On the Triviality of Aging

The dynamics of complex systems collectively known as glassy share important phenomenological traits. Whether structural or quenched, either in low-$T$ magnets or in dense colloids, physical changes occur in an intermittent fashion and, on average, at a decreasing rate. Despite their microscopic differences, generally, a transition is observed from a time-homogeneous regime to one which is likewise homogeneous, but in terms of the \emph{logarithm} of time: A global change of the independent variable \emph{trivializes} the dynamics. Focusing here on experimental data from dense colloids\footnote{Courtland \& Weeks, {\it J. Phys.: Condens. Matter} {\bf 15}, S359 (2003).}, the crucial importance of record-size fluctuation for the aging dynamics is revealed. A model with a generic stochastic dynamics is introduced\footnote{see also: Boettcher \& Sibani, http://arxiv.org/pdf/0910.5470.} which relies on the growth and collapse of strongly correlated clusters (``dynamic heterogeneities''). In the limit where large clusters dominate the dynamics, intermittency in terms of record-size events occurs with rate $\propto1/t$, implying a homogeneous, $\log$-Poissonian process that qualitatively reproduces the experimental results for colloidal dynamics.\footnote{See also http://www.physics.emory.edu/faculty/boettcher/.}