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Friday, 20 November 2009 01:00 |
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There are two possible futures for our Universe, continual expansion (open
and flat), or turn-around and collapse (closed). Note that flat is the
specific case of expansion to ever slowly speeds aproaching zero velocity.
One of the key factors that determines which history is correct is the amount of
mass/gravity for the Universe as a whole. If there is sufficient mass,
then the expansion of the Universe will be slowed to the point of
stopping, then retraction to collapse. If there is not a sufficient
amount of mass, then the Universe will expand forever without stopping.
The flat Universe is one where there is exactly the balance of mass to
slow the expansion to zero, but not for collapse.
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