|undead||Date: Thursday, 13-September-2012, 2:22 PM | Message # 1|
A pair of detectors that measure minute distortions in images of distant galaxies will probe the riddle of cosmic acceleration
By Eric Hand of Nature magazine
Even the best pictures of a distant galaxy are a bit lopsided. But this is an attribute, not a bug. Because mass distorts space-time, light coming from distant galaxies is bent as it passes through intervening shoals of invisible matter, leaving the images of these distant objects minutely sheared and stretched.
Two astronomical surveys now scheduled to come online seek to take advantage of this effect, which is known as weak gravitational lensing. The surveys aim to use the technique to get a firmer handle on dark energy, the mysterious force that is apparently speeding up the expansion of the Universe. By observing the patterns of distortions across large swathes of sky (see ‘Falling into line’), astronomers hope to map the density and distribution of dark matter, the web-like invisible scaffolding around which visible matter is thought to have first coalesced. Then, by looking at changes in this hidden web across cosmic time, they hope to discern the imprint of dark energy.
Read more/Full article/source - http://www.scientificamerican.com/article....-energy