this post was submitted on 27 Sep 2023
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It has a positive mass, and in every other way it acts just like normal matter going backwards in time (cpt inversion).
If, despite its positive mass, it was pushed back by gravity, then it would have given even more weight to the theory that antimatter is just matter moving backwards.
Since gravity is such a wonky interaction, I'm not even sure this result disproves the time-reversal theory entirely!
Why would inverting charge make particles go backwards in time? Electrons have opposite charge to protons and they don't seem to. Positrons have the opposite charge to electrons and as far as I know they don't go backwards?
I think you're misinterpreting cpt reversal symmetry, which is if you mirrored the universe in terms of charge, time and parity it would essentially evolve the same
It's been many years since I was invited with particle physics, so it's a bit muddled in my memory... i could be wrong on the details here. It could be the CP symmetry instead of the CPT symmetry.
It's not that positrons go back in time, but more like "if an electron went backwards in time, it would look exactly like a position". The Feynman diagram of an electron and position annihilaton is the same as that of an electron bouncing on photons, expect the angle is rotated such that the electron bounces backwards in time.
https://commons.m.wikimedia.org/wiki/File:Feynman_EP_Annihilation.svg#mw-jump-to-license
Ah yeah makes more sense