What is programmable matter, and how close are we to materials that can change shape on command?

The answer

Programmable matter refers to materials that can autonomously change their physical properties - shape, density, stiffness, or optical characteristics - in response to external stimuli or user commands. MIT's Self-Assembly Lab has created materials that fold into predetermined 3D shapes when heated. Carnegie Mellon University researchers developed a gallium-based metal alloy in 2023 that transitions between solid and liquid states using magnetic fields, capable of escaping a cage by melting and reforming outside. DARPA's Programmable Matter program has funded research into "catoms" (claytronics atoms) - millimeter-scale robots that would link together electromagnetically to form arbitrary shapes. In 2024, researchers at the University of Virginia created 4D-printed structures using shape-memory polymers that morph through multiple configurations. True programmable matter at macro scale remains decades away, but the building blocks are rapidly emerging.