Far, far away in our infinite space. Further than we can see, because if we look more than 14B light years away we're blinded by the Big Bang of our own creation.
Max Tegmark calculated out that parallel universes are probablistically present around 10^21 an 10^23 light years out from us, if matter's about as dense and as randomly distributed as in our universe.
Max Tegmark calculated out that parallel universes are probablistically present around 10^21 an 10^23 light years out from us, if matter's about as dense and as randomly distributed as in our universe.