Why the Past May Be Physically Inaccessible: A Theoretical Review and Compatibility Framework

Abstract

Abstract Macroscopic backward time travel (BTT) — the physical process by which a macroscopic observer traverses from a later time t₂ to an earlier time t₁ < t₂ while retaining memory, biological state, and quantum correlations — remains one of the most conceptually challenging problems in theoretical physics. While General Relativity admits Closed Timelike Curves (CTCs) as exact mathematical solutions, mathematical existence does not entail physical realizability. We formulate the central question as the Historical Information Accessibility Problem (HIAP): Can a macroscopic physical system in state ρ(t₂) be consistently re-embedded into the admissible physical state space H_adm(t₁) of an earlier epoch, without violating geometric, quantum, causal, thermodynamic, and historical-information consistency conditions? We analyze six consistency conditions and synthesize them into a compatibility framework A_BTT. We further introduce Historical Exchange Asymmetry (HXA) as a new E6-level conceptual layer that asks what happens after successful historical re-embedding: can a physical system re-establish an information-exchange channel with its own already-realized historical state? HXA does not modify the six-condition HIAP framework; it identifies a structurally distinct question that HIAP does not address. We find that no currently established physical mechanism has been demonstrated to satisfy all six consistency conditions simultaneously. We do not claim a universal no-go theorem. The HIAP, FHR, and HXA frameworks are author-proposed conceptual contributions (Evidence Classification E6).