In his chemistry class in Newark, NJ, USA, Robert Brill was told: "Glass is actually a liquid." "You can tell this from the stained glass windows of old cathedrals in Europe. Glass is thicker on the bottom than it is on the top." Most people seem to want to believe it, but not Robert Brill, who says its easy to understand why the myth persists and in this article explains that liquids flow because there are no strong cohesive forces holding their molecules together. These molecules move freely past one another, so that liquids can be poured, splashed or spilled. However, unlike the molecules in conventional liquids, the atoms in glasses are all held together tightly by strong chemical bonds, in a way, like the glass were one giant molecule. This makes glasses rigid so they cannot flow at room temperatures & thus, the analogy fails in the case of fluidity & flow.
