scholarly journals Cosmic censorship, massless fermionic test fields, and absorption probabilities

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Koray Düztaş
Keyword(s):  
Black Holes ◽  
Space Time ◽  
Low Frequencies ◽  
New Approach ◽  
Naked Singularities ◽  
Self Energy ◽  
Massless Spin ◽  
Divergence Problem ◽  
Time Parameters ◽  
Absorption Probabilities

AbstractIn the conventional approach, fermionic test fields lead to a generic overspinning of black holes resulting in the formation of naked singularities. The absorption of the fermionic test fields with arbitrarily low frequencies is allowed for which the contribution to the angular momentum parameter of the space-time diverges. Recently we have suggested a more subtle treatment of the problem considering the fact that only the fraction of the test fields that is absorbed by the black hole contributes to the space-time parameters. Here, we re-consider the interaction of massless spin (1/2) fields with Kerr and Kerr–Newman black holes, adapting this new approach. We show that the drastic divergence problem disappears when one incorporates the absorption probabilities. Still, there exists a range of parameters for the test fields that can lead to overspinning. We employ backreaction effects due to the self-energy of the test fields which fixes the overspinning problem for fields with relatively large amplitudes, and renders it non-generic for smaller amplitudes. This non-generic overspinning appears likely to be fixed by alternative semi-classical and quantum effects.

scholarly journals DUALITIES, COMPOSITENESS AND SPACE–TIME STRUCTURE OF 4D EXTREME STRINGY BLACK HOLES

1999 ◽  
Vol 14 (07) ◽  
pp. 1015-1034 ◽  
Author(s):  
MARIANO CADONI
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
String Theory ◽  
Bound States ◽  
Bound State ◽  
Space Time ◽  
Naked Singularities ◽  
Heterotic String Theory ◽  
Space Time Structure ◽  
Black Hole Solutions

We study the BPS black hole solutions of the (truncated) action for heterotic string theory compactified on a six-torus. The O (3,Z) duality symmetry of the theory, together with the bound state interpretation of extreme black holes, is used to generate the whole spectrum of the solutions. The corresponding space–time structures, written in terms of the string metric, are analyzed in detail. In particular, we show that only the elementary solutions present naked singularities. The bound states have either null singularities (electric solutions) or are regular (magnetic or dyonic solutions) with near-horizon geometries given by the product of two 2d spaces of constant curvature. The behavior of some of these solutions as supersymmetric attractors is discussed. We also show that our approach is very useful to understand some of the puzzling features of charged black hole solutions in string theory.

scholarly journals Singularities in Cosmology

1974 ◽  
Vol 63 ◽  
pp. 263-272
Author(s):  
Roger Penrose
Keyword(s):  
Black Holes ◽  
Big Bang ◽  
Space Time ◽  
Closed Universe ◽  
Naked Singularities ◽  
The Big Bang ◽  
Topology Of The Universe ◽  
The Universe

Singularities in space-time can be broadly divided into three classes: past-spacelike (in white holes or the big bang), timelike (naked singularities) and future-spacelike (in black holes or the final recollapse). In a closed Universe, if a simple restriction is made to eliminate timelike singularities, the inference may be drawn that the topology of the Universe is unchanging with time. Thermodynamical considerations lead one to infer that the final singularity of recollapse must differ markedly in structure from the initial big bang. This may plausibly be related to the existence of black holes and the presumed non-existence of white holes.

The principles of duality in the light of the system economic theory

2019 ◽  
pp. 127-149
Author(s):  
George B. Kleiner
Keyword(s):  
Economic Theory ◽  
Economic System ◽  
External Environment ◽  
Black Box ◽  
Space Time ◽  
Production Cycle ◽  
Economic Systems ◽  
New Approach ◽  
Reproduction Cycle ◽  
Basic Concepts

This paper shows the diversity and significance of relations of duality among different economic systems. The composition of the principles underlying the system economic theory used for the analysis of duality in the economy is investigated. The concept of the economic system is clarified and the equivalence of three basic concepts of the economic system is shown: a) as a space-time volume (“black box”); b) as a complex of elements and connections among them; c) as a tetrad, including object, project, process and environment components. In a new way, the concept of the tetrad is revealed. The actual interpretation of the interrelationships of its components, based on the mechanisms of intersystem circulation of spatial and temporal resources and the transmission of abilities from one economic system to another, is proposed. On the basis of the obtained results, the most essential aspects of duality in the theory of economic systems are considered. It is shown that the interaction of internal content and the nearest external environment of economic systems lies in the nature of the relations of duality. A new approach to modeling the structure and to functioning of the economic system, based on the description of its activities in the form of two interconnected tetrads (the first tetrad reflects the intrasystem production cycle and the second one — the external realization-reproduction cycle) is put forward. It is shown that the concept of duality in a system economy creates prerequisites for adapting the functioning of local economic systems (objects, projects, etc.) in a market, administrative and functional environments and, as a result, harmonizing the economy as a whole.

scholarly journals Low Frequency Oscillations drive EEG's complexity changes during wakefulness and sleep

2021 ◽  
Author(s):  
Joaquin Gonzalez ◽  
Diego M. Mateos ◽  
Matias Cavelli ◽  
Alejandra Mondino ◽  
Claudia Pascovich ◽  
...  
Keyword(s):  
Slow Wave Sleep ◽  
Low Frequency ◽  
Neuronal Population ◽  
Complexity Measures ◽  
Low Frequencies ◽  
New Approach ◽  
Frequency Bands ◽  
Cortical Oscillations ◽  
Brain Signals ◽  
Low Frequency Oscillations

Recently, the sleep-wake states have been analysed using novel complexity measures, complementing the classical analysis of EEGs by frequency bands. This new approach consistently shows a decrease in EEG's complexity during slow-wave sleep, yet it is unclear how cortical oscillations shape these complexity variations. In this work, we analyse how the frequency content of brain signals affects the complexity estimates in freely moving rats. We find that the low-frequency spectrum - including the Delta, Theta, and Sigma frequency bands - drives the complexity changes during the sleep-wake states. This happens because low-frequency oscillations emerge from neuronal population patterns, as we show by recovering the complexity variations during the sleep-wake cycle from micro, meso, and macroscopic recordings. Moreover, we find that the lower frequencies reveal synchronisation patterns across the neocortex, such as a sensory-motor decoupling that happens during REM sleep. Overall, our works shows that EEG's low frequencies are critical in shaping the sleep-wake states' complexity across cortical scales.

scholarly journals Unified Explanation of Big Bang, Inflation, Charged Black Hole Decay, Galaxy Formation, Proton Spin Crisis and Elementary Particle Masses

2021 ◽  
Author(s):  
Jae-Kwang Hwang
Keyword(s):  
Black Holes ◽  
Euclidean Space ◽  
Big Bang ◽  
Space Time ◽  
Proton Spin ◽  
Gravitational Forces ◽  
Normal Matter ◽  
Dark Matters ◽  
Spin Crisis ◽  
The Big Bang

Space-time evolution is briefly explained by using the 3-dimensional quantized space model (TQSM) based on the 4-dimensional (4-D) Euclidean space. The energy (E=cDtDV), charges (|q|= cDt) and absolute time (ct) are newly defined based on the 4-D Euclidean space. The big bang is understood by the space-time evolution of the 4-D Euclidean space but not by the sudden 4-D Minkowski space-time creation. The big bang process created the matter universe with the positive energy and the partner anti-matter universe with the negative energy from the CPT symmetry. Our universe is the matter universe with the negative charges of electric charge (EC), lepton charge (LC) and color charge (CC). This first universe is made of three dark matter -, lepton -, and quark - primary black holes with the huge negative charges which cause the Coulomb repulsive forces much bigger than the gravitational forces. The huge Coulomb forces induce the inflation of the primary black holes, that decay to the super-massive black holes. The dark matter super-massive black holes surrounded by the normal matters and dark matters make the galaxies and galaxy clusters. The spiral arms of galaxies are closely related to the decay of the 3-D charged normal matter black holes to the 1-D charged normal matter black holes. The elementary leptons and quarks are created by the decay of the normal matter charged black holes, that is caused by the Coulomb forces much stronger than the gravitational forces. The Coulomb forces are very weak with the very small Coulomb constants (k1(EC) = kdd(EC) ) for the dark matters and very strong with the very big Coulomb constants (k2(EC) = knn(EC)) for the normal matters because of the non-communication of the photons between the dark matters and normal matters. The photons are charge dependent and mass independent. But the dark matters and normal matters have the similar and very weak gravitational forces because of the communication of the gravitons between the dark matters and normal matters. The gravitons are charge independent and mass dependent. Note that the three kinds of charges (EC, LC and CC) and one kind of mass (m) exist in our matter universe. The dark matters, leptons and quarks have the charge configurations of (EC), (EC,LC) and (EC,LC,CC), respectively. Partial masses of elementary fermions are calculated, and the proton spin crisis is explained. The charged black holes are not the singularities.

scholarly journals HIGHER DIMENSIONAL INHOMOGENEOUS DUST COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 17 (20) ◽  
pp. 2747-2747
Author(s):  
A. BEESHAM
Keyword(s):  
Black Holes ◽  
Cosmic Censorship ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Naked Singularities ◽  
Singularity Theorems ◽  
Sitter Spacetime ◽  
Higher Dimensional ◽  
Cosmic Censorship Hypothesis ◽  
Strong Curvature

The singularity theorems of general relativity predict that gravitational collapse finally ends up in a spacetime singularity1. The cosmic censorship hypothesis (CCH) states that such a singularity is covered by an event horizon2. Despite much effort, there is no rigorous formulation or proof of the CCH. In view of this, examples that appear to violate the CCH and lead to naked singularities, in which non-spacelike curves can emerge, rather than black holes, are important to shed more light on the issue. We have studied several collapse scenarios which can lead to both situations3. In the case of the Vaidya-de Sitter spacetime4, we have shown that the naked singularities that arise are of the strong curvature type. Both types of singularities can also arise in higher dimensional Vaidya and Tolman-Bondi spacetimes, but black holes are favoured in some sense by the higher dimensions. The charged Vaidya-de Sitter spacetime also exhibits both types of singularities5.

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