This question is a continuation from this one.
A material disk have two sides, one that is reflective and another absorptive of electromagnetic radiation in the range where the background cosmic radiation spectrum is significative.
It is pretty clear that the disk will not accelerate any further after thermalizing with the background radiation.
Question: what is the condition for the net exchange of momentum between the background radiation and the disk to become zero?
will the disk accelerate until the momentum of the blueshifted radiation absorbed at the front equates the momentum of redshifted photons being reflected at the back side?
Will the reflective side stop reflecting efficiently after the disk reaches the same temperature as the background radiation?