Fundamental Interaction

In the Standard Model the fundamental interactions are the strong, electromagnetic, weak, and gravitational interactions. There is at least one more fundamental interaction in the theory that is responsible for fundamental particle masses. Five interaction types are all that are needed to explain all observed physical phenomena.

Strong force

A short-range force—holds the nucleus together.

Weak force

A short-range force, responsible for radioactive β-decay processes.

See also: Standard Model.