I have a question (as a layman) about many-worlds interpretation. Let's say we are indeed living in that kind of universe. From Wikipedia:
In layman's terms, the hypothesis states there is a very large—perhaps infinite—number of universes, and everything that could possibly have happened in our past, but did not, has occurred in the past of some other universe or universes.
So, my question is two-fold.
Does hypothetical "snapshot" of our whole universe have many different (so, non-deterministic) possibilities to happen at the next very "moment"?
And if (1) holds (e.g. many different possibilities), then this claim "...everything that could possibly have happened..." cannot be true. Because even if we have infinite number of universes, there are still more infinite possibilities (if (1) holds) that can happen.
So conclusion of this (naive?) deduction could be: NOT everything possible can happen in many-worlds interpretation?
There is a total confusion about two entirely different concepts.
There is the multiverse hypothesis in cosmology asserting that there is a large number of "universes". Now there are lots of different version of it, either the universes differ in their laws, or only initial conditions, or both.
It is a speculation that many, including me, would dismiss because it is not parsimonious (what a good theory should be) and utterly non-falsifiable. But if you postulate that all possible initial conditions are true in some universe, then it would make sense to claim that in your model, everything possible happens. Where possible is well-defined by the usual laws of physics.
There is the many-worlds interpretation of quantum mechanics, totally unrelated to number 1, which states something like that the quantum wave function indeed never collapsed but the different superpositions are becoming different "worlds" and we perceive only one of those. This is far from saying that anything possible happens, but only cares about the quantum measurement processes, where then all possible outcomes are realized. This interpretation may have its problems, but as I said, has nothing to do what you are thinking about the hypothetical universes with different laws or initial conditions.