  This talk has the goal of introducing two upcoming exciting avenues of
discovery in precision Cosmology: spectral distortions (SDs) and gravitational
waves (GWs). The former signals offer a clear window into the state of the
primordial plasma at times prior to recombination, and thus sheds light on
small-scale primordial perturbations, dark matter decay and black hole
formation to just mention a few scenarios. The latter signals, which are
already offering new insights into the landscape of black hole and neutron star
mergers, will reveal intricate dynamics of the early universe including
primordial black holes, inflationary potentials, and even reheating dynamics.
An elegant link is drawn between these two future observations since primordial
GW backgrounds will source SDs, a coupling which offers unique insight to over
six decades of GW frequencies. More importantly the SD visibility window
bridges the gap between astrophysical high- and cosmological low-frequency
measurements. This means SDs will not only complement other GW observations,
but will be the sole probe of physical processes at certain scales.
