Feynman's One-Electron Universe: Every Electron Is the Same Particle
In 1940, Richard Feynman called John Wheeler with a wild idea: all electrons might be a single particle, moving forward and backward in time. A positron is just that electron traveling backward. Feynman admitted he didn't take it too seriously, but the concept inspired his Nobel-winning work in quantum electrodynamics.
I did not take the idea that all the electrons were the same one from him as seriously as I took the observation that positrons could simply be represented as electrons going from the future to the past in a back section of their world lines.