A bead-spring polymer chain in 2D thermal noise. Watch end-to-end distance fluctuate, Rouse modes relax, and the chain explore configuration space. Color = local tension.
The Rouse model (1953): a polymer is a chain of N beads connected by harmonic springs, each subject to Brownian noise and drag. Rouse modes are normal-mode vibrations; relaxation time τ_p ∝ N²/p². End-to-end R ~ N^0.5 (ideal chain, ν=1/2 Flory exponent).