Bubble raft

A bubble raft is an array of bubbles. It demonstrates materials' microstructural and atomic length-scale behavior by modelling the {111} plane of a close-packed crystal. A material's observable and measurable mechanical properties strongly depend on its atomic and microstructural configuration and characteristics. This fact is intentionally ignored in continuum mechanics, which assumes a material to have no underlying microstructure and be uniform and semi-infinite throughout.

Bubble rafts assemble bubbles on a water surface, often with the help of amphiphilic soaps. These assembled bubbles act like atoms, diffusing, slipping, ripening, straining, and otherwise deforming in a way that models the behavior of the {111} plane of a close-packed crystal. The ideal (lowest energy) state of the assembly would undoubtedly be a perfectly regular single crystal, but just as in metals, the bubbles often form defects, grain boundaries, and multiple crystals.