Nuclear Stability and the Strong Nuclear Force

A crucial puzzle about the nucleus is why it holds together at all. The nucleus is packed with protons, all carrying positive charge, crammed into a region only a few femtometers across. According to Coulomb's law, these protons repel one another with enormous electrostatic forces at such tiny separations. If the electric force were the only force acting, no nucleus containing more than one proton could exist; the protons would fly apart instantly. Clearly there must be another, stronger force at work inside the nucleus that binds the nucleons together and overcomes this repulsion.

This is the strong nuclear force, sometimes called the strong interaction. It is one of the four fundamental forces of nature and is the strongest of them all over its range of action. The strong force acts betw