CMB Lensing: Fundamental Physics from Maps of the Invisible
Blake Sherwin

Dark matter not only forms an invisible cosmic scaffolding within which galaxies form, its distribution in the universe also contains a wealth of information about neutrinos, dark energy, and physics at the earliest times. Analyses of gravitational lensing in the cosmic microwave background (CMB) allow this matter distribution to be directly seen and mapped, resulting in powerful probes of fundamental physics. In my talk, I will first describe ongoing work to extract the lensing signal from AdvACT and Simons Observatory CMB experiment data and derive precise cosmological constraints. Lensing is not only a signal, however, but also a source of noise that limits how much we can learn about the very early universe. With illustrations from recent work, I will explain why delensing - removing the lensing effect to reveal the primordial sky - will soon be of great importance for CMB cosmology.