event horizons
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Universe ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 15
Author(s):  
Soon-Tae Hong ◽  
Yong-Wan Kim ◽  
Young-Jai Park

Making use of the higher dimensional global embedding Minkowski spacetime (GEMS), we embed (3 + 1)-dimensional Schwarzschild and Reissner-Nordström (RN) black holes written by the Painlevé-Gullstrand (PG) spacetimes, which have off-diagonal components in metrics, into (5 + 1)- and (5 + 2)-dimensional flat ones, respectively. As a result, we have shown the equivalence of the GEMS embeddings of the spacetimes with the diagonal and off-diagonal terms in metrics. Moreover, with the aid of their geodesic equations satisfying various boundary conditions in the flat embedded spacetimes, we directly obtain freely falling temperatures. We also show that freely falling temperatures in the PG spacetimes are well-defined beyond the event horizons, while they are equivalent to the Hawking temperatures, which are obtained in the original curved ones in the ranges between the horizon and the infinity. These will be helpful to study GEMS embeddings of more realistic Kerr, or rotating BTZ black holes.


Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 499
Author(s):  
Adrián Terrones ◽  
Carlos Sabín

We propose quantum simulations of 1 + 1D radial sections of different black hole spacetimes (Schwarzschild, Reissner–Nordstrøm, Kerr and Kerr–Newman), by means of a dc-SQUID array embedded on an open transmission line. This was achieved by reproducing the spatiotemporal dependence of 1 + 1D sections of the spacetime metric with the propagation speed of the electromagnetic field in the simulator, which can be modulated by an external magnetic flux. We show that the generation of event horizons—and therefore Hawking radiation—in the simulator could be achieved for non-rotating black holes, although we discuss limitations related to fluctuations of the quantum phase. In the case of rotating black holes, it seems that the simulation of ergospheres is beyond reach.


Author(s):  
Tianxi ZHANG ◽  

The first four days of Genesis are scientifically interpreted according to the author’s well-developed black hole universe model. From this scientific view for the creation of the universe described in the book of Genesis, God in the first day created the space and time, matter and motion, charge and fundamental forces, energy and light for the infinite large entire universe. Then, in the second day, God hierarchically structured the entire universe by separating the matter and space with infinite layers that are bounded by event horizons and further formed our finite black hole universe. In the third day, God constructed the interiors of our finite black hole universe with planets, stars, galaxies, and clusters, etc. And, in the fourth day, God finally created our home planet Earth and the solar system and made lights including the Sun, Moon, and stars to give light to our universe and Earth. This up-to-date explanation to God’s creative work during the first four days has bridged the gap between Genesis and observations of the universe and brought us a scientific view and understanding on the book of Genesis. This innovative interpretation of Genesis also strongly supports the black hole universe model to be capable of revealing the mysteries of the universe. This is a synthetic article of the four papers recently published on IJTPS to interpret the first through fourth day of Genesis according to the black hole model of the universe.


2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Christophe De Beule ◽  
Solofo Groenendijk ◽  
Tobias Meng ◽  
Thomas Schmidt

We investigate transport in type-I/type-II Weyl semimetal heterostructures that realize effective black- or white-hole event horizons. We provide an exact solution to the scattering problem at normal incidence and low energies, both for a sharp and a slowly-varying Weyl cone tilt profile. In the latter case, we find two channels with transmission amplitudes analog to those of Hawking radiation. Whereas the Hawking-like signatures of these two channels cancel in equilibrium, we demonstrate that one can favor the contribution of either channel using a non-equilibrium state, either by irradiating the type-II region or by coupling it to a magnetic lead. This in turn gives rise to a peak in the two-terminal differential conductance which can serve as an experimental indicator of the artificial event horizon.


Author(s):  
Valeria Ramírez ◽  
L.A. López ◽  
Omar Pedraza ◽  
V.E. Ceron

In this paper, we study the scattering and absorption sections of the Schwarzschild--anti de Sitter black hole surrounded by quintessence. The critical values of the cosmological constant and the normalization factor are obtained. We describe the event horizons and the extremal condition of the black hole surrounded by quintessence. The effects of quintessence on the classical and semi--classical scattering cross--sections have been estimated. Also, the absorption section is studied with the sinc approximation in the eikonal limit. We consider the quintessence state parameter in the particular cases ω = -2/3 and ω = -1/2.


Author(s):  
Tianxi ZHANG ◽  

Papers I through III has fully and self-consistently addressed the first three days of Genesis according to the author’s well-developed black hole universe model. In the first day, God created space and time, matter and motion, charge and fundamental forces, and energy and light for the infinite entire universe. Then, in the second day he hierarchically structured the entire universe by separating the matter and space with infinite layers bounded by event horizons and further formed our finite black hole universe. In the third day, God constructed the interiors of our black hole universe with planets, stars, galaxies, and clusters, etc. In this sequence of study as Paper-IV, we describe how God created our earth and solar system and generated lights including the Sun, the moon, and stars to give light to our universe and earth. The efforts of this systematic study on God’s creative work during the first four days bridged the gap between Genesis and observations of the universe and brought us a scientific understanding of the Genesis. This innovative interpretation of Genesis also strongly supports the black hole universe model to be capable of revealing the mysteries of the universe.


2021 ◽  
pp. 274-300
Author(s):  
Andrew M. Steane

We discuss event horizons and black holes. First Birkhoff’s theorem is derived, and we consider the general nature of spherically symmetric spaces. Then the concepts of null surface, Killing horizon and event horizon are defined and related to one another. Cosmic censorship is briefly discussed. The Schwarzshild horizon is discussed in detail. The divergence or otherwise of redshift, acceleration, speed and proper time is obtained for infalling observers and for Schwarzschild observers. Eddington-Finkelstein coordinates are introduced and used to discuss gravitational collapse. The growth of the horizon is noted, and the causality structure is briefly considered via an introduction to the conformal (Penrose-Carter) diagram. The maximal extension is then presented, with the Kruskal-Szekeres coordinates and associated diagram. Wormholes are briefly discussed. The chapter finishes with a survey of astronomical evidence for black holes.


Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 268
Author(s):  
Shamaila Rani ◽  
Nadeem Azhar

In the present manuscript, the evolution of the cosmic parameters and planes are being investigated in the framework of the DGP braneworld model. In this scenario, the interaction Γ between the Barrow holographic dark energy model (whose infrared cutoff scale is set by Hubble and event horizons) and pressureless dark matter are considered. We check the behavior of different cosmological parameters such as Hubble, equation of state, deceleration and squared speed of sound from the early matter-dominated era until the late-time acceleration. It is found that the range of Hubble parameter lies in the interval 95−35+35 (for Hubble horizon) and 97−23+23 (for event horizon). For both horizons, the equation of state parameter favors the phantom dominant era as well as the ΛCDM model while the deceleration parameter illustrates the accelerated expansion of the universe. Furthermore, stability of the underlying model is found through squared speed of sound. Furthermore, it is observed that ω−ωϑ′ plane corresponds to freezing and thawing region for Hubble and event horizons, respectively. Furthermore, statefinder plane shows the ΛCDM and Chaplygin gas behavior for both models. Finally, we investigate the thermodynamical nature of the underlying model through Barrow entropy as horizon entropy and found validity for both horizons.


Author(s):  
V. P. Neznamov

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.


2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Tomas Andrade ◽  
Christiana Pantelidou ◽  
Julian Sonner ◽  
Benjamin Withers

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.


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