Model of black hole and white hole in Minkowski spacetime

AbstractIn this paper, we construct toy models of the black hole and the white hole by setting proper boundaries in the Minkowski spacetime, according to the modern definition. We calculate the thermal effect of the black hole with the tunneling mechanism. We consider the role of boundary conditions at the singularity and on the horizon. In addition, we show that the white hole possesses a thermal absorption.

Download Full-text

Symmetries of the black hole interior and singularity regularization

SciPost Physics ◽

10.21468/scipostphys.10.1.022 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Marc Geiller ◽

Etera R. Livine ◽

Francesco Sartini

Keyword(s):

Black Holes ◽

Black Hole ◽

Black Hole Physics ◽

Proper Time ◽

White Hole ◽

Formula Group ◽

Physical Symmetry ◽

Black Hole Interior ◽

Group Quantization

We reveal an \mathfrak{iso}(2,1)𝔦𝔰𝔬(2,1) Poincar'e algebra of conserved charges associated with the dynamics of the interior of black holes. The action of these Noether charges integrates to a symmetry of the gravitational system under the Poincar'e group ISO(2,1)(2,1), which allows to describe the evolution of the geometry inside the black hole in terms of geodesics and horocycles of AdS{}_22. At the Lagrangian level, this symmetry corresponds to M"obius transformations of the proper time together with translations. Remarkably, this is a physical symmetry changing the state of the system, which also naturally forms a subgroup of the much larger \textrm{BMS}_{3}=\textrm{Diff}(S^1)\ltimes\textrm{Vect}(S^1)BMS3=Diff(S1)⋉Vect(S1) group, where S^1S1 is the compactified time axis. It is intriguing to discover this structure for the black hole interior, and this hints at a fundamental role of BMS symmetry for black hole physics. The existence of this symmetry provides a powerful criterion to discriminate between different regularization and quantization schemes. Following loop quantum cosmology, we identify a regularized set of variables and Hamiltonian for the black hole interior, which allows to resolve the singularity in a black-to-white hole transition while preserving the Poincar'e symmetry on phase space. This unravels new aspects of symmetry for black holes, and opens the way towards a rigorous group quantization of the interior.

Download Full-text

Absorption of dark matter by a supermassive black hole at the galactic center: Role of boundary conditions

JETP Letters ◽

10.1134/1.1897995 ◽

2005 ◽

Vol 81 (3) ◽

pp. 85-89 ◽

Cited By ~ 7

Author(s):

M. I. Zelnikov ◽

E. A. Vasiliev

Keyword(s):

Black Hole ◽

Dark Matter ◽

Boundary Conditions ◽

Galactic Center ◽

Supermassive Black Hole

Download Full-text

Determining preference for potential: The role of perceived economic mobility

Social Behavior and Personality An International Journal ◽

10.2224/sbp.8019 ◽

2019 ◽

Vol 47 (6) ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Chen Yang ◽

Shaochen Zhao

Keyword(s):

Boundary Conditions ◽

Economic Mobility ◽

Individual Perceptions ◽

Future Success ◽

The Future

Although previous researchers have demonstrated that people often prefer potential rather than achievement when evaluating other people or products, few have focused on the boundary conditions on this effect. We proposed that the preference for potential would emerge when individuals’ perception of economic mobility was high, but the preference for achievement would emerge among individuals with low perceptions of economic mobility. Our results showed that people paid more attention to the future (vs. the present) when their perception of economic mobility was high; this, in turn, promoted more favorable reactions toward potential (vs. achievement). Thus, we suggested circumstances under which highlighting a person’s potential for future success is effective and those when it is not effective. Moreover, we revealed the important role of individual perceptions regarding economic mobility in driving this effect.

Download Full-text

Charge algebra in Al(A)dSn spacetimes

Journal of High Energy Physics ◽

10.1007/jhep05(2021)210 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

Adrien Fiorucci ◽

Romain Ruzziconi

Keyword(s):

Boundary Conditions ◽

Dirichlet Boundary ◽

Three Dimensional ◽

Dirichlet Boundary Conditions ◽

Boundary Structure ◽

Asymptotic Symmetry ◽

Renormalization Procedure ◽

Field Dependent ◽

Odd Dimensions

Abstract The gravitational charge algebra of generic asymptotically locally (A)dS spacetimes is derived in n dimensions. The analysis is performed in the Starobinsky/Fefferman-Graham gauge, without assuming any further boundary condition than the minimal falloffs for conformal compactification. In particular, the boundary structure is allowed to fluctuate and plays the role of source yielding some symplectic flux at the boundary. Using the holographic renormalization procedure, the divergences are removed from the symplectic structure, which leads to finite expressions. The charges associated with boundary diffeomorphisms are generically non-vanishing, non-integrable and not conserved, while those associated with boundary Weyl rescalings are non-vanishing only in odd dimensions due to the presence of Weyl anomalies in the dual theory. The charge algebra exhibits a field-dependent 2-cocycle in odd dimensions. When the general framework is restricted to three-dimensional asymptotically AdS spacetimes with Dirichlet boundary conditions, the 2-cocycle reduces to the Brown-Henneaux central extension. The analysis is also specified to leaky boundary conditions in asymptotically locally (A)dS spacetimes that lead to the Λ-BMS asymptotic symmetry group. In the flat limit, the latter contracts into the BMS group in n dimensions.

Download Full-text

New non-extremal and BPS hairy black holes in gauged $$ \mathcal{N} $$ = 2 and $$ \mathcal{N} $$ = 8 supergravity

Journal of High Energy Physics ◽

10.1007/jhep04(2021)047 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Andres Anabalon ◽

Dumitru Astefanesei ◽

Antonio Gallerati ◽

Mario Trigiante

Keyword(s):

Black Holes ◽

Black Hole ◽

Boundary Conditions ◽

Charged Black Hole ◽

Dual Theory ◽

Real Numbers ◽

Hairy Black Holes ◽

Interpolation Parameter ◽

Black Hole Solutions ◽

Extremal Black Holes

Abstract In this article we study a family of four-dimensional, $$ \mathcal{N} $$ N = 2 supergravity theories that interpolates between all the single dilaton truncations of the SO(8) gauged $$ \mathcal{N} $$ N = 8 supergravity. In this infinitely many theories characterized by two real numbers — the interpolation parameter and the dyonic “angle” of the gauging — we construct non-extremal electrically or magnetically charged black hole solutions and their supersymmetric limits. All the supersymmetric black holes have non-singular horizons with spherical, hyperbolic or planar topology. Some of these supersymmetric and non-extremal black holes are new examples in the $$ \mathcal{N} $$ N = 8 theory that do not belong to the STU model. We compute the asymptotic charges, thermodynamics and boundary conditions of these black holes and show that all of them, except one, introduce a triple trace deformation in the dual theory.

Download Full-text

Understanding the critical role of boundary conditions in meso-scale finite element simulation of braided composites

Advanced Composites and Hybrid Materials ◽

10.1007/s42114-021-00284-3 ◽

2021 ◽

Author(s):

Zhenqiang Zhao ◽

Peng Liu ◽

Haoyuan Dang ◽

Yang Chen ◽

Chao Zhang ◽

...

Keyword(s):

Finite Element ◽

Boundary Conditions ◽

Finite Element Simulation ◽

Critical Role ◽

Braided Composites ◽

Element Simulation ◽

Meso Scale

Download Full-text

Mechanics of tubular helical assemblies: ensemble response to axial compression and extension

Acta Mechanica Sinica ◽

10.1007/s10409-021-01068-0 ◽

2021 ◽

Author(s):

Jacopo Quaglierini ◽

Alessandro Lucantonio ◽

Antonio DeSimone

Keyword(s):

Boundary Conditions ◽

Elastic Properties ◽

Central Region ◽

Mechanical Response ◽

Different Boundary Conditions ◽

Kirchhoff Rods ◽

Model Versus ◽

The Individual ◽

Opposite Chirality

Abstract Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these structures remain elusive. In this paper, we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchhoff rods, arranged in pairs with opposite chirality and connected by pin joints, both analytically and numerically. We first focus on compression and find that, whereas a single helical rod would buckle, the rods of the assembly deform coherently as stable helical shapes wound around a common axis. Moreover, we investigate the response of the assembly under different boundary conditions, highlighting the emergence of a central region where rods remain circular helices. Secondly, we study the effects of different hypotheses on the elastic properties of rods, i.e., stress-free rods when straight versus when circular helices, Kirchhoff’s rod model versus Sadowsky’s ribbon model. Summing up, our findings highlight the key role of mutual interactions in generating a stable ensemble response that preserves the helical shape of the individual rods, as well as some interesting features, and they shed some light on the reasons why helical shapes in tubular assemblies are so common and persistent in nature and technology. Graphic Abstract We study the mechanical response under compression/extension of an assembly composed of 8 helical rods, pin-jointed and arranged in pairs with opposite chirality. In compression we find that, whereas a single rod buckles (a), the rods of the assembly deform as stable helical shapes (b). We investigate the effect of different boundary conditions and elastic properties on the mechanical response, and find that the deformed geometries exhibit a common central region where rods remain circular helices. Our findings highlight the key role of mutual interactions in the ensemble response and shed some light on the reasons why tubular helical assemblies are so common and persistent.

Download Full-text

Influence of the geometric configuration of accretion flow on the black hole spin dependence of relativistic acoustic geometry

International Journal of Modern Physics D ◽

10.1142/s0218271818500232 ◽

2018 ◽

Vol 27 (03) ◽

pp. 1850023 ◽

Cited By ~ 2

Author(s):

Pratik Tarafdar ◽

Tapas K. Das

Keyword(s):

Black Hole ◽

Kerr Black Hole ◽

Geometric Configuration ◽

Surface Gravity ◽

Linear Perturbation ◽

Flow Profile ◽

White Hole ◽

Accretion Flow ◽

Black Hole Spin ◽

General Relativistic

Linear perturbation of general relativistic accretion of low angular momentum hydrodynamic fluid onto a Kerr black hole leads to the formation of curved acoustic geometry embedded within the background flow. Characteristic features of such sonic geometry depend on the black hole spin. Such dependence can be probed by studying the correlation of the acoustic surface gravity [Formula: see text] with the Kerr parameter [Formula: see text]. The [Formula: see text]–[Formula: see text] relationship further gets influenced by the geometric configuration of the accretion flow structure. In this work, such influence has been studied for multitransonic shocked accretion where linear perturbation of general relativistic flow profile leads to the formation of two analogue black hole-type horizons formed at the sonic points and one analogue white hole-type horizon which is formed at the shock location producing divergent acoustic surface gravity. Dependence of the [Formula: see text]–[Formula: see text] relationship on the geometric configuration has also been studied for monotransonic accretion, over the entire span of the Kerr parameter including retrograde flow. For accreting astrophysical black holes, the present work thus investigates how the salient features of the embedded relativistic sonic geometry may be determined not only by the background spacetime, but also by the flow configuration of the embedding matter.

Download Full-text