# Thermal equilibrium of universe

I am just an interested layman in the field of cosmology. In the usual account of the development of the universe, it is stated that about 380.000 years after the big bang the electromagnetic radiation was in thermal equilibrium with matter.

Does this mean that the universe was (and maybe is) an isolated thermodynamic system that was (and is) in internal thermodynamic equilibrium? Further, it is stated that this radiation is seen in todays cosmic microwave background radiation corresponding to a perfect blackbody radiation with a temperature of 2.7K after the expansion of the universe. Could this expansion be considered as an adiabatic expansion of the radiation system?

Then the radiation supposedly decoupled from matter due to recombination of electrons with atomic nuclei. Does this mean that after this (and now) radiation and matter (on the average) are no longer in thermal (thermodynamic) equilibrium in the universe?