It's possible that the you sitting there is but one you in a multiverse of yous. Which means that there are many earths and many alternate realities. Dun, dun, DUN!!!! Yes, it's this mind-blowing idea that YouTuber Matthew Santoro tackles in his video "10 Pieces of Evidence Alternate Realities Exist."
As the title suggests, Santoro lays down various theories—some of them scientific, some of them not so—that point to the existence of multiple universes. Which would mean multiple earths and multiple alternate realities which contain multiple versions of all of us.
So in one universe you might be a successful Hollywood star, while in another you might be married to an unsuccessful LA actor who's addicted to crack. The Rick and Morty episode "Rixty Minutes," where Rick hooks his family up to interdimensional cable so they can watch infinite television from across the multiverse, is a very funny example of this idea. However, Santoro doesn't use Rick and Morty as evidence, as that would be dumb. Instead he goes through ten varying theories.
10 Theories That Prove Alternate Realities Exist
He starts off with the Double Slit Experiment—a mindf*ck of an experiment that involved firing electrons through a piece of material with two slits to see how they impacted the wall behind the material. What they found was instead of producing two slit marks on the wall, a wave-like pattern was seen. It resulted in the conclusion that the electrons were existing in multiple places at once. Which is known as superimposition.
Another, perhaps more speculative and less scientific theory, is the appearance of various inexplicable artefacts that have, as yet, defied explanations. Along with this some date back to times before humans existed yet purport to be made by human hands. Spooky.
Another example for alternate realities is what's called the fourth dimension. It exists only in theory at the moment and, Santoro notes, only a few mathematicians and physicists can fully understand it. But if it is proven to exist, it points to the idea that there may be a fifth, sixth, seventh and many more dimensions.
Also, if we can breach the fourth dimension, then we could possibly travel through time and land on an alternate earth, and so discover alternate realities to our own.
Like I said, dun, dun, DUUUN! It's all very Twilight Zone-esque and you're probably best to watch this after smoking a whole load of weed.
Another tip is, be watchful for doppelgangers. Because they might actually be yous from alternate realities who have come to steal your life because they messed up so badly in their own universe they had to flee.