The idea of a parallel Universe can spark even our wildest dreams. Should there be other Universes where events had different outcomes than they have in our own Universe? In these parallel Universes, just one important decision can lead to way different outcomes. There is the possibility that fields, particles or even individuals could be somehow transported from one Universe to another. This could allow us to somehow live in a Universe that is substantially better than the Universe we live in.
All of these ideas are now starting to be relevant in theoretical physics as a myriad of possible outcomes in the field of quantum mechanics keep appearing. But we must now find out if any of these actually have a connection to the measurable and observable reality. A recent claim has come up with evidence for a parallel Universe.
Strictly from a physics point of view, parallel Universes are part of a set of ideas that are quite imaginative, extremely compelling, but almost impossible to test. This theory first came up in the context of quantum physics, which is well known for resulting in unpredictable outcomes, even if you know everything about the little-understood outcome. If one takes a single electron and shoots it through a double slit, there is no way of finding out exactly where it will land. One can only estimate where the electron will end up.
A fascinating idea, the so-called many-world interpretation of quantum mechanics, suggests that all outcomes could occur somewhere, but in each Universe, only one outcome is possible. In order to account for every single possibility, it would take an infinite number of possibilities. Still, this interpretation remains as valid as any other interpretation of quantum mechanics. The simple reason is that there just are not any experiments or observations that could infirm it.