What is glass: amorphous solid or supercooled liquid? I have read glass is amorphous solid and also supercooled liquid. I know that all solids are frozen liquids. But is it fair to say that everything which is an amorphous solid is also a supercooled liquid?
 A: Because liquids get somewhat thicker as they are cooled, and glass acts as a liquid when in its molten state,many believe that glass is a supercooled liquid.
The truth is that glass IS a solid.
If glass flows,its motion apparently requires more than four thousand years to be detectable,cause that is how long glass has been around for ,but no one can explain its motion .
One point for the solid .
This dilemma comes up , as no sudden transition takes place from liquid and solid.Moreover, most solids are crystalline.But glass, when it cools down ,its molecules form random arrangements.
Glass is a solid all right; its just not a crystalline one.
Now to address the urban legend : Windowpanes in several-hundred-year-old buildings are thicker at the bottom,than at the top,because the glass flowed down.If you do examine old buildings,the former statement stands true.The trouble is that no one has taken the effort to examine enough panes , to check if they are significantly thicker at the top ,sides or the bottom.Early windows were made with crude instruments and hence, uneven thickness would be preferable to bubbles in the glass.
Now if you were a workman assembling windows of panes with different thicknesses would you not be inclined to set them with their thickest part at the bottom ?
