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Some Inconvenient Truths

A recent paper by Fröb employs the linearized Weyl-Weyl correlator to construct the tensor power spectrum. Although his purpose was to argue that infrared divergences and secular growth in the graviton propagator are gauge artefacts, a closer examination of the problem leads to the opposite conclusion. The analogies with the BMS symmetries of graviton scattering on a flat background, and with the Aharonov-Bohm effect of quantum mechanics, suggest that de Sitter breaking secular growth is likely to be observable in graviton loop effects. And a recent result for the vacuum polarization does seem to show it.