Fluid droplets form spheres to minimize their surface energy. But when electrified in a surrounding gas or liquid—in a thunderstorm cloud, say, or an inkjet printer—they can become unstable and deform into cones that emit streams of smaller droplets. G. I. Taylor explained the phenomenon in 1964, and it has been extensively explored and exploited ever since.
The behavior of electrified droplets in an elastic solid, in contrast, has remained largely mysterious. For one thing, solids usually suffer electric breakdown at field strengths comparable to those required to trigger an instability in a trapped water drop, air bubble, or other fluid inclusion. For another, soft dielectric polymers—an important class of materials that commonly contain such defects—also change shape in an electric field (see the article by Siegfried Bauer, Reimund Gerhard-Multhaupt, and Gerhard Sessler in Physics Today, February 2004, page 37), and the coupled deformations of solid and fluid...
