Extensive composable entropy for the analysis of cosmological data

In recent decades, an intensive worldwide research activity is focusing both black holes and cosmos (e.g. the dark-energy phenomenon) on the basis of entropic approaches. The Boltzmann-Gibbs-based Bekenstein-Hawking entropy SBH∝A/lP2 (A≡ area; lP≡ Planck length) systematically plays a crucial theore...

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Main Authors: Constantino Tsallis, Henrik Jeldtoft Jensen
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S0370269324007962
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author Constantino Tsallis
Henrik Jeldtoft Jensen
author_facet Constantino Tsallis
Henrik Jeldtoft Jensen
author_sort Constantino Tsallis
collection DOAJ
description In recent decades, an intensive worldwide research activity is focusing both black holes and cosmos (e.g. the dark-energy phenomenon) on the basis of entropic approaches. The Boltzmann-Gibbs-based Bekenstein-Hawking entropy SBH∝A/lP2 (A≡ area; lP≡ Planck length) systematically plays a crucial theoretical role although it has a serious drawback, namely that it violates the thermodynamic extensivity of spatially-three-dimensional systems. Still, its intriguing area dependence points out the relevance of considering the form W(N)∼μNγ(μ>1;γ>0), W and N respectively being the total number of microscopic possibilities and the number of components; γ=1 corresponds to standard Boltzmann-Gibbs (BG) statistical mechanics. For this W(N) asymptotic behavior, we make use of the group-theoretic entropic functional Sα,γ=k[ln⁡Σi=1Wpiα1−α]1γ(α∈R;S1,1=SBG≡−k∑i=1Wpiln⁡pi), first derived by P. Tempesta in Chaos 30,123119, (2020). This functional is extensive (as required by thermodynamics) and composable, ∀(α,γ). Being extensive means that in the micro-canonical, or uniform, ensemble where all micro-state occur with the same probability, the entropy becomes proportional to N asymptotically: S(N)∝N for N→∞. An entropy is composable if it satisfies that the entropy SA of a system A=B×C consisting of two statistically independent parts B and C is given in a consistent way as SA=Φ(SB,SC) where the composition function Φ(x,y) is obtained from group-theory.We further show that (α,γ)=(1,2/3) satisfactorily agrees with cosmological data measuring neutrinos, Big Bang nucleosynthesis and the relic abundance of cold dark matter particles, as well as dynamical and geometrical cosmological data sets.
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spelling doaj-art-66ffa9ef4c154a50a5c6f3f25efe6bd92025-02-10T04:33:50ZengElsevierPhysics Letters B0370-26932025-02-01861139238Extensive composable entropy for the analysis of cosmological dataConstantino Tsallis0Henrik Jeldtoft Jensen1Centro Brasileiro de Pesquisas Físicas and National Institute of Science and Technology of Complex Systems, Rua Xavier Sigaud 150, 22290-180, Rio de Janeiro RJ, Brazil; Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, 87501 NM, USA; Complexity Science Hub Vienna, Metternichgasse 8, 1030 Vienna, Austria; Corresponding author.Centre for Complexity Science and Department of Mathematics, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom; School of Computer Science, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Yokohama 226-8502, Japan; Complexity Science Hub Vienna, Metternichgasse 8, 1030 Vienna, AustriaIn recent decades, an intensive worldwide research activity is focusing both black holes and cosmos (e.g. the dark-energy phenomenon) on the basis of entropic approaches. The Boltzmann-Gibbs-based Bekenstein-Hawking entropy SBH∝A/lP2 (A≡ area; lP≡ Planck length) systematically plays a crucial theoretical role although it has a serious drawback, namely that it violates the thermodynamic extensivity of spatially-three-dimensional systems. Still, its intriguing area dependence points out the relevance of considering the form W(N)∼μNγ(μ>1;γ>0), W and N respectively being the total number of microscopic possibilities and the number of components; γ=1 corresponds to standard Boltzmann-Gibbs (BG) statistical mechanics. For this W(N) asymptotic behavior, we make use of the group-theoretic entropic functional Sα,γ=k[ln⁡Σi=1Wpiα1−α]1γ(α∈R;S1,1=SBG≡−k∑i=1Wpiln⁡pi), first derived by P. Tempesta in Chaos 30,123119, (2020). This functional is extensive (as required by thermodynamics) and composable, ∀(α,γ). Being extensive means that in the micro-canonical, or uniform, ensemble where all micro-state occur with the same probability, the entropy becomes proportional to N asymptotically: S(N)∝N for N→∞. An entropy is composable if it satisfies that the entropy SA of a system A=B×C consisting of two statistically independent parts B and C is given in a consistent way as SA=Φ(SB,SC) where the composition function Φ(x,y) is obtained from group-theory.We further show that (α,γ)=(1,2/3) satisfactorily agrees with cosmological data measuring neutrinos, Big Bang nucleosynthesis and the relic abundance of cold dark matter particles, as well as dynamical and geometrical cosmological data sets.http://www.sciencedirect.com/science/article/pii/S0370269324007962
spellingShingle Constantino Tsallis
Henrik Jeldtoft Jensen
Extensive composable entropy for the analysis of cosmological data
Physics Letters B
title Extensive composable entropy for the analysis of cosmological data
title_full Extensive composable entropy for the analysis of cosmological data
title_fullStr Extensive composable entropy for the analysis of cosmological data
title_full_unstemmed Extensive composable entropy for the analysis of cosmological data
title_short Extensive composable entropy for the analysis of cosmological data
title_sort extensive composable entropy for the analysis of cosmological data
url http://www.sciencedirect.com/science/article/pii/S0370269324007962
work_keys_str_mv AT constantinotsallis extensivecomposableentropyfortheanalysisofcosmologicaldata
AT henrikjeldtoftjensen extensivecomposableentropyfortheanalysisofcosmologicaldata