Mesozoic contraction deformation in the Yanshan and Taihang mountains is characterized by basement-involved thrust tectonics,basement-cored buckling anticlines and ductile thrust and nappe tectonics.Most of these defo...Mesozoic contraction deformation in the Yanshan and Taihang mountains is characterized by basement-involved thrust tectonics,basement-cored buckling anticlines and ductile thrust and nappe tectonics.Most of these deformations are orientated west-east,west-northwest and northeast to north-northeast.The contraction deformations began in the Permian,continued through the Triassic and Jurassic and terminated in the Early Cretaceous,and constitute an important part of the destruction of the North China Craton.It is estimated,from balanced cross-section reconstructions,that the north-south shortening of the central part of the Yanshan belt before 135 Ma was around 38%.The initial crust thickness,pre-dating the major contraction deformation in late Paleozoic and early Mesozoic,was estimated to be around 35 km based on paleogeographic characteristics.Assuming that the inferred depth of ductile thrusting deformation,20-25 km,was the crust thickness involved in the contraction deformation,and also assuming that the N-S contraction deformation was accommodated by vertical crust thickening,the thickness of the crust after the contraction deformation was expected to be around 47-50 km.This was the approximate crust thickness required for the eclogitization of the lower crust for delamination.The gravity potential accumulated by the isostatic uplift of the thickened crust,together with the decrease in crustal strength caused by the coeval magmatisms associated with the contraction deformation,led to the subsequent extensional collapse of the middle and upper crust although the regional stress regime associated with the plate interactions remained constant.It is inferred that the Mesozoic contraction deformations in the Yanshan and Taihang mountains were not only a significant tectonic process contributing to the destruction of the craton in middle and upper crust but also stimulated delamination at a deep level and the extension of the shallow crust.In other words,both the suspected delamination of the lower crust and upper ma展开更多
The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau＇s tectonic evolution. Here we present new findings on the deforma- tion ...The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau＇s tectonic evolution. Here we present new findings on the deforma- tion geometry and timing of the Wupoer thrust belt at the northeastem margin of Pamir. Field investigations and interpretations of seismic profiles indicate that the eastern portion of the Wupoer thrust belt is dominated by an underlying foreland basin and an overlying piggy-back basin. A regional unconformity occurs between the Pliocene （N2） and the underlying Miocene （NI） or Paleogene （Pg） strata associated with two other local unconformities between Lower Pleistocene （Q1） and N2 and between Middle Pleistocene （Q2-4） and Q1 strata. Results of structural restorations suggest that compres- sional deformation was initiated during the latest Miocene to earliest Pliocene, contributing a total shortening magnitude of 48.6 km with a total shortening rate of 48.12%, most of which occurred in the period from the latest Miocene to earliest Pliocene. These results, com- bined with previous studies on the Kongur and Tarshkor- gan extensional system, suggest an interesting picture of strong piedmont compressional thrusting activity concur- rent with interorogen extensional rifting. Combining these results with previously published work on the lithospheric architecture of the Pamir, we propose that gravitational collapse drove the formation of simultaneous extensional and compressional structures with a weak, ductile middle crustal layer acting as a decollement along which both the extensional and compressional faults merged.展开更多
We conduct numerical investigations on the critical collapse of spherically symmetric massless scalar fields in asymptotically anti-de Sitter spacetime.Our primary focus is on the behavior of the critical amplitude un...We conduct numerical investigations on the critical collapse of spherically symmetric massless scalar fields in asymptotically anti-de Sitter spacetime.Our primary focus is on the behavior of the critical amplitude under various initial configurations of the scalar field.Through our numerical results,we obtain a formula that determines critical amplitude in terms of cosmological constantΛ:A^(*)∝(0.01360σ/v_(0)+0.001751)Λ,whereσdenotes the initial width of the scalar field and is the initial position of the scalar field.Notably,we highlight that the slope of this linear relationship depends on the initial configuration of the scalar field.展开更多
This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results sho...This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results show that a lot of normal faulting type earthquakes concentrate in the central Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of the normal faulting earthquakes are almost in the N-S direction based on the analyses of the equal area projection diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extension is probably an eastward extensional motion, mainly a tectonic active regime in the altitudes of the plateau. The tensional stress in the E-W or WNW-ESE direction predominates the earthquake occurrence in the normal event region of the central plateau. A number of thrust fault and strike-slip fault type earthquakes with strong compressive stress nearly in the NNE-SSW direction occurred on the edges of the plateau. The eastward extensional motion in the Tibetan plateau is attributable to the eastward movement of materials in the upper mantle based on_seismo-tomographic results. The eastward extensional motion in the Tibetan plateau may be related to the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. The northward motion of the Tibetan plateau shortened in the N-S direction probably encounters strong obstructions at the western and northern margins. Extensional motions from the relaxation of the topography and/or gravitational collapse in the altitudes of the plateau occur hardly in the N-S direction. The obstruction for the plateau to move eastward is rather weak.展开更多
The distinctive topography in western Shandong province consists of several NW-WNW-trending mountain ranges and intervening basins. Basins, in which late-stage sediments to the south have progressively overlapped the ...The distinctive topography in western Shandong province consists of several NW-WNW-trending mountain ranges and intervening basins. Basins, in which late-stage sediments to the south have progressively overlapped the earlier sediments and ＂basement＂ rocks of the hanging-wall block, are bounded by S-SW-dipping normal faults to the north. Basin analysis reveals the Jurassic-Cretaceous sedimentary rocks accumulated both within the area of crustal extension and during extensional deformation; they contain a record of a sequence of tectonic events during stretching and can be divided into four tectonic-sequence episodes. These basins were initially developed as early as ca. 200 Ma in the northern part of the study area, extending dominantly N-S from the Early Jurassic until the Late Cretaceous. Although with a brief hiatus due to changes in stress field, to keep uniform N-S extensional polarity in such a long time as 130 Ma requires a relatively stable tectonic controlling factor responsible for the NW- and E-W-extensional basins. The formation of the extensional basins is partly concurrent with regional magmatism, but preceded magmatism by 40 Ma. This precludes a genetic link between local magmatism and extension during the Mesozoic. Based on integrated studies of basins and deformation, we consider that the gravitational collapse of the early overthickened continental crust may be the main tectonic driver for the Mesozoic extensional basins. From the Early Jurassic, dramatic reduction in north-south horizontal compressive stress made the western Shandong deformation belt switch from a state of failure under shortening to one dominated by extension and the belt gravitationally collapsed and horizontally spread to the south until equilibrium was established; synchronously, the normal faults and basins were developed based on the model of simple-shear extensional deformation. This may be relative to the gravitational collapse of the Mesozoic plateau in eastern China.展开更多
A succession of 5 FIA trends（foliation intersection or inflection axes in porphyroblasts） preserved in high temperature-low pressure regime PreCambrian rocks in the Texas Creek, Arkansas River region reflected by th...A succession of 5 FIA trends（foliation intersection or inflection axes in porphyroblasts） preserved in high temperature-low pressure regime PreCambrian rocks in the Texas Creek, Arkansas River region reflected by the fold axial plane traces and schistosity data in this region. Similar fold axial plane trace data measured in Palaeozoic rocks in Chester Dome, Vermont, which is high temperature to medium pressure regime, only preserve the effects of the youngest FIAs of the all 5 FIA sets that obtained in this region. The other three FIA sets have no equivalent fold axial planes. This difference from shallow to deeper orogenic regimes reflects decreasing competency at greater pressure with collapse and unfolding of earlier formed folds. The greater overlying load of rocks has tended to flatten all but the very largest early-formed structures, preserving only those folds that were more recently developed.展开更多
Various earthquake fault types were analyzed for this study on the crust movement in the high region of the Tibetan plateau by analyzing mechanism solutions and stress fields. The results show that a lot of normal fau...Various earthquake fault types were analyzed for this study on the crust movement in the high region of the Tibetan plateau by analyzing mechanism solutions and stress fields. The results show that a lot of normal faulting type earthquakes are concentrated in the central High Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of normal faulting earthquakes are almost in an N-S direction based on the analyses of the Wulff stereonet diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extensions probably are an eastward extensional mo- tion, being mainly a tectonic active regime in the plateau altitudes. The tensional stress in the E-W or NWW-SEE direction predominates earthquake occurrences in the normal event region of the central plateau. The eastward extensional motion in the high Tibetan plateau is attributable to the gravitational collapse of the high plateau and the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. Extensional motions from the relaxation of the topography and/or gravitational collapse in the high plateau hardly occurred along the N-S direction. The obstruction for the plateau to move eastward is rather weak.展开更多
We discuss the Oppenheimer-Snyder-Datt (OSD) solution from a new perspective, introduce a completely new formulation of the problem exclusively in external Schwarzschild space-time (ESM) and present a new treatment of...We discuss the Oppenheimer-Snyder-Datt (OSD) solution from a new perspective, introduce a completely new formulation of the problem exclusively in external Schwarzschild space-time (ESM) and present a new treatment of the singularities in this new formulation. We also give a new Newtonian approximation of the problem. Furthermore, we present new numerical solutions of the modified OSD-model and of the ball-to-ball-collapse with 4 different numerical methods.展开更多
We introduce a novel model for the origin of the observable universe in which a flat universe with a positive vacuum energy is proceeded by a flat universe with a negative vacuum energy. A negative vacuum energy is co...We introduce a novel model for the origin of the observable universe in which a flat universe with a positive vacuum energy is proceeded by a flat universe with a negative vacuum energy. A negative vacuum energy is consistent with a supersymmetric ground state similar to that predicted by superstring theories. A positive vacuum energy could emerge as a result of the gravitational collapse of the negative vacuum energy universe when the matter temperature reaches a characteristic value where supersymmetry is strongly broken. In principle this allows one to derive all the features of our expanding universe from a single parameter: the magnitude of the pre-big bang negative vacuum energy density. In this paper, a simple model for the big bang is introduced which allows us to use the present day entropy density, and temperature fluctuations of the CMB, together with the present day density of dark matter, to predict the magnitude of the negative vacuum energy. This model for the big bang also makes a dramatic prediction: dark matter consists of compact objects with masses on the order of 104 solar masses. Remarkably this is consistent with numerical simulations for how the primordial fluctuations in the density of dark matter give rise to the observed inhomogeneous distribution of matter in our universe. Our model for the big bang also allows for the production of some compact objects with masses greater than 104 solar masses which are consistent with observations of massive compact objects at the center of the earliest galaxies.展开更多
Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal ...Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal state neutron star, manifests nature’s ultimate density of mass and possesses the ultimate electromagnetic barrier. It is then shown how this structure is central to the remarkable mechanism whereby the density is prevented from going higher. A simple process assures that such density is not exceeded—regardless of the quantity of additional mass. As an example, the discourse focuses on the expected progression and outcome when a compact star of <img src="Edit_2c290d68-3330-4724-9e68-e7f1c9d3df1a.png" width="25" height="15" alt="" />—far more mass than can be accommodated by the basic Terminal state structure—undergoes total gravitational collapse. An examination of what happens to the considerable excess mass leads the discussion to the <i>principle of mass extinction by the process of aether deprivation</i> and its profound implications for black-hole physics and the current revolution in cosmology.展开更多
We present a number of parametric class of exact solutions of a radiating star and the matching conditions required for the description of physically meaningful fluid. A number of previously known class of solutions h...We present a number of parametric class of exact solutions of a radiating star and the matching conditions required for the description of physically meaningful fluid. A number of previously known class of solutions have been rediscovered which describe well behaved nature of fluid distributions. The interior matter fluid is shear-free spherically symmetric isotropic and undergoing radial heat flow. The interior metric obeyed all the relevant physical and thermodynamic conditions and matched with Vaidya exterior metric over the boundary. Initially the interior solutions represent a static configuration of perfect fluid which then gradually starts evolving into radiating collapse. The apparent luminosity as observed by the distant observer at rest at infinity and the effective surface temperature are zero in remote past at the instant when collapse begins and at the stage when collapsing configuration reaches the horizon of the black hole.展开更多
Spherical gravitational collapse towards a black hole with non-zero tangential pressure is studied.Exact solutions corresponding to different equations of state are given.We find that when taking the tangential pressu...Spherical gravitational collapse towards a black hole with non-zero tangential pressure is studied.Exact solutions corresponding to different equations of state are given.We find that when taking the tangential pressure into account,the exact solutions have three qualitatively different outcomes.For positive tangential pressure,the shell around a black hole may eventually collapse onto the black hole,or expand to infinity,or have a static but unstable solution,depending on the combination of black hole mass,mass of the shell and the pressure parameter.For vanishing or negative pressure,the shell will collapse onto the black hole.For all eventually collapsing solutions,the shell will cross the event horizon,instead of accumulating outside theeventhorizon,even if clocked by a distant stationary observer.展开更多
We analyze the role of the electromagnetic field for the stability of a shearing viscous star with spherical symmetry. Matching conditions are given for the interior and the exterior metrics. We use a perturbation sch...We analyze the role of the electromagnetic field for the stability of a shearing viscous star with spherical symmetry. Matching conditions are given for the interior and the exterior metrics. We use a perturbation scheme to construct the collapse equation. The range of instability is explored in Newtonian and post Newtonian （pN） limits. We conclude that the electromagnetic field diminishes the effects of the shearing viscosity in the instability range and makes the system more unstable in both Newtonian and post Newtonian approximations.展开更多
According to general relativity the geometry of space depends on the distribution of matter or energy fields. The relation between the local geometrical parameters and the volume enclosed in given limits varies with t...According to general relativity the geometry of space depends on the distribution of matter or energy fields. The relation between the local geometrical parameters and the volume enclosed in given limits varies with the distribution of matter. Thus properties like particle number, mass or energy density, defined in the Euclidean tangent space, cannot be integrated to give conserved integral data like total number, mass or energy. To obtain integral conservation, a correction term must be added to account for the curvature of space. For energy this correction term is the equivalent of potential energy in Newtonian gravitation. With this correction the formation of black holes in the sense of singularities by gravitational collapse does no longer occur and the so called dark energy finds its natural explanation as potential energy of matter itself.展开更多
基金supported by the National Natural Science Foundation of China (Grants Nos. 90814002,40672150,40272086)
文摘Mesozoic contraction deformation in the Yanshan and Taihang mountains is characterized by basement-involved thrust tectonics,basement-cored buckling anticlines and ductile thrust and nappe tectonics.Most of these deformations are orientated west-east,west-northwest and northeast to north-northeast.The contraction deformations began in the Permian,continued through the Triassic and Jurassic and terminated in the Early Cretaceous,and constitute an important part of the destruction of the North China Craton.It is estimated,from balanced cross-section reconstructions,that the north-south shortening of the central part of the Yanshan belt before 135 Ma was around 38%.The initial crust thickness,pre-dating the major contraction deformation in late Paleozoic and early Mesozoic,was estimated to be around 35 km based on paleogeographic characteristics.Assuming that the inferred depth of ductile thrusting deformation,20-25 km,was the crust thickness involved in the contraction deformation,and also assuming that the N-S contraction deformation was accommodated by vertical crust thickening,the thickness of the crust after the contraction deformation was expected to be around 47-50 km.This was the approximate crust thickness required for the eclogitization of the lower crust for delamination.The gravity potential accumulated by the isostatic uplift of the thickened crust,together with the decrease in crustal strength caused by the coeval magmatisms associated with the contraction deformation,led to the subsequent extensional collapse of the middle and upper crust although the regional stress regime associated with the plate interactions remained constant.It is inferred that the Mesozoic contraction deformations in the Yanshan and Taihang mountains were not only a significant tectonic process contributing to the destruction of the craton in middle and upper crust but also stimulated delamination at a deep level and the extension of the shallow crust.In other words,both the suspected delamination of the lower crust and upper ma
文摘The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau＇s tectonic evolution. Here we present new findings on the deforma- tion geometry and timing of the Wupoer thrust belt at the northeastem margin of Pamir. Field investigations and interpretations of seismic profiles indicate that the eastern portion of the Wupoer thrust belt is dominated by an underlying foreland basin and an overlying piggy-back basin. A regional unconformity occurs between the Pliocene （N2） and the underlying Miocene （NI） or Paleogene （Pg） strata associated with two other local unconformities between Lower Pleistocene （Q1） and N2 and between Middle Pleistocene （Q2-4） and Q1 strata. Results of structural restorations suggest that compres- sional deformation was initiated during the latest Miocene to earliest Pliocene, contributing a total shortening magnitude of 48.6 km with a total shortening rate of 48.12%, most of which occurred in the period from the latest Miocene to earliest Pliocene. These results, com- bined with previous studies on the Kongur and Tarshkor- gan extensional system, suggest an interesting picture of strong piedmont compressional thrusting activity concur- rent with interorogen extensional rifting. Combining these results with previously published work on the lithospheric architecture of the Pamir, we propose that gravitational collapse drove the formation of simultaneous extensional and compressional structures with a weak, ductile middle crustal layer acting as a decollement along which both the extensional and compressional faults merged.
基金Supported by the National Natural Science Foundation of China (11925503)the Guangdong Major project of Basic and Applied Basic Research (2019B030302001).
文摘We conduct numerical investigations on the critical collapse of spherically symmetric massless scalar fields in asymptotically anti-de Sitter spacetime.Our primary focus is on the behavior of the critical amplitude under various initial configurations of the scalar field.Through our numerical results,we obtain a formula that determines critical amplitude in terms of cosmological constantΛ:A^(*)∝(0.01360σ/v_(0)+0.001751)Λ,whereσdenotes the initial width of the scalar field and is the initial position of the scalar field.Notably,we highlight that the slope of this linear relationship depends on the initial configuration of the scalar field.
基金supported by the Natural Science Foundation of China (No. 40674026)Commonweal Special Science Foundation of China (Grant No. 200811037)
文摘This paper analyzes various earthquake fault types, mechanism solutions, stress field as well as other geophysical data to study the crust movement in the Tibetan plateau and its tectonic implications. The results show that a lot of normal faulting type earthquakes concentrate in the central Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of the normal faulting earthquakes are almost in the N-S direction based on the analyses of the equal area projection diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extension is probably an eastward extensional motion, mainly a tectonic active regime in the altitudes of the plateau. The tensional stress in the E-W or WNW-ESE direction predominates the earthquake occurrence in the normal event region of the central plateau. A number of thrust fault and strike-slip fault type earthquakes with strong compressive stress nearly in the NNE-SSW direction occurred on the edges of the plateau. The eastward extensional motion in the Tibetan plateau is attributable to the eastward movement of materials in the upper mantle based on_seismo-tomographic results. The eastward extensional motion in the Tibetan plateau may be related to the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. The northward motion of the Tibetan plateau shortened in the N-S direction probably encounters strong obstructions at the western and northern margins. Extensional motions from the relaxation of the topography and/or gravitational collapse in the altitudes of the plateau occur hardly in the N-S direction. The obstruction for the plateau to move eastward is rather weak.
基金This work is the outgrowth of the regional geological study in western Shandong supported by the 973 Project of China(G 1999075502)the National Natural Science Foundation of China(grant 40372050).
文摘The distinctive topography in western Shandong province consists of several NW-WNW-trending mountain ranges and intervening basins. Basins, in which late-stage sediments to the south have progressively overlapped the earlier sediments and ＂basement＂ rocks of the hanging-wall block, are bounded by S-SW-dipping normal faults to the north. Basin analysis reveals the Jurassic-Cretaceous sedimentary rocks accumulated both within the area of crustal extension and during extensional deformation; they contain a record of a sequence of tectonic events during stretching and can be divided into four tectonic-sequence episodes. These basins were initially developed as early as ca. 200 Ma in the northern part of the study area, extending dominantly N-S from the Early Jurassic until the Late Cretaceous. Although with a brief hiatus due to changes in stress field, to keep uniform N-S extensional polarity in such a long time as 130 Ma requires a relatively stable tectonic controlling factor responsible for the NW- and E-W-extensional basins. The formation of the extensional basins is partly concurrent with regional magmatism, but preceded magmatism by 40 Ma. This precludes a genetic link between local magmatism and extension during the Mesozoic. Based on integrated studies of basins and deformation, we consider that the gravitational collapse of the early overthickened continental crust may be the main tectonic driver for the Mesozoic extensional basins. From the Early Jurassic, dramatic reduction in north-south horizontal compressive stress made the western Shandong deformation belt switch from a state of failure under shortening to one dominated by extension and the belt gravitationally collapsed and horizontally spread to the south until equilibrium was established; synchronously, the normal faults and basins were developed based on the model of simple-shear extensional deformation. This may be relative to the gravitational collapse of the Mesozoic plateau in eastern China.
基金supported in part by grants from National Natural Science Foundation of China (41202153)China Council Scholarship (2013693)+1 种基金MLR, China (201211093)Institute of Geology, CAGS (J1101)
文摘A succession of 5 FIA trends（foliation intersection or inflection axes in porphyroblasts） preserved in high temperature-low pressure regime PreCambrian rocks in the Texas Creek, Arkansas River region reflected by the fold axial plane traces and schistosity data in this region. Similar fold axial plane trace data measured in Palaeozoic rocks in Chester Dome, Vermont, which is high temperature to medium pressure regime, only preserve the effects of the youngest FIAs of the all 5 FIA sets that obtained in this region. The other three FIA sets have no equivalent fold axial planes. This difference from shallow to deeper orogenic regimes reflects decreasing competency at greater pressure with collapse and unfolding of earlier formed folds. The greater overlying load of rocks has tended to flatten all but the very largest early-formed structures, preserving only those folds that were more recently developed.
基金supported financially by the National Natural Science Foundation of China (No. 40674026)
文摘Various earthquake fault types were analyzed for this study on the crust movement in the high region of the Tibetan plateau by analyzing mechanism solutions and stress fields. The results show that a lot of normal faulting type earthquakes are concentrated in the central High Tibetan plateau. Many of them are nearly perfect normal fault events. The strikes of the fault planes of normal faulting earthquakes are almost in an N-S direction based on the analyses of the Wulff stereonet diagrams of fault plane solutions. It implies that the dislocation slip vectors of the normal faulting type events have quite great components in the E-W direction. The extensions probably are an eastward extensional mo- tion, being mainly a tectonic active regime in the plateau altitudes. The tensional stress in the E-W or NWW-SEE direction predominates earthquake occurrences in the normal event region of the central plateau. The eastward extensional motion in the high Tibetan plateau is attributable to the gravitational collapse of the high plateau and the eastward extrusion of hotter mantle materials beneath the east boundary of the plateau. Extensional motions from the relaxation of the topography and/or gravitational collapse in the high plateau hardly occurred along the N-S direction. The obstruction for the plateau to move eastward is rather weak.
文摘We discuss the Oppenheimer-Snyder-Datt (OSD) solution from a new perspective, introduce a completely new formulation of the problem exclusively in external Schwarzschild space-time (ESM) and present a new treatment of the singularities in this new formulation. We also give a new Newtonian approximation of the problem. Furthermore, we present new numerical solutions of the modified OSD-model and of the ball-to-ball-collapse with 4 different numerical methods.
文摘We introduce a novel model for the origin of the observable universe in which a flat universe with a positive vacuum energy is proceeded by a flat universe with a negative vacuum energy. A negative vacuum energy is consistent with a supersymmetric ground state similar to that predicted by superstring theories. A positive vacuum energy could emerge as a result of the gravitational collapse of the negative vacuum energy universe when the matter temperature reaches a characteristic value where supersymmetry is strongly broken. In principle this allows one to derive all the features of our expanding universe from a single parameter: the magnitude of the pre-big bang negative vacuum energy density. In this paper, a simple model for the big bang is introduced which allows us to use the present day entropy density, and temperature fluctuations of the CMB, together with the present day density of dark matter, to predict the magnitude of the negative vacuum energy. This model for the big bang also makes a dramatic prediction: dark matter consists of compact objects with masses on the order of 104 solar masses. Remarkably this is consistent with numerical simulations for how the primordial fluctuations in the density of dark matter give rise to the observed inhomogeneous distribution of matter in our universe. Our model for the big bang also allows for the production of some compact objects with masses greater than 104 solar masses which are consistent with observations of massive compact objects at the center of the earliest galaxies.
文摘Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal state neutron star, manifests nature’s ultimate density of mass and possesses the ultimate electromagnetic barrier. It is then shown how this structure is central to the remarkable mechanism whereby the density is prevented from going higher. A simple process assures that such density is not exceeded—regardless of the quantity of additional mass. As an example, the discourse focuses on the expected progression and outcome when a compact star of <img src="Edit_2c290d68-3330-4724-9e68-e7f1c9d3df1a.png" width="25" height="15" alt="" />—far more mass than can be accommodated by the basic Terminal state structure—undergoes total gravitational collapse. An examination of what happens to the considerable excess mass leads the discussion to the <i>principle of mass extinction by the process of aether deprivation</i> and its profound implications for black-hole physics and the current revolution in cosmology.
文摘We present a number of parametric class of exact solutions of a radiating star and the matching conditions required for the description of physically meaningful fluid. A number of previously known class of solutions have been rediscovered which describe well behaved nature of fluid distributions. The interior matter fluid is shear-free spherically symmetric isotropic and undergoing radial heat flow. The interior metric obeyed all the relevant physical and thermodynamic conditions and matched with Vaidya exterior metric over the boundary. Initially the interior solutions represent a static configuration of perfect fluid which then gradually starts evolving into radiating collapse. The apparent luminosity as observed by the distant observer at rest at infinity and the effective surface temperature are zero in remote past at the instant when collapse begins and at the stage when collapsing configuration reaches the horizon of the black hole.
基金Supported by National Natural Science Foundation of China(11373036,11133002)the National Program on Key Research and Development Project(2016YFA0400802)the Key Research Program of Frontier Sciences,CAS,(QYZDY-SSW-SLH008)
文摘Spherical gravitational collapse towards a black hole with non-zero tangential pressure is studied.Exact solutions corresponding to different equations of state are given.We find that when taking the tangential pressure into account,the exact solutions have three qualitatively different outcomes.For positive tangential pressure,the shell around a black hole may eventually collapse onto the black hole,or expand to infinity,or have a static but unstable solution,depending on the combination of black hole mass,mass of the shell and the pressure parameter.For vanishing or negative pressure,the shell will collapse onto the black hole.For all eventually collapsing solutions,the shell will cross the event horizon,instead of accumulating outside theeventhorizon,even if clocked by a distant stationary observer.
基金the Higher Education Commission, Islamabad, Pakistan, for its financial support through the Indigenous Ph.D. 5000 Fellowship Program Batch-Ⅶ
文摘We analyze the role of the electromagnetic field for the stability of a shearing viscous star with spherical symmetry. Matching conditions are given for the interior and the exterior metrics. We use a perturbation scheme to construct the collapse equation. The range of instability is explored in Newtonian and post Newtonian （pN） limits. We conclude that the electromagnetic field diminishes the effects of the shearing viscosity in the instability range and makes the system more unstable in both Newtonian and post Newtonian approximations.
文摘According to general relativity the geometry of space depends on the distribution of matter or energy fields. The relation between the local geometrical parameters and the volume enclosed in given limits varies with the distribution of matter. Thus properties like particle number, mass or energy density, defined in the Euclidean tangent space, cannot be integrated to give conserved integral data like total number, mass or energy. To obtain integral conservation, a correction term must be added to account for the curvature of space. For energy this correction term is the equivalent of potential energy in Newtonian gravitation. With this correction the formation of black holes in the sense of singularities by gravitational collapse does no longer occur and the so called dark energy finds its natural explanation as potential energy of matter itself.
