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Inhomogeneous alternative to dark energy
Recently, there have been suggestions that the apparent accelerated expansion of the universe is not caused by repulsive gravitation due to dark energy, but is rather a result of inhomogeneities inExpand
The Weyl curvature conjecture and black hole entropy
The universe today, containing stars, galaxies and black holes, seems to have evolved from a very homogeneous initial state. From this it appears as if the entropy of the universe is decreasing, inExpand
The Weyl Curvature Conjecture
In this paper we review Penrose’s Weyl curvature conjecture which states that the concept of gravitational entropy and the Weyl tensor is somehow linked, at least in a cosmological setting. We give aExpand
Gravitational entropy and quantum cosmology
We investigate the evolution of different measures of `gravitational entropy' in Bianchi type I and Lemaitre-Tolman universe models. A new quantity behaving in accordance with the second law ofExpand
Note on rotating universe models
In some recent papers it has been stated that the Godel space-time may be generalized to the non-stationary case, simply by allowing the scale-factor to be a function of cosmic time. We here showExpand
Observational Status of Tachyon Natural Inflation and Reheating
We study observational viability of Natural Inflation with a tachyon field as inflaton. By obtaining the main perturbation parameters in this model, we perform a numerical analysis on the parameterExpand
A new standard model of the universe
Up to about four years ago the dynamical properties of the evolution of the universe were assumed to be well described by the Einstein-de Sitter universe model, which is a flat universe modelExpand
Viscous Cosmology for Early- and Late-Time Universe
From a hydrodynamicist’s point of view the inclusion of viscosity concepts in the macroscopic theory of the cosmic fluid would appear most natural, as an ideal fluid is after all an abstractionExpand
The research on relativistic universe models with viscous fl uids is reviewed. Viscosity may have been of significance during the early inflatio nary era, and may also be of importance for the lateExpand