Gravitational waves and the conformal transformation (Q1596253)

In scalar-tensor theories of gravity one encounters the so called ambiguity of ``frames'', refering to the freedom of conformally rescaling the metric tensor and, at the same time, appropriately transforming the scalar field. In this way, e.g., a non-minimally coupled scalar-tensor theory can be equivalently rewritten as a minimally coupled one. In the paper under review the authors discuss the behavior of gravitational waves under such a change of frames. In particular, they consider the case that an inflationary solution in one frame is related to a non-inflationary solution in another frame.