whenever relativity is freakin you out and you can't figure out how to make heads or tails of a thought experiment, just remember:
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Moving objects look thin
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Moving objects age slower
(In the above image, each muon thinks the other muon is moving (both are correct!), so they each see the other muon as having dilated time (still both correct!) and will each see themselves be outlived by the other muon. They disagree about who lived longer, and an outside observer would see them as dying at the same time. The fact that all 3 observers can be correct while disagreeing about the order in which the muons decayed leads us into the final point....)
- Simultaneity is not absolute
(in the above image, I'm moving to the right, away from you, so your life (vertical) intersects with my present (red) in such a way that if I were to have instant knowledge of what you were up to, I'd see your 'past' (but of course having this instant knowledge is impossible 'cause lightspeed and such which is what prevents paradoxes) )
Relativity is a bitch!!! And not just the curved-space gravitational tensor stuff; even the "simple" stuff like twin paradoxes and ladder paradoxes can be really fucking hard to grasp!!!!! I still feel like every other month I forget how it all works and I'm back to square one in terms of understanding relative simultaneity lmao. Just remember that your notion of "present" can be sort of "tilted" in spacetime... I think that helps a lot!
