Fredagskollokvium: Characterizing the primordial universe: the search for primordial gravitational waves from inflation

The ESA Planck satellite mapped the temperature anisotropies of the cosmic microwave background (CMB) almost to the cosmic variance limit over a large range of angular scales. However there remains considerable discovery potential in observations of the CMB polarization anisotropies, and in particular in the search for the B mode polarization, which is the tell-tale sign of primordial gravitational waves generated during inflation. I will describe some of the efforts underway to search for B modes including the Japanese-led LiteBIRD mission and a possible European M5 dedicated polarization satellite. I will also describe some of the formidable challenges that must be overcome in order to realize this programme as well as the lessons learned from the BICEP2 experiment, which mistook polarized dust emission from our own Galaxy for a primordial signal.