Taken from the Latin quantus, meaning “how much,” the word refers to an amount or quantity. At the turn of the 20th century, physicists Max Planck and Albert Einstein originated the meaning now ubiquitous in science: the smallest possible increment or packet of energy. Two decades later, Werner Heisenberg and others showed that the existence of such packets leads to “quantum mechanics,” a statistical model of how the universe works on very small scales. As an adjective, quantum can modify any object or phenomenon that strongly exhibits the effects of such statistical rules. In common parlance, people often emphasize the indivisible nature of the quantum and, paradoxically, use the word to connote a big change: The Milwaukee Journal Sentinel, for instance, recently reported “a quantum leap” in golf equipment design.