My fictional worlds reside in a multiverse. More specifically, they reside in a universe within that multiverse that is very similar to ours.
But here are some big differences:
This is the complete penrose diagram for an eternal black hole with 0 charge or rotation. It doesn't quite describe what I mean by white holes in equilibrium with black holes because it is across time, not space.
But for every black hole in the multiverse, there is a white hole it is connected to via the singularity. This means there must be negative gravity in the white hole. Or in Einsteinian terms, space-time curvature must be negative in the white hole. This means the white hole has the negative of the mass of the black hole.
But just because the multiverse has this equilibrium does not mean that a given universe will also have this equilibrium. Some have more black holes, some have more white holes, some have equal numbers, and sometimes the white hole forms a totally new universe.
In this case, black holes would correspond to dark matter and white holes to dark energy in the sense that white holes cause expansion and the more white holes, the faster it expands. Black holes due to general relativity would slow down this expansion.
White holes forming new universes implies that every universe within the multiverse must be cyclic. In other words, every universe must collapse to infinite density via gravity. This requires that there is dark matter and dark energy and more specifically that dark matter must be synthesized in some way.
Maybe virtual particles having a chance to turn into gravitons(gravity carrying particles) and that chance being way higher in areas of dark matter. This way, an observer would notice an increase in dark matter and thus gravity. More dark matter = higher chance of graviton formation = even more gravity -> gravitational collapse of universe -> Another big bang.
This means that there must be quantum spacetime.
But with these white holes and cyclic universes as I have written, what physical laws would need to be different from those of our universe and how? Would there need to be a quantum relativity?