Today, we are on the brink of a new age of fundamental discoveries in particle and nuclear science. Current and future experiments at the Relativistic Heavy Ion Collider, Large Hadron Collider, Electron-Ion Collider, and the Deep Underground Neutrino Experiment open windows on new physics and are poised to answer some of the most pressing fundamental questions that have remained unresolved within the Standard Model itself. In this talk, I will describe how these experiments and the related theory and computing can provide new insights into the early stages of the evolution of the universe. Effective field theories, brought into the mainstream by Steven Weinberg, have recently been adapted to describe particle dynamics in the extreme environments of high temperature, density, and strong color fields. I will show how these theoretical advances, coupled to precision phenomenology, can constrain the properties of the strongly coupled primordial plasmas, shed new light on the formation and structure of hadrons and nuclei, and help determine neutrino properties. Synergies with machine learning and, in the future, quantum computing can shorten the path to these discoveries.