摘要：We have computed the number of polarization modes of gravitational waves propagating in the Minkowski background in gravity. These are three of two from transverse-traceless tensor modes and one from a massive trace mode, which confirms the results found in the literature. There is no massless breathing mode and the massive trace mode corresponds to the Ricci scalar. A newly defined metric tensor in gravity satisfies the transverse-traceless (TT) condition as well as the TT wave equation.
