On thermodynamics and kinetics of antisystems

This work explores the thermodynamics and kinetics of thermodynamic antisystems, which possess a reversed arrow of thermodynamic time. Assuming the existence of true (ontic) randomness in the laws of nature, and allowing for two-end boundary conditions, we show that antisystems are permitted by those laws and may exist locally in our time, although they are generally not observed in practice. We analyse energy exchange between systems and antisystems, as well as their interaction with radiation, using generalised kinetic and Einstein-type equations. These suggest that, while equilibrium with antisystems is conceptually possible under certain conditions, it would be dynamically unstable. This otherwise abstract analysis becomes practically important when we ask a fundamental question: does antimatter form thermodynamic systems (CP-invariant thermodynamics) or thermodynamic antisystems (CPT-invariant thermodynamics)? Although challenging, this question is experimentally testable and still awaits resolution. In most cases, the laws of thermodynamics favour the transfer of energy and matter from antisystems to systems, a process with cosmological implications for the limited presence of antimatter in our epoch. Finally, we consider whether bulk antimatter, if isolated, could realise antisystem behaviour in practice. High-energy antiproton–antiproton collisions may be instrumental in examining possible antisystem properties of antimatter. While other approaches may be conceivable, this route appears to offer the most direct and feasible experimental pathway – though it remains largely unexplored at present. The philosophy of stochastic realism—which bears on time priming and physical irreversibility—is discussed in the Appendix. The Appendix also briefly outlines the cosmological implications of CPT-invariant thermodynamics.