36 E=MC2 1905 IT MIGHT have been easy to dismiss Albert Einstein's September 1905 paper as an afterthought, a minor coda to an extraordinary year. After all, in 12 months, Einstein had produced five revolutionary physics tracts, covering the special theory of relativity, the quantum theory of light, and more. Any one of the young patent clerk's after-hours efforts would have been enough to promote him to the highest levels of achievement in physics.
But the September paper, a three-page examination of one consequence of special relativity, had the power to change the world. Einstein's "thought experiment" delved into the underlying connection between matter and energy, the two basic components of the universe.
Within the principles of special relativity--nothing in the universe can travel faster than light in a vacuum, and the speed of light remains constant to all observers regardless of their own motion--Einstein found that he had imagined a strange universe where objects changed size and mass depending on how fast they traveled. These effects, unimaginably small at ordinary speeds, would become evident only as velocities neared that of light. However, if the energy of motion could change mass, Einstein concluded, mass itself could become energy. He published his famous equation E=MC2 (Energy = mass x speed of light squared) and noted, almost in passing, "It is not impossible that . . . the theory may be successfully put to the test."
Within 40 years, research in radioactivity and physics, fueled by the desperation of a ghastly world conflict, led to the development of nuclear energy and the atomic bomb--dramatic realizations of Einstein's straightforward assertion. Einstein, a lifelong pacifist, deplored the destructive use of his ideas and regretted encouraging President Franklin D. Roosevelt to push development of nuclear weapons. Einstein was disappointed, and the world was changed inalterably.