Glossary

Brownian motion

The random jitter of tiny particles in a fluid — explained by Einstein in 1905, key evidence that atoms are real.

Image: Roque345 (Wikipedia). CC BY 3.0, via Wikimedia Commons (Source)

Brownian motion is the erratic, random movement of microscopic particles suspended in a liquid or gas. In 1905 Einstein showed it results from countless collisions with invisible molecules and gave a precise mathematical theory.

Jean Perrin's experiments soon confirmed it, providing decisive evidence that atoms and molecules really exist.

Try it yourself

The year 1905, day by day Four papers that changed physics – when he wrote, submitted and published them. On the page: 1905 — The Miracle Year tried
Source: Wikipedia: Brownian motion — Read the full article on Wikipedia.

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