Reverse Cerenkov Radiation (IMAGE) American Physical Society Caption (Top left) Schematic of Cerenkov radiation in a conventional natural medium with positive refractive index, such as water, in which the radiation falls in a cone in the forward direction. (Bottom left) Schematic of backward Cerenkov radiation in a left-handed medium, showing the reversed cone. (Right) Schematic of the two-dimensional experimental configuration and the photographic image of the negative index metamaterials used to demonstrate backward Cerenkov radiation. The metamaterials consist of in-plane split-ring resonators and metal wires. Credit Illustration: Alan Stonebraker 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.