In the voter model, each agent copies a random neighbor's opinion. Consensus time scales as N·ln(N) in 2D, driven by coarsening domain walls.
Mean consensus time on N-node graph: T_c ~ N log N (2D). Magnetization m = (N₊−N₋)/N performs a martingale random walk until ±1. Interface density decays as ρ(t) ~ 1/ln(t) in 2D — logarithmically slow coarsening.