ASTRONOMY COLLOQUIUM - FEBRUARY 14, 2006

Robert Caldwell , Dartmouth

Dark Energy -- Accelerating Towards the Vacuum

Dark Energy comprises the majority of the energy of the universe, and is responsible for the accelerating cosmic expansion. The nature of dark energy is speculative. Leading theories propose that dark energy is a static, cosmological constant consisting of quantum zero-point energy, or a dynamical field. Alternatively, it has been proposed that the dark energy phenomena are due to a change in the form of gravitation on cosmological length scales. Confirmation of any one of these ideas would have a profound impact on physics. In this talk I will give a brief summary of theoretical models for dark energy. I will present recent work on a classification scheme, valid for the simplest of these scenarios, which distinguishes between dynamical fields which relax or rush towards the vacuum. Last, I will examine other, phenomenological models to help give a clearer view of the challenges for dark energy observations and experiments.