Physics
Pauli Exclusion Principle
Quick fact
The Pauli Exclusion Principle explains why neutron stars can hold themselves up against gravity—it's the same reason atoms have structure.
Why this is interesting
You already know that no two people can occupy the same seat. But did you know that at the quantum level, a similar rule forbids two electrons from being in the same place at the same time—with profound consequences for all of matter?