Glass is such a unique substance, scientists are still learning a lot about its fundamental nature even though we've been making it for thousands of years. On this week's podcast I talked to Douglas Allan a researcher at the Corning glass company. He and his teammates recently published an article in Physical Review Letters where a big piece of glass shrank by about 10 microns. He told me why that tiny change is such a big deal.
Glass exists at this weird half-way point of being both a liquid and a solid. Heat it up and it flows like a thick fluid. Cool it down past its "glass transition temperature," and it'll hold its shape for ages. It's actually still flowing, but at room temperatures it would take tens of thousands for anything to happen.
The best way to see glass transition from a hot flowing liquid to a cool rigid solid, is with a smooth jazz soundtrack. Check out this great short film from 1958 by Dutch filmmaker Bert Haanstra about bottle making. Watch how the glass solidify the longer its out of the hot furnace. That's the glass transition in action!