The many-worlds interpretation is one idea in physics that supports the concept of multiple universes existing. It stems from the way we comprehend quantum mechanics, which defy the rules of our regular world. While it’s impossible to test and is considered an interpretation rather than a scientific theory, many physicists think it could be possible.
“When you look at the regular world, things are measurable and predictable – if you drop a ball off a roof, it will fall to the ground. But when you look on a very small scale in quantum mechanics, the rules stop applying. Instead of being predictable, it becomes about probabilities,” says Sarah Martell, Associate Professor at the School of Physics, UNSW Science.
This interpretation of quantum mechanics is important, as it helps explain some of the quantum paradoxes that logic can’t answer, like why a particle can be in two places at once. While it might seem impossible to us, since we experience time and space as fixed, mathematically it adds up.
Like it is depicted in many science fiction films, the many-world interpretation suggests our reality is just one of many. The universe supposedly splits or branches into other universes any time we take action – whether it’s a molecule moving, what you decide to eat, or your choice of career.
In physics, this is best explained through the thought experiment of Schrodinger’s cat. In the many-worlds interpretation, when the box is opened, the observer and the possibly alive cat split into an observer looking at a box with a deceased cat and one looking at a box with a live cat.