Dark energy, a cosmic substance thought to be speeding up the expansion of the Universe, really does exist, according to a team of astronomers at the University of Portsmouth and LMU University Munich.
The scientists conducted a two-year study and concluded that the likelihood of dark energy’s existence stands at 99.996 per cent (the same level of significance as the recent discovery of the Higgs Boson). Their findings have been published in the journal Monthly Notices of the Royal Astronomical Society.
Professor Bob Nichols, a member of the Portsmouth team told Laboratory News, “You can’t see or touch dark energy. It’s like nothing else we know of so it’s not surprising scientists question its existence. That’s why it’s important to keep layering on the evidence.”
Last year, the Nobel Prize for Physics was awarded to astronomers who on observing the brightness of distant supernovae over a decade ago, realised that the expansion of the universe seemed to be accelerating. The acceleration is attributed to the repulsive force associated with dark energy, but its existence is a highly debated topic.
In 1967, Rainer Sachs and Arthur Wolfe proposed gravitational redshift: light from radiation of the residual heat remaining from the Big Bang would become slightly bluer, gaining energy as it passed through the gravitational fields of lumps of matter in the universe.
The integrated Sachs Wolfe effect was first detected in 2003 and is seen as corroborative evidence for dark energy. It is a comparison of the temperature of the radiation within maps of the local universe and the residual cosmic radiation. But there are many arguments against the integrated Sachs Wolfe effect due to its weak signal and the suggestion that its effect could be instead be caused by dust in our galaxy.
The team re-examined all the arguments against the Integrated Sachs Wolfe detection and improved the maps used in the original work.
“This is the most methodical work that’s been achieved on this matter. We are now more confident than ever that this exotic component of the universe exists, even if we still have no idea what it consists of,” added Nichols.