The universe expansion is accelerating , an observation that prompted astronomers
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to invoke an unknown entity called dark energy to explain it, has been further confirmed by new measurements. Scientists have used cosmic magnifying glasses called gravitational lenses to observe super-bright distant galaxies, giving a measure of how quickly the universe is blowing up like a giant balloon. They found, in agreement with previous measurements, that the universe’s expansion is indeed speeding up over time. The first measurement of this phenomenon, based on exploding stars called supernovae, was made in the 1990s. Scientists still don’t have much of an idea why the universe is not only expanding doing so ever-faster. The gravity of all the mass in the universe would be expected to pull everything back inward, so scientists call whatever force is counteracting gravity dark energy. As said Masamune Oguri, of the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe their new result using gravitational lensing not only provides additional strong evidence for the accelerated cosmic expansion, but also is useful for accurate measurements of the expansion speed, which is essential for investigating the nature of dark energy. Ogiri led the new study of quasars with Naohisa Inada at Japan’s Nara National College of Technology. Quasars are objects bright enough to be spotted halfway across the universe. The light from quasars sometimes passes by massive objects on its way to telescopes on Earth, and the gravity from these objects bends space-time, causing the light to travel along a curved path. This can produce warped and distorted double images of a single distant quasar. As the universe expands, the distance to quasars increases, and so do the chances that a quasar’s light will pass by a massive object and be gravitationally lensed. Thus the frequency of gravitationally lensed quasars can indicate the expansion speed of the universe.