Prof. Wei Li, Rice University

The visible universe is built upon a profound mystery: the Higgs boson provides only about 1% of the mass of protons and neutrons, while the remaining 99% emerges dynamically from the complex interactions of gluons. To "see" this emergent mass, we need a probe that acts as both a high-resolution microscope and an ultra-fast camera. While the relativistic heavy-ion program at the Large Hadron Collider (CERN) is famous for creating the Quark-Gluon Plasma, a transformative new direction has emerged: utilizing the LHC as the world's highest-energy gamma-ray collider.

By exploiting the intense electromagnetic fields surrounding relativistic ions, we can study ultra-peripheral collisions (UPCs) where nuclei interact via nearly real photons. These processes allow us to "freeze" the subatomic dynamics through time dilation, providing a unique snapshot of the 2D gluon distribution inside the nucleus. In this talk, I will present key findings in UPCs from the CMS experiment at the LHC, including intriguing results in imaging the gluonic structure of nuclei and precision tests of the standard model. I will then discuss the future of the field over the next two decades, highlighting how the high-luminosity LHC program and upcoming detector upgrades will enable a new era of "femtometer tomography". Finally, I will describe the synergy between the LHC program and the future Electron-Ion Collider, illustrating how we are paving the way for the next generation of precision nuclear physics.