Jordan in The Church of The Higher Hilbert Space: Entanglement and Thermal Fluctuations

I revisit Jordan's derivation of Einstein's formula for energy fluctuations in the black body thermal equilibrium. This is usually taken to represent unification wave and particle aspects electromagnetic field since can be shown sum wave-like particle-like contributions. However, treatment there no mention Planck distribution all averages are performed with respect pure number states radiation (mixed had not yet been discovered!). The chief reason why Jordan does reproduce result despite using that he focuses on a small (compared whole) volume body. state highly entangled rest which leads correct even though overall might, fact, assumed (i.e. at zero temperature). present simple as an instance mixed being reductions higher level states, representation affectionately known "Church Higher Hilbert Space". According this view temperature nothing but amount entanglement between system its environment.Quanta 2022; 11: 1–4.