Each site copies a random neighbor's opinion. In 1D, interface density ρ(t) ~ 1/√t — slow coarsening toward consensus. In 2D, domains grow as R(t) ~ √(t/ln t), slower than Ising.
Parameters
Update rule: pick site i at random,
copy spin of neighbor i±1.
Interface density:
ρ(t) = (# sign changes) / N
Theory: ρ(t) ~ (πt)^{−1/2}
1D voter model = annihilating random walks of domain walls.