About the Cover

The blue-ringed octopus’s distinguishing characteristics owe their bright color to the self-assembly of colloidal particles. On page 38 , Bas van Ravensteijn and Ilja Voets describe colloidal materials whose self-assembly out of equilibrium requires light or molecular fuel to sustain it. On page 30 , Amanda Parker describes how the soft tissues of humans and other organisms can be regarded as mechanical metamaterials. Together, the two articles provide a taste of the vitality and variety of the physics of soft matter. (Photo by kaschibo/Shutterstock.com.)