this post was submitted on 27 Sep 2023
260 points (100.0% liked)

Science

374 readers
1 users here now

Subscribe to see new publications and popular science coverage of current research on your homepage


founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[–] dingleberry@discuss.tchncs.de 43 points 1 year ago (2 children)

Antimatter still has a positive mass. It's not some exotic negative mass matter.

[–] Nawor3565@lemmy.blahaj.zone 58 points 1 year ago

Well, yes, as far as our theories go. But we also "knew" that light was a wave that traveled through the luminiferous aether, which permiated all of space... Until we tested that theory with the Michelson-Morely experiment, and it turned out our theories were completely wrong and physics as we knew it was completely upended.

Point being, it's important to actually test our theories instead of assuming they're completely correct just because most of their predictions are accurate.

[–] i_love_FFT@lemmy.ml 4 points 1 year ago* (last edited 1 year ago) (1 children)

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!

[–] ryannathans@aussie.zone 10 points 1 year ago (2 children)

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

[–] i_love_FFT@lemmy.ml 4 points 1 year ago (1 children)

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

[–] ryannathans@aussie.zone 3 points 1 year ago

Ah yeah makes more sense

load more comments (1 replies)