Cosmic Microwave Background Observations in the Post-Planck Era

The Microwave Anisotropy Probe and Planck missions will provide low noise maps of the temperature of the cosmic microwave background (CMB). These maps will allow measurement of the power spectrum of the CMB with measurement noise below cosmic variance for l < 1500. It is anticipated that no further all sky CMB temperature observations will be needed after Planck. There are, however, other CMB measurements for which Planck will be not the end but the beginning. Following Planck, precise CMB polarization observations will offer the potential to study physical processes at energies as high as 10^19 GeV. In addition, arcminute scale, multi-frequency observations will allow study of the early phases of the formation of large-scale structure in the universe.