Scale: 10^-14 meters = 10 fm = 10 femtometers

The Carbon Nucleus

What is it that holds this nucleus together? After all, there are 6 protons, each carrying a +1 electric charge, crammed together with 6 neutrons in a very tiny space. The mutual electromagnetic repulsion of the 6 protons is overcome by the strong nuclear force, which is also responsible for creating the protons and neutrons from their constituent quarks. In the theory of Quantumchromodynamics (QCD) gluons bind together three distinctly "colored" quarks to form the color-neutral protons and neutrons. The strong binding of the color-neutral protons and neutrons to form nuclei is due to residual strong interactions between their color-charged constituents. It is similar to the residual electrical interaction which binds electrically neutral atoms to form molecules.