Updated Tuesday, May 20, at 1:35 p.m. ET
Although the idea of a relationship between mass and energy was not new, in the early years of the 20th century, physicist Albert Einstein created a formula that was the first to correctly state that relationship. This practical information led to the creation of nuclear power reactors and atomic bombs.
This discovery basically states that the properties of mass and energy are interchangeable, and what people call matter is really just energy in a different form. The idea has some startling implications.