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 cannot represent a possible generalization of blackbody-like systems. In addition, thermodynamic curvature scalar R is evaluated for a thermodynamic metric, giving R=0, which validates the non-interaction hypothesis stating that the scalar curvature vanishes for non-interacting systems.