Friday, July 04, 2008

75% of the Universe is "dark energy"

UK astronomers, as a part of the Dark Energy Survey collaboration, have reached a milestone in the construction of one of the largest ever cameras to detect dark energy by completing the shipment of the glass required for the five special lenses. Each step in the process of completing this sophisticated camera brings scientists closer to detecting the invisible matter that cosmologists estimate makes up around 75% of our universe.

The Dark Energy Survey (DES) collaboration involves over 100 scientists from the US, UK, Spain, and Brazil. The goal of DES is to map 300 million galaxies using the Blanco 4-meter telescope; this is a large telescope with new advanced optics, at Chile’s Cerro Tololo Inter-American Observatory. In order to complete the DES camera assembly, the pieces of glass have been shipped from the US to France, where they will be shaped and polished into their final form. The largest of the five lenses is one meter in diameter, making it one of the largest in the world.

Observations suggest that roughly 4% of the universe is made up from ordinary matter and 22% from dark matter; this leaves 74% unaccounted for – the so-called “dark energy” which scientists claim to be the factor which drives the universe's accelerating expansion. The vast DES galaxy map will enable the astronomers to measure the dark energy far more precisely than current observations. Professor Ofer Lahav, head of the UCL Astrophysics Group, who also leads the UK DES Consortium, said: "Dark energy is one of the biggest puzzles in the whole of physics, going back to a concept proposed by Einstein 90 years ago. The DES observations will tell us if Einstein was right or if we need a major shift in our understanding of the universe.”

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