An international team of astronomers, led by scientists at the University of Manchester have produced new evidence that most of the energy in the Universe is in the form of the mysterious "Dark Energy". The new evidence comes from a 10-year census of the sky for examples of gravitational lenses, which are seen when a galaxy bends the light from a distant quasar to form several images of the same quasar. Linking the number of lenses they found with the latest information on the numbers of galaxies, the scientists have been able to infer that most of the energy in the Universe is likely to be in an invisible, and presently unknown, form.
Dark Energy is closely related to the idea of a Cosmological Constant introduced by Einstein over 80 years ago, but most astronomers, including Einstein himself, have always strongly doubted its reality. However, in the past 5 years several independent groups of astronomers have amassed evidence suggesting that Dark Energy exists and could well dominate the total energy of the Universe.
Dark Energy only affects the properties of the Universe over very large distances. As a result, the observations which are sensitive to its presence, in particular studies of exploding stars in distant galaxies, are all close to the limit of current capabilities. Astronomers have therefore been keen to exploit many different tests and Dr. Ian Browne makes the point that "the new gravitational lens test is based on completely different physical arguments to the previous ones and so provides independent evidence in support of Dark Energy".
Ian Browne | alfa
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