Can the Universe be spatially closed and expand forever? In the lambda-CDM model, the Universe is spatially flat, and will expand forever. Is possible that a spatially closed Universe expands forever?
Yes, if the Universe is matter-dominated and spatially closed, then a cosmological constant:

$\Lambda &gt; \frac{4\pi G \rho}{c^2}$

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.