# E = mc2

An equation derived by the twentieth-century physicist Albert Einstein, in which E represents units of energy, m represents units of mass, and c2 is the speed of light squared, or multiplied by itself. (See relativity.)

## notes for E = mc2

Because the speed of light is a very large number and is multiplied by itself, this equation points out how a small amount of matter can release a huge amount of energy, as in a nuclear reaction.

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