It seems to be quite a common question to ask "what is the universe expanding into?" However I want to ask "where is the universe expanding from?"
Is there a "centre of expansion" of our universe and if so do we know where it is? To me it would seem that there must be a "centre of expansion" - the point from which the big bang occurred. However I have never heard any mention of it so maybe my reasoning is wrong.
If you are a 2D ant confined to the 2D surface of a balloon, and someone is blowing up your balloon, you might notice that your world is expanding; objects are getting further away from each other! However, there would be no "center of expansion". No point on the balloon would any more be the center than any other; the space you are living on is just getting bigger.
The answer for our universe is similar: our 3D space is expanding, but there is no center. The whole of space is getting bigger, not from anywhere, and not into anywhere, just getting bigger.
