I tried asking this question on Worldbuilding.SE but did not get much response outside of, "you cant do that." I've also seen many similar questions without the type of answer I am looking for. So I apologize in advance if I am breaking any rules. I will do my best to stay within them.

A ring, approximately 100 meters in diameter, and 1 meter in all other dimensions. And for this experiments purposes this ring is perfectly rigid.
If you spin this ring to ever increasing velocities (10-20-30-50-90% of $c$). What effects/affects would it display or take on the local environment?

I'm certain that there would be effects manifested I am not equipped to even ask about.

  • I have imagined that it would deflect any dust or solar wind particles in spectacular fashion with mini nuclear explosions.

  • How would it appear visually?

  • If you could see the object, would it appear to be moving(rotating)? If it did would the spinward (approaching) side appear blue, and anti-spinward appear red?

  • Would it begin to emit any radiation of it's own? How much? in dangerous amounts?

  • Or would it be EM quiet if it were not acted on from the outside?

  • Gravity? Would it produce gravitational or magnetic effects in its vicinity? Would this ring shape produce any special interactions?

  • Unruh radiation, dynamical Casimir effect other exotic side effects?

I am aware that there are no perfectly ridged object, and even if there were it's still impossible. I'm also aware that the centrifugal forces would tear this structure into itty-bitty bits.
Also note: The question does not mean this object is spinning FASTER that C. Only approaching the speed of light. 30-50-90% the seed of what ever allows an answer.

  • 6
    $\begingroup$ It's a bit difficult to give a physically correct answer to a question about a scenario that breaks the laws of physics. ;) As I mentioned here, rotating objects are limited to the speed of sound in the medium. Now that can be quite high in neutron star matter, but good luck building a ring out of that stuff. $\endgroup$
    – PM 2Ring
    Jan 12, 2022 at 15:11
  • $\begingroup$ @PM2Ring would it be more plausible if it were say a 1kg bearing moving in a small 100m orbit? or a series of bearings in the same orbit? $\endgroup$
    – Gillgamesh
    Jan 12, 2022 at 15:29
  • $\begingroup$ To get relativistic orbital speeds, you need to be orbiting a black hole or neutron star. You won't get a 100 m radius orbit around one of those, and there's also the huge tidal force to consider. A 3 solar mass BH has a Schwarzschild radius of 8.86 km, but the tidal force at 110 km is strong enough to rip apart a 1 m steel bar in freefall. $\endgroup$
    – PM 2Ring
    Jan 12, 2022 at 16:09
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    $\begingroup$ OTOH, there is a history of thought experiments involving relativistic spinning bodies, see en.wikipedia.org/wiki/Ehrenfest_paradox so I guess your question shouldn't be closed as non-mainstream. $\endgroup$
    – PM 2Ring
    Jan 12, 2022 at 16:13
  • 1
    $\begingroup$ I do understand the impossibility of the question, but as @PM2Ring related above; with the amount of discussion on the thought experiment itself, it is hard to believe it is so hard to get an answer as to how an artifact like this would present it's self in real space/time. $\endgroup$
    – Gillgamesh
    Jan 18, 2022 at 13:36


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