The Futurama Theorem

Interviewed for Episode 118 of the Geek's Guide to the Galaxy podcast, TV writer David X. Cohen identifies "the highlight of Futurama math."

In an episode of Futurama written by applied mathematics Ph.D. Ken Keeler, a brain-switching machine swaps the characters' brains, with the restriction that once a pair's brains have been exchanged, they can't be switched back. Keeler was able to prove that, no matter how mixed up the brains got, the introduction of two new people would ensure that everyone could be reunited with his or her brain.

"So I was very excited about this," Cohen recalled, "because you rarely get to see science, let alone math, be the hero of a comedy episode of TV."