I personally have a theory on alternate dream-universes that's far too complicated to write down now, since it's 5:34am here and I'm about to die of sleep deprevation.
But another idea I have that I like is that when you die, lying there in your comfy coffin slowly rotting, you can revisit anytime in your life you want, re-live past experiences, loves, victories etc. It's all basically a little parallel unoverse to yourself, where you can change the outcome of anything but your death. A personal god thing. I like it.