atomism The theory that all matter consists of atoms – minute indestructible particles, homogeneous in substance but varied in shape. It was also the earliest cosmological worldview to espouse pluralism and the existence of extraterrestrial life. Developed in Greece in the fourth and fifth centuries BC by Leucippus and Democritus, and later by Epicurus, Metrodorus, and Lucretius, atomism taught that the cosmos consists of nothing but identical, indestructible particles moving randomly in a void. It is a philosophical school of thought and should not be confused with the much later atomic theory of John Dalton or the modern physics of atoms. Starting from the assumption that the Earth had come about by the chance association of atoms, it was a natural step to postulate that other Earths and other life-forms had originated elsewhere in the same way. However, the atomists considered that these other worlds, held to exist both simultaneously and in temporal succession, lay within their own self-contained universes – distinct kosmoi (see cosmos) which were entirely separate and inaccessible from our own. It is important to recognize that this was a purely philosophical doctrine which made no appeal to empirical evidence or observation and is therefore completely distinct from post-Copernican notions of other possibly inhabited worlds in the Solar System and planets circling around other stars. The atomist doctrine, as expressed in the writings of Lucretius, was eventually rediscovered in medieval Europe where, once again, it clashed with the one-world system of Aristotle. Related entry ancient philosophy, related to the possibility of extraterrestrial life Related categories ATOMIC AND NUCLEAR PHYSICS HISTORY OF SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) |