  The Born-Markov master equation analysis of the vibrating mirror and photon
experiment proposed by Marshall, Simon, Penrose and Bouwmeester is completed by
including the important issues of temperature and friction. We find that at the
level of cooling available to date, visibility revivals are purely classical,
and no quantum effect can be detected by the setup, no matter how strong the
photon-mirror coupling is. Checking proposals of universal nonenvironmental
decoherence is ruled out by dominating thermal decoherence; a conjectured
coordinate-diffusion contribution to decoherence may become observable on
reaching moderately low temperatures.
