You are trying to think about the expansion of the universe in terms of three dimensions. It's not a sphere expanding, the expansion is the 3 dimensional universe expanding with a 4th dimension. The analogy is blowing up a balloon. The surface of the balloon is 2 dimensions, it has no edges, yet as you blow it up it expands within a third dimension. The problem is obviously as inhabitants of a 3 dimensional space we can not envisage the equivalent 3 dimensional expansion. The maths is there though to show it. Not that I understand or want to look at the maths, just wrapping my head around the concept gives me a headache.Technically I thought that if it was caused by a 'big bang' then it would be expanding and therefore would have an edge/ end to it. But if we're saying that there already was a space and the big bang happened in space then it would be never ending???




