bagaimana diagram Feynman bisa menjelaskan tentang interaksi antar partikel?

In quantum field theory a Feynman diagram is a graphical representation of the transition amplitude of a quantum system.

Within the canonical formulation of quantum field theory a Feynman diagram represents a term in the Wick's expansion of the perturbative S-matrix. The transition amplitude is the matrix element of the S-matrix between the initial and the final states of the quantum system.

Alternatively, and perhaps more intuitively, the path integral formulation of quantum field theory represents the transition amplitude as an integral over (a weighted sum of) all possible paths of the system from the initial to the final state. A Feynman diagram is then identified with a particular path of the system contributing to the transition amplitude.

Feynman diagrams are named after Richard Feynman.