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.
Einstein's work on the Special Theory of Relativity prompted him to rethink the fundamental laws of physics. He realized that one of the long-held views of nature—that matter could not be created or destroyed—was wrong. Einstein showed instead that matter can be destroyed and converted to energy. Conversely, energy can be converted to mass.
The implications of E=mc2 are profound. For centuries, scientists had considered energy and mass to be completely distinct and unrelated to each other. Einstein showed that in fact, energy and mass are different forms of the same thing.
Einstein first published his Special Theory of Relativity—which describes his revolutionary ideas about light, time and energy—in 1905.
Decades after Einstein published his famous equation, E=mc2, other scientists realized that it did explain a number of physical phenomena. Perhaps most famously, E=mc2 helps explain the energy released by atomic bombs and produced by nuclear power plants.