Fundamental Physics from the Cosmic Microwave Background: Neutrino Masses and Inflation
James Colin Hill
Princeton University

The cosmic microwave background (CMB) remains the preeminent source from which to extract information about fundamental physics from cosmology, due to its clean, well-understood origin and immense constraining power on many types of new physics. The next decade of CMB observations will yield answers to at least two fundamental questions: (1) what is the absolute mass scale of the neutrinos? (2) did large-field inflation source the initial density perturbations in our universe? In this talk, I will explain the routes by which these answers will be obtained. Both are reliant on highly precise measurements of the polarization of the CMB, which can be used to measure the growth of structure via gravitational lensing (answering the first question) and can be used to search for the signature of primordial gravitational waves (answering the second question). I will highlight the major role that the Simons Observatory and CMB-Stage IV experiments will play in these exciting developments. Finally, I will highlight additional unique information about the physics of inflation and the growth of cosmic structure that could be extracted from precise measurements of the CMB energy spectrum, which has been the focus of renewed theoretical attention and experimental proposals in recent years.