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General Relativity and Gravitation最新文献

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Geometry from geodesics: fine-tuning Ehlers, Pirani, and Schild 测地线几何：微调Ehlers， Pirani和Schild
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-02-02 DOI: 10.1007/s10714-025-03355-8
James T. Wheeler
{"title":"Geometry from geodesics: fine-tuning Ehlers, Pirani, and Schild","authors":"James T. Wheeler","doi":"10.1007/s10714-025-03355-8","DOIUrl":"10.1007/s10714-025-03355-8","url":null,"abstract":"<div><p>Ehlers, Pirani, and Schild argued that measurements of null and timelike geodesics yield Weyl and projective connections, respectively, with compatibility in the lightlike limit giving an integrable Weyl connection. Their conclusions hold only for a 4-dim representation of the conformal connection on the null cone, and by restricting reparameterizations of timelike geodesics to yield a torsion-free, affine connection. An arbitrary connection gives greater freedom. A linear connection for the conformal symmetry of null geodesics requires the SO(4,2) representation. The enlarged class of projective transformations of timelike geodesics changes Weyl’s projective curvature, and we find invariant forms of the torsion and nonmetricity, along with a new, invariant, second rank tensor field generalizing the dilatational curvature without requiring a metric. We show that either projective or conformal connections require a monotonic, twice differentiable function on a spacetime region foliated by order isomorphic, totally ordered, twice differentiable timelike curves in a necessarily Lorentzian geometry. We prove that the conditions for projective and conformal Ricci flatness imply each other and gauge choices within either can reduce the geometry to the original Riemannian form. Thus, measurements of null and timelike geodesics lead to an SO(4,2) connection, with no requirement for a lightlike limit. Reduction to integrable Weyl symmetry can only follow from the field equations of a gravity theory. We show that the simplest quadratic spacetime action leads to this reduction.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03355-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077490","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}
引用次数: 0
The backreaction problem for black holes in semiclassical gravity 半经典引力下黑洞的反反应问题
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-02-01 DOI: 10.1007/s10714-025-03352-x
Adrian del Rio
{"title":"The backreaction problem for black holes in semiclassical gravity","authors":"Adrian del Rio","doi":"10.1007/s10714-025-03352-x","DOIUrl":"10.1007/s10714-025-03352-x","url":null,"abstract":"<div><p>The question of black hole evaporation is reviewed in the framework of quantum field theory in curved spacetimes and semiclassical gravity. We highlight the importance of taking backreaction effects into account to have a consistent picture of the fate of gravitational collapse in this framework. We describe the difficulties of solving the backreaction semiclassical equations due to practical complications of renormalizing the stress-energy tensor of quantum fields in general 3+1 spacetimes. We end with some personal views and plans on the subject.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03352-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071352","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}
引用次数: 0
Lorentzian Robin Universe of Gauss-Bonnet Gravity 高斯-邦尼引力的洛伦兹-罗宾宇宙
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-31 DOI: 10.1007/s10714-025-03369-2
Manishankar Ailiga, Shubhashis Mallik, Gaurav Narain
{"title":"Lorentzian Robin Universe of Gauss-Bonnet Gravity","authors":"Manishankar Ailiga,&nbsp;Shubhashis Mallik,&nbsp;Gaurav Narain","doi":"10.1007/s10714-025-03369-2","DOIUrl":"10.1007/s10714-025-03369-2","url":null,"abstract":"<div><p>The gravitational path-integral of Gauss–Bonnet gravity is investigated and the transition from one spacelike boundary configuration to another is analyzed. Of particular interest is the case of Neumann and Robin boundary conditions which is known to lead to a stable Universe in Einstein–Hilbert gravity in four spacetime dimensions. After setting up the variational problem and computing the necessary boundary terms, the transition amplitude is computed <i>exactly</i> in the mini-superspace approximation. The <span>(hbar rightarrow 0)</span> limit brings out the dominant pieces in the path-integral which is traced to an initial configuration corresponding to Hartle–Hawking no-boundary Universe. A deeper study involving Picard–Lefschetz methods not only allow us to find the integration contour along which the path-integral becomes convergent but also aids in understanding the crossover from Euclidean to Lorentzian signature. Saddle analysis further highlights the boundary configurations giving dominant contribution to the path-integral which is seen to be those corresponding to Hartle–Hawking no-boundary proposal and agrees with the exact computation. To ensure completeness, a comparison with the results from Wheeler–DeWitt equation is done.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071350","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}
引用次数: 0
Dynamics of redshift/blueshift during free fall under the Schwarzschild horizon 史瓦西视界下自由落体过程中的红移/蓝移动力学
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-31 DOI: 10.1007/s10714-025-03370-9
H. V. Ovcharenko, O. B. Zaslavskii
{"title":"Dynamics of redshift/blueshift during free fall under the Schwarzschild horizon","authors":"H. V. Ovcharenko,&nbsp;O. B. Zaslavskii","doi":"10.1007/s10714-025-03370-9","DOIUrl":"10.1007/s10714-025-03370-9","url":null,"abstract":"<div><p>We consider a free-falling observer who crosses the event horizon in the Schwarzschild background. In the course of this fall, he/she can receive signals from an object (like a star surface) that emits radiation. We study how the frequency received by an observer changes depending on the proper time on his/her trajectory. The scenarios are classified depending on whether the frequency is infinite, finite or zero near the singularity and the horizon. This depends crucially on the angular momenta of an observer and a photon. In this work we consider also emission process, and, as we show, conditions of emission strongly influence parameters of a photon, and thus received frequency. As one of our main results, we present numerical calculations showing evolution of the received frequency during the process of diving into a black hole, depending on parameters of an observer and emitter. We also analyze how a falling observer will see a night sky as he/she approaches the singularity. We show that there appear several blind zones, which were not analyzed previously.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143072095","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}
引用次数: 0
Gravitational reduction of the wave function through the quantum theory of motion 重力还原波函数通过量子运动理论
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-29 DOI: 10.1007/s10714-025-03365-6
Faramarz Rahmani
{"title":"Gravitational reduction of the wave function through the quantum theory of motion","authors":"Faramarz Rahmani","doi":"10.1007/s10714-025-03365-6","DOIUrl":"10.1007/s10714-025-03365-6","url":null,"abstract":"<div><p>We present a novel perspective on gravity-induced wave function reduction using Bohmian trajectories. This study examines the quantum motion of both point particles and objects, identifying critical parameters for the transition from quantum to classical regimes. By analyzing the system’s dynamics, we define the reduction time of the wave function through Bohmian trajectories, introducing a fresh viewpoint in this field. Our findings align with results obtained in standard quantum mechanics, confirming the validity of this approach.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143056212","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}
引用次数: 0
Quantum theory of the Lemaître model for gravitational collapse 引力坍缩的lema<e:1>模型的量子理论
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-28 DOI: 10.1007/s10714-025-03349-6
Claus Kiefer, Hamid Mohaddes
{"title":"Quantum theory of the Lemaître model for gravitational collapse","authors":"Claus Kiefer,&nbsp;Hamid Mohaddes","doi":"10.1007/s10714-025-03349-6","DOIUrl":"10.1007/s10714-025-03349-6","url":null,"abstract":"<div><p>We investigate the quantum fate of the classical singularities that occur by gravitational collapse of a dust cloud. For this purpose, we address the quantization of a model first proposed by Georges Lemaître in 1933. We find that the singularities can generically be avoided. This is a consequence of unitary evolution in the quantum theory, whereby the quantum dust cloud collapses, bounces at a minimal radius and re-expands.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10714-025-03349-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050012","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}
引用次数: 0
Quantum black holes: from regularization to information paradoxes 量子黑洞：从正则化到信息悖论
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-24 DOI: 10.1007/s10714-025-03356-7
Niayesh Afshordi, Stefano Liberati
{"title":"Quantum black holes: from regularization to information paradoxes","authors":"Niayesh Afshordi,&nbsp;Stefano Liberati","doi":"10.1007/s10714-025-03356-7","DOIUrl":"10.1007/s10714-025-03356-7","url":null,"abstract":"<div><p>Quantum black holes, a broad class of objects that refine the solutions of general relativity by incorporating semiclassical and/or quantum gravitational effects, have recently attracted renewed attention within the scientific community. This resurgence of interest is largely driven by advances in gravitational wave astronomy, which have opened the possibility of testing some of these models in the near future. In this essay, we provide a concise overview of the key discussions that emerged during the “Black Hole Inside/Out\" meeting, held in August 2024 in Copenhagen. We report these ideas, their connections to the information paradox, and the potential use of analogue gravity as a test bed for these concepts.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026537","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}
引用次数: 0
Non-commutative classical and quantum fractionary cosmology: anisotropic Bianchi type I case 非交换经典和量子分数宇宙学：各向异性Bianchi I型情况
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-24 DOI: 10.1007/s10714-025-03363-8
J. Socorro, J. Juan Rosales, Leonel Toledo Sesma
{"title":"Non-commutative classical and quantum fractionary cosmology: anisotropic Bianchi type I case","authors":"J. Socorro,&nbsp;J. Juan Rosales,&nbsp;Leonel Toledo Sesma","doi":"10.1007/s10714-025-03363-8","DOIUrl":"10.1007/s10714-025-03363-8","url":null,"abstract":"<div><p>In this work, we explore non-commutative effects in fractional classical and quantum schemes using the anisotropic Bianchi type I cosmological model coupled to a scalar field in the K-essence formalism. We introduce non-commutative variables considering that all minisuperspace variables <span>(q^{i}_{nc})</span> do not commute, so the symplectic structure was modified, resulting in some changes concerning the traditional formalism. In the quantum regime, the probability density presents a new structure in the scalar field corresponding to the value of the non-commutative parameter.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026535","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}
引用次数: 0
Simulating black hole imposters 模拟黑洞冒名顶替者
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-24 DOI: 10.1007/s10714-025-03354-9
Frans Pretorius
{"title":"Simulating black hole imposters","authors":"Frans Pretorius","doi":"10.1007/s10714-025-03354-9","DOIUrl":"10.1007/s10714-025-03354-9","url":null,"abstract":"<div><p>I briefly describe motivation for, and the current state of research into understanding the structure and dynamics of black hole “imposters”: objects that could be misidentified as Kerr black holes given the current precision of LIGO/Virgo gravitational wave observations, or EHT accretion disk measurements. I use the term “weak imposter” to describe an object which is a black hole, i.e. it has an event horizon, but whose structure and dynamics is governed by a modified gravity theory. At the other end of the spectrum are “strong imposters”: hypothetical horizonless, compact objects conjectured to form instead of black holes during gravitational collapse. To discover or rule-out imposters will require a quantitative understanding of their merger dynamics. This is hampered at present by a dearth of well-posed theoretical frameworks to describe imposters beyond perturbations of Kerr black holes and their general relativistic binary dynamics. That so little is known about non-perturbative modifications to dynamical, strongfield gravity is, I argue, due to a lamppost effect.</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026536","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}
引用次数: 0
Inflation and acceleration of the universe from nonminimal coupling gravity with nonlinear electrodynamics 非极小耦合引力与非线性电动力学下的宇宙膨胀与加速
IF 2.1 4区 物理与天体物理
General Relativity and Gravitation Pub Date : 2025-01-23 DOI: 10.1007/s10714-025-03358-5
Chilwatun Nasiroh, Ramy F. Izzah, Fiki T. Akbar, Bobby E. Gunara
{"title":"Inflation and acceleration of the universe from nonminimal coupling gravity with nonlinear electrodynamics","authors":"Chilwatun Nasiroh,&nbsp;Ramy F. Izzah,&nbsp;Fiki T. Akbar,&nbsp;Bobby E. Gunara","doi":"10.1007/s10714-025-03358-5","DOIUrl":"10.1007/s10714-025-03358-5","url":null,"abstract":"<div><p>In this paper, we consider a nonminimal coupling model between gravity and nonlinear electrodynamics with cosmological constant. This cosmological model is designed to account for both the inflationary epoch of the early universe and the current phase of accelerated cosmic expansion. The nonlinear electrodynamic fields provide a mechanism for a graceful exit from the inflationary period, preventing the universe from entering an eternal inflation state. The addition of nonminimal coupling plays a crucial role in shaping the early evolution of the universe. We compare the theoretical predictions of our model with recent observational data and other leading cosmological models, showing that our approach provides a viable and competitive explanation for key aspects of the universe’s evolution. Our results suggest that this model offers a consistent and compelling framework to explain both early-time inflation and the late-time accelerated expansion of the universe, in line with current observations.\u0000</p></div>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026534","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}
引用次数: 0
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