Brownian Motion

Interactions

Click the nosepiece to swing in the other objective: at high power several hundred hard-disc water molecules appear and their impacts alone move the grain
Click the spirit lamp to turn the wick up: the water warms, the molecules speed up and the grains jiggle more; click again to let it cool
Click a grain to swap it for a smaller or larger one: smaller grains wander faster
Drag a grain to place it; Perrin's track restarts from there
Idle: the track, the pin-pricked target and the pencil curve of mean squared displacement build by themselves while the observer changes objectives and lights the lamp now and then