Young Brunette Girl Posing In A Transparent Vitreous Glass Swing Chair

- Unsolved problems in physics
What is the nature of the transition between a fluid or regular solid and a glassy phase?
"The deepest and most interesting unsolved problem in solid state theory is probably the theory of the nature of glass and the glass transition." P.W. Anderson
Glass is an amorphous solid. It exhibits an atomic structure close to that observed in the supercooled liquid phase but displays all the mechanical properties of a solid. The notion that glass flows to an appreciable extent over extended periods of time is not supported by empirical research or theoretical analysis.