Using galaxies as yardsticks
Daniel Eisenstein is investigating the universe, using galaxies as his ruler, seeking to understand the cosmos’ large-scale structure and confirm theories about the dark energy that drives its expansion. Eisenstein is a professor of astronomy in the Harvard Astronomy Department and at the Harvard Smithsonian Center for Astrophysics. He also heads a major study of the heavens, the Sloan Digital Sky Survey, which is building the most detailed map of the universe ever made. Eisenstein has devised a new method to determine galaxies’ positions in order to understand more about the universe and to test theories about how it operates. So far, he said, the galactic positions have confirmed findings from the 1990s that we live in a universe that is not only expanding but accelerating, fueled by the invisible force of dark energy. “One of the ways of studying dark energy is by making extremely precise measurements of cosmological distance,” Eisenstein said. His...