Grant: Discovery Grants Program - Individual

The most common assumption in the study of modern cosmology is that the gravitational field is described by Einstein's Theory of General Relativity. Cosmological models based on this assumption have been very successful in explaining a wide range of observational phenomena. Despite the plethora of strong observational evidence supporting General Relativity, there continues to be significant problems with the widely accepted Lambda Cold Dark Matter model of the universe. In this model, both "Dark Matter" and "Dark Energy" are primary ingredients. They are added to the model to make it realizable with current observation and do not come out of the model naturally as a prediction. Furthermore, there are fundamental issues regarding the isotropy and spatial homogeneity assumptions. The Universe is not homogeneous on all scales, we observe structures, and, therefore, the assumption of homogeneity and isotropy on the largest of scales needs to be questioned. The question then arises, "Is there is a more natural way to explain the effects of Dark Matter and Dark Energy?" A new theory of gravity based on General Relativity, called Macroscopic Gravity, smooths inhomogeneities that may be present in any gravitational field and is, therefore, appropriate for the analysis of large-scale gravitational systems such as the Universe. Given that there are fundamental problems within cosmological models based on General Relativity, one ought to investigate the appropriateness of using Macroscopic Gravity in those arenas in which classical General Relativity fails in some sense. We will determine the corresponding system of field equations arising from Macroscopic gravity and will seek solutions to these equations. Where appropriate, the stability of these solutions within a wider class of models will be investigated. The resulting investigations may yield cosmological models that provide alternative explanations to explain the effects of Dark Matter and Dark Energy.