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I think you might mean the one _electron_ conjecture. It’s fun because you have anti-electrons whose Feynman diagrams look like electrons going backwards in tim
by heisenzombie 2y ago
I think you might mean the one _electron_ conjecture. It’s fun because you have anti-electrons whose Feynman diagrams look like electrons going backwards in time. So you could conceivably be observing the tangled world line of a single electron bouncing back and forward in time — sometimes observing it as an antielectron.
Doesn’t work with photons because there’s not an anti-photon.
Anyway it’s sort of a fun “woah!” moment that Feynman was so good at producing, but I don’t think it’s taken particularly seriously as a theory.
- gradschool 2y agoThe version of that story I remember is that John Wheeler said to Feynman that the reason all electrons are alike is that there's only one electron, which we perceive as a positron when it's going backwards in time. Feynman instantly refuted the idea by pointing out that there are more electrons than positrons.
- heisenzombie 2y agoYes I think I probably saw/read Feynman retelling the story. And yes, where’s all the antimatter, right!?
- cvoss 2y agoPositrons don't merely look like time-reversed electrons, and it's not limited to Feynman diagrams. Everything we know about those particles, experimentally and in our best theory, says that they literally are identical but for a minus sign on the time variable. And it does work for photons because there is an anti-photon: the photon itself. The particle is symmetric under time reversal.
- heisenzombie 2y agoOf course you’re right about photons!