The cosmic microwave background (CMB) research told us a remarkable story: the structure we see in our Universe such as galaxies, stars, planets, and eventually ourselves originated from tiny quantum fluctuations generated in the early Universe. With the WMAP we have confirmed many of the key predictions of inflation including flatness and statistical homogeneity of our Universe, Gaussianity and adiabaticity of primordial density fluctuations, and a small but non-zero deviation from the scale-invariant spectrum of density fluctuations. Yet, the extraordinary claim requires extraordinary evidence. The last prediction of inflation that is yet to be confirmed is the existence of primordial gravitational waves whose wavelength can be as big as billions of light years. To this end we have proposed to JAXA a new satellite mission called LiteBIRD, whose primary scientific goal is to find signatures of gravitational waves in the polarisation of the CMB. In this presentation we describe the current state of affairs regarding our understanding of the early Universe, physics of polarisation of CMB, and the LiteBIRD mission.
Local contact: V. Pettorino