Evolving glass

Ultrastable forms of glass can be evolved, or aged, in a matter of days rather than having to wait thousands of years for their atomic structure to settle down to a lower-energy form. Computational and experimental studies suggest that a vapor-deposition process might allow researchers at the University of Chicago to design a new class of materials at the molecular level. Juan de Pablo of the University of Chicago points out that amber is an aged glass, but its particular structural properties cannot be emulated in the laboratory yet. Finding ways to make materials with related amorphous, glassy structures, could lead to stronger metals or even faster-acting pharmaceuticals that do not crystallize in storage and so are more rapidly delivered once ingested. Thankfully, Ulrich Schneider and his colleagues are not claiming to have broken the laws of thermodynamics. We have achieved an inverted Boltzmann distribution, the hallmark of negative absolute temperature, Schneider says. The inversion of the gas's energy and the manifestation of a negative absolute temperature means that the gas is actually hotter than a positive temperature and is essentially a consequence of the limited definition of the Kelvin scale.