Although a cloud of potential doom has shadowed the future since the first atomic bomb was tested in the New Mexico desert in July 1945, the process that led to that moment also paved the way for myriad technologies that have improved the lives of millions around the world.

It all began with perhaps the most famous formula in the history of science—Albert Einstein's deceptively simple mathematical expression of the relationship between matter and energy. E=mc², or energy equals mass multiplied by the speed of light squared, demonstrated that under certain conditions mass could be converted into energy and, more significantly, that a very small amount of matter was equivalent to a very great deal of energy. Einstein's formula, part of his work on relativity published in 1905, gained new significance in the 1930s as scientists in several countries were making a series of discoveries about the workings of the atom. The culmination came in late 1938, when Lise Meitner, an Austrian physicist who had recently escaped Nazi Germany and was living in Stockholm, got a message from longtime colleagues Otto Hahn and Fritz Strassmann in Berlin. Meitner had been working with them on an experiment involving bombarding uranium atoms with neutrons, and Hahn and Strassman were reporting a puzzling result. The product of the experiment seemed to be barium, a much lighter element. Meitner and her nephew, physicist Otto Frisch, recognized that what had occurred was the splitting of the uranium atoms, a process Meitner and Frisch were the first to call "fission." Italian physicist Enrico Fermi had achieved the same result several years earlier, also without realizing exactly what he had done. Among other things, fission converted some of the original atom's mass into energy, an amount Meitner and Frisch were able to calculate accurately using Einstein's formula. The news spread quickly through the scientific community and soon reached a much wider audience. On January 29, 1939, the New York Times, misspeaking slightly, headlined the story about the discovery: "Atomic Explosion Frees 200,000,000 Volts."