Acoustic Tractor Beam (IMAGE) American Institute of Physics Caption This image shows levitating a 3cm diameter expanded polysterine sphere with a DIY portable tractor beam. Credit Asier Marzo 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.