I found some information here:

Barring any new discoveries that may refute the WMAP’s findings, it’s official – the Universe is flat. That also means it should be infinite in extent. Still, that doesn’t mean we can altogether throw other models, like that of a finite one, into the trash bin. After all, the colorful history of science has oftentimes been dotted by discoveries that have sea-sawed contradicting models.

Take the particle and wave theory of light for example. These two opposing theories strived to define the true nature of light. Eventually, it was found that both theories were correct after all. Of course, that doesn’t happen all the time. But what if beyond the horizon the Universe is found to be in fact a finite one?

What then are the characteristics of a finite universe?

If our universe is finite in extent, that would only mean that it is closed or, for purposes of visualization, shaped like a sphere. That’s the reason why we said earlier that if we traveled in one direction on it, we can find ourselves back at our point of origin.

A closed and finite universe may also mean that the average density of matter inside it is greater than what is known as the critical density. Combining what they know about the geometry and density of matter inside it, scientists can predict the possible ending our universe may have.

For one, when all matter has an average density greater than the pre-determined critical density, they (matter) would have enough gravitational force to pull the entire universe back into a singularity.

I am not saying that our universe is finite! I am saying a finite Universe is possible. But we may not live in one.