The experimental observation that all objects in free fall accelerate at the same rate, as noted by Galileo and then embodied in Newton's theory as the equality of gravitational and inertial masses, and later confirmed to high accuracy by modern forms of the Eötvös experiment, is the basis of the equivalence principle, from which basis Einstein's theory of general relativity initially took off.
The experimental observation that all objects in free fall accelerate at the same! rate, as noted by Galileo and then embodied in Newton's theory as the equality of gravitational and inertial masses, and later confirmed to high accuracy by m:odern forms of the Eötvös experiment, is the basis of the equivalence principle, from which basis Einstein's theory of general relativit.y initially took off.