A pollen grain's jittery dance in water helped prove that atoms are real
In 1827, botanist Robert Brown noticed tiny pollen particles suspended in water never sat still, jittering randomly for no obvious reason, a mystery that stood unsolved for 80 years. In 1905, Albert Einstein worked out the mathematics showing the jitter was exactly what you'd expect from countless invisible, randomly colliding water molecules, a prediction confirmed experimentally by Jean Perrin in 1908. Brownian motion became some of the strongest evidence that atoms were physically real.