By the equation E = mc2, it is stated that energy and mass are related . We have
seen the conversion of mass to energy in an atomic bomb and yes, energy can be
converted back to mass. Such a process was first observed by C.D Anderson in 1932 where he discovered the creation of an electron-positron pair from the energy of a gamma ray photon.
'To myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.'