There May Be More Universes

The idea that we live in a multiverse, in which our universe is one of many, comes from a theory called eternal inflation, which suggests that shortly after the Big Bang, spacetime expanded at different rates in different places. According to the theory, this gave rise to bubble universes that could function with their own separate laws of physics. The concept is controversial and had been purely hypothetical until recent studies searched for physical markers of the multiverse theory in the cosmic microwave background, which is a relic of the Big Bang that pervades our universe.