Princeton Univ.

Microscopically, glasses are solids that look more like liquids—they lack a regular crystalline structure. The liquid character is no accident, since a typical glass is made by cooling a fluid rapidly. If done in the right way, this skips the usual crystallization that occurs at the freezing point of the material, leaving a disordered state. If we want to create a glass with specific properties, we need precise control over the fluid-to-glass transition, but that has proven very difficult to achieve in practice.