Saturday, 12 January 2013

cosmology - Can the Universe be spatially closed and expand forever?

Yes, if the Universe is matter-dominated and spatially closed, then a cosmological constant:



$Lambda > frac{4pi G rho}{c^2}$



Where $rho$ is the critical energy density (of matter) of the Universe, will cause it to expand forever.



NB Where $Lambda$ is equal to this value you get the (unstable) Einstein static Universe.

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