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Unformatted text preview: cosmological times. The greater the value of the Hubble constant at a given cosmological time, the faster the universe is expanding at that time. Gravity slows the expansion of the universe, so the early universe was expanding faster than it is now. That means that the critical density was greater at earlier times. It changes by the same factor that the actual density of the universe changes throughout the expansion. So if the universe starts out with a density greater than the critical density, then its density will always be greater than critical density. If the universe starts out with a density less than the critical density, then its density will always be less than the critical density....
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 Fall '10
 EmilyHoward
 Astronomy

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