Is glass a solid or an extremely slow-moving liquid?
Is glass a solid?
For decades, physicists, who view window glass at the molecular level, have pondered the question of whether or not glass is a solid or merely an extremely slow-moving liquid. An Emory University research team led by physicist Eric Weeks has yielded another clue in the glass puzzle, demonstrating that, unlike liquids, glasses aren’t comfortable in confined spaces.
Scientists fully understand the process of water turning to ice. As the temperature cools, the movement of the water molecules slows. At 32 F, the molecules form crystal lattices, solidifying into ice. In contrast, the molecules of glasses do not crystallize. The movement of the glass molecules slows as temperature cools, but they never lock into crystal patterns. Instead, they jumble up and gradually become glassier, or more viscous. No one understands exactly why.
Previous research has shown groups of particles in dense suspensions move cooperatively. “Our work suggests glasses are solid-like because these groups can’t move when the sample chamber is thinner than the typical size of these groups,” Weeks says.
Yes, my first thought was of Bob Shaw’s short story classic, “Light of Other Days” - about slow glass.
Posted: Tue - August 14, 2007 at 08:51 AM