Physics of the Early Universe
The cosmology theory group is active in a number of areas. We are studying models of the early universe based on contemporary ideas in fundamental physics, including string theory and M-theory. Testing these models against astronomical observations will give clues to the nature of physics at very high energy. We are especially active in the inflationary scenario.
In addition, we are studying patterns in the statistical distribution of galaxies that may give clues to modifications of gravity on very large scales. Recent observations have shown that the expansion rate of the universe is accelerating rather than decelerating, suggesting that gravity may become effectively repulsive rather than attractive on the largest possible scale. By borrowing techniques from collider phenomenology we are producing very accurate predictions for galaxy-survey observables that are sensitive to such changes.
In collaboration with the theoretical particle physics group, we are interested in the consequences of cosmological phase transitions such as the one which may have ended inflation. These transitions can lead to formation of cosmic strings or other topological defects, which may be detectable through their influence on the cosmic microwave background. They may also give a background of stochastic gravitational waves detectablel by LISA, and we are working on how to predict and extract that signal.