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 mom...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.展开更多
FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and...FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and rigorously define a cosmological arrow of time. This is in sharp contrast to inflationary models, which appear to violate the second law of thermodynamics within the early universe. Furthermore, by virtue of the same physical assumptions applying at any cosmic time t, the perpetually-flat FSC model predicts the degree of scale invariance observed in the CMB anisotropy pattern, without requiring an explosive and exceedingly brief inflationary epoch. Penrose’s concepts, as described in this paper, provide support for the idea that FSC models gravitational entropy and Verlinde’s emergent gravity theory.展开更多
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 instabil...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.展开更多
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,whic...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.展开更多
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 (cosmo...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.展开更多
该文首先简要介绍了无线电掩星探测技术及其发展现状和传统Abel变换方法面临的问题。为改进传统Abel变换反演方法,利用电子密度廓线的分离假设,引进了分离假设反演法。随后利用国际电离层参考模式IRI2007给出1000个掩星事件截面的模拟...该文首先简要介绍了无线电掩星探测技术及其发展现状和传统Abel变换方法面临的问题。为改进传统Abel变换反演方法,利用电子密度廓线的分离假设,引进了分离假设反演法。随后利用国际电离层参考模式IRI2007给出1000个掩星事件截面的模拟数据及COSMIC卫星星座的一天实测数据,进行比较计算,并对结果进行了分析,验证了分离假设反演法的有效性。文中还给出了垂直电子总量VTEC(Vertical Total Electron Content)先验场的获取途径。最后,对分离假设反演法的进一步研究的方向进行了探讨。展开更多
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-...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.展开更多
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 thermody...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.展开更多
Several significant events of a geological nature occurred approximately 800 ka before the present: (1) Australasian tektite fall (AA), (2) Brunhes-Matuyama geomagnetic reversal (BMR), (3) mid-Pleistocene changes in i...Several significant events of a geological nature occurred approximately 800 ka before the present: (1) Australasian tektite fall (AA), (2) Brunhes-Matuyama geomagnetic reversal (BMR), (3) mid-Pleistocene changes in ice age cycles. Add to these the undated fault system (4) in the South-West (SW) of the South China Sea (SCS). Here we offer a unified cause for all four of these in (5), an impact in the SCS of a large, massive cosmic object, likely a comet, obliquely coming from the SW at an extremely shallow angle, striking the Sunda shelf yet unexploded with the shock of its compressed air bow wave, and causing the continual shelf and slope to collapse, resulting in the fault system (4), then traveling almost tangentially to the surface, exploding at impact with the sea surface, ejecting the tektites (1), creating the formation underlying the later atolls of Spratlies Archipelago (6), Nansha Islands in Chinese, & causing the BMR (2). An explanation of event (3) was Richard Muller’s hypothesis of planet Earth passing through an interplanetary dust cloud periodically due to ecliptic precession. Here we hypothesize this cloud actually is a belt of Australasian tektites ejected into space at super-orbital velocities that Earth encounters about every 100 ka.展开更多
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 ener...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.展开更多
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...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.展开更多
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...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.展开更多
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 ...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.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11875095 and 11903025)the Basic Research Project of Science and Technology Committee of Chongqing(Grant No.cstc2018jcyjA2480)the Fundamental Research Funds of ChinaWest Normal University(Grant No.18Q062).
文摘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.
文摘FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and rigorously define a cosmological arrow of time. This is in sharp contrast to inflationary models, which appear to violate the second law of thermodynamics within the early universe. Furthermore, by virtue of the same physical assumptions applying at any cosmic time t, the perpetually-flat FSC model predicts the degree of scale invariance observed in the CMB anisotropy pattern, without requiring an explosive and exceedingly brief inflationary epoch. Penrose’s concepts, as described in this paper, provide support for the idea that FSC models gravitational entropy and Verlinde’s emergent gravity theory.
基金supported by the National Natural Science Foundation of China(Grant No.12005080)supported by the National Natural Science Foundation of China(Grant No.12205014)+1 种基金the Guangdong Basic and Applied Research Foundation(Grant No.217200003)the Talents Introduction Foundation of Beijing Normal University(Grant No.310432102)。
文摘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.
基金supported by Foundation Research Project of Shaanxi Province in Natural Science (Grant No.2019JQ-919)Special Project of Education Department of Shaanxi Province in Natural Science (Grant No.20JK0635)Talent Foundation of Weinan Normal University (Grant No.201120039)。
文摘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.
文摘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.
文摘该文首先简要介绍了无线电掩星探测技术及其发展现状和传统Abel变换方法面临的问题。为改进传统Abel变换反演方法,利用电子密度廓线的分离假设,引进了分离假设反演法。随后利用国际电离层参考模式IRI2007给出1000个掩星事件截面的模拟数据及COSMIC卫星星座的一天实测数据,进行比较计算,并对结果进行了分析,验证了分离假设反演法的有效性。文中还给出了垂直电子总量VTEC(Vertical Total Electron Content)先验场的获取途径。最后,对分离假设反演法的进一步研究的方向进行了探讨。
基金NSFC(Grant No.11505119,11005016,11875196 and 11375121)。
文摘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.
基金Supported by the National Natural Science Foundation of China(11205125,11875095)
文摘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.
文摘Several significant events of a geological nature occurred approximately 800 ka before the present: (1) Australasian tektite fall (AA), (2) Brunhes-Matuyama geomagnetic reversal (BMR), (3) mid-Pleistocene changes in ice age cycles. Add to these the undated fault system (4) in the South-West (SW) of the South China Sea (SCS). Here we offer a unified cause for all four of these in (5), an impact in the SCS of a large, massive cosmic object, likely a comet, obliquely coming from the SW at an extremely shallow angle, striking the Sunda shelf yet unexploded with the shock of its compressed air bow wave, and causing the continual shelf and slope to collapse, resulting in the fault system (4), then traveling almost tangentially to the surface, exploding at impact with the sea surface, ejecting the tektites (1), creating the formation underlying the later atolls of Spratlies Archipelago (6), Nansha Islands in Chinese, & causing the BMR (2). An explanation of event (3) was Richard Muller’s hypothesis of planet Earth passing through an interplanetary dust cloud periodically due to ecliptic precession. Here we hypothesize this cloud actually is a belt of Australasian tektites ejected into space at super-orbital velocities that Earth encounters about every 100 ka.
基金Supported by the National Natural Science Foundation of China(11875095)Basic Research Project of Science and Technology Committee of Chongqing(cstc2018jcyj A2480)
文摘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.
基金Supported by National Natural Science Foundation of China(11875095)Basic Research Project of Science and Technology Committee of Chongqing(cstc2018jcyjA2480,cstc2019jcyjA2091)
文摘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.
基金supported in part by NSFC(Grant No.11375121,11747171,11747302 and 11847305)Natural Science Foundation of Chengdu University of TCM(Grants No.ZRYY1729 and ZRQN1656)+2 种基金Discipline Talent Promotion Program of Xinglin Scholars(Grant No.QNXZ2018050)The Key Fund Project for Education Department of Sichuan(Grant No.18ZA0173)Sichuan University Students Platform for Innovation and Entrepreneurship Training Program(Grant No.C2019104639).
文摘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.
文摘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.