S-Matrix Theory

S-Matrix (scattering matrix) theory is a framework in quantum physics that describes how particles interact and scatter off each other. It focuses on the initial and final states of particles before and after a collision, capturing the probabilities of different outcomes. Instead of detailing the complex intermediate processes, the S-matrix summarizes all possible interactions in a way that allows physicists to predict experimental results. This approach simplifies the study of particle physics by relating measurable quantities—like scattering angles and energies—without needing to understand every detail of the interaction process itself.