That window you're looking through? It's technically not a solid - it's an extremely slow-flowing liquid!
Unlike most materials that have a clear melting point where they transform from solid to liquid, glass undergoes a gradual transition. Scientists classify it as an "amorphous solid" or a "supercooled liquid" because its molecules are arranged randomly (like a liquid) rather than in the ordered crystalline structure of true solids.
The most fascinating evidence? In many medieval buildings throughout Europe, the glass in old windows is noticeably thicker at the bottom than at the top. This happens because, over centuries, the glass has actually flowed downwarddue to gravity!
This extremely slow flow happens because glass never fully solidifies - instead, it becomes increasingly viscous as it cools, with its molecules continuing to move in relation to each other, just at an imperceptibly slow pace.
The viscosity of room-temperature glass is so high that it would take approximately 10 million yearsfor it to flow noticeably under normal conditions. So while your modern windows won't sag in your lifetime, given enough time, they would eventually begin to pool at the bottom!
This unusual property is what makes glass so versatile for everything from windows to smartphone screens - it exists in a unique state between solid and liquid, giving it properties unlike any other common material!