A Crumpled Sheet’s Remembrance of Things Past

What does a material “know” about its past? Exploring this question can yield insights into a material’s internal structure and dynamics. A new paper by Yoav Lahini and colleagues at Harvard University [1] shows that the act of crumpling a thin sheet—for instance, wadding up a candy wrapper—allows it to “remember” past events for days. This memory effect indicates that crumpled sheets are more similar to other structurally disordered systems, like glass, than previously thought.