by houserichichi » Fri Sep 22, 2006 2:14 pm
Physically visible/observable.
The universe as we know it is 14 billion years old, but that's only the part that we can see. Since cosmology now generally accepts inflation as a subset of the Big Bang, we must necessarily accept that there is light that has not been able to reach us due to the expansion rate of the early universe and, thus, there is more to the universe than just our 28 billion light year diameter field of vision. Now whether what lies beyond our field of vision is finite or infinite is still up for debate.
Also note that since there is no center of the universe, every point in the visible universe will also have its own 28 billion light year diameter field of vision and they will appear to be the center of the universe from their perspective.