Let's say you have the Earth, or any celestial body, spinning as it is. What if you build a tower from the surface, and extended it out into space. If it was built far enough, could the furthest end exceed the speed of light?


marked as duplicate by Kyle Kanos, Jim, Brandon Enright, BMS, Qmechanic Apr 3 '14 at 19:23

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    $\begingroup$ possible duplicate of Is it possible for information to be transmitted faster than light by using a rigid pole? $\endgroup$ – Danu Apr 3 '14 at 10:58
  • $\begingroup$ Regarding the dupicate: Agree. The kinematics of the setup are different, but the answer to the question is the same. $\endgroup$ – BMS Apr 3 '14 at 16:05
  • $\begingroup$ I don't think the proposed question is a duplicate. This question is similar to the relativistic rotating disk and that's hard enough that I've never seen a really convincing analysis of it. The question isn't about signalling, as in the rigid rod. You could accelerate your spinning rod arbitrarily slowly to avoid problems with stresses propogating along the rod at finite speed. $\endgroup$ – John Rennie Apr 3 '14 at 16:27

What you're asking is essentially whether anything can rotate faster than the speed of light. Just like how it would take infinite energy to accelerate an object to the speed of light in a straight line, it would also take an infinite amount of energy to rotationally accelerate an object to the speed of light.

In any practical sense, this tower would be torn apart by tension long before you would reach luminal speeds, which is actually one of the challenges with building a space elevator.


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