Astrophysicists shed light today on one of the deepest mysteries in science -- baffling stuff called "dark energy" that they can't detect and barely understand, but which is stifling the growth of clusters of galaxies, they said.
The finding from Harvard-Smithsonian researchers yields further clues about a cosmic conundrum that emerged a decade ago, when scientists first reported the universe was expanding, and that galaxies were picking up speed as they raced away from one another. Now, scientists also know that as the universe stretches, its most massive objects' growth is choked off by dark energy, which makes up 72 percent of the universe.
"This may well be called the arrested development of the universe," said Alexey Vikhlinin, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge who led the work.
The researchers used NASA's Chandra X-ray Observatory to measure the masses of the galaxy clusters, and other scientists said that the finding was an important independent confirmation of the findings made a decade ago.
That work started a cosmological free-for-all as scientists tried to understand why the universe's expansion was accelerating, and not slowing down in the 13 billion years since the Big Bang.
"It's been 10 years since we discovered the universe is speeding up and not slowing down, and even those of us who are professional cosmologists have yet to get our heads around that," said Michael Turner, a professor of astrophysics at the University of Chicago who coined the term "dark energy." "This is a big, big mystery. I call it the most profound mystery in science...This result puts a new arrow in our quiver," in trying to understand that "weird stuff out there."