BTW. Towards the close of last year I offered a non-mathematical suggestion as a possible answer to the original question.

"At the time of the Big Bang we are told that all the matter and energy of the Universe occupied a very small area. The energy of the BB forced this matter and energy to expand. GPE is simply the equal and opposite force which, provided there were no "interference", would tend to bring everything back together.

Of course, this implies acceptance of the BB, the expanding Universe and equal and opposite forces, but, heck, where would we be without a little "faith"?"

No one responded; is that because it is too naive to deserve comment?

There never was nothing.