Albert Einstein called 1905 his "annus mirabilis," his miraculous year. That spring, using nothing more than his pad and pencil to puzzle through the most fundamental problems of the universe, he found revelatory solutions to some of physics' greatest mysteries. The Swiss patent clerk submitted handwritten drafts of three separate theoretical papers to the German Annalen der Physik, the world's most prestigious physics journal. In September 1905, the journal published all three of Einstein's essays in its volume 17—surely the most consequential issue of an academic journal ever printed. (A rare original copy of volume 17 fetched $15,000 in a 1994 auction.)
Einstein's three essays offered earthshaking new interpretations of three separate major problems in modern physics. The first explained the photoelectric effect, recently observed in laboratory experiments by other scientists, by arguing that light travels both as a wave and as packets of energy called "quanta." (It was Einstein's work on the photoelectric effect, not his better-known theory of relativity, that eventually won him a Nobel Prize.) The second paper explained Brownian motion, the unpredictable movement of tiny particles, as a result of the molecular action hypothesized by atomic theory. The third, and perhaps most famous, of Einstein's three essays introduced his special theory of relativity, which suggested that space and time were not, as Newtonian physics had long assumed, absolute, but rather that space and time would themselves expand or contract relative to an observer's rate of motion.
From his equations of special relativity, Einstein quickly deduced the revolutionary concept of mass-energy equivalence; a few weeks after submitting his three articles to the Annalen der Physik, he sent in a fourth essay, a kind of addendum to the paper on special relativity that introduced, for the first time, the twentieth century's most famous equation: E=mc2. Energy (E) and mass (m), Einstein argued, were interchangeable, and since the square of the speed of light (c2) was a staggeringly large multiplier, a tremendous amount of energy could theoretically be released from a tiny amount of matter. Thus did Albert Einstein's scribbled equations provide the genesis of the nuclear age.