Great suggestions, y'all!
I think one thing that I really want is to have
some idea of what the basis of this concept might even be, simply because I do think that the work of most writers really suffers if they themselves don't have some sort of grasp of the underpinnings of what they're writing about. This doesn't necessarily have much to do with whether or not the nuts and bolts will ever be spelled out.
To help make things a bit clearer (possibly) as far as what kind of help I might need:
The main character and his long-suffering friend (who's taking Holy Orders to become a priest in the church of the FSM, which is the official state religion, btw), are sitting in a coffeeshop in a bookstore, and an author is holding a booksigning. The book just happens to be titled:
Everything You Always Wanted to Know About Quantum Universe Hopping (But Were Too Confused to Ask. Part of the plot, in fact, is that this little trick
does work in this world, but not in the non-magical world, so it would be good to get some theories about how this might be possible. (Why yes, this IS Harry Potter fanfic, now that you ask. Yes. I've written an awful lot of it. Sometimes we have to be proud of the little things.) The protagonist decides that taking advantage of multiple realities is definitely the way to get the girl, so it's very deliberate on his part.
Now, I post fics on a shipping site, so the romantic aspect, quite honestly, is primarily what people are interested in reading, but OTOH, need to know that what I'm writing about at least has some plausibility.