November 21: E=mc²

Albert Einstein’s paper revealing his famous formula for the relationship between energy and mass -- energy equals mass times the velocity of light squared -- was published on this date in 1905 in the journal Annalen der Physik (Annals of Physics). The paper had no footnotes or references. It was the last of four papers he submitted that year to the journal, the first explaining the photoelectric effect, the second suggesting experimental proof of the existence of atoms, and the third introducing his theory of special relativity. The key insight of Einstein’s fourth paper was that energy and mass are two expressions of the same indestructible phenomenon -- and that the amount of energy contained within matter is IMMENSE (given that the velocity of light, an outermost limit -- nothing can travel faster -- is 186,282 miles per second, and Einstein’s formula squares it). “Before Einstein,” explains the Encyclopedia Brittanica, “entities such as time and space and mass and energy were separate. But by bringing these then seemingly unrelated elements together, first in the concept of space-time and immediately thereafter in the equation E = mc², Einstein completed his theory of special relativity . . . one of the least intuitive theories ever conceived in the history of science . . .” Einstein developed his formula after contemplating the matter for a decade; part of his breakthrough came when he assumed that light had a constant speed, which had not yet been proved. To hear Einstein declaring his formula, look below. “The difference between stupidity and genius is that genius has its limits.” --Albert Einstein