Recognition: no theorem link
Black Hole Thermodynamics via Tsallis Statistical Mechanics and Phase Transitions Probed by Optical Characteristics
Pith reviewed 2026-05-13 06:38 UTC · model grok-4.3
The pith
Tsallis statistics applied to a near-horizon photon gas produces Van der Waals phase transitions in Reissner-Nordström black holes, with photon-sphere observables tracking the critical behavior.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
By modeling the near-horizon photon gas with Tsallis statistics, the authors derive a generalized entropy for Reissner-Nordström black holes. This entropy leads to a thermodynamic phase structure with small, intermediate, and large black hole phases that undergo Van der Waals-like transitions. Additionally, observables from the photon sphere, including orbital periods and Lyapunov exponents, are related directly to thermodynamic quantities and qualitatively follow the critical behavior.
What carries the argument
The near-horizon photon-gas model in Tsallis statistics, which deforms the Bekenstein-Hawking entropy and establishes an analogy between photon-sphere dynamics and thermodynamic phase transitions.
Load-bearing premise
The near-horizon region of the black hole can be accurately modeled as a photon gas that follows Tsallis statistics, thereby determining the generalized entropy and phase structure.
What would settle it
Detection of black hole photon rings or shadows that do not exhibit the predicted variations in orbital periods or Lyapunov exponents corresponding to the thermodynamic phases would falsify the analogy.
Figures
read the original abstract
We develop a non-extensive thermodynamic framework for Reissner--Nordstr\"om black holes based on a near-horizon photon-gas model within Tsallis statistics. We derive the generalized Bekenstein--Hawking entropy based on such an approach, consistent with the Bekenstein--Hawking area law in the extensive limit, $q \rightarrow 1$. The induced deformation gives rise to a rich thermodynamic structure consisting of small, intermediate, and large black-hole branches, exhibiting Van der Waals-like phase transitions characterized by mean-field critical exponents. We further establish an optical--thermodynamic analogy by relating photon-sphere observables, including orbital periods and Lyapunov exponents, to thermodynamic variables. These optical signatures qualitatively track the thermodynamic critical behavior and phase structure, suggesting their potential relevance as observational probes in future high-resolution measurements. These results may shed light on a conceptual connection between non-extensive entropy, black-hole critical phenomena, and strong-gravity optics.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper develops a non-extensive thermodynamic framework for Reissner-Nordström black holes based on a near-horizon photon-gas model within Tsallis statistics. It derives a generalized Bekenstein-Hawking entropy S_q that is consistent with the standard area law when q → 1. The deformation leads to a thermodynamic structure with small, intermediate, and large black-hole branches exhibiting Van der Waals-like phase transitions with mean-field critical exponents. The authors establish an optical-thermodynamic analogy by relating photon-sphere observables such as orbital periods and Lyapunov exponents to thermodynamic variables, showing that these optical signatures qualitatively track the thermodynamic critical behavior.
Significance. Should the derivations prove robust, this manuscript contributes to the growing literature on modified entropies in black hole thermodynamics by providing a concrete model for non-extensive effects. The phase transition analysis aligns with known mean-field behavior, and the optical analogy, if strengthened, could suggest new ways to probe black hole phase transitions observationally through strong lensing or shadow measurements. The approach may stimulate further research into statistical mechanics foundations of gravity.
major comments (2)
- [Optical-thermodynamic analogy section] The strongest claim regarding the optical-thermodynamic analogy is supported only by qualitative numerical tracking in plots rather than an explicit functional mapping. For instance, no analytic relation is derived showing that the Lyapunov exponent λ is a direct function of thermodynamic derivatives such as the second derivative of the free energy under the q-deformed entropy. This leaves the analogy as potentially metric-specific rather than a general consequence of the framework.
- [Derivation of generalized entropy] The generalized entropy is obtained from the Tsallis model applied to the near-horizon photon gas. The manuscript should clarify the precise steps from the Tsallis partition function to the entropy expression (likely in the derivation section) to confirm it is not ad hoc and to verify the q → 1 limit rigorously.
minor comments (2)
- [Notation] Ensure consistent use of symbols for the Tsallis parameter q and the deformation in equations throughout the text.
- [Figures] The figures illustrating the phase structure and optical tracking would benefit from clearer labeling of the different black hole branches (small, intermediate, large).
Simulated Author's Rebuttal
We thank the referee for the careful reading of our manuscript and the constructive comments, which have helped us identify areas for improved clarity. We address each major comment below and outline the corresponding revisions.
read point-by-point responses
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Referee: [Optical-thermodynamic analogy section] The strongest claim regarding the optical-thermodynamic analogy is supported only by qualitative numerical tracking in plots rather than an explicit functional mapping. For instance, no analytic relation is derived showing that the Lyapunov exponent λ is a direct function of thermodynamic derivatives such as the second derivative of the free energy under the q-deformed entropy. This leaves the analogy as potentially metric-specific rather than a general consequence of the framework.
Authors: We agree that the optical-thermodynamic analogy rests on qualitative numerical tracking of critical behavior between thermodynamic quantities and photon-sphere observables (orbital periods and Lyapunov exponents), rather than an explicit analytic functional mapping such as expressing λ directly in terms of derivatives of the q-deformed free energy. The manuscript presents this as an observed correspondence arising from the shared phase structure under the Tsallis framework applied to the RN metric, without claiming a general functional relation. Such a direct mapping is not derived because the optical quantities are computed from the geodesic equations independently of the thermodynamic potentials. We will revise the section to explicitly state the qualitative nature of the analogy, discuss its metric-specific aspects, and note the absence of a general functional link as a limitation of the current approach. revision: partial
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Referee: [Derivation of generalized entropy] The generalized entropy is obtained from the Tsallis model applied to the near-horizon photon gas. The manuscript should clarify the precise steps from the Tsallis partition function to the entropy expression (likely in the derivation section) to confirm it is not ad hoc and to verify the q → 1 limit rigorously.
Authors: We appreciate this suggestion for greater transparency. In the revised manuscript we will expand the derivation section to provide a step-by-step outline: starting from the Tsallis partition function for the near-horizon photon gas, through the maximization procedure leading to the generalized entropy S_q, and including an explicit verification that the q → 1 limit recovers the standard Bekenstein-Hawking area law. This will confirm the construction is not ad hoc. revision: yes
Circularity Check
No significant circularity detected; derivation remains self-contained
full rationale
The paper starts from the explicit modeling assumption of a near-horizon photon gas in Tsallis statistics to obtain the deformed entropy S_q, which is then used in the standard thermodynamic relations to produce the phase structure. Photon-sphere quantities (orbital periods, Lyapunov exponents) are obtained from the unmodified Reissner-Nordström metric via conventional geodesic equations, independent of the q-deformation. The optical-thermodynamic analogy is exhibited only as qualitative numerical tracking in overlaid plots, not as an analytic identity that would force the optical observables to equal thermodynamic derivatives by construction. No self-citation chain, fitted-parameter renaming, or ansatz smuggling is required for the central steps. The chain is therefore externally falsifiable and does not reduce to its own inputs.
Axiom & Free-Parameter Ledger
free parameters (1)
- q
axioms (1)
- domain assumption Tsallis statistical mechanics can be applied to the photon gas near the black hole horizon to derive thermodynamics
invented entities (1)
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generalized Bekenstein-Hawking entropy
no independent evidence
Reference graph
Works this paper leans on
-
[1]
Orbital Half-Period Continuing from the discussion of photon spheres, we now introduce theorbital half- periodτ, which characterizes the coordinate time required for a photon to complete half of its unstable circular orbit around the black hole, as measured by a static observer at infinity. This timescale captures the dynamics of light propagation near th...
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[2]
Angular Lyapunov Exponent Building on the analysis of circular photon orbits, theangular Lyapunov exponentλ L quantifies the rate at which photons diverge from unstable circular trajectories under small radial perturbations. Its magnitude is determined by the second radial derivative of the effective potential evaluated at the photon-sphere radius, thereb...
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[3]
Temporal Lyapunov Exponent Extending the analysis of circular photon orbits, we now introduce thetemporal Lyapunov exponentγ L, which measures the exponential growth of small radial perturbations with respect to the coordinate timetas observed at infinity. Thus,γL captures the instability in the time domain and sets the characteristic decay timescale of p...
-
[4]
S. W. Hawking, Particle creation by black holes, Communications in Mathematical Physics 43, 199 (1975)
work page 1975
-
[5]
J. D. Bekenstein, Black holes and entropy, Physical Review D7, 2333 (1973)
work page 1973
-
[6]
S. W. Hawking, Black hole explosions?, Nature248, 30 (1976)
work page 1976
-
[7]
J. W. York, Black-hole thermodynamics and the euclidean einstein action, Phys. Rev. D33, 2092 (1986)
work page 2092
-
[8]
J. M. Bardeen, B. Carter, and S. W. Hawking, The four laws of black hole mechanics, Com- munications in Mathematical Physics31, 161 (1973)
work page 1973
-
[9]
R. M. Wald,Quantum Field Theory in Curved Space-Time and Black Hole Thermodynamics, Chicago Lectures in Physics (University of Chicago Press, Chicago, IL, 1995)
work page 1995
-
[10]
S. Kolekar and T. Padmanabhan, Ideal gas in a strong gravitational field: Area dependence of entropy, Phys. Rev. D83, 064034 (2011)
work page 2011
- [11]
-
[12]
S.Bhattacharya, S.Chakraborty,andT.Padmanabhan,Entropyofaboxofgasinanexternal gravitational field – revisited, Phys. Rev. D96, 084030 (2017)
work page 2017
-
[13]
D. Li, B. Wu, Z. Xu, and W. Yang, A shell of bosons in spherically symmetric spacetimes, Phys. Lett. B820, 136588 (2021)
work page 2021
-
[14]
E. Sourtzinou and C. Anastopoulos, Quantum statistical mechanics near a black hole horizon, Phys. Rev. D107, 085006 (2023)
work page 2023
-
[15]
C. Tsallis, Possible generalization of boltzmann-gibbs statistics, Journal of Statistical Physics 52, 479 (1988)
work page 1988
-
[16]
C. Tsallis, What should a statistical mechanics satisfy to reflect nature?, Physica D: Nonlinear Phenomena193, 3–34 (2004)
work page 2004
-
[17]
T. S. Biró and P. Ván, Zeroth law compatibility of nonadditive thermodynamics, Phys. Rev. E83, 061147 (2011). 76
work page 2011
-
[18]
A. Rényi, On measures of information and entropy, inProceedings of the Fourth Berkeley Sym- posium on Mathematical Statistics and Probability, Volume 1: Contributions to the Theory of Statistics(University of California Press, Berkeley, CA, 1961) pp. 547–561
work page 1961
-
[19]
S. Abe, A note on the q-deformation-theoretic aspect of the generalized entropies in nonex- tensive physics, Physics Letters A224, 326 (1997)
work page 1997
- [20]
- [21]
-
[22]
S. Capozziello and M. Shokri, Barrow entropies in black hole thermodynamics, Eur. Phys. J. C85, 200 (2025), arXiv:2501.12987 [gr-qc]
-
[23]
A. A. Mamon, A. K. Saha, and R. Myrzakulov, Generalized second law of thermodynamics with barrow entropy, Eur. Phys. J. C81, 644 (2021)
work page 2021
- [24]
- [25]
-
[26]
Y. Ladghami, A. Bargach, A. Bouali, T. Ouali, and G. Mustafa, Spacetime foam ef- fects on charged AdS black hole thermodynamics, Nucl. Phys. B1018, 117015 (2025), arXiv:2411.06271 [hep-th]
-
[27]
Y. Ladghami, B. Asfour, A. Bouali, A. Errahmani, and T. Ouali, Barrow entropy and AdS black holes in RPS thermodynamics, Phys. Dark Univ.44, 101470 (2024), arXiv:2403.08991 [hep-th]
- [28]
-
[29]
B. D. Sharma and D. P. Mittal, New non-additive measures of entropy for discrete probability distributions, J. Math. Sci10, 28 (1975)
work page 1975
-
[30]
S. Ghaffari, A. H. Ziaie, H. Moradpour, F. Asghariyan, F. Feleppa, and M. Tavayef, Black hole thermodynamics in sharma–mittal generalized entropy formalism, General Relativity 77 and Gravitation51, 10.1007/s10714-019-2578-2 (2019)
-
[31]
S. Nojiri and S. D. Odintsov, Modified gravity with negative and positive powers of the curvature: Unification of the inflation and of the cosmic acceleration, Physical Review D68, 123512 (2003), arXiv:hep-th/0307288
- [32]
-
[33]
A. Alonso-Serrano, M. P. Dąbrowski, and H. Gohar, Nonextensive black hole entropy and quantum gravity effects at the last stages of evaporation, Physical Review D103, 026021 (2021)
work page 2021
- [34]
- [35]
-
[36]
S. Odintsov and T. Paul, A non-singular generalized entropy and its implications on bounce cosmology, Phys. Dark Univ.39, 101159 (2023)
work page 2023
-
[37]
I.ÇimşitCimidiker, M.P.Dąbrowski,andH.Gohar,Generalizeduncertaintyprincipleimpact on nonextensive black hole thermodynamics, Classical and Quantum Gravity40, 145001 (2023)
work page 2023
- [38]
-
[39]
Padmanabhan, Statistical Mechanics of Gravitating Systems, Phys
T. Padmanabhan, Statistical Mechanics of Gravitating Systems, Phys. Rept.188, 285 (1990)
work page 1990
-
[40]
C. Tsallis and L. J. L. Cirto, Black hole thermodynamical entropy, Eur. Phys. J. C73, 2487 (2013)
work page 2013
-
[41]
A. Plastino and A. Plastino, Stellar polytropes and tsallis’ entropy, Physics Letters A174, 384 (1993)
work page 1993
-
[42]
J. A. S. Lima, R. Silva, and A. Plastino, Nonextensive thermostatistics and the h theorem, Physical Review Letters86, 2938 (2001)
work page 2001
-
[43]
A. Taruya and M.-a. Sakagami, Gravothermal catastrophe and generalized entropy of self- gravitating systems, Physica A307, 185 (2002), arXiv:cond-mat/0107494
-
[44]
R. Silva and J. A. S. Lima, Relativity, nonextensivity, and extended power law distributions, Physical Review E72, 057101 (2005). 78
work page 2005
-
[45]
Chavanis, Statistical mechanics of two-dimensional vortices and stellar systems, Lect
P.-H. Chavanis, Statistical mechanics of two-dimensional vortices and stellar systems, Lect. Notes Phys.602, 208 (2002), arXiv:cond-mat/0212223
work page internal anchor Pith review arXiv 2002
-
[46]
D. Jiulin, Nonextensive power law distributions and the q-kinetic theory for the systems with self-gravitating long-range interactions, Astrophysics and Space Science312, 47 (2007)
work page 2007
-
[47]
D. J. Louis-Martinez, Classical relativistic ideal gas in thermodynamic equilibrium in a uni- formly accelerated reference frame, Classical and Quantum Gravity28, 035004 (2011)
work page 2011
-
[48]
L. Zhipeng, D. Jiulin, and G. Lina, Nonextensivity and q-distribution of a relativistic gas under an external electromagnetic field, Chinese Science Bulletin56, 3689 (2011)
work page 2011
- [49]
-
[50]
P. Chunaksorn, R. Nakarachinda, and P. Wongjun, q-Equilibrium of gas in spacetime of multi-horizon black holes, Nucl. Phys. B1016, 116922 (2025), arXiv:2402.13742 [gr-qc]
-
[51]
G. G. Luciano, Tsallis statistics and generalized uncertainty principle, Eur. Phys. J. C81, 672 (2021)
work page 2021
-
[52]
F. C. S. B. C. Tsallis and E. D. Loh, Generalization of the planck radiation law and application to the cosmic microwave background radiation, Phys. Rev. E52, 1447 (1995)
work page 1995
-
[53]
Sheykhi, Modified friedmann equations from tsallis entropy, Physics Letters B785, 118 (2018)
A. Sheykhi, Modified friedmann equations from tsallis entropy, Physics Letters B785, 118 (2018)
work page 2018
-
[54]
A. Lymperis and E. N. Saridakis, Modified cosmology through nonextensive horizon thermo- dynamics, European Physical Journal C78, 993 (2018)
work page 2018
- [55]
-
[56]
A. Sheykhi, New explanation for accelerated expansion and flat galactic rotation curves, European Physical Journal C80, 10.1140/epjc/s10052-019-7599-1 (2020)
-
[57]
P. Jizba and G. Lambiase, Constraints on tsallis cosmology from big bang nucleosynthesis and the relic abundance of cold dark matter particles, Entropy25, 1495 (2023)
work page 2023
-
[58]
R. Nakarachinda, C. Pongkitivanichkul, D. Samart, L. Tannukij, and P. Wongjun, Rényi Holographic Dark Energy, Fortsch. Phys.72, 2400073 (2024), arXiv:2312.16901 [gr-qc]
-
[59]
Dehpour, Thermal leptogenesis in nonextensive cosmology, European Physical Journal C 84, 340 (2024)
M. Dehpour, Thermal leptogenesis in nonextensive cosmology, European Physical Journal C 84, 340 (2024). 79
work page 2024
-
[60]
C. Tsallis and L. J. L. Cirto, Black hole thermodynamical entropy, The European Physical Journal C73, 2487 (2013), 1202.2154 [physics.gen-ph]
-
[61]
V. G. Czinner and H. Iguchi, Rényi entropy and the thermodynamic stability of black holes, Physics Letters B752, 306 (2016)
work page 2016
-
[62]
V. G. Czinner and H. Iguchi, Thermodynamics, stability and hawking–page transition of kerr black holes from rényi statistics, European Physical Journal C77, 892 (2017)
work page 2017
- [63]
-
[64]
L. Tannukij, P. Wongjun, E. Hirunsirisawat, T. Deesuwan, and C. Promsiri, Thermodynamics andphasetransitionofsphericallysymmetricblackholeindesitterspacefromrényistatistics, European Physical Journal Plus135, 500 (2020)
work page 2020
-
[65]
C. Promsiri, E. Hirunsirisawat, and W. Liewrian, Thermodynamics and van der waals phase transition of charged black holes in flat spacetime via rényi statistics, Physical Review D102, 064014 (2020)
work page 2020
-
[66]
C. Promsiri, E. Hirunsirisawat, and W. Liewrian, Solid-liquid phase transition and heat engine inanasymptoticallyflatschwarzschildblackholeviatherényiextendedphasespaceapproach, Physical Review D104, 064004 (2021)
work page 2021
- [67]
-
[68]
R.Nakarachinda, E.Hirunsirisawat, L.Tannukij,andP.Wongjun,Effectivethermodynamical system of schwarzschild–de sitter black holes from rényi statistics, Physical Review D104, 064003 (2021)
work page 2021
-
[69]
E. Hirunsirisawat, R. Nakarachinda, and C. Promsiri, Emergent phase, thermodynamic ge- ometry, and criticality of charged black holes from rényi statistics, Physical Review D105, 124049 (2022)
work page 2022
-
[70]
P. Chunaksorn, E. Hirunsirisawat, R. Nakarachinda, L. Tannukij, and P. Wongjun, Thermo- dynamics of asymptotically de sitter black hole in drgt massive gravity from rényi entropy, European Physical Journal C82, 1174 (2022)
work page 2022
-
[71]
R. Nakarachinda, C. Promsiri, L. Tannukij, and P. Wongjun, Thermodynamics of black holes with Rényi entropy from classical gravity, Nucl. Phys. B1011, 116796 (2025), arXiv:2211.05989 [gr-qc]. 80
-
[72]
T. Anusonthi, P. Wongjun, and R. Nakarachinda, Thermodynamic Stability of Schwarzschild- de Sitter Black holes with Rényi entropy, J. Phys. Conf. Ser.2934, 012011 (2025), arXiv:2501.04378 [gr-qc]
- [73]
-
[74]
E. Elizalde, S. Nojiri, and S. D. Odintsov, Black Hole Thermodynamics and Generalised Non-Extensive Entropy, Universe11, 60 (2025), arXiv:2502.05801 [gr-qc]
- [75]
- [76]
-
[77]
P. Chunaksorn, R. Nakarachinda, and P. Wongjun, Black hole thermodynamics via Tsallis statistical mechanics, Eur. Phys. J. C85, 532 (2025), arXiv:2502.02522 [gr-qc]
-
[78]
X. He, B. Wang, R. G. Cai, and C. Y. Lin, Signature of the black hole phase transition in quasinormal modes, Phys. Lett. B688, 230 (2010)
work page 2010
-
[79]
Y. Liu, D. C. Zou, and B. Wang, Signature of the van der waals like small-large charged ads black hole phase transition in quasinormal modes, JHEP2014(9), 179
- [80]
discussion (0)
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