• Flying Squid@lemmy.worldOP
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    5 months ago

    The speed of light in a vacuum unaffected by external forces such as gravity should be the same no matter what direction it is in. I’m not sure why it wouldn’t be. That’s like saying a kilometer is longer if you go East than if you go West.

    However, it’s actually far more complicated than that, and much of it beyond my understanding.

    https://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/speed_of_light.html

    That said, direction should not matter.

    • vithigar@lemmy.ca
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      5 months ago

      There’s no reason it wouldn’t be. The point is that it’s impossible to prove that it is. There is no conceivable experiment that can be performed to prove the two-way speed of light is symmetric.

      • Flying Squid@lemmy.worldOP
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        5 months ago

        That’s not how anything works. It’s impossible to prove that the universe wasn’t created last Thursday with everything in place as it is now. There’s no point in assuming anything that can’t be proven has validity.

        • vithigar@lemmy.ca
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          5 months ago

          …but that’s exactly what you’re doing. The fact that light travels at the same speed in all directions cannot be proven. You’re the one insisting that it does.

          • Flying Squid@lemmy.worldOP
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            5 months ago

            I’m not insisting anything. I’m saying that, based on everything we know, the direction of light has no bearing on its speed.

            Suggesting that it does just because we don’t have evidence that it doesn’t is no different, as I said, as claiming the universe was created last Thursday.

            Maybe the speed of light doubles when it goes through the exact right type of orange. You can’t prove it doesn’t.

            • InnerScientist@lemmy.world
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              5 months ago

              This is slighlty different though, we only know the two-way speed of light, not the one way speed of light.

              We only know that this trip, to and back, takes x seconds. We cannot prove that the trip to the mirror takes the same length of time as the way back.

              The special theory of relativity for example does not depend on the one way speed of light to be the same as the two way speed of light.

              Wiki

              • ricdeh@lemmy.world
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                5 months ago

                Synchronise two high-precision clocks at different locations. Transmit the signal from A to a receiver at B and then send a signal back (or reflect the initial signal) from B to A. Both locations will record the synchronised time that their sensors picked up the transmission. Then, compare their clocks.

                  • Munkisquisher@lemmy.nz
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                    5 months ago

                    Sync them right next to each other, then move one of them. The other way you could test this theory is to have one clock tell the other the time over an optical link and then have the other do the same. If the speed of light was different in different directions. Each would measure a different lag.