Abstract We advance the Information Boundary Principle (IBP): an event becomes irreversible when its informational content is recorded or irreversibly entangled with the environment, thereby fixing it within globally consistent boundary conditions across spacetime. In delayed‑choice quantum eraser experiments, correlations appear to allow future measurements to determine past behavior. We argue these results reveal a boundary‑value structure of quantum reality: histories are selected to satisfy both initial and final constraints, with inconsistency forbidden by the information boundary. We formalize the IBP using density‑matrix dynamics, decoherence, mutual information, and the Englert duality relation, derive observational consequences for eraser‑type experiments, and outline empirical tests capable of discriminating our view from competing interpretations. While fully consistent with special and general relativity, the IBP imposes an additional global constraint on their solution space. Einstein’s equations admit mathematically valid but unphysical spacetimes—tachyonic world‑lines, closed timelike curves, traversable wormholes sustained by exotic matter, and naked singularities. As energy conditions, quantum stability, and Hawking’s chronology‑protection principle already restrict many such solutions, the IBP further filters the admissible set by excluding any geometry that cannot maintain coherent, non‑contradictory informational records. Thus the IBP acts as an information‑theoretic selection rule layered over, not against, relativity’s geometry. Keywords: delayed choice; quantum eraser; decoherence; mutual information; causality; two‑state vector; information theory; relativity.
Abstract We advance the Information Boundary Principle (IBP): an event becomes irreversible when its informational content is recorded or irreversibly entangled with the environment, thereby fixing it within globally consistent boundary conditions across spacetime. In delayed‑choice quantum eraser experiments, correlations appear to allow future measurements to determine past behavior. We argue these results reveal a boundary‑value structure of quantum reality: histories are selected to satisfy both initial and final constraints, with inconsistency forbidden by the information boundary. We formalize the IBP using density‑matrix dynamics, decoherence, mutual information, and the Englert duality relation, derive observational consequences for eraser‑type experiments, and outline empirical tests capable of discriminating our view from competing interpretations. While fully consistent with special and general relativity, the IBP imposes an additional global constraint on their solution space. Einstein’s equations admit mathematically valid but unphysical spacetimes—tachyonic world‑lines, closed timelike curves, traversable wormholes sustained by exotic matter, and naked singularities. As energy conditions, quantum stability, and Hawking’s chronology‑protection principle already restrict many such solutions, the IBP further filters the admissible set by excluding any geometry that cannot maintain coherent, non‑contradictory informational records. Thus the IBP acts as an information‑theoretic selection rule layered over, not against, relativity’s geometry. Keywords: delayed choice; quantum eraser; decoherence; mutual information; causality; two‑state vector; information theory; relativity.
Delayed-choice and quantum eraser experiments are frequently interpreted as implying retrocausal effects, in which present measurement decisions influence past physical events. This paper develops an Observer-First Interpretation (OFI) in which quantum states are treated as observer-relative informational constructs constrained by evidence accessibility and record availability. Within this framework, delayed-choice phenomena do not involve backward-in-time physical influence, but instead arise from conditional informational updates applied to measurement records that were never globally fixed. Temporal paradoxes emerge only when observer-relative state assignments are illegitimately promoted to observer-independent histories. The proposed interpretation preserves causal ordering, respects relativistic constraints, and reproduces all standard quantum predictions without modifying the formalism of quantum mechanics.
Prefatory Note This article uses the comparison to clarify IBP/MIB, not to dismiss the compared theory. The “Sudoku universe” analogy offers a clear and accessible way to illustrate one important idea in contemporary discussions of physics, time, and global constraint: the physical record must cohere as a whole. Individual events cannot be understood as isolated entries detached from the larger structure of reality. This article uses that analogy as a point of comparison for a further question. A constraint metaphor can illustrate why the completed physical record must be internally consistent. A separate question remains: by what mechanism do possible events become admissible entries in that record? The Information Boundary Principle and the Minimum Informational Boundary are introduced here as a proposed account of that mechanism. IBP/MIB accepts the global-consistency insight reflected in the Sudoku analogy, while focusing on the prior question of event admission: how a possible event becomes part of the physical record without violating causality, conservation, probability continuity, Lorentz structure, or geometric coherence. Abstract Recent discussions in philosophy of physics and quantum foundations have advanced the idea that physical reality may be understood as a globally constrained structure. One popular explanatory metaphor is the “Sudoku universe,” under which the universe is compared to a completed puzzle whose entries must fit the rules of the whole. This article accepts the useful portion of that analogy: physical reality must be globally coherent and cannot contain contradiction. The difficulty is that the analogy does not identify the mechanism by which contradiction-producing possibilities are excluded from physical reality. It describes the consistency of the completed record, but not the conditions by which possible events become admissible entries in that record. The Information Boundary Principle (IBP) and the Minimum Informational Boundary (MIB) address that prior question. Under IBP/MIB, a possible event becomes part of the physical record only when it satisfies boundary-condition and causal-admissibility requirements. This article compares the constraint metaphor with the IBP/MIB framework and argues that Lorentz structure, scalar-field formalism, and the Einstein field equations are better understood as layered examples of causal and structural admissibility than as instances of a static puzzle analogy. The conclusion is that global constraint identifies the requirement of consistency, while IBP/MIB proposes the gate through which possible events become physically admissible records.
The delayed-choice quantum eraser is frequently presented as suggesting that a measurement performed in the future can influence an event that has already occurred. However, the experimental observations themselves do not require such a retrocausal interpretation. This paper reexamines the quantum eraser from the perspective of the Intrinsic Observability Framework (IOF), with particular attention to the role of distinguishability in the idler measurement. The essential experimental distinction is whether the idler is measured in a basis that preserves the distinguishability of the two generation alternatives or in a superposition basis that removes this distinguishability. In the former case, no conditional interference pattern appears, whereas in the latter, complementary interference patterns can be recovered through coincidence analysis. Importantly, this delayed choice does not modify any previously recorded signal event. Rather, the later idler outcome determines how the already recorded signal events are conditionally classified according to the implemented measurement basis. Within the IOF, this structure is interpreted by distinguishing Potential Observability (PO) from operationally established observable values. PO may contain phase relations, entanglement, and correlation structures without requiring pre-existing definite observable values. Measurement grants accessibility and establishes observable values, while subsequent correlation analysis reveals relational structures preserved among those values. From this perspective, the quantum eraser neither erases nor rewrites the past; it reveals how different accessibility conditions expose different conditional structures within the same set of measurement records. The analysis further shows that the beam splitter itself is not the fundamental element of quantum erasure: the essential condition is whether the idler measurement preserves or removes distinguishability between the alternatives. This distinction provides a direct connection between quantum erasure and the broader IOF concept of accessibility while remaining compatible with the standard quantum-mechanical formalism.
Quantum eraser experiments are frequently interpreted as providing evidence for the retroactive erasure of recorded information, seemingly implying a modification of the past. In this paper, we demonstrate that within the "Time as Index" (TASI) framework, quantum eraser phenomena do not necessitate such retrocausal interpretations. By defining time as the irreversible indexing of distinctions into a trace space \mathcal{T}, the framework rigorously differentiates between non-indexed (reversible) correlations and newly indexed histories. The analysis decomposes the problem into two exhaustive and mutually exclusive cases: • Case I: The information was erasable because it was never indexed, meaning no irreversible trace was formed and thus no "past" existed to be modified. • Case II: The act of erasure itself produces an irreversible trace, constituting a new indexing event or "past succession" rather than a modification of an existing history. This document provides a structural resolution to the apparent paradoxes in both standard and delayed-choice quantum erasers. It further includes two reviewer-style commentaries that evaluate the consistency of the argument and analyze how the delayed-choice variant serves to sharpen the criterion for indexing boundaries.
This paper presents a conceptual and analytical investigation into the limits of temporal access through the combined perspectives of causality, relativity, quantum mechanics, thermodynamics, and information theory. The work introduces the concept of the “Temporal Causality Barrier,” a selective and logically grounded framework that distinguishes between passive temporal observation and active temporal intervention. The paper argues that passive observation of the past is both physically permissible and continuously occurring through ordinary causal processes such as light propagation, memory, historical records, and astronomical observation. In contrast, active intervention into the past including backward information transfer, causal alteration of previous events, and closed causal loops is shown to generate logical contradictions and violations of causal consistency. The analysis critically examines major theoretical approaches related to time travel and retrocausality, including closed timelike curves, Novikov’s self-consistency principle, Deutsch’s quantum closed timelike curve model, and the two-state vector formalism in quantum mechanics. The paper argues that while some interpretations may mathematically describe retrocausal correlations, none currently provide an operational mechanism for backward information transmission without encountering paradoxes or information-theoretic inconsistencies. The framework further connects the causal structure of spacetime with the thermodynamic arrow of time, emphasizing the role of entropy, light cone geometry, and information propagation in preserving temporal coherence. The work also explores broader philosophical implications concerning the nature of time, consciousness, causality, and agency within a causally structured universe. Rather than proposing a new physical force or replacing existing theories, this paper provides a logically structured analysis of why temporal observation is compatible with known physics while active temporal intervention remains fundamentally constrained by both physical law and logical consistency.
Single-photon interference and delayed-choice experiments resist any account that treats the photon as a localized object carrying a private classical history. We propose the boundary-defined null connection (BDNC) view: a photon event is a null spacetime relation completed jointly by emission and absorption, with observable behavior fixed by the complete experimental boundary. The null-relation primitive itself is not novel — it appears in Kastner's relativistic transactional interpretation, Sorkin's causal-set null-link program, and the all-at-once / TSVF / Fixed Point Formulation literature. The contribution is unifying language: BDNC compresses these into a single vocabulary and identifies one operational criterion — whether the boundary modifies only post-selected correlations or also unsorted marginals. The latter case, parameterized by a generic future-state weighting ansatz, amounts to no-signaling violation rather than a BDNC-specific law; we outline two marginal-stability protocols and one weak-measurement consistency check that would constrain such deviations. The principal claim is therefore a unifying diagnostic, not a new falsifiable prediction: any predictive version must derive a BDNC-specific functional form for the future-state weighting. §11 sketches Twistor-Boundary Phase Geometry as a possible mathematical language for the framework, with the explicit caveat that minimal TBPG is empirically equivalent to standard twistor / gauge / QED. The paper is paired with a companion predictive extension: "Null-Boundary Response: A No-Signaling-Preserving Predictive Extension of the Boundary-Defined Null Connection Framework" (Zhang 2026, TBD Zenodo DOI), which proposes a candidate predictive law that produces a no-signaling-preserving channel-antisymmetric correction to coincidence statistics, with a six-feature experimental fingerprint testable in a phase-scanned delayed-choice quantum eraser.