The case for artificial black holes

2008 ◽  
Vol 366 (1877) ◽  
pp. 2851-2857 ◽  
Author(s):  
Ulf Leonhardt ◽  
Thomas G Philbin
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Event Horizon ◽  
Quantum Vacuum ◽  
Quantum Radiation

The event horizon is predicted to generate particles from the quantum vacuum, an effect that bridges three areas of physics—general relativity, quantum mechanics and thermodynamics. The quantum radiation of real black holes is too feeble to be detectable, but black-hole analogues may probe several aspects of quantum black holes. In this paper, we explain in simple terms some of the motivations behind the study of artificial black holes.

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.

Black hole fusion made easy

2016 ◽  
Vol 25 (12) ◽  
pp. 1644015
Author(s):  
Roberto Emparan ◽  
Marina Martínez
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Critical Behavior ◽  
Equivalence Principle ◽  
The Other ◽  
Schwarzschild Solution ◽  
Null Geodesics ◽  
Light Rays

The fusion of two black holes — a signature phenomenon of General Relativity — is usually regarded as a process so complex that nothing short of a supercomputer simulation can accurately capture it. In this essay, we explain how the event horizon of the merger can be found in an exact analytic way in the limit where one of the black holes is much smaller than the other. Remarkably, the ideas and techniques involved are elementary: the equivalence principle, null geodesics in the Schwarzschild solution, and the notion of event horizon itself. With these, one can identify features such as the line of caustics at which light rays enter the horizon, and find indications of universal critical behavior when the two black holes touch.

scholarly journals The shadow of M87∗ black hole within rational nonlinear electrodynamics

2020 ◽  
Vol 35 (35) ◽  
pp. 2050291
Author(s):  
S. I. Kruglov
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Magnetic Charge ◽  
Nonlinear Electrodynamics ◽  
Black Hole Mass

We consider rational nonlinear electrodynamics with the Lagrangian [Formula: see text] ([Formula: see text] is the Lorentz invariant), proposed in Ref. 63, coupled to General Relativity. The effective geometry induced by nonlinear electrodynamics corrections are found. We determine shadow’s size of regular non-rotating magnetic black holes and compare them with the shadow size of the super-massive M87[Formula: see text] black hole imaged by the Event Horizon Telescope collaboration. Assuming that the black hole mass has a pure electromagnetic nature, we obtain the black hole magnetic charge. The size of the shadow obtained is very close to the shadow size of non-regular neutral Schwarzschild black holes. As a result, we can interpret the super-massive M87[Formula: see text] black hole as a regular (without singularities) magnetized black hole.

Extremal Kerr Black Holes, Naked Singularity & Wormholes

2020 ◽  
Author(s):  
Deep Bhattacharjee
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Angular Momentum ◽  
Event Horizon ◽  
Kerr Black Hole ◽  
Naked Singularity ◽  
Kerr Metric ◽  
Spin Angular Momentum ◽  
The Way

This paper is totally based on the mathematical physics of the Black holes. In Einstein’s theory of “General Relativity”, Schwarzschild solution is the vacuum solutions of the Einstein Field Equations that describes the gravity potential from outside the body of a spherically symmetric object having zero charge, zero mass and zero cosmological constant[1]. It was discovered by Karl Schwarzschild in 1916, a little more than a month after the publication of the famous GR and the singularity is a point singularity which can be best described as a coordinate singularity rather than a real singularity, however, the drawback of this theory is that it fails to take into account the real life scenario of black holes with charge and spin angular momentum. The black hole is based on event horizon and Schwarzschild radius. However, Physicists were trying to develop a metric for the real life scenario of a black hole with a spin angular momen-tum and ultimately the exact solution of a charged rotating black hole had been discovered by Roy Kerr in 1965 as the Kerr-Newman metric[2][3]. The Kerr metric is one of the toughest metric in physics and is the extensional generalization to a rotating body of the Schwarzschild metric. The metric describes the vacuum geometry of space-time around a rotating axially-symmetric black hole with a quasipotential event horizon. In Kerr metric there are two event hori-zons (inner and outer), two ergospheres and an ergosurface. The most important effect of the Kerr metric is the frame dragging (also known as Lense-Thirring Precession) is a distinctive prediction of General relativity. The first direct observation of the collision of two Kerr Black Holes has been discovered by LIGO in 2016 hence setting up a milestone of General Relativity in the history of Physics. Here, the Kerr metric has been introduced in the Boyer-Lindquist forms and it is derived from the Schwarzschild metric using the Spin-Coefficient formalism. According to the “Cosmic Censorship Hypothesis”, a naked singularity cannot exist in nature as nature always hides the singularity via an event horizon. However, in this paper I will prove the existence of the “Naked Singularity" taking the advantage of the Ring Singularity of the Kerr Black Hole and thereby making the way to manipulate the mathematics by taking the larger root of Δ as zero and thereby vanishing the ergosphere and event horizon making the way for the naked ring singularity which can be easily connected via a cylindrical wormhole and as ‘a wormhole is a black hole without an event horizon’ therefore, this cylindrical connection paved the way for the Einstein-Rosen Bridge allowing particles or null rays to travel from one universe to another ending up in a future directed Cauchy horizon while changing constantly from spatial to temporal and again spatial paving the entrance to another Kerr Black hole (which would act as a white hole) in the other universes. I will not go in detail about the contradiction of ‘Chronology Protection Conjecture” [4]whether the Stress-Energy-Momentum Tensor can violate the ANEC (Average Null Energy Conditions) or not with the values of less than zero or greater than, equal to zero, instead I will focus definitely on the creation of the mathematical formulation of a wormhole from a Naked Ring Kerr Singularity of a Kerr Black Hole without any event horizon or ergosphere. Another important thing to mention in this paper is that I have taken the time to be imaginary[5] as because, a singularity being an eternal point of time can only be smoothen out if the time is imaginary rather than real which will allow the particle or null rays inside a wormhole to cross the singularity and making entrance to the other universe. The final conclusion would be to determine the mass-energy equivalence principle as spin angular momentum increases with a decrease in BH mass due to the vanishing event horizon and ergosphere thereby maintaining the equivalence via apparent and absolute masses in relation to spin J along the orthogonal Z axis. A ‘NAKED SINGULARITY’ alters every parameters of a BH and to include this parameters along with affine spin coefficient, it has been proved that without any spin angular momentum the generation of wormhole and vanishing of event horizon and singularity is not possible.

Quantum probing of singularities at event horizons of black holes

2021 ◽  
pp. 2150147
Author(s):  
V. P. Neznamov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Event Horizon ◽  
Stationary States ◽  
Coordinate Transformations ◽  
Event Horizons ◽  
Schwarzschild Metric

It is proved that coordinate transformations of the Schwarzschild metric to new static and stationary metrics do not eliminate the mode of a particle “fall” to the event horizon of a black hole. This mode is unacceptable for the quantum mechanics of stationary states.

AN ANSWER TO THE MAIN BLACK HOLE PATHOLOGY: FORMING NONSINGULAR BLACK HOLES FROM DUST COLLAPSE

2009 ◽  
Vol 18 (14) ◽  
pp. 2221-2229 ◽  
Author(s):  
R. MAIER ◽  
I. DAMIÃO SOARES
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Nonlinear Resonance ◽  
Space Time ◽  
Low Energy ◽  
Spherically Symmetric ◽  
Energy Limit ◽  
Exterior Space

The dynamics of gravitational collapse is examined in the realm of string-based formalism of D-branes which encompasses general relativity as a low energy limit. A complete analytical solution is given to the spherically symmetric collapse of a pure dust star, including its matching with a corrected Schwarzschild exterior space–time. The collapse forms a black hole (an exterior event horizon) enclosing not a singularity but perpetually bouncing matter in the infinite chain of space–time maximal analytical extensions inside the outer event horizon. This chain of analytical extensions has a structure analogous to that of the Reissner–Nordstrom solution. The interior trapped bouncing matter has the possibility of being expelled by disruptive nonlinear resonance mechanisms.

scholarly journals The Shadow of M87* Black Hole within Rational Nonlinear Electrodynamics

2020 ◽  
Author(s):  
Sergey Kruglov
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Magnetic Charge ◽  
Nonlinear Electrodynamics

We consider rational nonlinear electrodynamics coupled to General Relativity. The effective geometry induced by nonlinear electrodynamics corrections are found. We determine shadows of regular non-rotating magnetic black holes and compare them with the shadow of the super-massive M87* black hole imaged by the Event Horizon Telescope collaboration. This allows us to obtain the black hole magnetic charge. The size of the shadow is very close to the shadow of non-regular neutral Schwarzschild black holes. As a result, we can interpret the super-massive M87* black hole as a regular (without singularities) magnetized black hole.

scholarly journals BLACK HOLES AND STRINGS: THE POLYMER LINK

1998 ◽  
Vol 13 (17) ◽  
pp. 1407-1411 ◽  
Author(s):  
RAMZI R. KHURI
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Quantum Gravity ◽  
Soft Matter ◽  
Black Hole Entropy ◽  
Entropy Formula ◽  
Recent Success ◽  
Thermodynamics And Statistical Mechanics

Quantum aspects of black holes represent an important testing ground for a theory of quantum gravity. The recent success of string theory in reproducing the Bekenstein–Hawking black hole entropy formula provides a link between general relativity and quantum mechanics via thermodynamics and statistical mechanics. Here we speculate on the existence of new and unexpected links between black holes and polymers and other soft-matter systems.

scholarly journals Venturing beyond the ISCO: detecting X-ray emission from the plunging regions around black holes

2020 ◽  
Vol 493 (4) ◽  
pp. 5532-5550 ◽  
Author(s):  
D R Wilkins ◽  
C S Reynolds ◽  
A C Fabian
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Energy Band ◽  
Strong Field ◽  
Time Lags ◽  
X Ray ◽  
Region Detection ◽  
Improving Accuracy

ABSTRACT We explore how X-ray reverberation around black holes may reveal the presence of the innermost stable circular orbit (ISCO), predicted by general relativity, and probe the dynamics of the plunging region between the ISCO and the event horizon. Being able to directly detect the presence of the ISCO and probe the dynamics of material plunging through the event horizon represents a unique test of general relativity in the strong field regime. X-ray reverberation off of the accretion disc and material in the plunging region is modelled using general relativistic ray tracing simulations. X-ray reverberation from the plunging region has a minimal effect on the time-averaged X-ray spectrum and the overall lag-energy spectrum, but is manifested in the lag in the highest frequency Fourier components, above $0.01\, c^{3}\, (GM)^{-1}$ (scaled for the mass of the black hole) in the 2–4 keV energy band for a non-spinning black hole or the 1–2 keV energy band for a maximally spinning black hole. The plunging region is distinguished from disc emission not just by the energy shifts characteristic of plunging orbits, but by the rapid increase in ionization of material through the plunging region. Detection requires measurement of time lags to an accuracy of 20 per cent at these frequencies. Improving accuracy to 12 per cent will enable constraints to be placed on the dynamics of material in the plunging region and distinguish plunging orbits from material remaining on stable circular orbits, confirming the existence of the ISCO, a prime discovery space for future X-ray missions.

scholarly journals Mechanism for nonlocal information flow from black holes

2020 ◽  
Vol 35 (06) ◽  
pp. 2050031
Author(s):  
Adithya Kandhadai ◽  
Antony Valentini
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Event Horizon ◽  
Information Flow ◽  
Entangled State ◽  
Born Rule ◽  
Pilot Wave ◽  
De Broglie Bohm

We show that quantum nonequilibrium (or deviations from the Born rule) can propagate nonlocally across space. Such phenomena are allowed in the de Broglie–Bohm pilot-wave formulation of quantum mechanics. We show that an entangled state can act as a channel whereby quantum nonequilibrium can be transferred nonlocally from one region to another without any classical interaction. This suggests a novel mechanism whereby information can escape from behind the classical event horizon of an evaporating black hole.

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