EIC Proton Graphic (IMAGE) DOE/Argonne National Laboratory Caption Graphical representation of the proton. The large spheres represent the three valence quarks, the small spheres represent the other quarks that make up the proton, and the springs represent the nuclear force holding them together. Credit (Image by Brookhaven National Laboratory.) 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.