After a decade and a half of research motivated by the accelerating universe, theory and
experiment have reached a certain level of maturity. The development of theoretical models …

We review recent progress in massive gravity. We start by showing how different theories of
massive gravity emerge from a higher-dimensional theory of general relativity, leading to the …

Gravitational waves (GWs) provide a new tool to probe the nature of dark energy (DE) and
the fundamental properties of gravity. We review the different ways in which GWs can be …

Given the proliferation of bouncing models in recent years, we gather and critically assess
these proposals in a comprehensive review. The PLANCK data shows an unmistakably red …

This review is dedicated to recent progress in the field of classical, interacting, massive spin-
2 theories, with a focus on ghost-free bimetric theory. We will outline its history and its …

Massive gravity provides a holographic model for theories exhibiting momentum
dissipation.<? format?> We provide an analytic expression for the DC conductivity. The …

We make precise the heretofore ambiguous statement that anisotropic stress is a sign of a
modification of gravity. We show that in cosmological solutions of very general classes of …

We investigate the coupling to matter in ghost-free massive (bi-) gravity. When species in the
matter sector couple covariantly to only one metric, we show that at one-loop these …

Bimetric theory describes gravitational interactions in the presence of an extra spin-2 field.
Previous work has suggested that its cosmological solutions are generically plagued by …

We give a simple derivation of a cosmological bound on the graviton mass for spatially flat
FRW solutions in massive gravity with an FRW reference metric and for bigravity theories …