Atomism

Atomism (from Ancient Greekἄτομον (atomon)'uncuttable, indivisible') is a natural philosophy proposing that the physical universe is composed of fundamental indivisible components known as atoms.

The concept of atomism appeared in both ancient Greek and ancient Indian philosophical traditions. Atomism in multiple different forms originated in ancient Greece. The word atom is derived from the term atomos ("uncuttable") used by the Greek philosophers Leucippus and his pupil Democritus, who developed this idea in the 5th century BC. Leucippus, Democritus, and other ancient Greek atomists argued that nature consists of two fundamental principles: atoms and void. Clusters of different shapes, arrangements, and positions give rise to the various macroscopic substances in the world.A similar idea was developed by Kanāda of the Vaiśeṣika school, who proposed indivisible particles (paramāṇu). IndianBuddhists, such as Dharmakirti (fl.c. 6th or 7th century) and others, developed distinctive theories of atomism, for example, involving momentary (instantaneous) atoms (kalapas) that flash in and out of existence.

The particles of chemical matter for which chemists and other natural philosophers of the early 19th century found experimental evidence were thought to be indivisible, and therefore were given by John Dalton the name "atom", long used by the atomist philosophy. Although the connection to historical atomism is at best tenuous, elementary particles have become a modern analogue of philosophical atoms.