The idea that the Universe is just one of many, making up one, truly infinite ‘multiverse’ is among the most intriguing – and controversial – theories in modern physics. It’s based on attempts to find the one true ‘Theory of Everything’ (ToE) that describes all the particles and forces making up reality in a single set of equations.
Some attempts to create the ToE suggest that there are myriad different universes beyond our own, each with different laws of physics. According to some theorists, these differences may reveal the existence of universes neighbouring our own. Exactly how they’ll be revealed is unclear, but one possibility is via distortions in the heat left from the Big Bang. This has been mapped with exquisite precision, and may contain telltale patterns consistent with the lurking presence of another universe.