THE case for dark energy - the mysterious force that seems to be pushing the Universe apart - is stronger than ever, thanks to a study that measured the density of matter in the cosmos.
Five years ago, a group of astronomers concluded that the expansion of the Universe is accelerating, instead of slowing down as most had thought. They cited observations of distant supernovae that appeared fainter, and therefore farther away, than expected. But critics pointed out that the dimness could be due to other causes, such as intervening dust.
What's more, theorists have struggled to explain how dark energy could even exist. "I think most particle physicists would rather it went away," says Ian Browne of the Jodrell Bank Observatory at the University of Manchester. However, he has just completed a 10-year international survey of gravitational lensing that convinces him dark energy is real, "much to my personal ...
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