I'd argue that a better representation (unfortunately it's not in unicode [yet?]) of independent servers would be Figure 3.8 "Atoms of different species in a single box": https://archive.org/details/kittel-thermal-physics.-80/page/...
I'd argue that a better representation (unfortunately it's not in unicode [yet?]) of independent servers would be Figure 3.8 "Atoms of different species in a single box": https://archive.org/details/kittel-thermal-physics.-80/page/...