This chapter reviews standard tools used in the analysis of horizon and black hole physics,
most notably the congruences of null geodesics crossing a horizon. Rindler, event, Killing …

General relativity marked the beginning of modern cosmology and it has since been at the
centre of many of the key developments in this field. In the present review, we discuss the …

Beyond Einstein's Gravity is a graduate level introduction to extended theories of gravity and
cosmology, including variational principles, the weak-field limit, gravitational waves …

The effective evolution of an inhomogeneous universe model in any theory of gravitation
may be described in terms of spatially averaged variables. In Einstein's theory, restricting …

Abstract Structure occurs over a vast range of scales in the Universe. Our large-scale
cosmological models are coarse-grained representations of what exists, which have much …

The exact solution of a two-scale Buchert average of the Einstein equations is derived for an
inhomogeneous universe that represents a close approximation to the observed universe …

In this review, we investigate the question of backreaction in different approaches to
cosmological perturbation theory, and with a special focus on quantum theoretical aspects …

We examine the properties of a recently proposed observationally viable alternative to
homogeneous cosmology with smooth dark energy, the timescape cosmology. In the …

The problems of coarse-graining and averaging of inhomogeneous cosmologies, and their
backreaction on average cosmic evolution, are reviewed from a physical viewpoint. A …

We derive the redshift and the angular diameter distance in rotationless dust universes
which are statistically homogeneous and isotropic, but have otherwise arbitrary geometry …