astrophysics: dark energy fuels expanding universe

A new study using NASA’s orbiting Chandra X-ray Observatory seems to confirm the existence of dark energy, which may have implications for the ultimate fate of the universe. Dark energy is a mysterious force pushing the universe apart as well as accelerating its expansion, and remains “perhaps the biggest mystery in physics,” according to study leader Steve Allen from the Institute of Astronomy at the University of Cambridge in England. Allen and his team used the Chandra telescope to study 26 clusters of galaxies located 1 billion to 8 billion light years away. The researchers measured the distances to the clusters, and then by plotting those distances over time, they determined that the expansion of the universe started speeding up about 6 billion years ago. This acceleration, they state, is due to dark energy. Study coauthor Andy Fabian, also from the Institute of Astronomy, stated in a press release: “The new Chandra results suggest the dark energy density does not change quickly with time and may even be constant.” If it does remain constant, the universe is expected to expand forever. The team’s findings also agree with other estimates that dark energy makes up about 75 percent of the universe. The study will appear in a forthcoming issue of the Monthly Notices of the Royal Astronomy Society.

This news brief appeared in the Discoveries column of the Boston Globe’s Health/Science section on 5/25/2004.