In this digitally colorized image, one of two small sailboats floats on the underside of a blue layer of water. Researchers filled a container with viscous liquid, which they vibrated vigorously at a high frequency. The fast vibrations caused the liquid to “levitate” within the container. Stable air bubbles lay beneath it. There, the scientists found, small objects (up to seven grams in mass and 2.5 centimeters in length or diameter) could float on the underside of the water layer, appearing upside down. This “antigravity” effect, they speculate, is created by fluctuating gravity formed within the container by the rapid vibrations.