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There's evidence that, shortly after the Big Bang, the universe was essentially uniform in its density and appearance. When we peer out to the cosmos today, it's evident that the distribution of matter is far from uniform. In fact it's positively lumpy, even on a large scale, and clearly exhibits a hierarchical organization. As far as we can tell, planets formed sometime during starbirth, giving rise to solar systems such our own. Stars are organized into galaxies, which in turn appear to be bound gravitationally together in clusters. Superclusters of galaxies stretch as gigantic sheets across hundreds of billions of light years, bounded by enormous voids with like dimensions.
How can this evident "lumpiness" be explained? That's but one of the questions challenging cosmologists, as they try to explain the universe we see today. Other difficult questions about cosmic origins and evolution preoccupy their minds, such as:
To answer these questions, cosmologist are turning to an impressive array of tools. On the one hand, new, powerful new telescopes, earth-bound and spaceborn, enable them to peer out (and back in time) as never before. On the other, alternative models of cosmic creation and evolution can be tested as simulations in advanced computers. Better observations, new theories and now computation hold the keys to solving these ancient mysteries.
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