Youre thinking in medieval terms
We exist in 4 dimensions which contain the illusion of material objects and movement such as lifting. God exists in a higher dimension containing our 4 where material objects & movement have no meaning.
All known matter was present at the singularity of the Big Bang. That would have been the "Heaviest" object imaginable to us and God created it.
The expansion of our universe takes place within Gods being which is eternal & infinite