Speculations on dark matter as a luminiferous medium

Assuming the features commonly ascribed to dark matter, we discuss our glimpse of the possibility that dark matter as a light transmitting medium played a role that accounts for the discordant inferences about the dynamical behaviour of light, in which some optical experiments cannot detect the earth's motion in space, while others definitely can. In a converse way, the mentioned laboratory and astronomical observations provide an accessible experimental proof for the existence of a transparent, non-baryonic earth-bound medium which does not occupy the whole of universal space, dark matter being a possible candidate medium.