1D contact process: active sites infect neighbors at rate λ, deactivate spontaneously at rate 1. Below λ_c ≈ 3.298, activity dies (absorbing state). Above λ_c, activity persists indefinitely. Space-time kymograph — DP universality class.
Active sites: 0 | Time: 0 | λ_c ≈ 3.298
DP exponents: β ≈ 0.276, ν_⊥ ≈ 1.097, ν_∥ ≈ 1.734. Below critical: exponential decay. At critical: power-law P(active)~t^(-δ). The absorbing state transition is irreversible — once all sites die, no recovery.