Connected, Not Identical: Gravity, Thermodynamics, and Physical Information Across Regimes

This paper examines the relationships among gravity, thermodynamics, and physical information across multiple physical regimes, emphasizing that these concepts are connected through specific physical laws but are not interchangeable. Black-hole physics provides a central setting for investigating these relationships through horizon thermodynamics, Hawking radiation, entanglement entropy, the black-hole information paradox, Page curves, generalized entropy, island calculations, and holography. The analysis distinguishes established physical relationships from model-dependent results and interpretive proposals, identifying the assumptions and limitations of each. The discussion extends beyond black holes to ordinary information thermodynamics, quantum fields without gravity, static gravitational equilibrium, self-gravitating matter, bounded-system entropy relations, the Unruh effect, and local causal horizons. Particular attention is given to Landauer’s principle, the distinction between information in inaccessible subsystems and information fundamentally destroyed, and the persistence of physical records. An asymmetric uncertainty coefficient is used to illustrate how present physical correlations can retain partial information about a specified classical past variable without implying universal information conservation or complete historical recoverability. The central conclusion is that gravity, thermodynamic entropy, quantum-state information, and physical records form a network of meaningful but domain-dependent relationships. Understanding these connections requires preserving their distinct definitions, operational conditions, and explanatory limits rather than reducing them to a single physical quantity.