Visualizing the interior of the nucleon: quark-gluon imaging with spin

2025 is the centenary of the discovery of spin. Spin led to structure and order in the elements and atomic nuclei. Deeper in the interior of matter, the proton is an absolutely unique quantum system, in which the constituent particles – quarks and gluons - move near or at the speed of light. In the tiny quantum world of the proton, particles pop in and out of existence. As a result, the proton changes pending how one looks at it and can manifest itself in very different ways, like a living organism. Without spin, motion in a proton is spherically symmetric. With spin, a new order is established. Quark-gluon imaging of protons and nuclei provides a means to understand their internal spin structure. Animations add a beautiful tool to visualize this understanding. In this talk we will illustrate visualizations of the nucleus, of the proton, and show how spin provides structure and order.