Why universal law of gravitation cannot be proved?

Question

kashif · Answer

can someone answer my questions????

nafisa · Answer

The theory (not law) isn't universal because it hasn't been proven all over the universe. If we assume that tides can be explained by the movement of the moon around the earth, then there lies a flaw in our assumption since there are two high tides in one day, but the moon only revolves once a day around the earth. This link below has a very detailed explanation https://www.google.com.bd/url?sa=t&source=web&rct=j&url=https://ncse.com/library-resource/gravity-its-only-theory&ved=0ahUKEwjktNbHl6bOAhVFuY8KHfIUCPgQFggZMAA&usg=AFQjCNF0fKG5OJRiCaeuqrbndaB6Z0V89w

sharmagk83 · Answer

The theory  or laws of gravitation are based on the concept of mass and even mass is not properly defined and even we have not understood the gravitation completely for example if gravitation only affect masses than how light is affected by gravity why a black hole does not allow light to come back if photons are mass less. So until we don't understand mass completely gravitation cannot be understood completely.