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Unformatted text preview: the density of a representative region of the universe. The density = (mass in the region)/(volume of the region). If the region is truly representative, then the total mass of the universe = the density the total volume of the universe. If the density is great enough, then the universe is closed. If the density is low enough, then the universe is open. In the popular astronomy magazines, you will probably see the mass density of the universe specified by the symbol `` ''. It is the ratio of the current density to the ``critical density'' described in the next paragraph . If < 1, the universe is open; if > 1, the universe is closed....
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