I rather like the fish tank analogy. When placed side by side Space would appear infinite but actually be quite finite. Observation only would be a poor predictor of size as that you would peer into other Universes without ever realizing there existed a barrier or that the other side of the other "Verse" had different properties much like a fish would feel outside of it's Universal tank and in Ours. Just a thought. However,this could also partly explain how particles such as photons could travel and bounce back and forth between as if no barriers existed in the first place.