …

The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation
and observations in cosmological models. In this article, we propose a detailed …

How does a smooth cosmic distance ladder emerge from observations made from a single
location in a lumpy Universe? Distances to the Type Ia supernova (SN1A) in the Hubble flow …