Multi-hadron observables from lattice QCD

The strong force is governed by a mathematical framework called quantum chromodynamics (QCD). The building blocks of QCD are quarks and gluons, and the interactions of these constituents leads to a rich variety of observed phenomena. A particularly intriguing aspect of QCD physics is the nature and behavior of resonances, short-lived states that decay via the strong force. In this talk I will discuss progress in studying these states, by calculating multi-hadron scattering observables. This by achieved by combining field-theoretic ideas with large scale numerical calculations based in lattice QCD. In particular, I will focus on the idea of using the finite volume required for numerical calculations as a tool, rather than an unwanted artifact, to extract dynamical observables such as two- and three-hadron scattering amplitudes.