On the uncertain distinction between fast landscape exploration and second amorphous phase (ideal glass) interpretations of the ultrastable glass phenomenon

This paper is written as a challenge to the ultrastable glass community to distinguish phenomenologically between the fast landscape searching scenario under discussion in the ultrastable glass community, and the alternative scenario in which the material in the ultrastable state is actually an attempted realization of the low temperature ideal glass phase of the system that can be reached in some systems, like ST2 water and amorphous silicon, and model systems like the attractive Jagla model, by a first order thermodynamic transition. These are special in that they exhibit first order phase - transitions to the ground state that are accessible above the normal T-g of the high temperature phase and in consequence exhibit vanishingly small excess entropies over crystal, and none of the "ubiquitous" glassy state cryogenic anomalies. In particular we show how, near a liquid-liquid critical point, the diffusivity can decrease arbitrarily rapidly over several orders of magnitude and that a growth front transformation from ultraslow phase to normal viscous liquid will be very difficult to distinguish from nucleation and growth of a new phase of different mobility. (C) 2014 Elsevier B.V. All rights reserved.