IT'S official. The universe is slowly fading away into the distance. An invisible force thought to be pushing the cosmos ever faster apart does exist, Australian astronomers have concluded.

The team is the first to have looked at the structure of the universe more than halfway back in time, to a period when this repulsive force, known as dark energy, began to dominate over the pull of gravity.

Albert Einstein.

Chris Blake, of Swinburne University, said the results of their four-year survey of more than 200,000 distant galaxies show the mysterious force is a property of space itself.

''Dark energy is real,'' Dr Blake said. ''It fills the universe.''