Probing the origin of our Universe through cosmic microwave background
  constraints on gravitational waves
  The next generation of instruments designed to measure the polarization of
the cosmic microwave background (CMB) will provide a historic opportunity to
open the gravitational wave window to the primordial Universe. Through high
sensitivity searches for primordial gravitational waves, and tighter limits on
the energy released in processes like phase transitions, the CMB polarization
data of the next decade has the potential to transform our understanding of the
laws of physics underlying the formation of the Universe.
