| Themes > Science > Astronomy > Modern Astronomy > Cosmology > Issues in Cosmology |
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The Central Themes of Modern CosmologyThe central tenet of modern cosmology is the idea that the Universe is expanding, and that this implies that at some time in the distant past it was incredibly dense and hot. This "explosion" from a hot, dense initial state is called the big bang (or sometimes the hot big bang, to emphasize the high temperature during its occurrence).Some of the most important problems in cosmology are associated with understanding how galaxies and clusters of galaxies formed, and determining the nature of the mass of the Universe (we can only identify 10 percent of what we know from its gravitational influence must be there!). |
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