Dark forces of the Universe
This image shows the galaxy cluster Abell 1689, with the mass distribution of the gravitational lens overlaid (in purple). The mass in this lens is made up partly of normal (baryonic) matter and partly of dark matter. Distorted galaxies are clearly visible around the edges of the gravitational lens. The appearance of these distorted galaxies depends on the distribution of matter in the lens and on the relative geometry of the lens and the distant galaxies, as well as on the effect of dark energy on the geometry of the universe.
Dark energy is a cosmic phenomenon that mysteriously powers the accelerating expansion of the Universe. Discovered as early as early as 1998, this strange force, though invisible, makes up a staggering 72 per cent of our known Universe! Of the rest, 24 per cent is made up of "dark matter", which is also invisible but can be detected by its gravitational pull. And as for the rest of the Universe, a measly 4 per cent is actually made up of "the stuff that makes up people, planets, stars and everything that are made up of atoms". Scientists strongly believe that the pressure exerted by this dark energy is exactly what that pushes the Universe to expand at an ever-increasing rate. And a recent finding by an international team of astronomers, with the aid of NASA's Hubble Space Telescope (HST) and European Space Agencies Very Large Telescope, concludes that, it is very likely that our Universe will expand forever. Led by Prof. Eric Jullo of NASA's Jet Propulsion Laboratory in California, the study findings, the details of which have been published in the August 20 issue of the journal Science, also conclude that not only the Universe will not stop growing but also eventually it would become a dead and cold wasteland with a temperature that is scientifically referred as "absolute zero". In order to understand how dark energy is spread through the space, scientists used HST to observe the way light from distant stars became distorted around Abell 1689, a nearby cluster of galaxies, found in the constellation of Virgo, which is one of the biggest galactic clusters of the Universe. Due to its huge mass, the cluster acts as a cosmic magnifying glass, causing light to bend around it. And through this gravitational "lens" of Abell 1689, the astronomers were able to detect the faint, distant background galaxies, whose light was not only bent but also projected by the cluster's massive gravitational pull. Almost the same way a magnifying lens distorts an objects image. This gravitational lensing is a phenomenon predicted by Einstein's theory of general relativity and the team of researchers applied this knowledge to determine how the cosmological distances along with the shape of space-time are modified by the dark energy. By studying the distant and distorted images, scientists were able to reconstruct the path that light from faraway galaxies takes to make its long journey to Earth. And this also allowed them to study the effects of the dark energy on the geometry of space in the light path from the distant objects to the lensing cluster and from the cluster to us. And since the dark energy pushes the Universe to expand ever faster, the precise path that the light beams follow as they travel through space contain great deal of information about the most fundamental yet crucial contents of our cosmology. According to co-author of the paper, Prof. Priyamvada Natarajan of Yale University, "The geometry, the content and the fate of the Universe are all intricately linked. If you know two, you can deduce the third. We already have a pretty good knowledge of the Universe's mass-energy mass, so if we can get a handle on its geometry then we will be able to work-out exactly what the fate of the Universe will be". And it seems the fate is, ever expansion. Experts believe that the real strength of this new study lies in the fact that it devices a totally new way of analyzing the elusive dark energy which is not only unique but also powerful one and offers a great deal of promise for the future research centered on cosmology. The result of this study also confirms the previous findings which state that the nature of dark energy likely corresponds to a flat Universe.
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