Eli5: what is superposition of particles and how is it possible?
In: Physics
“Superposition” is a word that means that the math that describes a particle adds together nicely. When I say “add” I mean literally the operation of addition, like 2+2=4.
So what does that really mean, physically? Well, particles are, at least in some sense, waves. We describe them as functions [just like this](http://www.science4all.org/wp-content/uploads/2013/01/Wave-Function1.png). Okay, not exactly like that, there’s also imaginary numbers involved, but don’t stress on that as this is ELI5.
In a sense, the wave function sort-of-kind-of is the particle, or at least the square of the wave function (called the probability density function) sort-of-kind-of is the particle.
And this is where we get to superposition. When people talk about particle superposition, they mean that when 2 particles are occupying the same region of space, the wave functions add together, [just like this](https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/1989/2017/06/13225738/figure-17-10-04a.jpeg). That’s all there is to it. If the height of the waves at a specific point are 2 and 5, they add up to 7 at that spot.
How is it possible? It’s a general property of basically everything unless there’s a specific phenomena that physically causes the particles to separate. It’s just like how if two ocean waves collide they can add together to make a bigger wave, or how noise cancelling headphones add the negative version of a sound wave to the ambient noise in a room so the total sound wave adds up to 0.
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