Measurements of the Cosmic Microwave Background radiation have taught us a great deal about the origins and content of the universe, but there is still more information to be extracted. In the next decade we anticipate using new polarized microwave background data, and other cosmological data, to measure both the total mass of the neutrino particles, and the number of neutrino or other relativistic species. I will discuss our path to making this indirect detection of the absolute neutrino mass scale using the gravitational lensing of the microwave background and the clustering of galaxies, which will complement direct measurements. This will progress from data taken with the Planck satellite and the Atacama Cosmology Telescope Polarimeter in Chile, moving to new measurements made from the ground with the Simons Observatory and the CMB-S4 experiment, and from space with the PIXIE satellite.
Followed by wine and cheese in Pupin 301.