dehammer wrote:
"so what was filling the space 1 billion light years away from the big bang"

Nothing. Because what you are describing never existed and violates every concept of modern day physics.

There was never anything even one angstrom away from the big bang. The big bang was and is all there ever was, all there is, and all there ever will be.

This material is well covered in my high school physics books and astronomy curricula.

DA Morgan