Gravity !

[pitchharmonics]

Does rotation of the earth, become a variable in the quest for the theory of gravity?

[pitchharmonics]

or is there an invisible force that causes rotation to occur and gravity to exist on earth?

[ramollari]

Does rotation of the earth, become a variable in the quest for the theory of gravity?
Rotation of the Earth has not to do with gravity, especially as we consider general gravity.

[ramollari]

or is there an invisible force that causes rotation to occur and gravity to exist on earth?
No invisible or magical force! Rotation occurs as an inertial phenomenon (kinetic energy), while gravity is a fundamental force that results from its mass.

[theriddler876]

yeah gravity is a by product of mass, the more massive the object, the more gravity. now if you are talking about rotation and the creation of artificial gravity, then that's just the centrifugal motion created by the spin pushes anything towards the edges thus creating an illusion of gravity

[pervect]

I'm not sure I understand the question, but the gravity of the rotating earth is ever so slightly different than the gravity it would have if it were non-rotating. This "frame-dragging" effect is currently being confirmed by Gravity probe B.