It sounds like something that jumped out of a science fiction script, but trust a physicist who was an adviser on Avengers: Endgame to flesh out a theory that essentially says there are many (and possibly infinite) versions of you that exist in just as many parallel universes.
In a sci-fi mashup of science and philosophy, CalTech theoretical physicist Sean Carroll just released the book Something Deeply Hidden. It explores a weird arm of quantum mechanics known as the Many-Worlds Interpretation (MWI). Endgame wouldn’t have had the same, uh, endgame if certain superheroes couldn’t travel back in time, where alternate versions of themselves existed, to (insert spoilers here).
“If electrons (or cats) can be in superpositions, so can the universe,” Carroll said in a recent speech for Google. “Every version of quantum mechanics includes wave functions that describe many worlds. The only questions is whether you let them be real.”
Back up a second. What Carroll was trying to say refers to the MWI concept of there being possibly endless versions of us and the world we live in. Theoretically, the universe could split any way depending on where some random molecule bounces. Every single thing we do could make the universe keep splitting — and when it splits, it takes everything with it. When you perform a quantum experiment with multiple outcomes, all of them are supposed to happen. It’s just that each happens in a different world.
Oh, and of course we’re not aware of these alternate universes. We just haven’t figured out a way to access these myriad versions of ourselves yet.
MWI is essentially an answer to all the what ifs lingering in the backs of our minds. You see this in Doctor Who when an identical version of the Tenth Doctor exists on a planet identical to Earth, yet not Earth. He still wears his suit jacket and Converse hi-tops, but the difference is that this version doesn't shatter Rose’s heart.
In what we perceive as reality, something (or someone) exists in the place they are right now. Things get freaky in the quantum realm where objects, alive or not, only exist if you actually see them. Anything not seen only exists in the bubble of possibility until it is seen, which totally sounds like the special effects in a really trippy movie.
“It's absolutely possible that there are multiple worlds where you made different decisions. We're just obeying the laws of physics,” Carroll told NBC Mach. “We don't know whether the number of worlds is finite or infinite, but it's certainly a very large number. There’s no way it’s, like, five.”
Some physicists have dismissed this idea as absurd, but when even Stephen Hawking backed it, that makes you wonder.
(via NBC Mach)