Thermodynamics and weak cosmic censorship conjecture of charged AdS black hole in the Rastall gravity with pressure

Treating the cosmological constant as a dynamical variable,we investigate the thermodynamics and weak cosmic censorship conjecture(WCCC)of a charged AdS black hole(BH)in the Rastall gravity.We determine the energy momentum relation of charged fermion at the horizon of the BH using the Dirac equation.Based on this relation,it is shown that the first law of thermodynamics still holds as a fermion is absorbed by the BH.However,the entropy of both the extremal and near-extremal BH decreases in the irreversible process,which means that the second law of thermodynamics is violated.Furthermore,we verify the validity of the WCCC by the minimum values of the metric function h(r)at its final state.For the extremal charged AdS BH in the Rastall gravity,we find that the WCCC is always valid since the BH is extreme.While for the case of near-extremal BH,we find that the WCCC could be violable in the extended phase space(EPS),depending on the value of the parameters of the BH and their variations.

Weak cosmic censorship conjecture in BTZ black holes with scalar fields

The weak cosmic censorship conjecture in the near-extremal BTZ black hole has been tested using test particles and fields.It has been claimed that such a black hole can be overspun.In this paper,we review the thermodynamics and weak cosmic censorship conjecture in BTZ black holes using the scattering of a scalar field.The first law of thermodynamics in the non-extremal BTZ black hole is recovered.For the extremal and near-extremal black holes,due to the divergence of the variation of entropy,we test the weak cosmic censorship conjecture by evaluating the minimum of the function f,and find that both the extremal and near-extremal black holes cannot be overspun.

Strong Cosmic Censorship in accelerating spacetime

It has been established that Strong Cosmic Censorship Conjecture(SCCC)is respected by an asymptotically flat black hole with charge,but violated by a charged asymptotically de Sitter black hole.We studied the instability of the Cauchy horizon for an accelerating black hole in Einstein theory conformally coupled with a scalar field.The black hole is uncharged while having inner,outer,and acceleration horizons.In the limit of vanishing acceleration,denoted by A→0,it becomes asymptotically flat and extremal,with its acceleration horizon vanishing as well.By exploring the perturbation of the massless scalar field upon the accelerating black hole,whose decay rate is governed by the quasinormal mode spectra,we show that the SCCC is violated in the near-extremal regime and also in the A→0+limit.Our result is the first observation of a black hole violating the SCCC in an almost asymptotically Minkowskian flat regime,as well as the first example of a black hole violating the SCCC with neither charge nor rotation.

Strong cosmic censorship for a scalar field in an Einstein-Maxwell-Gauss-Bonnet-de Sitter black hole

It has been shown that the Christodoulou version of the strong cosmic censorship(SCC)conjecture can be violated for a scalar field in a near-extremal Reissner-Nordstrom-de Sitter black hole.In this paper,we investigate the effects of higher derivative corrections to the Einstein-Hilbert action on the validity of SCC,by considering a neutral massless scalar perturbation in 5 -and 6 -dimensional Einstein-Maxwell-Gauss-Bonnet-de Sitter black holes.Our numerical results show that the higher derivative term plays a different role in the d=5 case than it does in the d=6 case.For d=5 ,the SCC violation region increases as the strength of the higher derivative term increases.For d=6 ,the SCC violation region first increases and then decreases as the higher derivative correction becomes stronger,and SCC can always be restored for a black hole with a fixed charge ratio when the higher derivative correction is strong enough.Finally,we find that the C^(2) version of SCC is respected in the d=6 case,but can be violated in some near-extremal regimes in the d=5 case.

Validity of thermodynamic laws and weak cosmic censorship for AdS black holes and black holes in a cavity

By throwing a test charged particle into a Reissner-Nordstrom(RN)black hole,we test the validity of the first and second laws of thermodynamics and the weak cosmic censorship conjecture(WCCC)with two types of boundary conditions:the asymptotically anti-de Sitter(AdS)space and a Dirichlet cavity wall placed in an asymptot-ically flat space.For the RN-AdS black hole,the second law of thermodynamics is satisfied,and the WCCC is viol-ated for both extremal and near-extremal black holes.For the RN black hole in a cavity,the entropy can either in-crease or decrease depending on the change in the charge,and the WCCC is satisfied/violated for the extremal/near-extremal black hole.Our results indicate that there may be a connection between the black hole thermodynamics and the boundary condition imposed on the black hole.

Thermodynamics and weak cosmic censorship conjecture in Born-Infeld-anti-de Sitter black holes

In this study,we examine the laws of thermodynamics and the weak cosmic censorship conjecture in the normal and extended phase spaces of Born-Infeld-anti-de Sitter black holes by considering a charged particle absorption.In the normal phase space,the first and second laws of thermodynamics as well as the weak cosmic censorship are still valid.However,in the extended phase space,the second law of thermodynamics is violated for double-horizon black holes and part of single-horizon black holes.The first law of thermodynamics and the weak cosmic censorship conjecture are still valid for all types of black holes.In addition,we found that the shift of the metric function,which determines the locations of the horizons,takes the same form at the minimum point in both the normal and extended phase spaces,indicating that the weak cosmic censorship conjecture is independent of the thermodynamic phase space.

Thermodynamics and weak cosmic censorship conjecture of BTZ black holes in extended phase space

As a charged fermion drops into a BTZ black hole, the laws of thermodynamics and the weak cosmic censorship conjecture are investigated in both the normal and extended phase space, where the cosmological parameter and renormalization length are regarded as extensive quantities. In the normal phase space, the first and second law of thermodynamics, and the weak cosmic censorship are found to be valid. In the extended phase space, although the first law and weak cosmic censorship conjecture remain valid, the second law is dependent on the variation of the renormalization energy dK. Moreover, in the extended phase space, the configurations of extremal and near-extremal black holes are not changed, as they are stable, while in the normal phase space, the extremal and near-extremal black holes evolve into non-extremal black holes.

Strong cosmic censorshiP for a scalar field in a logarithmic-de Sitter black hole

It has been shown that the quasinormal modes of perturebated fields can be used to investigate the validity of strong cosmic censorship(SCC).Relevant issues for Reissner-Nordstrom-de Sitter(RN-dS)black holes and Born-Infeld-de Sitter black holes have been discussed.In this paper,we investigate SCC in an asymptotic RN-dS black hole with logarithmic nonlinear electromagnetic field perturbed by massless scalar fields.It has been argued that SCC can be violated in a near-extremal RN-dS black hole.However,we find that the NLED effect can rescue SCC for a near-extremal logarithmic-de Sitter black hole.Compared with Born-Infeld model,we find that the NLED effect has similar behavior.

Weak cosmic censorship conjecture and thermodynamics in quintessence Ad S black hole under charged particle absorption

Considering the cosmological constant as the pressure,this study addresses the laws of thermodynamics and weak cosmic censorship conjecture in the Reissner-Nordstrom-AdS black hole surrounded by quintessence dark energy under charged Particle absorption.The first law of thermodynamics i5 found to be valid as a Particle is absorbed by the black hole.The second law,however,is violated for the extremal and near-extremal black holes,because the entropy of these black hole decrease.Moreover,we find that the extremal black hole does not change its configuration in the extended phase space,implying that the weak cosmic censorship conjecture is valid.Remarkably,the near-extremal black hole can be overcharged beyond the extremal condition under charged particle absorption.Hence,the cosmic censorship conjecture could be violated for the near-extremal black hole in the extended phase space.For comparison,we also discuss the first law,second law,and the weak cosmic censorship conjecture in normal phase space,and find that all of them are valid in this case.

Weak cosmic censorship conjecture in the nonlinear electrodynamics black hole under the charged scalar field

In this paper,we study the thermodynamics and the weak cosmic censorship conjecture of the nonlinear electrodynamics black hole under the scattering of a charged complex scalar field.According to the energy and charge fluxes of the scalar field,the variations of this black hole’s energy and charge can be calculated during an infinitesimal time interval.With scalar field scattering,the variation of the black hole is calculated in the extended and normal phase spaces.In the normal phase space,the cosmological constant and the normalization parameter are fixed,and the first and second laws of thermodynamics can also be satisfied.In the extended phase space,the cosmological constant and the normalization parameter are considered as thermodynamic variables,and the first law of thermodynamics is valid,but the second law of thermodynamics is not valid.Furthermore,the weak cosmic censorship conjecture is both valid in the extended and normal phase spaces.

de Rham-Gabadadze-Tolley(dRGT)黑洞的热力学与弱宇宙监督假设

有质量引力理论作为修正引力理论之一,对探究宇宙加速膨胀,以及解释暗能量和暗物质问题等有重要意义.本文研究了在常规相空间中de Rham-Gabadadze-Tolley(dRGT)有质量引力下球对称黑洞的热力学第一定律、热力学第二定律与弱宇宙监督假设是否成立;并通过图像探究熵的微分变化量随事件视界r_(d)变化的影响,以及与dRGT黑洞无量纲自由参数α,β与引力子质量对该图像的影响.在研究过程中,通过引入标量粒子的能量G动量关系,来验证黑洞热力学第一定律是否成立,通过观察事件视界对熵的微分变化量的影响,来验证黑洞热力学第二定律是否成立.研究发现,黑洞在吸收粒子的同时,其视界半径始终存在,从而使奇点始终没有裸露出来.结果表明,在dRGT有质量引力下球对称黑洞的热力学第一定律,热力学第二定律与弱宇宙监督假设均成立.

彭罗斯对广义相对论和黑洞理论的贡献

这篇文章列出了2020年诺贝尔物理学奖获得者彭罗斯对广义相对论和黑洞理论做出的重要贡献.它包括著名的奇点定理、彭罗斯图、彭罗斯过程和宇宙监督假设等.介绍了彭罗斯和霍金之间的友谊和合作.也简要介绍了另两位2020年诺贝尔物理学奖获得者根泽尔和盖兹对存在于银河系中心的超大质量致密天体的发现.

黑洞热力学第三定律与宇宙监督假设

对黑洞视界的研究结果表明 :黑洞热力学第三定律可禁止裸奇性的出现 ;反之 ,裸奇性的出现必破坏黑洞热力学第三定律。由此推断宇宙监督假设就是黑洞热力学第三定律。

Non-Spherical Gravitational Collapse of Strange Quark Matter

We study the non-spherical gravitational collapse of the strange quark null fluid. The interesting feature which emerges is that the non-spherical collapse of charged strange quark matter leads to a naked singularity whereas the gravitational collapse of neutral quark matter proceeds to form a black hole. We extend the earlier work of Harko and Cheng [Phys. Lett. A 266 （2000） 249] to the non-spherical case.

Destroying MTZ black holes with test particles

Neglecting the self-force and radiative effects, we follow the spirit of Wald＇s gedanken experiment and discuss whether a （2＋1）-dimensional Martinez-Teitelboim-Zanelli （MTZ） black hole can turn into a naked singularity by cap- turing a charged and massive particle. We find that after capturing a charged and massive test particle, an extremal or near-extremal MTZ black hole could turn into naked singularity, leading to a possible violation of the cosmic censorship. There exist ranges of the test particles＇ energies ＆E which allow the appearance of naked singularities from both extremal and near extremal MTZ black holes.

The Reissner-Nordström black hole surrounded by quintessence may not be destroyed

In the study of weak cosmic censorship conjectures(WCCC),some research finds that the Reissner-Nordström black hole might be destroyed by a test particle with particular mass and charge under some conditions,which means that the naked singularity of the black hole could be observed.This is not allowed in WCCC.We have never observed such naked singularities which should not exist in theory,so we need to find a proper way to protect the black hole from being destroyed by such particles.In this paper,we study a Reissner-Nordström black hole that is surrounded by quintessence(RN-Q)and find that the black hole would be stable and safe because of the effective potential barrier induced by the quintessence term.This result may also show in a sense that the quintessence might have more potential value.

Modified White Hole Enthalpy Coupled to Quantum Bose-Einstein Condensate at Extremely Low Entropy

We model the universe as a white hole, and in the process we perform detailed analysis of the enthalpy equation of the modified white hole, and we get a much detailed picture of when and how did;quantum gravity (cosmology) phase, inflationary phase, and the acceleration phase of the universe happened. We determine the field equations of the modified white hole and evolve the scale factor and compare the evolution to the thermodynamic properties of the universe. We also illustrate that the strong energy condition is violated, but both the null energy condition and the strong cosmic censorship are not violated. Lastly, we couple the enthalpy to the Bose-Einstein condensate at extremely low entropy at the quantum gravity (cosmology) regime. Thereafter, we determine the unstable condition of the Bose-Einstein quantum equation which we interpret as the moment when the big bang occurred.

黑洞与奇点

黑洞可以说是引力最极端的体现,其视界内是个连光也逃不出去的时空区域。近来黑洞在天文观测方面取得令人惊讶的发展,这其中包括:黑洞碰撞的引力波探测以及M87星系的超大质量黑洞的所谓第一张黑洞照片。但是在理论的层面上,黑洞物理尚有许多未解之谜。其中,信息遗失的悖论是最有名的。但是,有另一个问题至少和信息的丢失一样-甚至更加-令人费解的,就是黑洞内部的奇点性质。时空奇点是广义相对论本身无法描述的,在那里究竟发生什么事?黑洞内部的奇点和宇宙大爆炸时的奇点有何不同?奇点是否会裸露在黑洞外面?所谓“宇宙监督猜想”的假设目前有何进展?我们在这篇半科普的文章中简单的介绍这些课题,希望本文章对物理和数学的本科生有所帮助。

Wald测试粒子近似方法在弱的宇宙监督假设中的应用

裸时空奇异点会使所有物理定律在该点失效,彭罗斯提出了宇宙监督假设猜想来避免宇宙中出现裸露的奇点。Wald于1974年提出一个思想实验来考察宇宙监督假设在特定背景下是否成立。本文回顾了Wald当年提出的思想实验,并介绍了一些近些年来基于该思想实验来证明/证伪该猜想的研究成果。

de Rham-Gabadadze-Tolley(dRGT)黑洞的热力学与弱宇宙监督假设

有质量引力理论作为修正引力理论之一,对探究宇宙加速膨胀,以及解释暗能量和暗物质问题等有重要意义。研究了在常规相空间中de Rham-Gabadadze-Tolley(dRGT)有质量引力下球对称黑洞的热力学第一定律、热力学第二定律与弱宇宙监督假设是否成立;并通过图像探究熵的微分变化量随事件视界r_(d)变化的影响,以及与dRGT黑洞无量纲自由参数α,β与引力子质量对该图像的影响。在研究过程中,通过引入标量粒子的能量-动量关系,来验证黑洞热力学第一定律是否成立,通过观察事件视界对熵的微分变化量的影响,来验证黑洞热力学第二定律是否成立。研究发现,黑洞在吸收粒子的同时,其视界半径始终存在,从而使奇点始终没有裸露出来。结果表明,在dRGT有质量引力下球对称黑洞的热力学第一定律,热力学第二定律与弱宇宙监督假设均成立。