On 12/26/2012 2:57 PM, Warren Smith wrote:
But insofar as glass is amorphous there are arbitrarily small energy barriers against changes of configuration and so it is technically a liquid, even though in practical terms it's a solid.
Brent Meeker
--I deny this. I claim, it is at least in principle possible for an amorphous solid to exist in which any change requires at least a fixed energy change. One simple example would be usual periodic packing of bricks, but each brick is in one of 2 orientations ("upside down" or "rightside up") selected randomly, and any switch takes 1 electron volt to get you over the barrier.
How is that amorphous? It seems to have a lot of periodic structure.
Also, re the claim glass is a "liquid with very high viscosity" how about solid crystalline metals? They can be deformed. In fact, they are a lot more deformable than glass. So are they liquids with high viscosity?
The criterion isn't whether they can be deformed, it's whether they can be permanently deformed under arbitrarily small stresses. Brent Meeker