Schelling Segregation on a Torus

Two groups of agents on a toroidal grid. Each unhappy agent (too few same-group neighbors) moves to a random empty cell. Mild preferences lead to strong segregation.

Step: 0 Unhappy: — Segregation: — Running: No
Grid size: 40
Density: 0.85
Threshold: 0.30
Steps/frame: 5

Schelling's Insight (1971)

Thomas Schelling showed that even weak individual preferences for same-group neighbors produce dramatic macro-level segregation. On the torus, edges wrap around — no boundary effects. The segregation index is the average fraction of same-group neighbors among occupied cells. Starting from random mixing, watch it rise toward 1 as clusters coalesce. This happens even when agents only require 30% similarity — far below what they'd claim they "need" to be happy.