I know that a black body is a hypothetical perfect absorber and radiator. It emits EM radiation with different intensities. But my doubt is, how can an empty container with a pinhole be considered a good assumption for a black body.
In Peter Atkins | Julio de Paula - Physical Chemistry, It's given that "A good approximation to a black body is a pinhole in an empty container maintained at a constant temperature: any radiation leaking out of the hole has been absorbed and re-emited inside so many times as it reflected around inside the container that is it has come to thermal equilibrium with the walls"
Does the hypothetical model allows accumulation of electromagnetic oscillators ? Isn't it's rate of absorption and emission be same?