• emizeko [they/them]@hexbear.net
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    4 months ago

    what really fucks me up is combining this with relativistic effects

    like what if you had a rod 100,000 km long and you started rotating it around one end. does the other end exceed the speed of light? I know the answer has to be no, which means you’re going to get all sorts of weird relativistic effects along the rod

    • quarrk [he/him]@hexbear.net
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      4 months ago

      I have heard this thought experiment before. I think the answer is that there is no perfectly rigid rod. The nudge at one end travels down the rod as a pressure wave at the speed of sound of the material, which will be much slower than the speed of light. And in reality, centripetal force would tear apart a rod well before its tips rotate at light speed.