Something Weird Happens When E=−mc²

Derek Muller takes us on a quirky journey through Paul Dirac’s mind-bending discovery: when you plug negative energy into quantum mechanics, you end up predicting a mirror universe of “anti-particles” zipping backward in time. From the Schrödinger and Klein-Gordon hiccups to Heisenberg’s uncertainty and Dirac’s iconic equation, we see how the theoretical oddball became the reason we know the positron—and glimpsed the anti-electron decades before it was spotted in the lab.

Along the way, we meet the fascinating, if intensely private, Dirac himself, hear how collaborators like Graham Farmelo and Cumrun Vafa kept him grounded, and learn why this twist in physics has been dubbed “the saddest chapter” and also one of the most thrilling.

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