Which Life Could You Be Living?
Have you ever wondered where you would be if you made a different decision in life? What if you chose a different subject at university? What if you never broke up with your first love? All these different choices might be lived out in other universes while you are reading this. Some scientists believe in the Multiverse Theory — the idea that there is more than one universe.
In popular culture, the Multiverse Theory is omnipresent. Marvel films, Doctor Strange, Spiderman, Rick and Morty, and many more make use of these brain-frying hypotheses. Matt Haig’s novel Midnight Library shows what travelling in between parallel universes could look like.
But there isn’t just one theory about it. Some experts believe that there are different regions of space in different planes. Others argue on the basis of Inflationary Cosmology: the universe that we live in was created by the big bang when the universe exponentially expanded. This cosmic inflation explains the structure and distribution of galaxies in our universe, and could happen at any time, over and over again, producing a system of multiple universes — like bubbles, scientists argue.
But if you’ve ever wondered ‘what if’, and whether that ‘if’ could be real, you were thinking of the Many-World Interpretation of Quantum Mechanics. It’s a theory that describes mathematically how physical matter behaves and suggests that there are alternate realities that constantly spring off of other uni- (or multi-?) verses. We just happen to live in the one where the outcome is the outcome that we see — meaning that on other earths, there might be different outcomes. This means that in another universe, you could be a different you, living a different life than the one you are living right now. You could have made different choices, which could have led to different outcomes.
However, experts say that it’s not that a new universe is created each time you make a decision. Sean Carroll, a U.S. American physicist and philosophist, claims that if this theory was real, it would mean that in other realities, there is a person like you, that would make different choices because different quantum measurements of subatomic particles force you to make a different decision.
Whatever the theory, the one thing all of them agree on is that the space-time continuum that we are experiencing is not the only one.
But the existence of these universes cannot be proven — not yet, that is. If they do exist, they are separate from ours, so far away that we cannot even fathom the distance. They would be undetectable by any measurement we have yet invented, so humans could never truly scientifically search for them.
So why do some scientists believe that they could be real?
Tom Siegfried, a science journalist, argues that if our universe was the only one, there would be features of ours that we would not be able to explain.
“Inability to observe the multiverse does not mean that it doesn’t exist, and it may be necessary to acknowledge its existence in order to explain observable features of the universe.” — Tom Siegfried, science journalist
Even though it is not possible for us to prove that they are real, the existence of multiple universes seems to be needed to explain ours.
But if alternate realities are real, would it be possible to travel between universes?
No, at least not yet. Due to quantum fluctuations, there may be different laws of physics in some of the other universes. This would make it impossible to travel from one of these universes to another because the charge of electrons and protons could be different, and the entire biochemistry of your body could be turned upside down. Some of these universes might have different chemical elements, or no stars, or no planets.
Who knows, maybe in the future, someone will be able to make the impossible possible and figure out if there are any other universes, and if so, how it would be possible to travel from one to another.
But as of now, we can only speculate about the existence of multiple universes. There are arguments for it, and there are arguments against it. However, none of these can be proven. Maybe in the future though, they can. And in the meantime, “[t]he universe can do whatever it wants,” says Tom Siegfried.
