scholarly journals Schrödinger's cat and the firewall

2014 ◽  
Vol 23 (12) ◽  
pp. 1441004 ◽  
Author(s):  
Timothy J. Hollowood
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
State Vector ◽  
High Energy ◽  
Quantum Systems ◽  
Hole State

It has been argued that when black holes are treated as quantum systems there are implications at the horizon and not just the singularity. Infalling observers will meet a firewall of high energy quanta. We argue that the question of whether an observer falling into a black hole experiences a smooth horizon or a firewall is identical to the question of whether Schrödinger's cat is either in a definite state, alive or dead, or in a superposition of the two. Since experience with real macro-systems indicate the former, the black hole state vector is seen to describe a set of decoherent alternatives each with a smooth horizon and the entanglement puzzle is thereby side stepped.

scholarly journals Very High-Energy Emission from the Direct Vicinity of Rapidly Rotating Black Holes

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 122 ◽  
Author(s):  
Kouichi Hirotani
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Black Hole ◽  
Electric Field ◽  
Gamma Rays ◽  
Accretion Rate ◽  
High Energy ◽  
Relativistic Electrons ◽  
Field Lines ◽  
The Magnetic Field

When a black hole accretes plasmas at very low accretion rate, an advection-dominated accretion flow (ADAF) is formed. In an ADAF, relativistic electrons emit soft gamma-rays via Bremsstrahlung. Some MeV photons collide with each other to materialize as electron-positron pairs in the magnetosphere. Such pairs efficiently screen the electric field along the magnetic field lines, when the accretion rate is typically greater than 0.03–0.3% of the Eddington rate. However, when the accretion rate becomes smaller than this value, the number density of the created pairs becomes less than the rotationally induced Goldreich–Julian density. In such a charge-starved magnetosphere, an electric field arises along the magnetic field lines to accelerate charged leptons into ultra-relativistic energies, leading to an efficient TeV emission via an inverse-Compton (IC) process, spending a portion of the extracted hole’s rotational energy. In this review, we summarize the stationary lepton accelerator models in black hole magnetospheres. We apply the model to super-massive black holes and demonstrate that nearby low-luminosity active galactic nuclei are capable of emitting detectable gamma-rays between 0.1 and 30 TeV with the Cherenkov Telescope Array.

scholarly journals GRAVITATIONAL LENSING IN THE WEAK FIELD LIMIT BY A BRANEWORLD BLACK HOLE

2005 ◽  
Vol 20 (32) ◽  
pp. 2487-2496 ◽  
Author(s):  
A. S. MAJUMDAR ◽  
NUPUR MUKHERJEE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Lensing ◽  
Cosmic Ray ◽  
Weak Field ◽  
High Energy ◽  
High Energy Particle ◽  
Field Limit ◽  
Weak Field Limit ◽  
Point Light

The existence of braneworld black holes may be of primordial origin, or may even be produced in high energy particle collisions in the laboratory and in cosmic ray showers as well. These black holes obey a modified mass–radius relationship compared to standard Schwarzschild black holes. Using the variational principle we calculate the bending angle of a light ray near the horizon of a braneworld black hole in the weak field limit. We next derive the expressions of several lensing quantities like the Einstein radius and the magnification for a point light source. These expressions are modified compared to the lensing quantities for standard Schwarzschild black holes and contain the scale of the extra dimensions.

scholarly journals From the Schwarzschild Anti-de Sitter Black Hole to the Conformal Field Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Akram Sadat Sefiedgar
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Central Charge ◽  
High Energy ◽  
De Sitter ◽  
Conformal Field ◽  
Verlinde Formula ◽  
Dimensional Spacetime ◽  
Very High Energy ◽  
High Energy Regime

The emergence of the quantum gravitational effects in a very high energy regime necessitates some corrections to the thermodynamics of black holes. In this letter, we investigate a possible modification to the thermodynamics of Schwarzschild anti-de Sitter (SAdS) black holes due to rainbow gravity model. Using the correspondence between a (d+1)-dimensional SAdS black hole and a conformal filed theory ind-dimensional spacetime, one may find the corrections to the Cardy-Verlinde formula from the modified thermodynamics of the black hole. Furthermore, we show that the corrected Cardy-Verlinde formula can also be derived by redefining the Virasoro operator and the central charge.

scholarly journals BLACK HOLES IN THEORIES WITH LARGE EXTRA DIMENSIONS: A REVIEW

2004 ◽  
Vol 19 (29) ◽  
pp. 4899-4951 ◽  
Author(s):  
PANAGIOTA KANTI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
Life Time ◽  
High Energy ◽  
High Energy Particle ◽  
Radiation Spectra ◽  
Black Hole Background

We start by reviewing the existing literature on the creation of black holes during high-energy particle collisions, both in the absence and in the presence of extra, compact, spacelike dimensions. Then, we discuss in detail the properties of the produced higher-dimensional black holes, namely the horizon radius, temperature and life-time, as well as the physics that governs the evaporation of these objects, through the emission of Hawking radiation. We first study the emission of visible Hawking radiation on the brane: we derive a master equation for the propagation of fields with arbitrary spin in the induced-on-the-brane black hole background, and we review all existing results in the literature for the emission of scalars, fermions and gauge bosons during the spin-down and Schwarzschild phases of the life of the black hole. Both analytical and numerical results for the graybody factors and radiation spectra are reviewed and exact results for the number and type of fields emitted on the brane as a function of the dimensionality of space–time are discussed. We finally study the emission of Hawking radiation in the bulk: graybody factors and radiation spectra are presented for the emission of scalar modes, and the ratio of the missing energy over the visible one is calculated for different values of the number of extra dimensions.

scholarly journals HAWKING RADIATION: A PARTICLE PHYSICS PERSPECTIVE

1993 ◽  
Vol 08 (18) ◽  
pp. 1661-1670 ◽  
Author(s):  
MATT VISSER
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Decay Rate ◽  
Hawking Radiation ◽  
Particle Physics ◽  
Naked Singularity ◽  
Black Body ◽  
Large Mass ◽  
High Energy ◽  
Radiation Process

It has recently become fashionable to regard black holes as elementary particles. By taking this suggestion reasonably seriously it is possible to cobble together an elementary particle physics based on estimate for the decay rate (black hole) i → (black hole) f+ (massless quantum) . This estimate of the spontaneous emission rate contains two free parameters which may be fixed by demanding that the high energy end of the spectrum of emitted quanta match a black body spectrum at the Hawking temperature. The calculation, though technically trivial, has important conceptual implications: (1) The existence of Hawking radiation from black holes seems ultimately dependent only on the fact that massless quanta (and all other forms of matter) couple to gravity. (2) The essentially thermal nature of the Hawking spectrum seems to depend only on the fact that the number of internal states of a large mass black hole is enormous. (3) Remarkably, the resulting formula for the decay rate gives meaningful answers even when extrapolated to low mass black holes. The analysis seems to support the scenario of complete evaporation as the end point of the Hawking radiation process (no naked singularity, no stable massive remnant).

Black holes and thermal Green functions

1978 ◽  
Vol 358 (1695) ◽  
pp. 467-494 ◽  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Field ◽  
Energy Density ◽  
Thermal Equilibrium ◽  
Heat Bath ◽  
High Energy ◽  
High Energy Density ◽  
Green Functions ◽  
External Gravitational Field

This paper concerns itself with the possibility of thermal equilibrium between a black hole and a heat bath implied by Hawking’s discovery of black hole emission. We argue that in an isolated box of radiation, for sufficiently high energy density a black hole will condense out. We introduce thermal Green functions to discuss this equilibrium and are able to extend the original arguments, that the equilibrium is possible based on fields interacting solely with the external gravitational field, to the case when mutual and self interactions are included.

scholarly journals HEAD-ON COLLISION AND MERGING ENTROPY OF BLACK HOLES: RECONSIDERATION OF HAWKING'S INEQUALITY

2013 ◽  
Vol 22 (07) ◽  
pp. 1350050 ◽  
Author(s):  
MASARU SIINO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Upper Bound ◽  
Gravitational Radiation ◽  
High Energy ◽  
Black Hole Thermodynamics ◽  
Black Hole Horizon ◽  
Energy Ratio ◽  
Area Theorem ◽  
Numerical Investigations

We evaluate the amount of energy that can be converted into gravitational radiation in head-on collision of black holes. We estimate it by the area theorem of black hole horizon incorporating merging entropy of colliding black holes from a viewpoint of black hole thermodynamics. Then we obtain an upper bound of energy ratio of the gravitational radiation which is smaller than the upper bound originally derived by Hawking. The fact that this estimation is not inconsistent with the results of both numerical investigations in low- and high-energy head-on collision implies that thermodynamics of coalescing black holes requires the contribution of the merging entropy.

scholarly journals Rotating and non-rotating AdS black holes in $$f(\mathcal{T})$$ gravity non-linear electrodynamics

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Salvatore Capozziello ◽  
Gamal G. L. Nashed
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Energy ◽  
Ads Black Holes ◽  
Central Singularity ◽  
Non Linear ◽  
Dimensional Black Hole ◽  
Quadrupole Term ◽  
Physical Quantities ◽  
Black Hole Solutions

Abstract We derive new exact charged d-dimensional black hole solutions for quadratic teleparallel equivalent gravity, $$f(\mathcal{T})=a_0+a_1\mathcal{T}+a_2\mathcal{T}^2$$f(T)=a0+a1T+a2T2, where $$\mathcal T$$T is the torsion scalar, in the case of non-linear electrodynamics. We give a specific form of electromagnetic function and find out the form of the unknown functions that characterize the vielbeins in presence of the electromagnetic field. It is possible to show that the black holes behave asymptotically as AdS solutions and contain, in addition to the monopole and quadrupole terms, other higher order terms whose source is the non-linear electrodynamics field. We calculate the electromagnetic Maxwell field and show that our d-dimensional black hole solutions coincide with the previous obtained one (Awad et al. in J High Energy Phys 13:1706.01773, 2017). The structure of the solutions show that there is a central singularity that is much mild in comparison with the respective one in general relativity. Finally, the thermodynamical properties of the solutions are investigated by calculating the entropy, the Hawking temperature, the heat capacity, and other physical quantities. The most important result of thermodynamics is that the entropy is not proportional to the area of the black hole. This inanition points out that we must have a constrain on the quadrupole term to get a positive entropy otherwise we get a negative value.

BRANEWORLD BLACK HOLES IN COSMOLOGY AND ASTROPHYSICS

2005 ◽  
Vol 14 (07) ◽  
pp. 1095-1129 ◽  
Author(s):  
A. S. MAJUMDAR ◽  
N. MUKHERJEE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Lensing ◽  
Strong Field ◽  
Planck Scale ◽  
High Energy ◽  
Field Equations ◽  
Large Extra Dimension ◽  
Gravitational Field Equations ◽  
Fundamental Scale

The braneworld description of our universe entails a large extra dimension and a fundamental scale of gravity that might be lower by several orders of magnitude compared to the Planck scale. An interesting consequence of the braneworld scenario is in the nature of spherically symmetric vacuum solutions to the brane gravitational field equations which could represent black holes with properties quite distinct compared to ordinary black holes in 4-dimensions. We discuss certain key features of some braneworld black hole geometries. Such black holes are likely to have diverse cosmological and astrophysical ramifications. The cosmological evolution of primordial braneworld black holes is described highlighting their longevity due to modified evaporation and effective accretion of radiation during the early braneworld high energy era. Observational abundance of various evaporation products of the black holes at different eras impose constraints on their initial mass fraction. Surviving primordial black holes could be candidates of dark matter present in galactic haloes. We discuss gravitational lensing by braneworld black holes. Observables related to the relativistic images of strong field gravitational lensing could in principle be used to distinguish between different braneworld black hole metrics in future observations.

scholarly journals Entanglement islands in higher dimensions

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Ahmed Almheiri ◽  
Raghu Mahajan ◽  
Jorge Santos
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Recent Work ◽  
Hawking Radiation ◽  
Higher Dimensions ◽  
Quantum Systems ◽  
Two Dimensional ◽  
Dimensional Gravity ◽  
Classical Gravity ◽  
Ads Geometry

It has been suggested in recent work that the Page curve of Hawking radiation can be recovered using computations in semi-classical gravity provided one allows for ``islands" in the gravity region of quantum systems coupled to gravity. The explicit computations so far have been restricted to black holes in two-dimensional Jackiw-Teitelboim gravity. In this note, we numerically construct a five-dimensional asymptotically AdS geometry whose boundary realizes a four-dimensional Hartle-Hawking state on an eternal AdS black hole in equilibrium with a bath. We also numerically find two types of extremal surfaces: ones that correspond to having or not having an island. The version of the information paradox involving the eternal black hole exists in this setup, and it is avoided by the presence of islands. Thus, recent computations exhibiting islands in two-dimensional gravity generalize to higher dimensions as well.

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