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arXiv:2607.14056

Acoustic Firewalls: Analogue Gravity Perspective on the AMPS Paradox

Nikolay S. Akintsov, Artyom P. Nevecheria, Stepan N. Andreev, Qing-Hua Qin

gr-qccond-mat.quant-gasquant-phSubmitted Jul 15, 2026• Announced Jul 16, 2026• Revised Jul 20, 2026 (v2)
v1 · Jul 15, 2026v2 · Jul 20, 2026
arXivHTMLPDF

Abstract

The monogamy of quantum entanglement, applied by Almheiri-Marolf-Polchinski-Sully (AMPS) to black holes, obstructs a smooth horizon vacuum after the Page time. We transcribe this argument to Hawking-like phonon radiation from a sonic horizon in the Unruh acoustic metric. An exact purity identity shows that post-Page-time unitarity forces the entanglement between an outgoing phonon and its interior partner to vanish, selecting a non-Hadamard (Boulware-like) phonon state, which we define as an acoustic firewall. Its renormalized stress tensor differs from the smooth state by a constant, negative near-horizon flux, and the thermal-atmosphere energy density it removes, measured by a static calorimeter, grows as $(δr)^{-2}$ in the radial coordinate toward the horizon (singular in the free-fall frame), cut off at the healing length. The construction is kinematic and does not resolve the information paradox; it yields one concrete, falsifiable prediction: a differential phonon-calorimetry signal $\mathcal{R}(δr)=|Δ\mathcal{E}|/\mathcal{E}^{(0)}\to(\ell_κ/δr)^{2}$, present only after the analogue Page time in a Bose-Einstein condensate.

Comments
Combined Letter and Supplemental Material (8 pages, 6 figures, 1 table). v2: references added, affiliation of S.N.A. updated. Submitted to Phys. Rev. Lett. Code and data: Zenodo, doi:10.5281/zenodo.21269544

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Black holes offer an exciting area to explore the nature of quantum gravity. The classic work on Hawking radiation indicates that black holes should decay via quantum effects, but our ideas about how this might work at a technical level are incomplete. Recently Almheiri-Marolf-Polchinski-Sully (AMPS) have noted an apparent paradox in reconciling fundamental properties of quantum mechanics with standard beliefs about black holes. One way to resolve the paradox is to postulate the existence of a ``firewall'' inside the black hole horizon which prevents objects from falling smoothly toward the singularity. A fundamental limitation on the behavior of quantum entanglement known as ``monogamy'' plays a key role in the AMPS argument. Our goal is to study and apply many-body entanglement theory to consider the entanglement among different parts of Hawking radiation and black holes. Using the multipartite entanglement measure called negativity, we identify an example which could change the AMPS accounting of quantum entanglement and perhaps eliminate the need for a firewall. Specifically, we constructed a toy model for black hole decay which has different entanglement behavior than that assumed by AMPS. We discuss the additional steps that would be needed to bring lessons from our toy model to our understanding of realistic black holes.
WITHDRAWAL / SUPERSESSION NOTICE (2026-05-31). Subsumed and refined by the canonical ANCHOR §11 black-hole paper (`updated_black_hole.tex`), which incorporates the firewall-resolution mechanism into a broader operator-algebra closure with KMS-derived Hawking temperature, monogamy-firewall horizon, condensate-core interior, and bulk-boundary scale separation. Current canonical version: doi.org/10.5281/zenodo.20478667. The AMPS firewall paradox [1] arises from three quantum-mechanical statements that are jointly required by standard physics for old black holes but mutually inconsistent: uni- tarity (information conservation), the equivalence principle in its quantum form (vacuum at the horizon), and monogamy of entanglement. Standard resolutions either weaken one of these or invoke complementarity / ER=EPR redundancy without specifying a concrete mechanism. We propose, building on the quantum-error-correcting substrate framework [6, 7, 8], that horizons are 2D surfaces of high stabilizer-measurement activity on the Trun- cated Cubic Honeycomb (TCH) substrate, structurally distinct from bulk vacuum but non- destructive (QND) at the quantum level. This proposal weakens the strong quantum form of the equivalence principle while preserving its geometric form, in a manner that is specific and physically motivated rather than ad-hoc. We identify three explicit derivations that would constitute a complete resolution: a derivation of horizon dynamics from substrate properties; an explicit isometry between interior and exterior mode-encodings establishing QEC redundancy; and recovery of Hawking’s thermal spectrum from substrate dynamics. The framework’s structural ingredients are laid out as a basis for these derivations. We do not claim the firewall paradox is resolved; we claim the framework provides specific tools that may resolve it, and that the proposed mechanism is structurally motivated rather than chosen to match desired outcomes.
On the Resolution of the Black Hole Information Paradox and Firewall Exclusion via the Boundary Formalism and Observer-State Interaction Dynamics Michael Allan A. Bahtaji, Ph.D. Department of Physics, College of Science Technological University of the Philippines Ayala Boulevard, Ermita, Manila, Philippines, 1000 Email: michaelallan_bahtaji@tup.edu.ph | michaelallanbahtaji336@gmail.com Abstract We present a self-contained, unitary quantum gravitational framework resolving the Black Hole Information Paradox and eliminating the AMPS energetic firewall problem. Utilizing the Finite Boundary Formalism, we establish that the event horizon acts as a dynamic state-density boundary governed by the inverse relation . By coupling the density matrix evolution of the black hole-radiation system to the observer-state interaction operator , we derive an exact conservation equation for the fine-grained entanglement entropy . We demonstrate that beyond the Page time , a negative observer-state interaction gradient forces the emission of high-order multi-qubit correlations via localized state fluctuations . This mechanism reproduces the symmetric Page curve, enforcing complete information recovery and -matrix unitarity () while preserving smooth Horizon geometry without singular energetic firewalls.
This article analyses the firewall paradox (wall‑of‑fire paradox, AMPS) — one of the most discussed challenges to modern quantum gravity. The paradox arises from an apparent contradiction between three postulates: the unitarity of quantum mechanics, the semiclassical description of Hawking radiation, and Einstein’s equivalence principle. Proponents of “informational language” argue that to save information, one must abandon the equivalence principle and accept the existence of a high‑energy “firewall” at the event horizon of a collapsar. It is shown that the firewall paradox is a problem of “informational language” , not a physical contradiction. The paradox is rooted in the conflation of the three senses of “information” (configuration, observer’s knowledge, pseudosubstance) introduced in Article 1. When reformulated in physical language (configuration, quantum correlations, unitary evolution), the need for a “firewall” disappears. Monogamy of entanglement is a property of quantum correlations, not an “informational principle”. The change in correlation structure after Page time is a technical problem, not a fundamental contradiction. Alternative approaches (Susskind’s complementarity) that do not require a firewall are considered. Responses to possible objections are given. The reformulation preserves the equivalence principle, eliminates the pseudo‑paradox, and turns the problem into a technical description of quantum correlations. The article is the seventh in the series “Reformulating Key Concepts of Physics Without Informational Language”. Keywords: firewall paradox, wall of fire, AMPS, collapsar, information, quantum correlations, monogamy of entanglement.
Alice stays outside a black hole; Bob falls in. Alice never sees the interior. Bob crosses the horizon but can never signal back. Physics holds subjectively for both, yet their realities objectively contradict. This illustrating a conflict between quantum and classical mechanics. AMPS is a thought experiment about this. It asks one observer to distil a purifier of a late Hawking mode B B B from early radiation RRR, then compare it with the interior partner A A A inside a single causal patch. The hidden cost is not just computation but control. If the correct decoder depends on the black hole microstate, the observer must carry a physical selector for the decoder family. I model that selector as a finite control register bounded by the covariant entropy bound on the patch. A covering argument shows that any fixed, state-independent decoder works on at most 2α∗SBH+cε 2^{\alpha_* S_{\mathrm{BH}}+c_\varepsilon} 2α∗​SBH​+cε​ microstates, so the observer needs at least (1−α∗)SBH−cε (1-\alpha_*)S_{\mathrm{BH}}-c_\varepsilon (1−α∗​)SBH​−cε​ control bits---requiring a patch with area fraction ρ2≥1−α∗−cε/SBH \rho^2 \ge 1-\alpha_* - c_\varepsilon/S_{\mathrm{BH}} ρ2≥1−α∗​−cε​/SBH​. A time-sharing objection fails because single-observer verification requires co-instantiation, not mere sequential occurrence; serialisation creates no free room. The conclusion: a subhorizon observer generally cannot certify the AMPS contradiction. In quantum gravity, control information is physical, and single-observer certification is a capacity problem. If the contradiction can never be measured, is it real?
We suggest a quantum circuit model which simulates the black-hole evaporation process. In particular, Almheiri-Marolf-Polchinski-Sully (AMPS) paradox and the ER=EPR correspondence are reconsidered regarding our proposed model, which assumes a Maxwell's demon operating within a black hole interior. In other words, we form a quantum circuit, mimicking the behavior of the entanglement structure of the near-horizon region and the early Hawking radiation located far from the black hole. Furthermore, we indicate how the demon, by applying nonlocal correlations, can mediate via Einstein-Rosen bridges for the purpose of simulating the transfer of quantum information across the horizon without violating the monogamy of entanglement. Finally, the thermodynamic cost of the demon's operations regarding Landauer's principle is analyzed. This indicates that the information erasure has an energy comparable to the black hole entropy.