Sphere and half-sphere (IMAGE) University of California - Santa Cruz Caption In addition to spheres representing nine different simulations, the researchers also printed half-spheres to reveal the mid-plane data. Lighter material corresponds to regions of higher density, while darker areas represent regions of low density and voids. Credit Photo by Saurabh Mhatre Usage Restrictions For use only with news coverage of this research License Original 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.