What is gravity?

I’m reading a fascinating book of cosmology called “You Are Here” and written by Christopher Potter. It raises some challenging topics.
For example, what is gravity?
Potter quotes John Wheeler as explaining: “Matter tells space how to curve and space tells matter how to move”. But he also quotes Michio Kaku as arguing: “In some sense, gravity does not exist; what moves the planets and the stars is the distortion of space and time”.
A discussion of gravity on Wikipedia states: “Modern physics describes gravitation using the general theory of relativity, in which gravitation is a consequence of the curvature of spacetime which governs the motion of inertial objects.”


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