General Relativity and Gravitation最新文献

{"title":"Cosmic inflation from entangled qubits: a white hole model for emergent spacetime","authors":"Roger Eugene Hill","doi":"10.1007/s10714-025-03428-8","DOIUrl":"10.1007/s10714-025-03428-8","url":null,"abstract":"<div><p>This paper presents the Horizon Model (HM) of cosmology, designed to resolve the cosmological constant problem by equating the vacuum energy density with that of the observable universe. Grounded in quantum information theory, HM proposes the first element of reality emerging from the Big Bang singularity as a Planck-sized qubit. The model views the Big Bang as the opening of a white hole, with spacetime and matter/energy emerging from the event horizon. Using the Schwarzschild solution and the Holographic Principle, HM calculates the number of vacuum qubits needed to equalize densities, and compares this to published estimates of the observable universe’s Shannon entropy (S). With this information, HM can calculate the state of the vacuum as a function of S. Results at S=1 (t=0) and <span>(S=1.46times 10^{104})</span> bits (t=now) are presented. At t=0, the radius of the event horizon is predicted to be <span>(sim 10^{-26})</span> m in good agreement with the ad-hoc requirement of the current cosmic inflation paradigm. At t=now, HM predicts Hubble flow within <span>(0.8sigma )</span> of the Planck collaboration measurement and can resolve the Hubble tension with a small adjustment of the vacuum energy density. HM predictions of the vacuum pressure (<span>(sim 10^{-10})</span> Pa) are in good agreement with pressure measurements made on the lunar surface by NASA and the Chinese space program. Aligned with current research for spacetime emerging from surfaces, HM suggests new theoretical directions, potentially leading to a quantum theory of gravity.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 6","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03428-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144140271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum field theory of black hole perturbations with backreaction IV: spherically symmetric 2nd order Einstein–Maxwell sector in generalised gauges","authors":"J. Neuser","doi":"10.1007/s10714-025-03423-z","DOIUrl":"10.1007/s10714-025-03423-z","url":null,"abstract":"<div><p>In previous papers of this series we analysed the reduced phase space approach to perturbations of Einstein–Maxwell theory to second order around spherically symmetric backgrounds in the Gullstrand Painlevé gauge and confirmed consistency with previous approaches. In the analysis, we defined the gauge invariant variables non-perturbatively and took backreaction effects explicitly into account. In this paper, as a non-trivial consistency check, we generalize the results and show that a similar analysis is possible for other choices of gauge for the background variables. We obtain the same structure for the reduced Hamiltonian that contains the well known Regge–Wheeler and Zerilli potentials. Possible applications of this generalization are discussed.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03423-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extra-Dimensional de Broglie-Bohm Quantum Cosmology","authors":"F. A. P. Alves-Júnior,&nbsp;A. S. Lemos,&nbsp;F. A. Brito","doi":"10.1007/s10714-025-03421-1","DOIUrl":"10.1007/s10714-025-03421-1","url":null,"abstract":"<div><p>In this work, we explore the de Broglie-Bohm quantum cosmology for a stiff matter, <span>(p=rho )</span>, anisotropic <i>n</i>-dimensional Universe. One begins by considering a Gaussian wave function for the Universe, which depends on the momenta parameters <span>(q_1)</span> and <span>(q_2)</span>, in addition to the dispersion parameters <span>(sigma _1)</span> and <span>(sigma _2)</span>. Our solutions show that the extra dimensions are stabilized through a dynamical compactification mechanism within the quantum cosmology framework. In this case, we find two distinct configurations for the dynamics of the extra dimensions. The first configuration features larger extra dimensions at the bounce, which subsequently undergo compactification to a smaller size. In contrast, the second configuration exhibits a smaller extra dimension at the bounce, evolving toward a larger, finite, and stabilized value. We also address the particular five-dimensional case where the Wheeler-DeWitt equation degenerates.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Entropy of Black Holes","authors":"Robert M. Wald","doi":"10.1007/s10714-025-03417-x","DOIUrl":"10.1007/s10714-025-03417-x","url":null,"abstract":"<div><p>The remarkable connection between black holes and thermodynamics provides the most significant clues that we currently possess to the nature of black holes in a quantum theory of gravity. The key clue is the formula for the entropy of a black hole. I briefly review some recent work that provides an expression for a dynamical correction to the entropy of a black hole and briefly discuss some of the implications of this new formula for entropy.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03417-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144100282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Addressing the so called quantum/classical “divide” in gravitational contexts, and its implications in cosmology","authors":"Rosa-Laura Lechuga-Solis,&nbsp;Daniel Sudarsky","doi":"10.1007/s10714-025-03420-2","DOIUrl":"10.1007/s10714-025-03420-2","url":null,"abstract":"<div><p>The manner in which one approaches the interface between gravitation and quantum theory is influenced by one’s posture regarding quantum mechanics and the issues that revolve about its interpretational problems. We discuss here the way in which these issues occur in the inflationary cosmology setting, the serious confusions that ensue, and one path that we have used to deal with the problem which perhaps surprisingly ends up, not just offering a conceptually clear physical picture, but also modifying some of the standard observational predictions of the inflationary approach.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03420-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144091058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fractional Einstein field equations in (2+1) dimensional spacetime","authors":"E. Contreras,&nbsp;A. Di Teodoro,&nbsp;M. Mena","doi":"10.1007/s10714-025-03419-9","DOIUrl":"10.1007/s10714-025-03419-9","url":null,"abstract":"<div><p>In this work, we introduce a new fractional derivative that modifies the conventional Riemann-Liouville operator to obtain a set of fractional Einstein field equations within a 2+1 dimensional spacetime by assuming a static and circularly symmetric metric. The main reason for introducing this new derivative stems from addressing the divergence encountered during the construction of Christoffel symbols when using the Caputo operator and the appearance of unwanted terms when using the Riemann-Liouville derivative because of the well-known fact that its action on constants does not vanish, as expected. The key innovation of the new operator ensures that the derivative of a constant is zero. As a particular application, we explore whether the Bañados-Teitelboim-Zanelli black hole metric is a solution to fractional Einstein equations. Our results reveal that for values of the fractional parameter close to one, the effective matter sector corresponds to a charged BTZ solution with an anisotropic cosmological constant.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03419-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical evolutions of the linearised conformal Einstein field equations in the inversion-Minkowski spacetime","authors":"Christian Peterson,&nbsp;Edgar Gasperín,&nbsp;Alex Vañó-Viñuales","doi":"10.1007/s10714-025-03415-z","DOIUrl":"10.1007/s10714-025-03415-z","url":null,"abstract":"<div><p>Numerical evolutions of a system of equations close to null infinity in the geometric background of the <i>inversion-Minkowski spacetime</i> are performed. The evolved equations correspond to the linearisation of a second order metric formulation of the conformal Einstein field equations (CEFEs). These linear equations were first presented in [1] and the main purpose of this paper is to illustrate, through numerical evolutions, the scri-fixing technique via gauge source functions introduced [1] for the linearised CEFEs. A comparison of evolutions using scri-fixing gauge sources and trivial gauge source function in spherical and axial symmetry is presented.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03415-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cosmological study of finite-time singularities under dynamical systems survey in covariant modified teleparallel gravity","authors":"M. G. Ganiou,&nbsp;M. Toure,&nbsp;C. Aïnamon,&nbsp;S. I. V. Hontinfinde,&nbsp;M. J. S. Houndjo","doi":"10.1007/s10714-025-03418-w","DOIUrl":"10.1007/s10714-025-03418-w","url":null,"abstract":"<div><p>In the present study, we deal with the cosmological evolution under autonomous and non-autonomous dynamical systems in the framework of covariant <i>f</i>(<i>T</i>) gravity where <i>T</i> is the scalar torsion. This work first investigates how the dynamical system survey can provide significant explanation near the cosmological finite-time singularities and then extracts the corresponding <i>f</i>(<i>T</i>) models. By studying the de Sitter evolution of the autonomous dynamical system generated from the Friedman equation in a vacuum, we obtain one equilibrium fixed point that describes a universe in accelerated expansion. A similar description is made with finite-time singularity where dynamical systems become necessarily non-autonomous. Near the Big-Rip singularity, an analytical resolution approach leads to finite values for the dynamic variables, which not only reveals an accelerated expanding universe but also makes it possible to reconstruct the corresponding <i>f</i>(<i>T</i>) models. In the case of the three other types of singularity, only type IV leads to an analytical solvable problem, and two of the asymptotic fixed-point coordinates diverge. Furthermore, using a classical approach based on the Hubble parameter of finite-time singularities combined with both Friedman and conservation equations, we provide in the first hand implicit <i>f</i>(<i>T</i>) models for all types of singularity and in the second hand explicit <i>f</i>(<i>T</i>) models whose stability is undertaken near each type of singularity in three different evolutions: de Sitter evolution, quintessence-like evolution, and the phantom-like evolution. The relative stability of the reconstructed models not only shows that they cannot describe all four types of singularity simultaneously but also proves that the cosmological evolution is not the same for the four types of singularity. These results confirm those obtained using the dynamical approach. The finite-time singularity avoidance is discussed at the end of the present investigation.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143979532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Primordial black holes and gravitational waves from inflation","authors":"Misao Sasaki","doi":"10.1007/s10714-025-03412-2","DOIUrl":"10.1007/s10714-025-03412-2","url":null,"abstract":"<div><p>Thanks to the rapid progress in gravitational wave astronomy/cosmology, primordial black holes (PBHs) have become one of the hot topics in cosmology. It has made projections of detecting signatures of PBHs feasible. In parallel, it has become clear that there exist a number of ways to produce PBHs from inflation. In this talk, I will review the PBH formation from inflation and the associated gravitational wave signatures.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03412-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143979528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonminimal coupling, quantum scalar field stress-energy tensor and energy conditions on global anti-de Sitter space-time","authors":"Sivakumar Namasivayam,&nbsp;Elizabeth Winstanley","doi":"10.1007/s10714-025-03411-3","DOIUrl":"10.1007/s10714-025-03411-3","url":null,"abstract":"<div><p>We compute the renormalized expectation value of the stress-energy tensor operator for a quantum scalar field propagating on three-dimensional global anti-de Sitter space-time. The scalar field has general mass and nonminimal coupling to the Ricci scalar curvature, and is subject to Dirichlet, Neumann or Robin boundary conditions at the space-time boundary. We consider both vacuum and thermal states, and explore whether the weak and null energy conditions are satisfied by the quantum stress-energy tensor. We uncover a rather complicated picture: compliance with these two energy conditions depends strongly on the mass and coupling of the scalar field to the curvature, and the boundary conditions applied.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 5","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03411-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}