Part of the Einstein exhibition.

Energy section of exhibition
AMNH; Photo Studio

The most famous equation in the world, E=mc2, arrived rather quietly.


In 1905, Einstein published two articles on the Special Theory of Relativity. He completed his first paper in June, on the properties of light and time. Then just three months later he finished a second, shorter article—essentially an addendum to his previous paper—describing a "very interesting conclusion" about energy. Einstein went on to present his findings mathematically: energy (E) equals mass (m) times the speed of light (c) squared (2), or E=mc2.

The secret the equation revealed—that mass and energy are different forms of the same thing—had eluded scientists for centuries. Einstein expected both of these revolutionary 1905 papers to arouse a lively debate among physicists. But for months, the often conservative scientific community was silent, and Einstein was disappointed by the lack of response. His isolation did not last long, however: by 1906, physicists from around Europe were journeying to Switzerland to discuss this intriguing new theory with the 27-year-old patent clerk.