re: #303 Achilles Tang
Not my field, but I don’t know if I agree with that, although it does occur that some crystalline structures can have vibration modes that have a preferential spatial orientation. I don’t see how amorphous solids or liquids could.
Ignoring gels, liquids can’t support shear forces at all. Solids, even amorphous ones like glass, can within their elastic limit. Beyond that limit they permanently deform, flow like a liquid, or crack/shatter.