Quantum mechanics is littered with different interpretations, but at the core of the entire school of thought is the question of whether there are multiple universes of not. At the core of this idea is the thought, explicated by quantum mechanics, that everything we observe is simply the collapse of all probable scenarios into one specific outcome. Reality, viewed from that perspective, has a very cluttered cutting room floor. But are the things removed from the reel scraps or alternative narratives? There’s the big question.
To answer that question, we need to dive a bit into the mechanisms of the thing. Quantum mechanics says that all particles in the universe can be represented by what are called “wave functions.” A single wave function basically illustrates all the information about a specific system (i.e. a particle), detailing everything from position to velocity. The wave function itself also outlines all the probable outcomes of that system as well.
In other words, the wave function says what a particle is, and — more importantly — what it might being doing any any given time. It represents all possible futures of that particle.