In glass, fast crowds boogie to brittle end
By Peter Weiss
Glass is clear, but the process by which it forms remains maddeningly opaque.
As a liquid hardens into a glass, its molecules become extremely sluggish—more so than expected at the temperatures or conditions of molecular crowding under which the process takes place. Moreover, the molecules remain disorderly even after solidification, unlike those in a crystal, where the molecules occupy a tightly bonded lattice. Something else must cause the molecular gridlock in a glass.
Studying suspensions, or colloids, of tiny plastic spheres that can form glasses, Eric R. Weeks of Harvard University and his colleagues have now observed a striking coordination that may play a role in creating gridlock.