scholarly journals No static black hole hairs in gravitational theories with broken Lorentz invariance

2017 ◽  
Vol 95 (12) ◽  
Author(s):  
Kai Lin ◽  
Shinji Mukohyama ◽  
Anzhong Wang ◽  
Tao Zhu
Keyword(s):  
Black Hole ◽  
Lorentz Invariance ◽  
Broken Lorentz Invariance ◽  
Gravitational Theories ◽  
Static Black Hole

scholarly journals ENERGY EXTRACTION FROM GRAVITATIONAL COLLAPSE TO STATIC BLACK HOLES

2003 ◽  
Vol 12 (01) ◽  
pp. 121-127 ◽  
Author(s):  
REMO RUFFINI ◽  
LUCA VITAGLIANO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Extraction Process ◽  
Maximum Efficiency ◽  
Energy Extraction ◽  
Mass Energy ◽  
Classical Level ◽  
Static Black Hole ◽  
Exact Analytic Expression ◽  
Analytic Expression

The mass-energy formula of black holes implies that up to 50% of the energy can be extracted from a static black hole. Such a result is reexamined using the recently established analytic formulas for the collapse of a shell and the expression for the irreducible mass of a static black hole. It is shown that the efficiency of energy extraction process during the formation of the black hole is linked in an essential way to the gravitational binding energy, the formation of the horizon and the reduction of the kinetic energy of implosion. Here a maximum efficiency of 50% in the extraction of the mass energy is shown to be generally attainable in the collapse of a spherically symmetric shell: surprisingly this result holds as well in the two limiting cases of the Schwarzschild and extreme Reissner–Nordström space–times. Moreover, the analytic expression recently found for the implosion of a spherical shell to an already formed black hole leads to a new exact analytic expression for the energy extraction which results in an efficiency strictly less than 100% for any physical implementable process. There appears to be no incompatibility between General Relativity and Thermodynamics at this classical level.

UNEXPECTED BEHAVIOR IN THE CROSSING OF MICROWAVE AND OPTICAL BEAMS

2005 ◽  
Vol 19 (27) ◽  
pp. 1403-1410 ◽  
Author(s):  
E. ALLARIA ◽  
R. MEUCCI ◽  
D. MUGNAI ◽  
A. RANFAGNI ◽  
C. RANFAGNI
Keyword(s):  
Lorentz Invariance ◽  
Point Of View ◽  
Experimental Results ◽  
Light Velocity ◽  
Broken Lorentz Invariance ◽  
Points Of View ◽  
Optical Beams ◽  
Definite Solution ◽  
Unexpected Behavior

The question of the superluminal speed of information was stopped at crossroads in the last few years. According to one point of view, this speed must be limited to the light velocity in vacuum, whereas a different point of view is more open in this respect and, under specific conditions, this limit is considered surmountable. Very recently, a third approach (based on the hypothesis of a local broken Lorentz-invariance) was proposed and, if confirmed, would go beyond the controversy of the two points of view mentioned above. It is therefore worthwhile to recall attention to this problem, which is far from having a definite solution. The present paper reports some experimental results (similar to those of Ref. 1) which can contribute to these discussions, and also considers the fact that they seem to give some support to the aforesaid third approach, although revised in terms of decaying waves.

Hawking Radiation from a Non-static Black Hole

1991 ◽  
Vol 8 (10) ◽  
pp. 548-550 ◽  
Author(s):  
Zhao Zheng ◽  
Dai Xianxin
Keyword(s):  
Black Hole ◽  
Hawking Radiation ◽  
Static Black Hole

scholarly journals HOLLOWGRAPHY DRIVEN HOLOGRAPHY: BLACK HOLE WITH VANISHING VOLUME INTERIOR

2010 ◽  
Vol 19 (14) ◽  
pp. 2345-2351 ◽  
Author(s):  
AHARON DAVIDSON ◽  
ILYA GURWICH
Keyword(s):  
Phase Transition ◽  
General Relativity ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Schwarzschild Solution ◽  
Entropy Formula ◽  
Gravitational Theories ◽  
Hollow Interior ◽  
Spatial Volume ◽  
Self Similar

Hawking–Bekenstein entropy formula seems to tell us that no quantum degrees of freedom can reside in the interior of a black hole. We suggest that this is a consequence of the fact that the volume of any interior sphere of finite surface area simply vanishes. Obviously, this is not the case in general relativity. However, we show that such a phenomenon does occur in various gravitational theories which admit a spontaneously induced general relativity. In such theories, due to a phase transition (one-parameter family degenerates) which takes place precisely at the would-have-been horizon, the recovered exterior Schwarzschild solution connects, by means of a self-similar transition profile, with a novel "hollow" interior exhibiting a vanishing spatial volume and a locally varying Newton constant. This constitutes the so-called "hollowgraphy" driven holography.

scholarly journals Black hole evaporation in Hořava–Lifshitz gravity

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Hao Xu ◽  
Yen Chin Ong
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Lorentz Invariance ◽  
Detailed Balance ◽  
Einstein Gravity ◽  
Zero Temperature ◽  
Black Hole Mass ◽  
Black Hole Evaporation ◽  
Higher Derivative ◽  
Temperature State

Abstract Hořava–Lifshitz (HL) gravity was formulated in hope of solving the non-renormalization problem in Einstein gravity and the ghost problem in higher derivative gravity theories by violating Lorentz invariance. In this work we consider the spherically symmetric neutral AdS black hole evaporation process in HL gravity in various spacetime dimensions d, and with detailed balance violation parameter $$0\leqslant \epsilon ^2\leqslant 1$$0⩽ϵ2⩽1. We find that the lifetime of the black holes under Hawking evaporation is dimensional dependent, with $$d=4,5$$d=4,5 behave differently from $$d\geqslant 6$$d⩾6. For the case of $$\epsilon =0$$ϵ=0, in $$d=4,5$$d=4,5, the black hole admits zero temperature state, and the lifetime of the black hole is always infinite. This phenomenon obeys the third law of black hole thermodynamics, and implies that the black holes become an effective remnant towards the end of the evaporation. As $$d\geqslant 6$$d⩾6, however, the lifetime of black hole does not diverge with any initial black hole mass, and it is bounded by a time of the order of $$\ell ^{d-1}$$ℓd-1, similar to the case of Schwarzschild-AdS in Einstein gravity (which corresponds to $$\epsilon ^2=1$$ϵ2=1), though for the latter this holds for all $$d\geqslant 4$$d⩾4. The case of $$0<\epsilon ^2<1$$0<ϵ2<1 is also qualitatively similar with $$\epsilon =0$$ϵ=0.

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