Thank you for that excellent bit on the multiverse/quantum mechanics thingie, I've read a lot of sci-fi based on it and nobody put it quite that way. Best example = Timeline (the book, not the movie, where they had to take the science out).
I think that the way it works is that time is an actual physical dimension of which we only perceive its intersection with our perceived three dimensions of space (like the squares in Flatland), which we receive as Now. Which means that all other times exist, just not where we are, but we can do the thought exxperiment of if we COULD be there, this is what we'd get as "now" (and it could be anything).