According to the One Electron theory, in the same way as an electron can be bounced around in space when hit with light, the electron might also be able to bounce backward in time.
Wheeler was nearly certain that his thought experiment wasn't a reflection of actual quantum reality, but he did note that the idea that there aren't the same number of positrons as electrons is only true for our observable universe.
The theory and these numbers imply that the one electron in existence has traveled through the universe 1080 times, each time taking 460 septillion years.
Here's what Feynman said: I received a telephone call one day at the graduate college at Princeton from Professor Wheeler, in which he said, "Feynman, I know why all electrons have the same charge and the same mass."
Like many quantum theories, the idea that every electron is the same electron, known as the One Electron Theory, is more of a thought experiment than a theory.