Can't we make amends? Can the average gravitational potential inside our Universe within some finite time frame be computed on an assumption the Universe is frozen within this time frame and the Killing vector field can be (approximately) defined? If the Universe were not expanding, and we could treat it as having finite dimension and uniform matter distribution on macro scale, we would get the simple expression for the potential relative to the Universe boundaries (or "center").
I wonder if the assumption of the infinite Universe leads to the accelerated expansion as to get density reduction with the distance, resulting in the finite gravitational energy within the Universe (which will likely be constant throughout it on macro scale, so no force).
