Glassy dynamics in thermally-activated list sorting

Sorting the integers 1 through $N$ into an ordered list is a simple task that can be done rapidly. However, using an algorithm based on the thermally-activated pairwise exchanges of neighboring list elements, we find sorting can display many features of a glass, even for lists as small as $N = 5$. This includes memory and rejuvenation effects during aging — two hallmarks of glassy dynamics that have been difficult to reproduce in standard glass simulations.