Title: The Missing Energy Problem
Speaker: Paul Steinhardt
Abstract: Growing evidence suggests that the matter density of the universe is significantly less than the critical density and that the expansion of the universe is accelerating. If true, this may emerge as one of the most profound and significant discoveries of cosmology, for it would mean that some form of exotic missing energy with negative pressure (i.e., not dark matter) fills the universe. This talk will discuss the leading candidates for the missing energy: the venerable cosmological constant and a recent proposal, quintessence. The discussion will focus on the theoretical and observational differences.
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