Dark energy is driving our universe apart at accelerating speeds, according to a five-year survey of 200,000 galaxies, stretching back seven billion years in cosmic time.The study offers new support for the favoured theory of how dark energy works - as a constant force, uniformly affecting the universe and propelling its runaway expansion.
Its findings are based on results from Nasa's space-based Galaxy Evolution Explorer and the Anglo-Australian Telescope on Siding Spring Mountain in Australia.
But they contradict an alternate theory, where gravity, not dark energy, is the force pushing space apart.
According to this alternate theory, with which the new survey results are not consistent, Albert Einstein's concept of gravity is wrong, and gravity becomes repulsive instead of attractive when acting at great distances.
'The action of dark energy is as if you threw a ball up in the air, and it kept speeding upward into the sky faster and faster,' said Chris Blake of the Swinburne University of Technology in Melbourne.
Blake is lead author of two papers describing the results that appeared in recent issues of the Monthly Notices of the Royal Astronomical Society.
'The results tell us that dark energy is a cosmological constant, as Einstein proposed. If gravity were the culprit, then we wouldn't be seeing these constant effects of dark energy throughout time.'
Dark energy is thought to dominate our universe, making up about 74 per cent of it. Dark matter, a slightly less mysterious substance, accounts for 22 per cent. So-called normal matter, anything with atoms, or the stuff that makes up living creatures, planets and stars, is only approximately 4 per cent of the cosmos. Read More
