Have you ever made a decision that you later regretted? Maybe you put all of your money on red instead of black, accepted one job offer instead of another, or prematurely sold your shares in Apple for a fraction of what they would eventually be worth. If you’ve ever done anything that you’ve later regretted, then we have some good news for you. You didn’t do it.

Well, you did and you didn’t. The Many Worlds Interpretation of quantum mechanics holds that any action with more than one possible outcome results in the universe splitting into parallel worlds for each and every possibility. If you put all of your money on red in one universe and lose, in another you’ll put all of your money on black and win. In another world still, you’ll bet on red and win. Any possible outcome that you can think of is accounted for in one of the infinite parallel universes that spring into existence with every action.

The Many Worlds Interpretation was conceived by physicist, Hugh Everett III, in 1957. Everett came up with the theory in an effort to reconcile Einstein’s theory of relativity with quantum theory. These two theories form the basis for our entire understanding of the laws of physics, yet they are fundamentally incompatible with one another.

The laws of physics according to the theory of relativity are entirely deterministic. Every cause has a precise and certain effect. This is not the case in quantum mechanics, however, where events happen seemingly at random. There are no certainties in the quantum universe, only probabilities. In further contrast to the theory of relativity, the Copenhagen interpretation of quantum mechanics holds that an object exists in all possible states until it is observed. You’re probably familiar with this concept through Schrödinger’s cat.

Erwin Schrödinger’s famous thought experiment proposes a scenario in which a cat is sealed in a box with a small amount of radioactive material, a geiger counter, a vial of poison and a hammer. Over the course of an hour, there is a 50/50 chance of the radioactive material decaying enough for the geiger counter to detect it. If radiation is detected, the hammer shatters the vial and the cat is killed by the poison. The cat’s fate would not be known until the container was opened and its contents observed. If we apply the Copenhagen interpretation to the cat’s predicament, the poor creature would be simultaneously alive and dead until the point that it is observed as being one or the other.

Schrödinger himself thought that this scenario was absurd, reasoning that the Copenhagen interpretation must be flawed. How and why would something go from being in two states at once, to just one state when we look at it? Everett’s Many Worlds Interpretation solves the problem by stating that an object exists in every possible state even when being observed. If we open up Schrödinger’s box and the cat is alive, then it’ll be dead in the parallel universe that was created before we opened the container. This would also imply that quantum theory is in fact deterministic, just like the theory of relativity. Every cause has the precise and certain effect of every possible outcome being achieved across infinite new timelines.

Everett’s theory was largely dismissed by the scientific community at the time. However, it has since gained substantial support to the extent that it is now considered to be a mainstream interpretation of quantum physics.

What do you think? Do parallel universes exist? Let us know what you think in the comments and don’t forget to follow us on Facebook and Twitter to avoid missing out on new articles!