Quantum fluctuation question ...?

Yes. Which is where the quantum fluctuation theory falls short. Unless gravity does indeed produce the mass around it rather than the mass producing gravity. Which came first, the chicken or the egg? Who knows.

As the universe fluctuates around net zero and the universe, the mother universe that laid the egg we call the big bang, is infinite and eternal, there is continual plus and minus energy throughout. Think of it like an AC current that is, in the net, zero current, but the rms current powers things and lights up your computer so you can read this.

And, a point you may have missed, energy is also a source of gravity space time warping according to the general theory of relativity. Mass, energy, and stress are the three possible sources of gravity according to the GTOR. As the mother universe is filled with energy, high entropy energy, that's all she needs now and then to lay one of those golden low entropy eggs, like our known universe.

No chicken egg thing...mother universe is the chicken filled with wiggly squiggly huge quanta that every once in a while plunk down a low entropy space time egg that results in some sort of universe. And yes, there is both space and time prior to our big bang...it exists in the mother universe. I suggest you also read "The Fabric of the Cosmos" by Brian Greene; he goes into several models of what the mother universe might be like.

All that is really truth in the natural world will be true at any scaled.

Fairly vulgarized, the void ask to be "filled". This is true with pressure, human relationship, biological entities and many others...

Thus, even on the level of waves and nothingness there is a contraction happening. Gravitation then appears on the form of centrifugal forces pulling toward many epicentres maybe responsible to the contrary force we know as "big bangs".

Then, the centrifugal forces countered by opposite reaction on the mechanical level become a progressively faster repeating phenomena. The encounter between the two waves creating rotation by not being able to coexist in the same space.

All the other theories relating to bodies in space are just another take on the Schroedinger paradox. If mind create matter by perception, then mind is in the origin what let matter be. Thus, matter is subjected to the pattern of existence that counsciouness has, and not the other way around. This may sound crazy, but it is the only way you can end up creating something out of nothing. Or to be fair, creating something out of the simple need of it. (as we did with money)

We then invented rules for the rational of human being by taking for granted that matter exist. This actually work until we try to figure out why matter would be there, which there has no answer yet. We do calculate a lot of things only by using perception to consolidate this basis on which we built traditional science. But as only machine we built can perceive the atomic level, we could state that the atomic level is in fact only a comfortable assumption to vehiculate "fate", or more scientifically quantum mechanic behind the probability that what we find reasonable can be a basis on which we can build other subsystem. These subsystem eventually end supporting the existence of each other the same way the two first rules of the universes eventually created rotation.

Otherly said, you can try and explain gravitation by what we have to perceive, or you can try to really understand the purpose of it by finding its origin in the quantum of creation. Depending on which way you take to look by the telescope, you will see a lot of different thing at the extremity, but what you are really looking at is the deformation of light happening in the tube. Which by the way, was probably not the focus of interest when you choose to look in the telescope...

You can find a similar relation between the medical specialist of an organ, and a enviro-biologist that try to understand the organism. Eventually, they'll find similar conclusion, but one is looking from the bottom up, and the other from above until he reaches the core. Their explanation will be radically different even when they agree on a treatment. The cause, however, will never be quite the same even talking of the same problem.

For a better understanding of those kind of clash in science, I recommend you "La Vie Antérieure" by the French biologist Henri Laborit. (I can assure you it has nothing to do with past lives... This is just his idea of how to title his biography.)