Britannica Sources used in this answer

How did Democritus explain the apparent birth and death of objects?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Bronze bust of Epicurus with a full beard and draped clothing, displayed on a round inscribed base at the National Archaeological Museum of Naples. — Atomism Epicurus, bronze bust from a Greek original, c. 280–270 bce; in the Museo Archeologico Nazionale, Naples.

Democritus explained the apparent birth and death of objects by distinguishing between the eternal nature of atoms and the temporary nature of the compounds they form.

According to his atomic theory, atoms are indivisible, immutable, and eternal. Because all physical phenomena are composed of these same unchanging particles, nothing truly comes into being or perishes in an absolute sense. Instead, what we perceive as the birth or death of an object is simply the result of atoms coming together or moving apart.1

When atoms collide and unite due to mechanical necessity, they form larger bodies, which we perceive as the "birth" or appearance of an object. Conversely, when these configurations break down or change, the object appears to "die" or disappear. Thus, while the compounds themselves are liable to increase and decrease, the underlying atoms remain constant, existing in an infinite void where they are in constant motion.1