The Belousov-Zhabotinsky reaction is a classic example of a dissipative structure — far-from-equilibrium self-organization. Oxidant (u) and reductant (v) concentrations obey the Oregonator model. Diffusion couples nearby cells, producing propagating spiral waves and target patterns. These structures persist because the system continuously dissipates free energy — they vanish at thermodynamic equilibrium. BZ reactions were the first chemical oscillators accepted by mainstream science (Prigogine Nobel 1977).