| This thesis is a report on the research I have done over the last three years. I begin by reviewing the Standard Big Bang cosmology and the theory of inflation. I then describe Island Cosmology, an alternative theory of cosmic origin, which is based on a different hypothesis, and can create the observed universe without requiring an inflationary phase. After fully describing this model, I move on to the subject of computing perturbation spectra. The theory of cosmological perturbations, as it applies to calculating the perturbation spectrum from inflation, is reviewed next. Computing the perturbation spectrum in Island Cosmology involves several challenges, which I then discuss and also review progress made so far in computing the spectrum. In the final part of this thesis I describe my research in gravitational collapse in the presence of a dynamical dark energy component (DDE). I review the very interesting result that in linear regime, the collapsing matter induces the formation of DDE voids, or regions of underdensity. I describe the physics behind the formation of these voids, as well as possible observational consequences. |
