Aging is a log-Poisson process, not a renewal process

Abstract

Aging is a ubiquitous relaxation dynamic in disordered materials. It ensues after a rapid quench from an equilibrium "fluid" state into a nonequilibrium, history-dependent jammed state. We propose a physically motivated description that contrasts sharply with a continuous-time random walk (CTRW) with broadly distributed trapping times commonly used to fit aging data. A renewal process such as CTRW proves irreconcilable with the log-Poisson statistic exhibited, for example, by jammed colloids as well as by disordered magnets. A log-Poisson process is characteristic of the intermittent and decelerating dynamics of jammed matter usually activated by record-breaking fluctuations ("quakes"). We show that such a record dynamics provides a universal model for aging, physically grounded in generic features of free-energy landscapes of disordered systems.

Universal features of annealing and aging in compaction of granular piles

“…Remarkably, we thus find that a tapped granular pile exhibits an aging phenomenology, after being driven out of equilibrium by a hard quench, akin to many other thermal systems, not only macroscopically ( 14 ) but also in the statistics of local events facilitating relaxation. The statistics of these events closely resemble a log-Poisson process, which is at the heart of a universal description—essential for explaining the ubiquity of this phenomenology across so many materials—in terms of record dynamics ( 12 , 37 – 40 ). These events are enabled, in fact, by statistically independent, record-sized fluctuations that evolve the dynamics irreversibly and in ever more rare increments.…”

Dynamics of dense hard sphere colloidal systems: A numerical analysis

“…Cage breakings have been modelled [11,12] using a Continuous Time Random Walk (CTRW) [13], a popular coarse-graining device recently criticized in [14,15]. Other approaches to coarse-graining are e.g.…”

“…To summarize, the phenomenology of glass formers and aging HSC is experimentally [1,2,4,5,7,29] and numerically [3,6,9,10] well described, but a unified theoretical description [11,12,28] is not yet available. RD has been proposed [15,24,28] as a viable candidate and its validity is investigated in the present work by extensive MD simulations of three dimensional HSC which extend over 6 order of magnitude in time. We first provide a macroscopic characterization of the dynamics in terms of particle MSD and potential energy, and compare with homologous results [6].…”

Differential Progression of Regional Hippocampal Atrophy in Aging and Parkinson’s Disease

“…Hippocampal atrophy is a key finding in neurodegenerative diseases (Camicioli et al, 2003 ; Small et al, 2011 ; Bartsch and Wulff, 2015 ; Yang and Yu, 2017 ), although it is also present in healthy aging (Fjell et al, 2014 ). In neuroimaging studies, the hippocampus has traditionally been assessed as a single component, but more advanced techniques have allowed studying the hippocampus as a complex structure with specific regional vulnerability to aging and subtypes of dementia (Small et al, 2011 ).…”