Making sense of a preposterous universe: Dark energy from extra dimensions

One of the most intruiging problems in modern cosmology is that of dark energy: Why does the expansion of the universe seem to be accelerating, when standard gravity is attractive? The absence of any kind of fundamental physical understanding of such seem ingly unnatural behaviour has led scientists to humorously call the observed universe preposterous -- a fundamental theory of dark energy is critically needed. The current project will explore one specific class of dark energy candidates, namely those a rising from gravity theories in extra dimensions. In particular, it will consider Gauss-Bonnet and other Lovelock gravity theories, which are natural extensions of standard Einstein gravity in higher dimensions. In four dimensions, these theories have the potential to describe standard Einstein gravity, now with naturally incorporated dark energy. Our goal is to determine whether one or more of these models are physically viable, both at the classical and quantum level. The project will be a collaboratio n between members of the theoretical physics group at the University of Oslo and of the Particle Theory Group at California Institute of Technology, one of the world's leading groups in theoretical physics.