Slower-motion bubble collapse The collapse of viscous bubbles is of practical interest to geophysics, glass manufacturing, and food processing. Previous studies have suggested that gravity or small punctures may play a role in the wrinkling and collapse of viscous bubbles. By studying bubbles with a range of viscosity and by tilting them both sideways and upside down, Oratis et al. conclude that gravity is not a factor. Instead, surface tension and dynamic stress of the compressed liquid seem to be the main driving mechanisms for the behavior of the bubbles and the wrinkling instability. Science , this issue p. 685