On the relation between tensor and scalar perturbation modes in   Friedmann cosmology
  An elementary derivation of the fundamental relation $T/S=4\gamma$ between the tensor and scalar modes of cosmological perturbations in the early universe is given. Statements by L.P.Grishchuk on this problem are commented on. 
V. N. Lukash (Astro Space Centre of the P.N.Lebedev Physics Institute,   Moscow)