Highlights of scientific achievements: Discovered a closed form for the spectral density of relic gravity waves originating during Inflation and showed how the gravity wave density depended upon Inflation- ary parameters and the post-inflationary equation of state of matter. Demonstrated that both gravity waves and density perturbations originating during Inflation created fluctuations in the Cosmic Microwave Background. Observations made by the COBE satellite were used to place constraints on inflationary models, the relic gravity wave spectrum and large scale structure. Established a cosmic no-hair theorem for Inflation. Discovered new statistical methods for analysing the large scale structure of the uni- verse called Shapefinders which can determine shapes and sizes of superclusters of galaxies and the morphology of sparsely populated intergalactic regions called voids. Discovered new models of dark energy and dark matter which could help provide a theoretical foundation to the recent observational discovery that the Universe is accelerating. Developed new statistical techniques to differentiate between different models of dark energy using observational data. These include the Statefinder and the Om diagnostic. Developed unified models of Inflation and dark energy based on extra dimensions. Demonstrated how Braneworld physics could circumvent the initial singularity which plagues standard Big Bang theory.