Which fundamental force is responsible for binding nucleons together in an atomic nucleus?

The strong nuclear force is the fundamental force responsible for binding nucleons, which are protons and neutrons, together in an atomic nucleus. This force acts at very short ranges, typically on the order of a femtometer (1 femtometer = 10^-15 meters), and is significantly stronger than the electromagnetic force and gravitational force at these small distances.

Nucleons are positively charged (protons) and would naturally repel each other due to electromagnetic interactions; however, the strong nuclear force overcomes this repulsion and holds them together within the nucleus. The strong nuclear force operates through the exchange of particles called gluons, which mediate the interaction between quarks, the building blocks of protons and neutrons.

This unique property of the strong nuclear force is crucial for the stability of atomic nuclei, enabling the existence of various elements and the complexities of matter as observed in the universe.