scholarly journals Black Hole Torsion Effect and Its Relation to Information

2019 ◽  
Vol 64 (8) ◽  
pp. 683
Author(s):  
I. Gkigkitzis ◽  
I. Haranas ◽  
E. Cavan
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Spin Density ◽  
Analytical Solutions ◽  
Analytic Solution ◽  
Particle Density ◽  
Gravitational Radius ◽  
Spin Particle ◽  
Torsion Effect ◽  
Information Number

In order to study the effects of the torsion on the gravitation in space-time and its relation to information, we use the Schwarzschild metric, where the torsion is naturally introduced through the spin particle density. In the black hole scenario, we derive an analytic solution for the black hole gravitational radius with the spin included. Then we calculate its entropy in the cases of parallel and antiparallel spins. Moreover, four analytical solutions for the spin density as a function of the number of information are found. Using these solutions in the case of parallel spin, we obtain expressions for the Ricci scalar as a function of the information number N, and the cosmological constant lambda is also revealed.

scholarly journals Does Hawking predict the correct temperature of a black-hole?

2020 ◽  
Vol 29 (1) ◽  
pp. 56-58
Author(s):  
Kapil Chandra
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Extreme Temperature ◽  
Extreme Value ◽  
Radiation Temperature ◽  
Calculated Temperature ◽  
Actual Temperature

AbstractIn our study of the validity of Hawking’s predicted radiation temperature of a black-hole, we found that the calculated temperature is another form of Zeldovich’s expression for the cosmological constant. We reasoned that as Zeldovich predicted the extreme value of cosmological constant thus Hawking might have also predicted an extreme temperature. However, the actual temperature might be something different. This result implies that all predictions based on Hawking’s radiation temperature might be incorrect.

scholarly journals How the Limit Values Work

2021 ◽  
Keyword(s):  
Cosmological Constant ◽  
Gravitational Radius ◽  
Limit Values ◽  
Event Horizons ◽  
Dirac Type ◽  
Large Numbers ◽  
Spatio Temporal ◽  
The Universe ◽  
Limiting Values ◽  
Physical Principles

The efficiency of limiting quantities as a tool for describing physics at various spatio-temporal scales is shown. Due to its universality, limit values allow us to establish relationships between, at first glance, distant from each other's characteristics. The article discusses specific examples of the use of limit values to establish such relationships between quantities at different scales. Based on the principle of reaching the limiting values on the event horizons, a connection was obtained between the Planck values and the values of the Universe. The resulting relation can be attributed to relations of the Dirac type - the coincidence of large numbers that emerged from empirical observations. In the article, the relationships between large numbers of the Dirac type are established proceeding, in a certain sense, from physical principles - the existence of limiting values. It is shown that this ratio is observed throughout the evolution of the Universe. An alternative way of solving the problem of the cosmological constant using limiting values and its relation to the minimum spatial scale is discussed. In addition, a one-parameter family of masses was introduced, including the mass of the Universe, the Planck mass and the mass of the graviton, which also establish relationships between quantities differing by 120 orders of magnitude. It is shown that entropic forces also obey the same universal limiting constraints as ordinary forces. Thus, the existence of limiting values extends to informational limitations in the Universe. It is fundamentally important that on any event horizon, regardless of its scale (i.e., its gravitational radius), the universal value of limit force c4/4G is realized. This allows you to relate the characteristics of the Universe related to various stages of its evolution.

scholarly journals Central charges for AdS black holes

2021 ◽  
Author(s):  
Malcolm Perry ◽  
Maria J Rodriguez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Central Charge ◽  
Negative Cosmological Constant ◽  
Ads Black Holes ◽  
Kerr Black Holes ◽  
Distinguishing Features ◽  
Area Law ◽  
Cardy Formula

Abstract Nontrivial diffeomorphisms act on the horizon of a generic 4D black holes and create distinguishing features referred to as soft hair. Amongst these are a left-right pair of Virasoro algebras with associated charges that reproduce the Bekenstein-Hawking entropy for Kerr black holes. In this paper we show that if one adds a negative cosmological constant, there is a similar set of infinitesimal diffeomorphisms that act non-trivially on the horizon. The algebra of these diffeomorphisms gives rise to a central charge. Adding a boundary counterterm, justified to achieve integrability, leads to well-defined central charges with cL = cR. The macroscopic area law for Kerr-AdS black holes follows from the assumption of a Cardy formula governing the black hole microstates.

scholarly journals The nature of the gravitational vacuum

2019 ◽  
Vol 28 (14) ◽  
pp. 1944005
Author(s):  
Samir D. Mathur
Keyword(s):  
Black Hole ◽  
String Theory ◽  
Cosmological Constant ◽  
Mass Formula ◽  
Vacuum Energy ◽  
Planck Scale ◽  
Cosmological Constant Problem ◽  
Horizon Radius ◽  
Number Formula ◽  
Gravitational Vacuum

The vacuum must contain virtual fluctuations of black hole microstates for each mass [Formula: see text]. We observe that the expected suppression for [Formula: see text] is counteracted by the large number [Formula: see text] of such states. From string theory, we learn that these microstates are extended objects that are resistant to compression. We argue that recognizing this ‘virtual extended compression-resistant’ component of the gravitational vacuum is crucial for understanding gravitational physics. Remarkably, such virtual excitations have no significant effect for observable systems like stars, but they resolve two important problems: (a) gravitational collapse is halted outside the horizon radius, removing the information paradox, (b) spacetime acquires a ‘stiffness’ against the curving effects of vacuum energy; this ameliorates the cosmological constant problem posed by the existence of a planck scale [Formula: see text].

scholarly journals Isotropic Gravastar Model in Rastall Gravity

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
G. Abbas ◽  
K. Majeed
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Analytical Solutions ◽  
Thin Shell ◽  
Graphical Analysis ◽  
Stiff Fluid ◽  
Matter Distribution ◽  
The Third ◽  
Schwarzschild Geometry ◽  
Third Phase

In the present paper, we have introduced a new model of gravastar with an isotropic matter distribution in Rastall gravity by the Mazur–Mottola (2004) mechanism. Mazur–Mottola approach is about the construction of gravastar which is predicted as an alternative to black hole. By following this convention, we define gravastar in the form of three phases. The first one is an interior phase which has negative density; the second part consists of thin shell comprising ultrarelativistic stiff fluid for which we have discussed the length, energy, and entropy. By the graphical analysis of entropy, we have shown that our proposed thin shell gravastar model is potentially stable. The third phase of gravastar is defined by the exterior Schwarzschild geometry. For the interior of gravastar, we have found the analytical solutions free from any singularity and the event horizon in the framework of Rastall gravity.

scholarly journals Extremal Cosmological Black Holes in Horndeski Gravity and the Anti-Evaporation Regime

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 210
Author(s):  
Ismael Ayuso ◽  
Diego Sáez-Chillón Gómez
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
Linear Order ◽  
Scalar Tensor Theory ◽  
De Sitter ◽  
Tensor Theory ◽  
Effective Cosmological Constant ◽  
Cosmological Black Holes ◽  
Extremal Black Holes

Extremal cosmological black holes are analysed in the framework of the most general second order scalar-tensor theory, the so-called Horndeski gravity. Such extremal black holes are a particular case of Schwarzschild-De Sitter black holes that arises when the black hole horizon and the cosmological one coincide. Such metric is induced by a particular value of the effective cosmological constant and is known as Nariai spacetime. The existence of this type of solutions is studied when considering the Horndeski Lagrangian and its stability is analysed, where the so-called anti-evaporation regime is studied. Contrary to other frameworks, the radius of the horizon remains stable for some cases of the Horndeski Lagrangian when considering perturbations at linear order.

scholarly journals A Conceptual Model for the Origin of the Cutoff Parameter in Exotic Compact Objects

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2072
Author(s):  
Wilson Alexander Rojas Castillo ◽  
Jose Robel Arenas Salazar
Keyword(s):  
Black Hole ◽  
Conceptual Model ◽  
Initial Position ◽  
Compact Objects ◽  
Field Equations ◽  
Gravitational Radius ◽  
Cutoff Parameter ◽  
Gravitational Field Equations ◽  
Dynamic Quantity ◽  
The Difference

A Black Hole (BH) is a spacetime region with a horizon and where geodesics converge to a singularity. At such a point, the gravitational field equations fail. As an alternative to the problem of the singularity arises the existence of Exotic Compact Objects (ECOs) that prevent the problem of the singularity through a transition phase of matter once it has crossed the horizon. ECOs are characterized by a closeness parameter or cutoff, ϵ, which measures the degree of compactness of the object. This parameter is established as the difference between the radius of the ECO’s surface and the gravitational radius. Thus, different values of ϵ correspond to different types of ECOs. If ϵ is very big, the ECO behaves more like a star than a black hole. On the contrary, if ϵ tends to a very small value, the ECO behaves like a black hole. It is considered a conceptual model of the origin of the cutoff for ECOs, when a dust shell contracts gravitationally from an initial position to near the Schwarzschild radius. This allowed us to find that the cutoff makes two types of contributions: a classical one governed by General Relativity and one of a quantum nature, if the ECO is very close to the horizon, when estimating that the maximum entropy is contained within the material that composes the shell. Such entropy coincides with the Bekenstein–Hawking entropy. The established cutoff corresponds to a dynamic quantity dependent on coordinate time that is measured by a Fiducial Observer (FIDO). Without knowing the details about quantum gravity, parameter ϵ is calculated, which, in general, allows distinguishing the ECOs from BHs. Specifically, a black shell (ECO) is undistinguishable from a BH.

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