> Spin? Hmmm. Relative to what? Are we spinning on the Earth? Depends
on your reference frame!
On earth, even if blind-folded to the universe, we can detect spin
because the planet is an oblate spheroid, yes? Also g is not precisely
what is predicted by G M and R alone but lower by 0.3% due to rotation rate.
And Foucault pendulums do their magic thing, regardless of reference
frame, yes?