Does it have an end or does it just go on and on forever and ever? Do you think we are the only things that live in the whole of space???? We can only see the universe out to our horizon (essentially the distance of cosmic microwave background radiation about 13.7 billion light years away). The size of the rest of the universe can't really be known. Some cosmologies make our corner of the universe as a "pocket universe" in a much larger multiverse where physical constants (and so the behavior of so called physical laws) vary over unfathomable distances with little universes peppered throughout it. So, we can't really say how big it is, only how big the portion we can actually see is.