Most popcorn lovers take for granted that a simple kernel of corn can metamorphose into a fluffy treat. But to a pair of French researchers, the popping of corn presents a powerful demonstration of how the laws of physics apply to everything — even a snack food. Until now, most research on popcorn has been focused on practical questions. Food chemists determined that the optimum moisture content of a kernel is 13.5% to 14% of its total weight. Food engineers concluded that the ideal shape for an unpopped kernel is a sphere. Plant breeders have reduced the rate of unpopped kernels by 75% since the 1950s. Virot and Ponomarenko aren’t interested in improving popcorn. They simply wanted to understand the physical origins of some of its most distinctive traits, like the forces that make kernels jump and the source of the iconic pop-pop-pop sound. Their fellow scientists were using a high-speed camera to take 2,900 pictures per second of physical phenomena, like a drop landing on the surface of water. Known scientifically as Zea Mays Evereta, popcorn is the only type of corn that pops. Its kernels are more spherical than other corn kernels, and its pericarp — the hull that surrounds the seed — is a little thicker. The starch inside the seed is embedded in a protein matrix called the endosper.