Five-Dimensional Space-Times with a Variable Gravitational and Cosmological Constant

space-times with a negative cosmological constant

We construct a large class of new singularity-free static Lorentzian fourdimensional solutions of the vacuum Einstein equations with a negative cosmological constant. The new families of metrics contain space-times with, or without, black hole regions. Two uniqueness results are also established.

The Cosmological Constant and Discrete Space-times

In this thesis the cosmological constant is investigated from two points of view. First, we study the influence of a time-dependent cosmological constant on the late-time expansion of the universe. Thereby, we consider several combinations of scaling laws motivated by renormalisation group running and different choices for the interpretation of the renormalisation scale. Apart from well known s...

Five-Dimensional Space-Times

Nonstandard Cosmology With Constant and Variable Gravitational and Variable Cosmological “Constants” and Bulk Viscosity

We have analyzed a nonsingular model with a variable cosmological term following the Carvalho et al. ansatz. The model was shown to approximate to the model of Freese et al. in one direction and to the Özer-Taha in the other. We have then included the effect of viscosity in this cosmology, as this effect has not been considered before. The analysis showed that this viscous effect could be impor...

Simple Brane World Scenario with Positive Five Dimensional Cosmological Constant

We present a simple brane-world model in five dimensions. In this model we do not need any fine-tuning between the five dimensional cosmological constant and the brane tension to obtain four dimensional flat Minkowski space. The spacetime of our solution has no naked singularities. Further the compactification scale of the fifth direction is automatically determined. [email protected]...