What is the meaning of the well-known Einstein equation E = mc 2?
A. Before the formulation of Einstein’s theory, were considered separately the fundamental principles of conservation of the mass and the one of the energy. The conservation principle of the mass, formulated in the eighteenth century by the chemist Lavoisier and already expressed by Lucretius in the poem “De rerum natura”, consists in considering constant and indestructible the quantity of matter existing in nature; that is, in any system and, by extension, in the universe the total quantity of matter is always the same. Matter is subjected to physical-chemical transformations, but it is not destroied (“in nature nothing is destroied, everything transforms ” ). The energy conservation principle, formulated in the nineteenth century, affirms that, whatever is the form of energy that is considered ( mechanical, thermal, electric, etc…) in any system and, by extension, in the universe, the total energy is constant. Einstein showed that both principles are nothing but two faces of the sa
