• FuglyDuck@lemmy.world
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    17 hours ago

    You have two observers, moving directly opposite each other.

    Each has a flashlight pointing back at the other.

    The speed of the light from those torched is the same for both observers.

    (Instead the light would be red-shifted.)

    Add a third observer, stationary to one and moving towards the other. As the third observer passes that observer, the speed of light from their flashlight never changes, and it’s the same speed as from the other two. (Instead it would go from being blue shifted to red shifted.)

      • derek@infosec.pub
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        9 hours ago

        It makes sense after accepting spacetime is mutable. Reference frames are merely referential localization.

      • LavaPlanet@sh.itjust.works
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        5 hours ago

        Different phases (colours of light) move at different speed, and have different longevity, I think. So how they always thought those pretty galaxy nebula photos, were red? Actually turns out that phase of light just travels for a longer time. Lasts longer. OK, now someone correct me, because I have absolutely no idea what I’m talking about. Just bring up vague floating memories from an article i read once.