Well,ok (to reply to Meeker) first of all, even a single grain perfect crystal metal could deform via the creation of a new grain and stretching of old one (via thermal fluctuations) , to a longer state. So it could stretch. It might be interesting to see actual systematic experiments on cable stretch for different kinds of cables, including monofilament/not, crystal/polycrystal/amorphous, etc. Nothing difficult about doing such experiments, it just requires time. It also is possible (re my nylon line that stretched ) that the rain and/or sun had something to do with it. Second, re the claim "there is no tensile strength" would be news to structural engineers -- well yes. They deserve to be edified. (Also the claim glass is a liquid might also be news to them.) I still think tensile strength is a myth,but the reason it is a persistent myth is that this kind of stretching can be very very slow. In particular I have seen estimates that window pane deformation via glass "flow" should take way longer than age of universe before it gets large enough to observe. Finally re Meeker's question about "exponential in what" well, for example, many phenomena obey a temperature dependence like exp(-E/(k*T)) where T=temperature and E,K are constant. This might be expected if defoming a solid requires overcoming an energy barrier E to do a rearrangement. Get 10 times colder and these phenomena get WAY slower. However, with E's that are distributed according to a power law, say, one might well get rate laws that depend on T in a way much less powerfully cut off when you get 10X colder. So this would provide a way to claim amorphous stuff and crystal stuff both stretch, but the cutoff as temp changes might exhibit different behaviors, thus allowing a distinction to be drawn, but not as silly as a Yes/no 100-0 distinction.