In a paper from Paik et al. 2016, they state (Section 3) that, a terrestrial gravitational wave (GW) detector measures only one off-diagonal component of the metric tensor.
Can anyone further expand on why this is so? From my copy of Misner, Thorne, and Wheeler, I understand that we work with a linearized theory and adopt the transverse traceless (TT) gauge, which reduces the perturbed metric to be written just in terms of 2 degrees of freedom corresponding to the two GW polarizations.
In this case, is a terrestrial detector (e.g. LIGO) not detecting two components, and they are not necessarily off-diagonal?