scholarly journals Radiation hydrodynamics in Kerr space-time: equations without coordinate singularity at the event horizon

2007 ◽  
Vol 383 (3) ◽  
pp. 1155-1165 ◽  
Author(s):  
Rohta Takahashi
Keyword(s):  
Event Horizon ◽  
Space Time ◽  
Radiation Hydrodynamics ◽  
Kerr Space ◽  
Coordinate Singularity

scholarly journals Bargmann–Wigner formulation and superradiance problem of bosons and fermions in Kerr space–time

2015 ◽  
Vol 30 (11) ◽  
pp. 1550052 ◽  
Author(s):  
Masakatsu Kenmoku ◽  
Y. M. Cho
Keyword(s):  
Negative Energy ◽  
Space Time ◽  
The Other ◽  
Positive Energy ◽  
Independent Components ◽  
Consistent Description ◽  
Other Hand ◽  
Kerr Space

The superradiance phenomena of massive bosons and fermions in the Kerr space–time are studied in the Bargmann–Wigner formulation. In case of bi-spinor, the four independent components spinors correspond to the four bosonic freedom: one scalar and three vectors uniquely. The consistent description of the Bargmann–Wigner equations between fermions and bosons shows that the superradiance of the type with positive energy (0 < ω) and negative momentum near horizon (p H < 0) is shown not to occur. On the other hand, the superradiance of the type with negative energy (ω < 0) and positive momentum near horizon (0 < p H ) is still possible for both scalar bosons and spinor fermions.

scholarly journals Spinning cosmic strings in conformal gravity

2020 ◽  
Vol 35 (05) ◽  
pp. 2050024
Author(s):  
Reinoud Jan slagter ◽  
Christopher Levi Duston
Keyword(s):  
Cosmic String ◽  
Energy Condition ◽  
Space Time ◽  
Special Choice ◽  
Mass Relation ◽  
Conformal Gravity ◽  
Field Equations ◽  
Closed Timelike Curves ◽  
The Core ◽  
Kerr Space

We investigate the space–time of a spinning cosmic string in conformal invariant gravity, where the interior consists of a gauged scalar field. We find exact solutions of the exterior of a stationary spinning cosmic string, where we write the metric as [Formula: see text], with [Formula: see text] a dilaton field which contains all the scale dependences. The “unphysical” metric [Formula: see text] is related to the [Formula: see text]-dimensional Kerr space–time. The equation for the angular momentum [Formula: see text] decouples, for the vacuum situation as well as for global strings, from the other field equations and delivers a kind of spin-mass relation. For the most realistic solution, [Formula: see text] falls off as [Formula: see text] and [Formula: see text] close to the core. The space–time is Ricci flat. The formation of closed timelike curves can be pushed to space infinity for suitable values of the parameters and the violation of the weak energy condition can be avoided. For the interior, a numerical solution is found. This solution can easily be matched at the boundary on the exterior exact solution by special choice of the parameters of the string. This example shows the power of conformal invariance to bridge the gap between general relativity and quantum field theory.

scholarly journals The Accurate Modification of Tunneling Radiation of Fermions with Arbitrary Spin in Kerr-de Sitter Black Hole Space-Time

2020 ◽  
Vol 2020 ◽  
pp. 1-6 ◽  
Author(s):  
Bei Sha ◽  
Zhi-E Liu ◽  
Xia Tan ◽  
Yu-Zhen Liu ◽  
Jie Zhang
Keyword(s):  
Black Hole ◽  
Dispersion Relation ◽  
String Theory ◽  
Event Horizon ◽  
Quantum Tunneling ◽  
Gravitational Theory ◽  
Arbitrary Spin ◽  
Space Time ◽  
De Sitter ◽  
Tunneling Radiation

The quantum tunneling radiation of fermions with arbitrary spin at the event horizon of Kerr-de Sitter black hole is accurately modified by using the dispersion relation proposed in the study of string theory and quantum gravitational theory. The derived tunneling rate and temperature at the black hole horizons are analyzed and studied.

scholarly journals Meaningless Questions in Cosmology and Relativistic Astrophysics

1976 ◽  
Vol 31 (11) ◽  
pp. 1271-1276 ◽  
Author(s):  
M. Heller ◽  
M. Reinhardt
Keyword(s):  
Event Horizon ◽  
Gravitational Collapse ◽  
Space Time ◽  
Initial Singularity ◽  
Relativistic Astrophysics ◽  
General Classification ◽  
The Universe

Abstract After a general classification of meaningless questions in science we concentrate on empirically meaningless questions. Introducing the concepts of informationally connected, semiconnected and disconnected observers, a formalism for the analysis of the informational structure of space-time is developed. We discuss some problems of epistemological nature in cosmology and blade hole physics. A number of questions like "What was 'before' the initial singularity of the universe?" or "What is the fate of matter in gravitational collapse inside the event horizon?" turn out to be empirically meaningless. We also show that a "wormhole" does not violate causality for the set of informationally connected observers who do not enter it.

QUANTUM PHASE TRANSITIONS AND EVENT HORIZONS: CONDENSED MATTER ANALOGIES

2006 ◽  
Vol 20 (19) ◽  
pp. 2647-2650
Author(s):  
GEORGE CHAPLINE
Keyword(s):  
General Relativity ◽  
Phase Transitions ◽  
Event Horizon ◽  
Thought Experiment ◽  
Quantum Phase Transitions ◽  
Martensitic Transformations ◽  
Space Time ◽  
Quantum Phase ◽  
Event Horizons ◽  
Heavy Fermion Materials

Although it has been generally believed that classical general relativity is always correct for macroscopic length scales, certain predictions such as event horizons and closed time-like curves are inconsistent with ordinary quantum mechanics. It has recently been pointed out that the event horizon problem can be resolved if space-time undergoes a quantum phase transition as one approaches the surface where general relativity predicts that the redshift becomes infinite. Indeed a thought experiment involving a superfluid with a critical point makes such a suggestion appear plausible. Furthermore the behavior of space-time near an event horizon may resemble quantum phase transitions that have been observed in the laboratory. For example, the phenomenology of metamagnetic quantum critical points in heavy fermion materials resembles the behavior expected, both in terms of time standing still and the behavior of quantum correlation functions. Martensitic transformations accompanied by non-adiabatic changes in the electronic wave function are also interesting in this connection.

Neutrino oscillation interference phase in Kerr space—time

2009 ◽  
Vol 18 (12) ◽  
pp. 5575-5582
Author(s):  
Ren Jun ◽  
Jia Meng-Wen ◽  
Yuan Chang-Qing
Keyword(s):  
Neutrino Oscillation ◽  
Space Time ◽  
Kerr Space ◽  
Interference Phase
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