Is dark energy getting weaker?

[n2doc]

10 April 2009 by Rachel Courtland
Magazine issue 2703.


AFTER billions of years of runaway expansion, is the universe starting to slow down? A new analysis of nearby supernovae suggests space might not be expanding as quickly as it once was, a tantalising hint that the source of dark energy may be more exotic than we thought.

For more than a decade, astrophysicists have grappled with evidence of a baffling force that seems to be pushing the universe apart at an ever-increasing rate. Exactly what constitutes the dark energy responsible for this cosmic speed-up is unknown, says Michael Turner at the University of Chicago. "The simplest question we can ask is 'does the dark energy change with time?'"

So far, the evidence has suggested that dark energy is constant, though its effect on the universe has become stronger as the universe has expanded and the gravitational force between objects weakens with distance.

Now an analysis of supernovae suggests dark energy may actually be on the wane. In a paper on the physics preprint website, a team led by Arman Shafieloo at the University of Oxford examined a newly released catalogue of supernova explosions, including a number of relatively recent blasts nearby (www.arxiv.org/abs/0903.5141). They found that the new data made the best fit with a universe in which dark energy is losing strength. "It seems acceleration is slowing down," says Shafieloo.

more:

http://www.newscientist.com/article/mg20227033.200-is-dark-energy-getting-weaker.html

[Aragorn]

1. GIGO

Insufficient data. Therefore no conclusion can be made.

Please.