Onsager reciprocal relations

Onsager reciprocal relations describe a fundamental symmetry in how different processes in thermodynamic systems influence each other near equilibrium. When one process (like heat flow) causes another (like electrical current), the same underlying factors determine how the second affects the first. In simple terms, it means that the strength of these mutual effects are equal when the system is near a stable state, reflecting a balance in the way energy or particles move within the system. This principle helps us understand and predict how coupled thermal, electrical, and chemical processes behave in materials and devices.