Brownian Motion
What Ye Be Seein'
The large particles be “pollen grains”—microscopic objects suspended in fluid. The smaller particles represent water molecules. This simulation uses a classical hard-sphere model, where every collision be calculated using deterministic Newtonian mechanics.
Tap Hide Fluid in the control panel to hide the fluid molecules. The pollen's motion now appears random—yet nothin' has changed. Every collision be still perfectly deterministic.
Einstein's Insight (1905)
In his “annus mirabilis,” Einstein provided a quantitative theory explainin' that Brownian motion—the jitterin' of microscopic particles systematically studied (though not discovered) by botanist Robert Brown in 1827—arises from the cumulative effect of countless molecular impacts. What appears random be actually the statistical signature of atomic reality.
Perrin's Proof
French physicist Jean Perrin meticulously tracked pollen grains and confirmed Einstein's predictions with striking precision. His work was considered decisive evidence for the atomic hypothesis by most of the scientific community—persuading even prominent skeptics like Wilhelm Ostwald—and earned him the Nobel Prize in Physics in 1926.
∇ Tap anywhere to add pollen grains