Ask Ethan: Why Haven’t We Bumped Into Another Universe Yet?
“If the Multiverse Theory is true, shouldn’t our expanding universe have bumped into another universe by now? After all, our universe is now so large that some describe it as “infinite” in size.”
The Multiverse is one of the most fascinating ideas to arise out of the past few decades. In short, it says that our Universe, as we know it, is just one of countlessly many in a vast sea of inflating spacetime. But with all of those other Universes out there, and with all of them expanding just as our own is, shouldn’t we have collided with another one by now? And if so, where’s the evidence for it? It’s a question that needs to be taken seriously, because if we make a scientific prediction that isn’t borne out, we need to understand why. But before we ever get there, we need to understand exactly what predictions come out of our theories, including the fact that even if our Universe is infinite, that doesn’t mean there isn’t another, bigger infinity preventing us from ever colliding with another one.