Classical physics claims that the difference between liquid and solid glass is simple static forces, something called the Mode Coupling Theory.

But some things seem not to add up: first some quantum liquids like

electron liquids or superfluid helium also form glasses which cannot be solidified by static forces (don’t ask me why!). On top of that one can find that the matter that forms glasses can be at the same time superfluid and in dynamical arrest (i.e. not moving), and that is called the “superglass” state.So these guys got clever and decided to have a look at the vitrification process at different temperature. They revamped the Mode Coupling Theory so that it could be used at very low temperature like 0K (-273 Celsius) and looked at what happens at the molecular level using computer modelling. What they found out is that as the temperature of liquid glass goes down, it solidifies. When the temperature keeps dropping and approaches 0K, the solid glass becomes liquid again! =:oWe are here once more in the eye of the tornado, the clash between classical (particle based) Physics and quantum (wave based) Physics. Basically they show that at very low temperatures, the atoms that form glass start acting like waves so that they are able to move again and the glass starts flowing! They say that the waves become more and more constricted in the space created by the structure and they start escaping, making the whole thing fluid again. They call it reentrant transition.Call me geek but I think that’s pretty cool! 🙂