big crunch?


by jjgillis1
Tags: big, crunch, end, redshift, universe
jjgillis1
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#1
Mar9-11, 03:38 PM
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First of all I'm a physics n00b so forgive me for intruding upon you people, whom I consider to be the pinnacle of humanity. I've always heard the universe is flying apart at a faster and faster rate as time passes. The more distant the galaxy the more redshifted it is, meaning the faster its flying away from us, but the further out we look the further back in time we look, meaning galaxies were flying apart faster in the past.

does this not mean the universe is slowing down and a big crunch is imminent? what am I not understanding here?
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bcrowell
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#2
Mar9-11, 04:17 PM
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The expansion of the universe used to be decelerating, but is now accelerating: http://en.wikipedia.org/wiki/Accelerating_universe

Before it was determined that the expansion was reaccelerating, nobody knew whether the universe was destined for a big crunch (deceleration stops the expansion and turns it around) or infinite expansion (deceleration never succeeds in stopping the expansion).

Now that we know it's accelerating, we know for sure that there won't be a Big Crunch.
Drakkith
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#3
Mar9-11, 05:59 PM
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Unless for some reason the acceleration starts to slow down in the future for some reason then there shouldn't be a big crunch.


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