Novel Directions in Physical Cosmology: Theory versus Observations

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The unprecedented sensitivity and angular resolution of current and upcoming cosmological observations such as WMAP and Planck satellites provide us great opportunities to test cosmological theories. This makes it more urgent than ever that we are prepared with concrete models to infer properties of matter and gravity. A primary objective of this research program is to study the physics of the early universe which determines how our cosmos looks like today. An ideal theory of the early universe would be well-motivated from our understanding of fundamental physics, sets the right initial conditions for later stages of the cosmos without fine tuning, and also provides testable predictions that makes it falsifiable. Inflation, the most prominent paradigm of the early universe, still remains under scrutiny and needs to be confirmed or falsified. Finding the best strategy to achieve this ambition is one of the objectives of my research program, which has already produced valuable results. As experience has shown, inflationary models are quite forgiving in accommodating a variety of observational predictions. The novelty of my approach relies on using the knowledge we have from observation and theory in a new way to derive the characteristic features of the history of the early universe and investigate whether inflation can be confirmed. My research program also focuses on different aspects of modified gravity and dark energy models. The nature of dark energy is probably the most important question in astronomy today, and its discovery led to last year's Nobel prize in Physics. While, on the observational front, future experiments such as WFIRST Observatory and EUCLID are being planned, the theory is yet to be equipped with methods to interpret the data properly, in order to shed light on the nature of dark energy. The program that I am most interested to continue is finding optimum methods that can help us distinguish between different paradigms for apparent acceleration of cosmic expansion. A comprehensive approach would employ probes of cosmic geometry, as well as large scale structure formation, gravitational lensing observations and features in cosmic microwave background.