Forgive the ignorance, but how does space (nothing) expand/contract?
A decent analogy (which, like all analogies has its problems) is the surface of the earth. To a very primitive person, there appears to be no limitation in the way you can travel around on its apparently flat surface. But the real truth is that you are limited to travel only along pieces of arcs of great circles [with the radius of the earth as their radius.] This becomes apparent if you have very good measuring equipment: after going only a few miles on an apparently flat plane you discover you've gone farther than a straight line would.