Co-occurrence of mutual information peak and the magnetic susceptibility phase transition as modelled by Vicsek. The mutual information, I (circles) peaks at approximately the same point as the susceptibility, χ (crosses) and with the critical noise η
= 1.33 marked. The system parameters are: interaction radius, R = 1, time step δ t = 1; particle speed v0 = 0.15; and particle density ρ = 0.31 per unit area with arbitrary length units. 3000 particles were used. Reprinted from Wicks et al. (2007) Figure5 with permission.