Transformative Insights into the Cosmic Baryon Cycle from JWST

Understanding the formation and evolution of galaxies remains one of the great challenges of modern cosmology. Rest-frame optical spectroscopy serves as a uniquely powerful tool for untangling many of the key processes in galaxy formation, including the nature of galaxies’ stars, gas, and dust. We present a brief history of rest-optical spectroscopic probes of the galaxy formation process at high redshift, ranging from early ground-based attempts to the very latest results from the James Webb Space Telescope, which has revolutionized our ability to learn about the most distant galaxies in the universe. We focus in particular on questions related to the evolving enrichment and physical conditions in the interstellar medium of star-forming galaxies in the early universe, as these place critical constraints on the cycle of baryons through galaxies over cosmic time.