Published on September 20th, 2012 | by Carl Mundy0
Dark Energy’s Latest Predator Awakens; The Dark Energy Survey
The surprising discovery in 1998 that the expansion of the universe was accelerating indicated even less was known about it than previously thought. All the matter in the universe – the galaxies and dark matter – exert an attractive gravitational force on everything else; the universe’s expansion should have been slowing down rather than speeding up. This observation not only led to the 2011 Nobel Prize in Physics but introduced the concept of ‘dark energy’, a form of energy present everywhere in space that causes the expansion to speed up. Dark energy is believed to account for nearly three quarters of the ‘stuff’ in the universe and is sometimes called vacuum energy or quintessence, although the latter is slightly different in that the strength of the dark energy can change in time and space.
An international collaboration are hoping to “probe the origin of the accelerating universe and help uncover the nature of dark energy” through four independent measurements. The Dark Energy Survey (DES) will look at exploding stars called Type Ia supernovae in the distant universe, characteristic temperature peaks and troughs in the cosmic microwave background (CMB), the distribution of clusters of galaxies throughout the universe’s history and the small distortions in the shapes of background galaxies caused by the gravitational field of foreground galaxy clusters (weak gravitational lensing).
Uniquely able to do all these measurements from a single facility, DES will use a massive custom camera called DECam. On September 12, 2012 the camera opened its eyes and captured its first image that marks the beginning of a testing and calibration period lasting several months. Comprised of 62 tiled CCDs, like those in your digital camera or smartphone, the camera boasts 570 megapixels – over 70 times the pixel count of the current iPhone’s camera. Over the next five years, the DES collaboration will probe the mysterious nature of dark energy whilst looking further and further into the distant universe. The results should be the tightest constraints yet on the mysterious force causing the acceleration and they should be able to determine whether or not our best understanding of gravity (i.e. general relativity) is indeed correct.