E = mc2 was discovered by Albert Einstein in 1905. It is a major result of his Special Theory of Relativity, which describes the relationship between how objects and electromagnetic radiation move through space and how they move through time. It means that the amount of energy in a piece of matter is equal to the mass of that piece of matter multiplied by the speed of light squared. This is a huge amount of energy, by the way, for even a tiny amount of matter; the energy contained in a penny far exceeds the explosive power of the atomic bombs detonated in 1945 over Hiroshima and Nagasaki combined.
