Glass is a commonplace word. One immediately thinks of windows or bottles and of properties like brittleness or transparency. However, for a glass blower another feature is more important: glass does not melt abruptly, as a crystal does, but gradually over a range of temperatures. This means that he or she can alter the temperature at which glass solidifies or becomes a liquid by changing the rate at which it is cooled or heated. This is in stark contrast to the behaviour observed when the crystalline form of a material is heated: it will always melt at the same temperature.
This unique melting behaviour is not limited to the glass of colloquial speech. All amorphous substances, such as plastic materials or amorphous semiconductors, exhibit similar features. The widespread use of these "glass formers" in real-life applications is therefore a strong incentive to understand better the microscopic origin of the glass transition.
In the December issue of Physics World magazine, Kurt Binder, Jörg Baschnagel, Walter Kob and Wolfgang Paul at the Physics Institute, University of Mainz, Germany explain the attraction and fascination of glass physics.