I think it is better to say that glass DOES flow, but it is a solid! For example, it would take several universe lifetimes to observe any appreciable flow (or m

I think it is better to say that glass DOES flow, but it is a solid! For example, it would take several universe lifetimes to observe any appreciable flow (or more quantifiably, the viscosity is circa 10^19 Pa-s). Similarly, lead flows and to a much lesser degree, steel too.