scholarly journals Bulk supertranslation memories: A concept reshaping the vacua and black holes of general relativity

2016 ◽  
Vol 25 (12) ◽  
pp. 1644006 ◽  
Author(s):  
Geoffrey Compère
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Memory Effect ◽  
Null Infinity ◽  
Asymptotically Flat ◽  
Fundamental Symmetry ◽  
Geometrical Features ◽  
Flat Spacetimes ◽  
Future Null Infinity

The memory effect is a prediction of general relativity on the same footing as the existence of gravitational waves. The memory effect is understood at future null infinity as a transition induced by null radiation from a Poincaré vacuum to another vacuum. Those are related by a supertranslation, which is a fundamental symmetry of asymptotically flat spacetimes. In this paper, I argue that finite supertranslation diffeomorphisms should be extended into the bulk spacetime consistently with canonical charge conservation. It then leads to fascinating geometrical features of gravitational Poincaré vacua. I then argue that in the process of black hole merger or gravitational collapse, dramatic but computable memory effects occur. They lead to a final stationary metric which qualitatively deviates from the Schwarzschild metric.

scholarly journals Black-hole boundaries

2005 ◽  
Vol 83 (11) ◽  
pp. 1073-1099 ◽  
Author(s):  
Ivan Booth
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Recent Work ◽  
Numerical Relativity ◽  
Null Infinity ◽  
Event Horizons ◽  
Traditional Definition ◽  
Classical Black Holes ◽  
Definition Of ◽  
Future Null Infinity

Classical black holes and event horizons are highly nonlocal objects, defined in relation to the causal past of future null infinity. Alternative, quasilocal characterizations of black holes are often used in mathematical, quantum, and numerical relativity. These include apparent, Killing, trapping, isolated, dynamical, and slowly evolving horizons. All of these are closely associated with two-surfaces of zero outward null expansion. This paper reviews the traditional definition of black holes and provides an overview of some of the more recent work on alternative horizons.PACS Nos.: 04.20.Cv, 04.70.–s, 04.70.Bw

STRINGS FROM BLACK HOLES

1992 ◽  
Vol 01 (02) ◽  
pp. 355-361 ◽  
Author(s):  
ICHIRO ODA
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Zero Mode ◽  
Center Of Mass ◽  
Two Dimensional ◽  
Null Infinity ◽  
Four Dimensions ◽  
Surface Fluctuation ◽  
Future Null Infinity

It is shown that surface fluctuation of the event horizon of black holes in four dimensions which have been previously studied by ’t Hooft can be understood in terms of the topological two-dimensional string. This interpretation is valid at the lowest order, with respect to the magnitude of the radial momentum per magnitude of the transverse momentum, when particles near the event horizon fall into the black hole and from which particles then emit to future null infinity, owing to the Hawking radiation. This implies that in such a kinematical regime only the zero mode, that is, the center-of-mass momentum of the Euclidean string, propagates on the surface of the event horizon.

scholarly journals Islands and stretched horizon

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Yoshinori Matsuo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Total System ◽  
Island Rule ◽  
Asymptotically Flat ◽  
Flat Spacetime ◽  
Ads Spacetime ◽  
Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

scholarly journals Driven black holes: from Kolmogorov scaling to turbulent wakes

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Tomas Andrade ◽  
Christiana Pantelidou ◽  
Julian Sonner ◽  
Benjamin Withers
Keyword(s):  
Nonlinear Dynamics ◽  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
De Sitter ◽  
Event Horizons ◽  
Binary Mergers ◽  
Tidal Deformations ◽  
Proof Of Principle

Abstract General relativity governs the nonlinear dynamics of spacetime, including black holes and their event horizons. We demonstrate that forced black hole horizons exhibit statistically steady turbulent spacetime dynamics consistent with Kolmogorov’s theory of 1941. As a proof of principle we focus on black holes in asymptotically anti-de Sitter spacetimes in a large number of dimensions, where greater analytic control is gained. We focus on cases where the effective horizon dynamics is restricted to 2+1 dimensions. We also demonstrate that tidal deformations of the horizon induce turbulent dynamics. When set in motion relative to the horizon a deformation develops a turbulent spacetime wake, indicating that turbulent spacetime dynamics may play a role in binary mergers and other strong-field phenomena.

scholarly journals Observations of Hawking radiation: the Page curve and baby universes

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Donald Marolf ◽  
Henry Maxfield
Keyword(s):  
Black Holes ◽  
Quantum Systems ◽  
Late Time ◽  
Asymptotically Flat ◽  
Black Hole Information ◽  
Flat Spacetimes ◽  
The Cost ◽  
Baby Universes ◽  
Time Extrapolation ◽  
Asymptotic Observers

AbstractWe reformulate recent insights into black hole information in a manner emphasizing operationally-defined notions of entropy, Lorentz-signature descriptions, and asymptotically flat spacetimes. With the help of replica wormholes, we find that experiments of asymptotic observers are consistent with black holes as unitary quantum systems, with density of states given by the Bekenstein-Hawking formula. However, this comes at the cost of superselection sectors associated with the state of baby universes. Spacetimes studied by Polchinski and Strominger in 1994 provide a simple illustration of the associated concepts and techniques, and we argue them to be a natural late-time extrapolation of replica wormholes. The work aims to be self-contained and, in particular, to be accessible to readers who have not yet mastered earlier formulations of the ideas above.

scholarly journals Mimicking Black Holes in General Relativity

2021 ◽  
Author(s):  
Thomas Berry
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Thin Shell ◽  
Classical General Relativity ◽  
Regular Black Hole ◽  
Regular Black Holes ◽  
Traversable Wormholes ◽  
Hole Model ◽  
Linearised Stability

<p><b>The central theme of this thesis is the study and analysis of black hole mimickers. The concept of a black hole mimicker is introduced, and various mimicker spacetime models are examined within the framework of classical general relativity. The mimickers examined fall into the classes of regular black holes and traversable wormholes under spherical symmetry. The regular black holes examined can be further categorised as static spacetimes, however the traversable wormhole is allowed to have a dynamic (non-static) throat. Astrophysical observables are calculated for a recently proposed regular black hole model containing an exponential suppression of the Misner-Sharp quasi-local mass. This same regular black hole model is then used to construct a wormhole via the "cut-and-paste" technique. The resulting wormhole is then analysed within the Darmois-Israel thin-shell formalism, and a linearised stability analysis of the (dynamic) wormhole throat is undertaken. Yet another regular black hole model spacetime is proposed, extending a previous work which attempted to construct a regular black hole through a quantum "deformation" of the Schwarzschild spacetime. The resulting spacetime is again analysed within the framework of classical general relativity. </b></p><p>In addition to the study of black hole mimickers, I start with a brief overview of the theory of special relativity where a new and novel result is presented for the combination of relativistic velocities in general directions using quaternions. This is succeed by an introduction to concepts in differential geometry needed for the successive introduction to the theory of general relativity. A thorough discussion of the concept of spacetime singularities is then provided, before analysing the specific black hole mimickers discussed above.</p>

Frontiers of Quantum Black Holes

2020 ◽  
Vol 29 (11) ◽  
pp. 10-16
Author(s):  
Wontae KIM ◽  
Mu-In PARK
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Direct Detection ◽  
Occupation Number ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Quantum Radiation ◽  
Points Of View ◽  
Massless Quantum

A black hole is a theoretical prediction of Einstein’s general theory of relativity, differently from Newtonian gravity, which is a non-relativistic gravity. In recent few years, its direct detection via gravitational waves and other multi-messenger observations have made it possible to test the prediction and hence its associated general relativity. From purely theoretical points of view, general relativity cannot be a complete description due to its not being compatible with quantum mechanics, which is a successful description of microscopic objects. In this article, we introduce the conceptional development of quantum-gravity theories and give brief sketches of fundamental problems in quantum black holes. As an interesting model of quantum black holes, we consider a collapsing shell of matter to form a Hayward black hole and investigate semiclassically quantum radiation from the shell. By using the Israel’s formulation and the functional Schrödinger formulation for massless quantum radiation, we find that the Hawking temperature can be deduced from the occupation number of excited states when the shell approaches its own horizon.

scholarly journals How fast can a black hole rotate?

2015 ◽  
Vol 24 (12) ◽  
pp. 1544022 ◽  
Author(s):  
Carlos A. R. Herdeiro ◽  
Eugen Radu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Mass Formula ◽  
Linear Velocity ◽  
Asymptotically Flat ◽  
Velocity Of Light ◽  
Universal Bound ◽  
Kerr Black Holes

Kerr black holes (BHs) have their angular momentum, [Formula: see text], bounded by their mass, [Formula: see text]: [Formula: see text]. There are, however, known BH solutions violating this Kerr bound. We propose a very simple universal bound on the rotation, rather than on the angular momentum, of four-dimensional, stationary and axisymmetric, asymptotically flat BHs, given in terms of an appropriately defined horizon linear velocity, [Formula: see text]. The [Formula: see text] bound is simply that [Formula: see text] cannot exceed the velocity of light. We verify the [Formula: see text] bound for known BH solutions, including some that violate the Kerr bound, and conjecture that only extremal Kerr BHs saturate the [Formula: see text] bound.

A ROBUST TEST OF GENERAL RELATIVITY IN SPACE

2007 ◽  
Vol 16 (12a) ◽  
pp. 2319-2324 ◽  
Author(s):  
JAMES GRABER
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Quadrupole Moment ◽  
Binary Systems ◽  
High Mass ◽  
Uniqueness Theorems ◽  
Mass Ratio ◽  
Intermediate Mass ◽  
Robust Test

LISA may make it possible to test the black-hole uniqueness theorems of general relativity, also called the no-hair theorems, by Ryan's method of detecting the quadrupole moment of a black hole using high-mass-ratio inspirals. This test can be performed more robustly by observing inspirals in earlier stages, where the simplifications used in making inspiral predictions by the perturbative and post-Newtonian methods are more nearly correct. Current concepts for future missions such as DECIGO and BBO would allow even more stringent tests by this same method. Recently discovered evidence supports the existence of intermediate-mass black holes (IMBHs). Inspirals of binary systems with one IMBH and one stellar-mass black hole would fall into the frequency band of proposed maximum sensitivity for DECIGO and BBO. This would enable us to perform the Ryan test more precisely and more robustly. We explain why tests based on observations earlier in the inspiral are more robust and provide preliminary estimates of possible optimal future observations.

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