Lyman Page, Henry De Wolf Smyth Professor of Physics. Chair, Department of Physics, Princeton University
The standard model of cosmology has passed many stringent tests and its basic parameters have been tightly constrained. The model is now so well established that we may use it as a foundation to address such questions as "What is the sum of the neutrino masses?" and "How many neutrino-like species are there?" We review the status of observations and recent results. We also present what we might hope to learn in the next half decade of observations.