Modified F ( R ) Hořava–Lifshitz gravity: a way to accelerating FRW cosmology

Viscous Frw Cosmology in Modified Gravity

We discuss a modified form of gravity implying that the action contains a power α of the scalar curvature. Coupling with the cosmic fluid is assumed. As equation of state for the fluid, we take the simplest version where the pressure is proportional to the density. Based upon a natural ansatz for the time variation of the scale factor, we show that the equations of motion are satisfied for gene...

Friedmann Equations of FRW Universe in Scalar - tensor Gravity , f ( R ) Gravity and First Law of

In the paper, hep-th/0501055 (R. it is shown that by applying the first law of thermodynamics to the apparent horizon of an FRW universe and assuming the geometric entropy given by a quarter of the apparent horizon area, one can derive the Friedmann equations describing the dynamics of the universe with any spatial curvature; using the entropy formula for the static spherically symmetric black ...

Modified gravity and cosmology

f(R) Quantum Cosmology

We have quantized a flat cosmological model in the context of the metric f(R) models, using the causal Bohmian quantum theory. The equations are solved and then we have obtained how the quantum corrections influence the classical equations.

Modified Averaging Processes in Cosmology and the Structured FRW model

We study the volume averaging of inhomogeneous metrics within GR and discuss its shortcomings such as gauge dependence, singular behavior as a result of caustics, and causality violations. To remedy these shortcomings, we suggest some modifications to this method. As a case study we focus on the inhomogeneous structured FRW model based on a flat LTB metric. The effect of averaging is then studi...