Onsager solution

The Onsager solution is a mathematical breakthrough that describes how certain materials, like two-dimensional magnets, change from being disordered to ordered as they cool down—specifically, the 2D Ising model. Disordered means particles are randomly arranged; ordered means they align in a pattern. Onsager found an exact way to calculate this transition point and the material’s behavior around it, providing deep insights into phase transitions and critical phenomena in statistical physics, which helps us understand how microscopic interactions lead to macroscopic properties in materials.