What Would the Rocks Be Rotating With Respect To in Newton's Thought Experiment?

chuckset
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I'm not sure where this thread should go, sorry if it's in the wrong place.

In Newton's thought experiment about the rotating rocks going taut in deep space. With respect to what would the rocks be rotating?
 
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An inertial frame of reference, of course.
 
chuckset said:
I'm not sure where this thread should go, sorry if it's in the wrong place.

In Newton's thought experiment about the rotating rocks going taut in deep space. With respect to what would the rocks be rotating?

If the rocks are in an otherwise empty universe with no other massive objects to relate to, then I guess you could use light as a frame of reference. If a laser is placed on one rock and aimed at a target on the other rock, the light would miss the target if the rocks are rotating. This is basically using a simple form of a Sagnac device to detect rotation.
 

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