Light Bottle (IMAGE) Vienna University of Technology Caption In a glass fiber -- with about half the diameter of a human hair -- light is kept in place. It cannot escape, because the diameter of the fiber decreases on both sides. Credit Vienna University of Technology 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.