Scientists at a Zurich university have demonstrated a technique for levitating objects using precisely controlled sound waves.
This video shows two droplets, acidic and alkaline, being combined in midair. When the mixture reaches a neutral ph, it glows green due to a chemical reaction. (In a previous demonstration the scientists combined water and coffee granules in midair. Paging the Starbucks concept store department.)
Previously when you saw things floating in midair, you could be fairly certain it involved magnets, electrical fields, or little tiny wires. This "acoustophoretic transport" method improves on these other techniques and tricks because it doesn't just work on magnetic materials—it can be applied to any object, and works especially well for liquids, which is potentially applicable to experiments and highly controlled drug manufacture. The only limitation is that the diameter of the object can't be more than half the wavelength of the sound wave being used.
[Image: Dimos Poulikakos]