Debunked Myths

The myth that glass is a supercooled liquid that flows imperceptibly over centuries is a beautiful piece of scientific folklore. It stems from observing medieval stained-glass windows that appear thicker at the bottom, suggesting the glass slowly flowed downward like a viscous fluid over hundreds of years. This explanation seems poetically plausible but is scientifically incorrect.

Materials science classifies glass as an 'amorphous solid'—a state of matter with the rigid structure of a solid but the disordered molecular arrangement of a liquid. The unevenness in old windows results from outdated manufacturing techniques like crown glass or cylinder glass, which produced panes of inconsistent thickness. Glaziers naturally installed these windows with the heavier, thicker edge at the bottom for stability.

If glass flowed on human timescales, ancient Egyptian glass artifacts would have deformed into puddles, which they haven't. The myth endures because it lends a sense of hidden, slow-motion life to an inanimate material, making our static world feel dynamic. The truth is that glass is a frozen liquid, but it has been completely solid since the moment it cooled from its molten state.