Ever since Albert Einstein, astronomers had wondered if gravity would slow the expansion of the Universe and make it collapse on itself in the so-called "Big Crunch." But in the late 1990's, two groups of scientists discovered that it's working the other way. The Universe is expanding faster and faster, and the cause is "Dark Energy." The latest Nobel Prize in Physics has gone to astronomers Saul Permutter, Brian Schmidt and Adam Riess, who are responsible for that discovery. Jonathan McDowell is an astronomer at the Harvard-Smithsonian Center for Astrophysics.