“…The geometrical interpretation of thermodynamic systems in equilibrium goes back already to the 19th century [ 1 ] and is reflected recently in Reference [ 2 ]. In modern terms, it is clear that thermodynamic states are Legendrian submanifolds, i.e., maximal integral manifolds of the structure contact form (for more details, see Reference [ 3 , 4 , 5 ]) in the contact space where the mentioned structure form is the first law of thermodynamics. Additional structures, such as Riemannian structures on these Legendrian manifolds, were studied in, for example, Reference [ 6 ].…”