As discussed in Section 1.1, new parameters are oten born out of the need to explain inconsistencies between experimental results and prevailing theory. In physics, mass is the property that determines the magnitude of the gravitational force, and charge is the property that determines the magnitude of the electromagnetic force. Particle physicists have ascribed a property they call color, which determines the magnitude of the strong force that binds protons and neutrons together to form atomic nuclei. What is it about the structure of the atomic nucleus that would lead physicists to believe a new property other than mass and charge was required to explain observations?