Physics
Spin-Statistics Theorem
Quick fact
The spin-statistics theorem was first derived by Wolfgang Pauli in 1940, and it is one of the few results in physics that relies on special relativity, quantum mechanics, and causality simultaneously.
Why this is interesting
You know that electrons can't share the same space, but photons can pile up without limit. What makes two identical particles behave so differently? The answer lies in a subtle link between their spin and their 'social' behavior.