The Multiplicity of an Einstein Solid

In this video, I introduce and define Einstein solids. I review some relevant equations for simple harmonic motion, and remind you of the energy levels in a quantum harmonic oscillator (These topics are covered in more depth in other lectures, if you need more of a review.) I then show a conceptual derivation of the multiplicity of an Einstein solid, which describes how the energy excited states are distributed amongst the oscillators (bonds) in the solid. We then discuss two interacting Einstein solids, and demonstrate that when they are placed in thermal contact, the system moves to distribute the energy levels equally--simply because that is the most probable outcome.