Sidney Bludman
Friday 4pm
Departamento de Astronomia
Universidad de Chile
Santiago, Chile
Abstract:
We review current observations of the homogeneous cosmological expansion history which, because they measure only kinematic variables, cannot determine the dynamics driving the recent accelerated expansion. The minimal fit to the data, the flat L CDM model, consisting of cold dark matter and a cosmological constant, interprets 4 L geometrically as a classical spacetime curvature constant of nature, avoiding any reference to quantum vacuum energy. (The observed Uehling and Casimir effects measure forces due to QED vacuum polarization, but not any quantum material vacuum energies.) An Extended Anthropic Principle, that Dark Energy and Dark Gravity be indistinguishable, selects out flat L CDM. Prospective cosmic shear and galaxy clustering observations of the growth of fluctuations, in principle, will test whether 'dark energy' is static or moderately dynamic and distinguish Dark Energy from Dark Gravity.