Searching for the Ideal Glass Transition: Going to Yotta Seconds and Beyond

Here we report results for the dynamics of a 50-million-year-old (geologically) aged Fushun amber that had a fictive temperature Tf approximately 193 K below its glass transition temperature Tg in the thermally reju-venated state. The density of this ultra-stable amber was found to be 14% greater than the post-rejuvenation value. Length change dilatometry was used to map the Tf by performing de-aging experiments and equilib-rium state dynamics were obtained by making measurements at T = Tf. Time-Temperature Superposition was applied to the frequency dependent storage and loss modulus measurements both along the equilibrium line and in upper-bound conditions where T > Tf. We find that the relaxation times cover >1027 s (1 ronna second), i.e., thousands of yotta seconds but do not follow the "expected" Vogel-Fulcher-Tammann (VFT) type of super-Arrhenius type of temperature dependence. Rather the deep glassy state equilibrium dynamics show no evi-dence of divergence at a finite temperature for temperatures that would be expected to be far below the ideal glass temperature Tg,ideal. In addition, at constant fictive temperature, we find that the relaxation times vary very strongly with specific volume v whereas, in isothermal conditions, the relaxation times are only weakly dependent on v. These results evidence that the deep glass state behavior presents a challenge to current ideas about glasses and the glass transition.