“Go then, there are other worlds than these.” –Stephen King, The Dark Tower
Ever since quantum mechanics first came along, we’ve recognized how tenuous our perception of reality is, and how — in many ways — what we perceive is just a very small subset of what’s going on at the quantum level in our Universe.
Then, along came cosmic inflation, teaching us that our observable Universe is just a tiny, tiny fraction of the matter-and-radiation filled space out there, with possibilities including Universes with different fundamental laws and constants, differing quantum outcomes existing in disconnected regions of space, and even the fantastic one of parallel Universes and alternate versions of you and me.
But is that last one really admissible? Here’s what the best modern evidence has to say, and it isn’t necessarily the outcome you’re looking for!