Why is Newtons law of universal gravitation called “universal”?
At the time Cavendish measured rhe weigth of the Earth and determined the Gravity constant ,it was called a Universal constant because observations of celestial bodies have shown that the constant applies to all large masses of all celestial bodies including the Earth. Basically all measurements are relative to the earth. It was Newton that first determined how to measured weight as a gravity force and calculated the Gravity constant which is now called Universal. Neverthe less when dealing with micromasses such as electrons the weight of the electron relative to the nucleous of the atom is related to a gravity constant which has much greater magnetude.Hence the electrostatic gravity constant is not the same in value as newton’s Universal gravity constant.
