Is the Universe Closed? - Current Big Questions in Cosmology

The question of whether the Universe will collapse in a big crunch or continue expanding forever hinges on knowing the density of the Universe. Density is defined as mass divided by volume. One can measure the density of the universe by observing the local group of galaxies and assuming that the Universe is all the same. One can also calculate the density required such that the Universe will eventually stop expanding. That density is called the critical density, and the ratio of the observed density to the critical density is given by the Greek letter omega. If omega is less than one the Universe will continue expanding until it is so large that it dies a cold death. If omega equals one the Universe will eventually stop expanding but will not collapse. In this case the Universe will also die a cold static death. But, if omega is greater than one, then the Universe is doomed to collapse under it's own gravitational mass, and will die a hot, fiery death in a big crunch. But don't worry, the ultimate fate of the Universe is atleast ten billion years away.
Omega (Density Ratio)
Fate of the Universe
Less than One
Open; Eternal Expansion, Cold Death
One
Flat; Cold Static Death
Greater than One
Closed; Big Crunch, Hot Death
For theoretical reasons, cosmologists believe that omega = 1. Unfortunately, attempts to measure omega yield results of about 0.1.