Science Forums 2

[Tormod]

This really depends on what you define as the "universe". If you are talking about the Observable Universe, then it simply expands into more of the same (more stars, more galaxies) - because it is defined by the distance of the most remote light we can see (imagine a sphere with a radious of some 13,7 billion years).

If you define the "universe" as everything that can possibly be, then there is nothing into which the Universe can expand. This would make the Universe infinite (but not necessarily occupying an infinite space - simply all the space that is available!).

Another way to view our Universe is to consider that it might be a part of a larger universe in which ours is only a small part (like an island in the ocean). This is actually just a modification of the first point above. However, depending on how each of the universes came into being, their physical laws and properties may be different.

According to the Anthropic principle, we live in the most likely of all universes. This principle in fact requires there to be an endless amount of possible universes, some of which must exist "out there".

Anyway, we have covered this before in our forums so try to look back through the posts and you might find some interesting points.

Tormod