Sine-Gordon kinks, phonons, and breathers on a coupled pendulum chain
The sine-Gordon equation ∂²θ/∂t² = c²∂²θ/∂x² − sin(θ) describes a chain of pendulums coupled by torsion springs. It supports topological solitons (kinks, anti-kinks) and breathers — localized oscillating solutions — that pass through each other like particles. Click to create disturbances.