A geometric description of blackbody-like systems in thermodynamic equilibrium

Riemannian and contact geometry formalisms are used to study the fundamental equation of electromagnetic radiation-like systems, obeying a Stefan-Boltzmann's-like law. The vanishing of metric determinant is used for classifying what kind of systems can not represent a possible generalization of blackbody-like systems. In addition, thermodynamic curvature scalar $\mathcal{R}$ is evaluated for a thermodynamic metric, giving $\mathcal{R}=0$, which validates the non-interaction hypothesis stating that the scalar curvature vanishes for non-interacting systems.