I don't know too much about this, I just wanted to bring up a point.

Right now, we can view objects that are about 15 billion light years away, and that's why we assume the universe is (roughly) that old?

Well, JCL, you said something about them wanting to discover if the universe was truly infinite in size. But let's say it is infinitely large. Wouldn't the sky always be just completely white? Because there would be infinite celestial bodies to light up the sky.

The only ways I can imagine avoiding this problem are:

1). After a certain point (based on what we can see about 15 billion lightyears), light can't reach earth anymore. Which doesn't seem likely, at least that it would stop so abruptly.

2). Space is infinite, but all of matter is expanding from a 'central point' in the infinite universe. I guess the only question at that point would be, what would cause matter to begin where it did as opposed to anywhere else in a universe of generally infinite size?

Also, if space exists but matter doesn't, is that even physically possible? Wouldn't that mean time also wouldn't exist until the moment that matter originated?

On the other hand I'm not an astronomer, or a physicist, and I haven't studied this too in depth so I could be way off. Just some thoughts, I figured we could discuss.