# Directed aging, memory and Nature's greed

## TL;DR

This paper explores how disordered materials can encode memories of their deformation history through a process called directed aging, where their elastic properties evolve in a way that reflects their past strains, acting like a natural greedy algorithm.

## Contribution

It introduces the concept of directed aging in disordered materials, demonstrating how their elastic properties evolve based on their aging history through experiments and simulations.

## Key findings

- Elastic properties evolve with aging history.
- Materials develop new responses not inherent initially.
- Directed aging acts as a natural greedy algorithm.

## Abstract

Disordered materials are often out of equilibrium and evolve very slowly. This allows a memory of the imposed strains or preparation conditions to be encoded in the material. Here we consider "directed aging", where the elastic properties of a material evolve in the direction defined by its aging history. The evolution to a lower-energy configuration is controlled by steepest decent and affects stressed regions differently from unstressed ones. This process can be considered to be a "greedy algorithm" of Nature. Our experiments and simulations illustrate directed aging in examples in which the material's elasticity evolves as a direct consequence of the imposed deformation; the material itself decides how to evolve in order to produce responses that were not present inherently in the material.