APPLIED MATHEMATICS SEMINAR AT THE UNIVERSITY OF SYDNEY Speaker: Professor Phil Broadbridge, Australian Mathematical Sciences Institute & University of Melbourne Title: Dark Energy States of a Scalar Field in an Unstable Universe DATE: Wednesday, March 7 TIME: 2:00pm LOCATION: University of Sydney, Eastern Avenue Lecture Theatre Abstract: Observations now indicate an expanding and accelerating universe. The simplest compatible large-scale model is the spatially flat FLRW universe with positive cosmological constant. The Hamiltonian of a scalar massless Klein-Gordon field, minimally coupled to the space-time geometry, naturally decomposes into a light component with well-defined particle numbers, plus a dark component whose most elementary quantized subsystems have continuous spectrum unbounded below. At a sequence of discrete times, progressively shorter wavelength components are lost from the light domain to the dark domain. http://www.maths.usyd.edu.au/u/AppliedSeminar ------------------------------------------------------------------------