Einstein's formula E=mc2
Einstein's famous formulae associates the mass, M, and the invariant energy, E, of a particle: E=Mc2, where c is the light speed in vacuum. As simple as the expression may be, the equation has profound consequences. First, mass is only a specific form of energy and can be expressed in energy units; then, the mass-energy equivalence means that, theoretically, one substance can be produced from the other. Given the high value of the c2 factor, mass contains a tremendous amount of energy.