The idea that there can be different regions of space-time where the local conditions are radically different comes from string theory. Then it's the idea of inflation in the early universe, a period of super-rapid expansion that never ends. And then we have the many-worlds idea that comes out of quantum mechanics and whoever at the third's PhD thesis in the 1950s. Is there a way of explaining to our listeners how that works without melting their brains right away? I don't think we should resist melting the brains. That's okay. We just got to bite the bullet and do that.