Thanks for this explanation. If I understand correctly then, the moon requires some centripetal force in order not to dissipate due to its rotation whereas e.g. my head or the Eiffel Tower do not because they are not subject to absolute rotation.

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card_zero 11 hours ago | parent | next [-]

They're rotating too.

If you rotate as part of some larger rotating thing then you still rotate. (You also move around.) It's all absolute.

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omnicognate 11 hours ago | parent [-]

Indeed. The Eiffel tower and your head do both have some (extremely small) centripetal force compensating for their rotation along with the earth.

(You can break that down in different ways, i.e. use various choices of generalised coordinates to describe it, so exactly what constitutes "centripetal", "centrifugal", "gravitational", "tidal", etc. forces depends on that. I'm being pretty vague in how I decribe it. Regardless, rotation is absolute, or in other words the equations of physics take a different form in a rotating frame of reference than in a non-rotating one.)

	▲	unhba 7 hours ago \| parent [-]
		Thanks for the clarification I completely mistook what you were saying. This is the fascinating bit for me then, that what’s happening with the moon’s rotation is also happening with everything else

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adastra22 11 hours ago | parent | prev [-]

Why is the Eiffel Tower not rotating?

	▲	4 hours ago \| parent \| next [-]
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	▲	omnicognate 10 hours ago \| parent \| prev [-]
		It is.