Do photons “experience” time, or does everything happen simultaneously for a photon?
I swear I read about a physicist who commented that all light in the universe could be the result of a single photon bouncing back and forth throughout time, and drew a 2-D “world sheet” to demonstrate the point.
Was I dreaming?
Photons do not experience time. A photon cannot have a frame of reference because light must travel at c wrt to all frames of reference and light cannot travel at c with respect to light. And therefore no photon can be emitted unless it’s absorbed. In more conventional terms the time dilation of a photon is infinite. 1 / sqrt (1 - c[sup]2[/sup] / c[sup]2[/sup]) = infinity.
All subatomic particles’ Feynman diagrams (a worldline of sorts) are symmetric wrt to time, and therefore all subatomic particles could be the result of one of those types bouncing back and forth throughout time
I don’t remember hearing that, but it brings to mind an idea that Wheeler briefly held: that all the electrons and positrons in the universe might be a single particle going back and forth in time. That would explain why all electrons have the same rest mass and charge, anyway.
It’s an interesting notion, that bouncing through time, but it’s disprovable. You can use a couple of gamma rays to produce an electron-positron pair, observe the two particles, and then let them re-annihilate into gammas. There you have it, an electron definitely disconnected from all other electrons.