23-08-2008 After the Big Bang. (Article 151)

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Simon Kenny
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23-08-2008 After the Big Bang. (Article 151)

Post by Simon Kenny » Tue Dec 30, 2008 9:22 pm

After the Big Bang. (Article 151)

The origin of the universe is undergoing intense scrutiny by scientific observatories on the ground and in space. Ever more powerful instruments are being designed to harvest the faintest wisps of radiation from deepest space that come not only from far away, but from deep in the universe’s past. Some of this ‘fossil’ radiation, like archaeological digs on Earth, gives scientists information on that mother of all explosions, the ‘Big Bang’ and what happened in the moments that followed it.

Understanding the Big Bang is essential to understanding the evolution of the universe. Many astronomical observatories on the ground and in the sky are gathering a wealth of data on the structure of matter in the universe and gradually establishing a large scale cosmic map. At the largest scale, the visible universe is now understood to be composed of untold billions of galaxies that form gravitational associations with neighbouring galaxies. These ‘local’ clusters of galaxies form similar associations with other groups, forming galactic ‘superclusters’ like the Virgo Supercluster, 100 million light years across, to which our Milky Way galaxy is linked, as are tens of thousands of other galaxies. In turn galaxy superclusters also link together to form knots, or extend as filaments that can be billions of light years long. The overall picture of the visible universe is not unlike a vast, glowing, intricate web of matter, strung out against an inky black void. However, darkness is not emptiness. Gravitational anomalies in the visible parts of the universe clearly indicate there is much more matter there than we can detect. This mysterious ‘dark matter’ is the subject of intense scrutiny and debate and one of the reasons why the origin of the universe is being closely studied.

Research into what happened after the Big Bang is trying to understand the forces that made the universe what it is and to predict its future. The ‘Big Bang’ theory is now widely accepted and explains the expansion of the universe Edwin Hubble first observed in the 1920s. Still unexplained by this model is the discovery, from Hubble telescope data, that this expansion is accelerating, which suggests that a previously unknown ‘dark energy’ is at work in the cosmos.

Latest models suggest the universe began about 13.7 billion years ago in an explosion of unimaginable force. In a split second it inflated from being smaller than an atomic nucleus, into a fiery furnace of subatomic particles, millions of kilometres across. In this promethean forge, matter, space and time were born. Since then, the universe has expanded at a much more leisurely, though slowly accelerating rate.

What is the fate of the universe? Will it expand forever, collapse on itself in a colossal ‘Big Crunch’ or stay as it is? The answer depends on what great forces are operating in the universe. Some of these forces are only recently discovered and poorly understood. The investigations continue.

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