Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves? Is this attribution unique, or are there other michanisms that could lead to the ecitation of tensor modes?
In explanation I have read recently is that gravitational waves turn the E-modes into the now observed B-modes somehow, but I dont understant this. So can somebody give a more detailled explanation of this intereaction of gravitational waves with the CMB?
LaTex and equations are welcome and appreciated :-)