Title: The Hubble Constant: Endgame
Speaker: John Huchra (Harvard-Smithsonian Center for Astrophysics)
Abstract: Over most of the previous four decades there was a debate about
the value of the Hubble Constant, the measure of the expansion rate
of the Universe. Even as late as 1992, there was a range of over a factor
of two in the published values of H0, with much of this wide dispersion
due to a dispersion in techniques. In just the last few years, the
combination of much improved local distance measurements from the Hubble
Space Telescope, a better understanding of Supernovae properties,
improved millimeter wave observations, and more accurate determinations
of the properties of gravitational lenses, has not only decreased
the errors in H0 measures but also decreased the range of H0 estimates
to less than +/-15% The global value of H0, estimated with a wide variety
of techniques, is approximately 65+/-10 km/s/Mpc. An H0 of this size has
profound implications for other cosmological parameters and the cosmological
model.