The edge of a spinning disc with sufficiently low mass to exclude gravity effects emits a light signal received in the center of the disc. Does the acceleration towards the center imply that the signal is blueshifted, alternatively is a signal from the center blueshifted as seen from the edge?
There is no kinematic blueshift because the edge is not moving toward (or away from) the center, but there is a frequency shift that arises entirely due to relativity. Since the edge of the disc is moving, its clocks run slower (in the center's frame), so the signal received by the center is slowed, i.e. redshifted. Another perspective is that within the frame of a section of the disk, there is a gravitational field pointing away from the center (which is responsible for the centrifugal force), so light climbing toward the center is redshifted.
