Opinion domains growing — interface density decays as 1/ln(t)
In the 2D voter model, each agent copies a random neighbor's opinion. The interface density ρ(t) decays logarithmically — far slower than phase-ordering systems (Ising model), because the voter model has no surface tension. Consensus time scales as T ~ N² ln N. This slow coarsening reflects the critical nature of the voter model, exactly equivalent to coalescing random walks.