Einstein’s famous formula E=mc<sup>2</sup> says that mass and energy can turn into each other. It was first published by H. Poincare. Einstein published an alternate derivation that was corrected and improved by M. Planck. E stands for [[energy]], m is [[mass]], and c is the [[speed of light]]. So, if you increase the energy of a substance, for example by heating it, it gains a minute amount of mass. It was later realized that if you split an atom apart, as in a nuclear explosion, it loses a tiny amount of mass and you release a huge amount of [[energy ]].