Why would'nt this work?
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A [email protected] shared this topic
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Short version: the speed if sound is slower than light regardless of the material it passes through.
Lets say your stick is made of steel. The speed of sound in steel is about 19,000 feet/second. Assuming you could push hard enough for the force to be felt on the other end, it'd take over 18 hours for the force to reach the other end of the rod.
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The speed of 'push' is effectivly the speed of sound in a medium. So your shove would be the same as propagating a soundwave through whatever that rod is made of.
Veritassium covers this
https://www.youtube.com/watch?v=EPsG8td7C5k&t=61s -
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The pole would basically be a space elevator. I suspect gravity and inertia would effectively keep you from moving the stick. Even if you could move it, you'd only be able to move it at a speed that would seem like it's stationary. As such, the light would still be faster.
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At this scale, the stick isn't as solid as your intuition would lead you to believe. Instead, you have to start thinking about the force at the atomic scale. The atoms in your hand have an outer shell of electrons which you use to impart a force to the electrons in the outer atoms of the stick on your end. That force needs to be transferred atom to atom inside the stick, much like a Newton's Cradle. Importantly, this transfer is not instantaneous, each "bump" takes time to propagate down the stick and will do so slower than the speed of light in a vacuum. It's basically a shockwave traveling down the length of the stick. The end result is that the light will get to the person on the other end before the sequence of sub-atomic bumps has the chance to get there.
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The whole poll does not move as end entire unit instantaneously. You send a sort of shock-wave through the poll, when you push it from your end. That shockwave has a travel time that's much slower than light. I suspect that the speed of that shockwave probably proportional to the speed of sound in the material that the poll is made of.
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that makes sense, i forgot that pushing something is basically like creating a sound wave on it ^^'
thank you
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You're gonna want a powerful laser probably and ain't no stick that big like not even fkn close not even we tried so that's why would'nt tbqh
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I ran this by an engineer and they said the same thing
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Excellent write up. -
There's a bunch of these thought experiments that try to posit scenarios where C is violated.
Here's one I remember from uni involving scissors. Similar to what OP was thinking, but really really big scissors.
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Long winded video about it:
'Are solid objects really “solid”?' (go-to 7:30)
