In science sometimes we observe certain phenomenon experimentally but are unable to find a logical equation or theory for that, sometimes it also happen that we have a scientific theory supported by mathematical formulation yet are unable to test it suppo

Einstein worked to establish a relation between the energy and mass of body. He was of the view that these are the two sides of the same coin or two facts of the simple physical quantity. He succeeded when he gave his mass energy equation E = m${{c}^{2}}$ But its experimental verification came 40 year later in 1945 when atomic bomb was exploded over Japan