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September 13, 2012

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Mysterious dark energy is real, researchers argue

DARK energy, the mysterious cosmic force thought to be the fuel behind the accelerating expansion of the universe, is real, according to an Anglo-German team of astronomers.

After a two-year study, scientists at the University of Portsmouth in Britain and LMU University Munich in Germany have concluded that the likelihood of dark energy's existence stands at 99.996 percent.

Although accepted by many scientists as the best explanation for why the universe expands at an ever-faster rate, the theory of dark energy has its skeptics.

Astronomers studying the brightness of distant supernovae over a decade ago won the 2011 Nobel Prize for Physics for their conclusion that the expansion of the universe was accelerating. But some scientists argue this is an illusion, caused by the relative movement of Earth in relation to the rest of the cosmos. Others suggest shortcomings in our understanding of gravity are more likely responsible than dark energy.

"Dark energy is one of the great scientific mysteries of our time, so it isn't surprising that so many researchers question its existence," said Bob Nichol, a member of the Portsmouth team involved in the research. "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."

A basic premise of modern cosmology is that the visible universe of stars, planets and gases makes up about 4 percent of the cosmos and is sitting like flotsam in a massive sea of unknown material referred to as dark energy. It is thought to make up 73 percent of the cosmos, while the slightly less mysterious dark matter comprises the remaining 23 percent.

In 1967, Rainer Sachs and Arthur Wolfe theorised that light from the radiation from the heat leftover from the Big Bang, would become slightly more blue as it passed through the gravitational fields of lumps of matter in the universe, an effect known as gravitational redshift.

Dark energy would cause light from this residual radiation to gain energy as it travels through large lumps of mass.





 

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