  In this essay we examine the response of an Unruh-DeWitt detector (a quantum
two-level system) to a gravitational wave background. The spectrum of the
Unruh-Dewitt detector is of the same form as some scattering processes or three
body decays such as muon-electron scattering or muon decay. Based on this
similarity we propose that the Unruh-DeWitt detector response implies a "decay"
or attenuation of gravitons, $G$, into photons, $\gamma$, via $G + G
\rightarrow \gamma + \gamma $ or $G \rightarrow \gamma + \gamma + G$. Over
large distances such a decay/attenuation may have consequences in regard to the
detection of gravitational waves.
