1D DP: activity spreads with prob p — absorbing-state transition at p_c ≈ 0.6447
p = — | p_c = 0.6447 | ρ = — | —
Directed percolation (DP) is the canonical universality class for absorbing-state transitions.
1D rule: an active site activates each of its neighbors independently with probability p.
Below p_c ≈ 0.6447: activity dies (absorbing state). Above: activity survives (active phase).
Order parameter ρ ~ (p−p_c)^β, β ≈ 0.276. Left: space-time diagram (y=time↓). Right: ρ(t).