The funnel landscape theory: Bryngelson & Wolynes (1987) proposed folding is guided by a funnel-shaped free energy surface with ruggedness from competing interactions.
Energy landscape: E(Q) = −slope·Q + ε·η(Q), where Q is the fraction of native contacts [0,1] and η is random ruggedness. Folding time scales as τ_fold ∝ exp(ε²/T²) (glass criterion: ε/T < Tf/Tg ≈ 1.5 for folding proteins). Trajectories are Langevin dynamics: dQ/dt = −dE/dQ + √(2T)·ξ(t).