Why do prime numbers make these spirals?
This video is pretty entertaining, at least if you like numbers. The first half is pretty straightforward. The second half where he starts talking about Dirichlet's Theorem (14:48) is a little more esoteric. I know some people are fascinated by infinity, but I am not one of them. It comes in handy for imagining how things will go, but for any kind of concrete answer, it's pretty worthless.