Mesoscopic theory of sound velocity in gases: an anisotropic approach

Abstract:This paper proposes a deterministic mesoscopic model for wave propagation in gases, developed within the framework of extended anisotropic thermodynamics. Classical statistical thermodynamics describes acoustic perturbations via macroscopic isotropic approximations (the Laplace equation) based on phenomenological parameters. However, the traditional assumption of permanent thermodynamic chaos and instantaneous energy equipartition encounters fundamental contradictions with experimental data, specifically failing to explain the non-monotonic behavior of sound speed during medium compression. The authors demonstrate that wave perturbations on the prerexalation stage are driven by the potential interaction of electronic shells forming dynamic elastic mesostructures ("molecular chains") rather than chaotic binary collisions. According to the law of conservation of momentum, the translation of directional momentum along the wave vector prevents transverse and rotational energy scattering. Any parasitic degrees of freedom are dynamically blocked by the longitudinal elastic interaction itself, forcing the effective number of degrees of freedom to unity and causing a localized jump in the adiabatic index to k = 3. An analytical dependence of the sound speed on the packaging density of electronic shells is derived. The model was verified using independent experimental data for the Earth's atmosphere, showing exceptional agreement with real-world measurements (with deviations under hundredths of a percent). The physical threshold for the existence of elastic wave chains is determined: when the translational kinetic energy exceeds the potential barrier of the shell interaction, dynamic destruction of the macro-oscillator occurs, and the medium transitions into a non-stationary shock-wave regime. This is the English version of the main article published in Russian