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JCSterlace t1_j0ggxgj wrote

Reply to comment by obog in Does rotation break relativity? by starfyredragon

The rotation of an isolated solid object does not need a constant force to continue - angular momentum is conserved. Some internal forces holding the object together (to make it solid) would be acting centripetally, but that's internal to the object, not acting on the object.

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obog t1_j0gjdr9 wrote

Those internal forces are what I meant, as such the object is still technically accelerating

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VoilaVoilaWashington t1_j0gmqc8 wrote

The internal forces are causing the outer parts to accelerate around the center. If you swing a hammer while you spin in a circle, it's your hand that's accelerating the hammer and keeping it moving around you. Let go, and it goes flying.

That was their point - you need something keeping it all together outside the center of mass, or it will just fall apart.

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