We have tested this since the time when scientific knowledge came into existence. After Newton formulated the theory of Gravitation, everybody in the world thought, thats it, there will be no other theory to describe the working of the Universe. read more
So, gravity explains why subatomic particles posses Energy proportional to a frequency and “Dual” why they posses non-zero spin-values with 2 possible spins of Bosons {1,2} and also 2 possible spins of Fermions {1/2, 3/2}. read more