Critical spreading on a 1D lattice — absorbing-state phase transition in the DP universality class
1.65
1.00
3
Active sites: 0
Generation: 0
λ/μ ratio: 1.65
Phase: —
The contact process is a prototypical absorbing-state model. Sites are either active (infected) or inactive. Active sites recover at rate μ and spread to neighbors at rate λ. At the critical point λ_c ≈ 1.65μ, the system lies at the directed percolation (DP) universality class boundary with β ≈ 0.277, ν_⊥ ≈ 1.097. The space-time diagram displays the full history, revealing fractal cluster boundaries near criticality.