Inside most materials, little is moving. But a new “active nanocomposite” is teeming with motion: small particles connect or separate, thus changing the color of the entire material. It was made by scientists of the Leibniz Institute for New Materials in Saarbrücken in an attempt to lend materials more dynamics. The transparent material can “answer” temperature changes or, in the future, the presence of chemical substances and toxins with a color change. The researchers want to create packaging films that change their color when food spoils, for example.