Click cells to toggle solid/liquid. Apply force. Watch the structure decide how to move.
In February 2026, researchers at Duke University demonstrated something remarkable: tiny cells made of gallium-iron alloy that can switch between solid and liquid states at room temperature. By controlling which cells are rigid and which are flexible, they built a robotic fish that could change the way it swims — not by reprogramming its motors, but by reprogramming its body.
The idea is deceptively simple. Take a grid of identical cells. Give each cell one binary choice: be solid or be liquid. Now apply a force. The structure's mechanical response — how it bends, where it flexes, what shape it takes under stress — emerges entirely from the pattern. The same material, the same force, but a different arrangement of solid and liquid produces a completely different behavior.
This is programmable matter: material whose physical properties can be rewritten on the fly. Not by changing what it's made of, but by changing how its parts choose to be.
The simulation above is a simplified 2D model. Solid cells resist displacement and transmit force to their neighbors. Liquid cells absorb force, deform freely, and dampen propagation. The emergent behavior — a fish tail that flexes, a bridge that holds, a snake that ripples — comes from nothing but the pattern.
"A thing is not just what it's made of, but how its parts decide to be."