Astronomy Colloquium

  The Planck satellite was launched by the European Space Agency in 2009 and mapped the sky in nine bands spanning the frequency range 30-857 GHz. Planck has given us the most accurate temperature and polarization measurements of the cosmic microwave background to date. The results are in beautiful agreement with simple single field inflationary models. The background cosmology is consistent, to high precision, with a spatially flat Universe dominated at the present day by weakly interacting cold dark and a cosmological constant. I will discuss the constraints on inflationary gravitational waves derived from the Planck temperature data and from a recent joint analysis of polarization measurements from BICEP/Keck Array and Planck. These results provide strong and reliable constraints on the physics that operated within 1035 seconds of the birth of our Universe.