Distances between galaxies measured to within 1% accuracy

BBC : Measuring distances on the scale of the universe is a difficult task, but the accuracy of the measurements has been steadily improving. New findings from the Baryon Oscillation Spectroscopic Survey (BOSS) have narrowed the range of uncertainty to just 1%. David Schlegel of the Lawrence Berkeley National Laboratory and his colleagues used the Sloan Foundation Telescope in New Mexico to measure the distances to galaxies within 6 billion light-years of Earth. The new level of accuracy they obtained was due to the use of baryon acoustic oscillations (BAOs)—regular variations in the density of visible matter. They are the result of pressure waves that moved through the early universe and influenced the distribution of galaxies. BAOs, which are separated by about a half billion light-years each, can be used as a ruler for measuring distance. The team’s measurements indicate that the cosmological constant for the rate of expansion of the universe doesn’t vary in space or time and that space has very little curvature.