Presentation #210.01 in the session An Update on Astrophysics and Cosmology from Cosmic Microwave Background Measurements in the Next Decade.
CMB-S4 is a ground-based cosmic microwave background experiment that will map the microwave sky with exquisite sensitivity. The data collected by CMB-S4 will provide extremely broad and deep insights into the history, evolution, and contents of the Universe. CMB-S4 will test a broad class of models of cosmic inflation by searching for the imprints of primordial gravitational waves. It will measure the density of light relics with unprecedented precision, thereby shedding light on the physics of the dark sector. CMB-S4 will detect thousands of high redshift galaxy clusters, providing a catalog useful for both cosmological and astrophysical studies. It will furthermore explore the millimeter-wave transient sky opening a new window for time domain astronomy and multi-messenger astrophysics. This talk will provide an overview of the exciting and transformative science that CMB-S4 will deliver.