Active Filament — Buckling Instability

Active filaments (actin+myosin, microtubule+kinesin): distributed motors generate compressive forces along the filament. When motor force f exceeds Euler buckling threshold f_c = π²κ/L², the filament buckles. In overdamped dynamics, buckling selects a wavelength λ ~ (κ/f)^½. Watch beating, coiling, and waveform emergence.