"Dark energy is one of the great scientific mysteries of our time, so it isn't surprising that so many researchers question its existence. But now, according to a team of astronomers at the University of Portsmouth and LMU University Munich, led by Tommaso Giannantonio and Robert Crittenden, the scientists the likelihood of the existence of dark matter stands at 99.996 per cent.
"But with our new work we're more confident than ever that this exotic component of the Universe is real – even if we still have no idea what it consists of," said Bob Nichol, a member of the Portsmouth team.
Over a decade ago, astronomers observing the brightness of distant supernovae realised that the expansion of the Universe appeared to be accelerating. The acceleration is attributed to the repulsive force associated with dark energy now thought to make up 73 per cent of the content of the cosmos. The researchers who made this discovery received the Nobel Prize for Physics in 2011, but the existence of dark energy remains a topic of hot debate. Many other techniques have been used to confirm the reality of dark energy but they are either indirect probes of the accelerating Universe or susceptible to their own uncertainties.
Clear evidence for dark energy comes from the Integrated Sachs Wolfe effect named after Rainer Sachs and Arthur Wolfe. The Cosmic Microwave Background, the radiation of the residual heat of the Big Bang, is seen all over the sky. In 1967 Sachs and Wolfe proposed that light from this radiation would become slightly bluer as it passed through the gravitational fields of lumps of matter, an effect known as gravitational redshift.
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