Singularities in any physical theory are either remarkable indicators of the unknown
underlying fundamental theory, or indicate a change in the description of the physical reality …

In this review we present a thoroughly comprehensive survey of recent work on modified
theories of gravity and their cosmological consequences. Amongst other things, we cover …

The classical generalization of general relativity is considered as the gravitational alternative
for a unified description of the early-time inflation with late-time cosmic acceleration. The …

Over the past decade, f (R) theories have been extensively studied as one of the simplest
modifications to General Relativity. In this article we review various applications of f (R) …

The gravitational wave (GW) event GW170817 from a binary neutron star merger together
with the electromagnetic counterpart showed that the speed of GWs ct is very close to that of …

We study a class of metric-variation f (R) models that accelerates the expansion without a
cosmological constant and satisfies both cosmological and solar-system tests in the small …

For the last 100 years, General Relativity (GR) has taken over the gravitational theory mantle
held by Newtonian Gravity for the previous 200 years. This article reviews the status of GR in …

We review the recent progress for modified gravity models of dark energy–including f (R)
gravity, scalar-tensor theories, and braneworld models. In f (R) gravity, where the …

We consider the cosmology where some function f (G) of the Gauss-Bonnet term G is added
to the gravitational action to account for the late-time accelerating expansion of the universe …

We derive conditions under which f (G) gravity models, whose Lagrangian densities f are
written in terms of a Gauss–Bonnet term G, are cosmologically viable. The most crucial …