Astronomers are announcing this week the sharpest view yet of the properties of dark energy -- the force that currently is driving the accelerated expansion of the universe "These results are a milestone in the study of the large-scale structure of the universe " said Penn State Professor Donald Schneider  who was the survey coordinator and scientific publications coordinator for the Sloan Digital Sky Survey III (SDSS-III) -- a collaboration of hundreds of scientists whose work produced the largest-ever  three-dimensional map of distant galaxies as well as one of the most precise measurements yet of dark energy