Levitating Styrofoam (IMAGE) University of Bristol Caption A styrofoam particle of 1.6cm (1.88 wavelengths of sound) trapped in the centre of a 40kHz ultrasonic generator of virtual vortices. Credit University of Bristol Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.