Refined Hubble constant narrows possible explanations for dark energy
Friday, May 8, 2009 - 00:42
in Astronomy & Space
Whatever dark energy is, explanations for it have less wiggle room following a Hubble Space Telescope observation that has refined the measurement of the universe's present expansion rate to a precision where the error is smaller than five percent. The new value for the expansion rate, known as the Hubble constant, or Ho (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometres per second per megaparsec (error margin of plus/minus 3.6). The results agree closely with an earlier measurement gleaned from Hubble of 72 plus/minus 8 km/sec/megaparsec, but are now more than twice as precise...