If the universe were infinite, does that necessarily mean that it must be filled with mass in the form of stars, and by the same token if the universe is infinite, we would never see most of the stars or matter, or whatever is out there because it would take an infinite amount of time for the light to reach us.
Yes, but if the universe is infinitely old, then that's not a problem - we'd see an infinite amount of light coming from an infinite number of stars, for an infinite amount of time, in every direction.
Basically imagine sight-lines extending from your eyes out into the universe. There's no direction you can direct your gaze where your sight-line doesn't intersect with a star - with an infinite number of stars behind it.
The idea of an infinite, eternal universe is fun but it's contrary to observation. So one of several possibilities must be true:
1) The universe is infinite but not eternal; it has a terminus at both ends of time.
2) The universe is infinite and eternal in the future only - the universe will always exist though it has not always existed.
3) The universe is finite in both time and space, but unbounded in the three spacial dimensions we percieve (so that it's not possible to travel to the "edge" of the universe).
I favor the last one, myself. I don't think infinity is actually a thing that can exist in any physical sense.
[This message has been edited by crashfrog, 10-10-2003]