S-matrix

The S-matrix, or scattering matrix, is a tool physicists use to describe how particles interact and change when they collide. It essentially links the initial state of particles before a collision to the final state afterward, showing the probabilities of different outcomes. Think of it as a sophisticated forecast for particle interactions, indicating what results are likely after particles bump into each other. The S-matrix helps scientists understand fundamental forces and the behavior of matter at the tiniest scales in the universe.