Dark energy is real, researchers argue

2012-09-12 11:27
Dark energy is real, astronomers have concluded. (Duncan Alfreds, News24)

Dark energy is real, astronomers have concluded. (Duncan Alfreds, News24)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

London - 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 the United Kingdom and LMU University Munich in Germany have concluded that the likelihood of dark energy's existence stands at 99.996%.

That's the same level of certainty as this year's celebrated discovery of the Higgs boson, or a subatomic particle that looks very much like it, by scientists at the Cern research centre near Geneva.

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

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, which was published in the academic journal Monthly Notices of the Royal Astronomical Society.

"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% of the cosmos and is sitting like flotsam in a massive sea of unknown material referred to as dark energy. Dark energy is thought to make up 73% of the cosmos, while the slightly less mysterious dark matter comprises the remaining 23%.

One of the strongest pieces of evidence for dark energy is in the so-called Integrated Sachs Wolfe effect.

In 1967, Rainer Sachs and Arthur Wolfe theorised that light from the radiation from the heat left over 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.

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

Square Kilometre Array

In 1996, astronomers Robert Crittenden and Neil Turok suggested overlaying a map of the local universe on the picture of the residual cosmic radiation could provide clues about where to look for the effect. In 2003, it was spotted, albeit weakly.

It was seen as supporting evidence for dark energy and hailed as the "Discovery of the Year" in Science magazine.

But some scientists argued it could have been caused by cosmic dust and questioned the discovery.

The Anglo-German team that carried out the latest study was led by Crittenden and Tommaso Giannantonio. They re-examined all the arguments against the detection and have improved the maps used in the original work.

They conclude that dark energy is almost certainly responsible for the hotter parts of the cosmic microwave background.

"We have methodically addressed all of these issues and concluded none of them can explain the observations we see," said Nichol. "In the end, the only remaining explanation is dark energy - if it walks like a duck and quacks like a duck, it's probably a duck."

Radio telescopes like the huge Square Kilometre Array, most of which will be sited in the Northern Cape province in South Africa, and a smaller part in Australia, should improve the tricky process of measuring distances in the universe and give more definitive data, he said.

"What dark energy could be, theoretically, is another question," Nichol said.
Read more on:    ska  |  astronomy

Join the conversation!

24.com encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.

linking and moving

2015-04-22 07:36

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Inside News24


Does your dog have separation anxiety?

We've got tips, advice and how to help your dog



Fascinating facts about dogs
Perfectly captured cat snapchats!
Out with the old dog, in with the new
Play with your pet when you're not at home
Traffic Alerts
There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.