Series: The London Relativity and Cosmology Seminar
Speaker: Geraint Pratten (Sussex)
Abstract: Numerous observations have firmly established the accelerated expansion of the Universe with the simplest explanation being a finely tuned cosmological constant. To date, there is no concrete theoretical explanation and numerous candidates have been proposed. Simple extensions include a single scalar field with a sufficiently flat potential that drives the expansion. This scalar could arise from a new form of matter or, as considered here, as an additional scalar gravitational degree of freedom that gives rise to an additional fifth force.