Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff. Lauren vogel Bomb here with today's question. Is glass a liquid or a solid? If you've ever looked the window panes in an old building, you may have noticed that the glass was rippley and thicker towards the bottom of the pane, and you might have leaped to the logical sounding conclusion that the glass had flowed into that shape
very slowly, over a couple of centuries. That while the window frames are solid wood and metal, the glass is a liquid, oh if a highly viscous, very slow flowing one. You might have even heard this explanation from a teacher or read it in a textbook. The truth, however, is that the glass has always been that way. Okay, So, up through the eighteen hundreds, panes of glass were made by hand. Glass blowers used what's called the Crown process.
Here's how it works. That take a flattened bubble of very hot glass and rotate it so fast that centrifugal force would spin it out into a large, mostly flat disk. The disc would be thicker at the edges, and each pain cut from it was bound to be a little bit lumpy, and workers tended to install them with a thicker side down, probably because the slightly larger edge provided better balance. So the glass in those old panes isn't
flowing at least not that researchers can discern. They've looked at samples of glass from two thousand years ago and haven't found any telltale evidence of flow. So glass is not a liquid, but it's not a normal solid either. Scientifically speaking, glass is considered an amorphous solid. That means it's atoms and molecules are locked into place, alike in a solid, but those molecules are arranged more randomly than
in most solids, a more similar to a liquid. If you wanted to get into semantics, you could sort of call glass a super cooled liquid. That's a liquid that's been cooled below it's melting point carefully so that it doesn't crystallize, and that's part of making glass. In its liquid stage, glasses hundreds of degrees above room temperature. It's then cooled rapidly and carefully in a process known as quenching, until it transitions into the rigid, amorphous solid that we
know and love. So you might say that glass is its own state of matter. Neither a liquid nor a solid. Today's episode was written by me and William Harris and produced by Tyler Clay. For more on this and that's of other translucent topics, visit how stuff works dot com. Brain Stuff is production of I heart Radio. For more podcasts from my heart Radio, visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.