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.
'There is no inductive method which could lead to the fundamental concepts of physics. Failure to understand this fact constituted the basic philosophical error of so many investigators of the nineteenth century.'