Post by bgans

Gravity as a phenomenon is observed and measured. For example, we can repeatedly measure the acceleration of falling objects, planetary motion, gravitational time dilation, and so forth.

A theory of gravity is our explanation/model of those observations. General Relativity, for example, has been tested against many observations and experiments and has survived those tests extremely well. But science normally doesn't call such a theory “proven” in the absolute mathematical sense, because future evidence could reveal limitations or require a deeper theory.