What does the big bang theory propose as a rational theory to the role of nothingness, or does it not include the effect of nothingness in its theory?

Nothingness would account for the universes expanding, as watter falls to fill an empty space, matter expands to find it. However, if the universe expands to reach other nothingness, it would create nothingness within itself (creating voids where it left space to fill other space), which may account for black holes. And if black holes were seen from this perspective... Everything running to it, rather than it pulling everything, then perhaps it would seem gravity itself is not a pulling force, but a lack of force which places (planets, parts of the planet itself) around it move to fill. That's interesting because it may leave an opening to bring to light again the hollow-Earth theory, though not hollow in the modern thought of it, where it is filled with air, but hollow where it is filled with nothing (that's truly hollow!!). Oh boy, I could go on for quite a few hours right now if I didn't have to worry about sleep.

Side note: Perhaps as water and oil have mix differnt than oils and oils and waters and waters, perhaps nothing and something mix similar.