who discovered the theory of mass energy equivalence
Mass–energy equivalence Mass–energy equivalence arose originally from special relativity as a paradox described by Henri Poincaré.[2] Einstein proposed it on 21 November 1905, in the paper Does the inertia of a body depend upon its energy-content?, one of his Annus Mirabilis (Miraculous Year) papers.[3] Einstein was the first to propose that the equivalence of mass and energy is a general principle and a consequence of the symmetries of space and time.