Physics
Bell States
Quick fact
The four Bell states are named after John Bell, who derived a testable inequality that showed quantum entanglement cannot be explained by any local hidden variable theory.
Why this is interesting
Imagine flipping two coins that always land on the same face—even when they are separated by galaxies. Bell states are the quantum version of this idea, but with a twist: the outcome isn't decided until you look, and the correlation is stronger than anything classical physics allows.