The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Blake Temple - One of the best experts on this subject based on the ideXlab platform.
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Applications of Shock-Waves in General Relativity
Hyperbolic Problems: Theory Numerics Applications, 1999Co-Authors: Blake Temple, Joel SmollerAbstract:We discuss recently published work and work in progress on applications of shock-waves in general relativity. We discuss the problem of constructing shock-waves arbitrarily close to the Schwarzschild Radius of a star, and the problem of introducing a shock-wave into the standard theory of cosmology.
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Shock waves near the Schwarzschild Radius and stability limits for stars
Physical Review D, 1997Co-Authors: Joel Smoller, Blake TempleAbstract:We analyze the time dilation associated with the propagation of a shock wave that moves outward into a static fluid sphere in general relativity. In this way we investigate the possibility that a shock wave inside a star could supply the pressure required to hold up a highly collapsed static outer layer. In such a model, one would observe a highly redshifted, time-independent emissions spectrum during the time interval between the time when the shock wave is formed, and the time when it reaches the star surface. Our conclusion is that the time it takes a shock wave to pass through a surface layer and reach the surface of a star, as seen by an observer in the far field, is on the order of the total mass of the star times a function that tends to infinity as the outer boundary of the star tends to its Schwarzschild Radius.
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Solutions of the Oppenheimer--Volkoff Equations Inside 9/8$^{ths}$ of the Schwarzschild Radius
Communications in Mathematical Physics, 1997Co-Authors: Joel Smoller, Blake TempleAbstract:We refine the Buchdahl 9/8ths stability theorem for stars by describing quantitatively the behavior of solutions to the Oppenheimer–Volkoff equations when the star surface lies inside 9/8ths of the Schwarzschild Radius. For such solutions we prove that the density and pressure always have smooth profiles that decrease to zero as the Radius r→ 0, and this implies that the gravitational field becomes repulsive near r= 0 whenever the star surface lies within 9/8ths of its Schwarzschild Radius.
Jun Fukue - One of the best experts on this subject based on the ideXlab platform.
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Sound Speed and the Pseudo-Newtonian Potential
Publications of the Astronomical Society of Japan, 2004Co-Authors: Jun FukueAbstract:We propose a special-relativistic correction to the sound speed calculated from the Paczynski and Wiita (1980) pseudo-Newtonian potential, in order to avoid divergence to infinity at the Schwarzschild Radius. Under this correction, the re-scaled sound speed approaches c/ √ 3 at the Schwarzschild Radius; otherwise, it diverges there. Spherical flows onto a black hole are briefly discussed.
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General Relativity and the Pseudo-Newtonian Potential
Publications of the Astronomical Society of Japan, 2004Co-Authors: Jun FukueAbstract:We propose a metric correction on velocities calculated from the Paczy´ nski and Wiita (1980) pseudo-Newtonian potential, in order to avoid the divergence to infinity at the Schwarzschild Radius. Cold disk flows onto a black hole are briefly discussed.
Joel Smoller - One of the best experts on this subject based on the ideXlab platform.
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Applications of Shock-Waves in General Relativity
Hyperbolic Problems: Theory Numerics Applications, 1999Co-Authors: Blake Temple, Joel SmollerAbstract:We discuss recently published work and work in progress on applications of shock-waves in general relativity. We discuss the problem of constructing shock-waves arbitrarily close to the Schwarzschild Radius of a star, and the problem of introducing a shock-wave into the standard theory of cosmology.
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Shock waves near the Schwarzschild Radius and stability limits for stars
Physical Review D, 1997Co-Authors: Joel Smoller, Blake TempleAbstract:We analyze the time dilation associated with the propagation of a shock wave that moves outward into a static fluid sphere in general relativity. In this way we investigate the possibility that a shock wave inside a star could supply the pressure required to hold up a highly collapsed static outer layer. In such a model, one would observe a highly redshifted, time-independent emissions spectrum during the time interval between the time when the shock wave is formed, and the time when it reaches the star surface. Our conclusion is that the time it takes a shock wave to pass through a surface layer and reach the surface of a star, as seen by an observer in the far field, is on the order of the total mass of the star times a function that tends to infinity as the outer boundary of the star tends to its Schwarzschild Radius.
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Solutions of the Oppenheimer--Volkoff Equations Inside 9/8$^{ths}$ of the Schwarzschild Radius
Communications in Mathematical Physics, 1997Co-Authors: Joel Smoller, Blake TempleAbstract:We refine the Buchdahl 9/8ths stability theorem for stars by describing quantitatively the behavior of solutions to the Oppenheimer–Volkoff equations when the star surface lies inside 9/8ths of the Schwarzschild Radius. For such solutions we prove that the density and pressure always have smooth profiles that decrease to zero as the Radius r→ 0, and this implies that the gravitational field becomes repulsive near r= 0 whenever the star surface lies within 9/8ths of its Schwarzschild Radius.
Yoshinori Matsuo - One of the best experts on this subject based on the ideXlab platform.
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Static black hole and vacuum energy: thin shell and incompressible fluid
Journal of High Energy Physics, 2018Co-Authors: Yoshinori MatsuoAbstract:With the back reaction of the vacuum energy-momentum tensor consistently taken into account, we study static spherically symmetric black-hole-like solutions to the semi-classical Einstein equation. The vacuum energy is assumed to be given by that of 2-dimensional massless scalar fields, as a widely used model in the literature for black holes. The solutions have no horizon. Instead, there is a local minimum in the Radius. We consider thin shells as well as incompressible fluid as the matter content of the black-hole-like geometry. The geometry has several interesting features due to the back reaction of vacuum energy. In particular, Buchdahl’s inequality can be violated without divergence in pressure, even if the surface is below the Schwarzschild Radius. At the same time, the surface of the star can not be far below the Schwarzschild Radius for a density not much higher than the Planck scale, and the proper distance from its surface to the origin can be very short even for very large Schwarzschild Radius. The results also imply that, contrary to the folklore, in principle the Boulware vacuum can be physical for black holes.
Espen Gaarder Haug - One of the best experts on this subject based on the ideXlab platform.
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Using a Grandfather Pendulum Clock to Measure the World’s Shortest Time Interval, the Planck Time (with Zero Knowledge of G).
viXra, 2019Co-Authors: Espen Gaarder HaugAbstract:Haug [1] has recently introduced a new theory of unified quantum gravity coined “collision space-time.” From this new and deeper understanding of mass we can also understand how a grandfather pendulum clock can be used to measure the world shortest time interval, namely the Planck time [2, 3], indirectly. Such a clock can, therefore, also be used to measure the diameter of an indivisible particle indirectly. Further, such a clock can easily measure the Schwarzschild Radius of the gravity object and what we will call “Schwarzschild time.” This basically proves that the Newton gravitational constant is not needed to find the Planck length or the Planck time; it is also not needed to find the Schwarzschild Radius. Unfortunately, there is significant inertia in the current physics establishment towards new ideas that could significantly alter our perspective on the fundamentals, but this is not new in the history of science. Still, the idea that the Planck time can be measured totally independent of any knowledge of Newton’s gravitational constant could be very important for moving forward in physics.
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Maximum Velocity for Matter in Relation to the Schwarzschild Radius Predicts Zero Time Dilation for Quasars
viXra, 2018Co-Authors: Espen Gaarder HaugAbstract:This is a short note on a new way to describe Haug’s newly introduced maximum velocity for matter in relation to the Schwarzschild Radius. This leads to a probabilistic Schwarzschild Radius for elementary particles with mass smaller than the Planck mass. In addition, our maximum velocity, when linked to the Schwarzschild Radius, seems to predict that particles just at that Radius cannot move. This implies that radiation from the Schwarzschild Radius not can undergo velocity time dilation. Our maximum velocity of matter, therefore, seems to predict no time dilation, even in high Z quasars, as has surprisingly been observed recently.
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Gravity without Newton's Gravitational Constant and No Knowledge of Mass Size
2018Co-Authors: Espen Gaarder HaugAbstract:In this paper we show that the Schwarzschild Radius can be extracted easily from any gravitationally-linked phenomena without having knowledge of the Newton gravitational constant or the mass size of the gravitational object. Further, the Schwarzschild Radius can be used to predict any gravity phenomena accurately, again without knowledge of the Newton gravitational constant and also without knowledge of the size of the mass, although this may seem surprising at first. Hidden within the Schwarzschild Radius are the mass of the gravitational object, the Planck mass (their relative mass), and the Planck length. We do not claim to have all the answers, but this seems to indicate that gravity is quantized, even at a cosmological scale, and this quantization is directly linked to the Planck units. This also supports our view that the Newton gravitational constant is a universal composite constant of the form G = l p 2 c 3 ℏ , rather than relying on the Planck units as a function of G. This does not mean that Newton’s gravitational constant is not a universal constant, but that it is instead a composite universal constant that depends on the Planck length, the speed of light, and the Planck constant. Further, G × 1   weight  unit c 2 = G c 2 is the Schwarzschild Radius off one weight unit. So G is only needed when we want to use gravity to find the weight of an object, such as weighing the Earth. This is, to our knowledge, the first paper that shows how a long series of major gravity predictions and measurements can be completed without any knowledge of the mass size of the object, or Newton’s gravitational constant. As a minimum we think it provides an interesting new angle for evaluating existing gravity theories, and it may even give us a small hint on how to combine quantum gravity with Newton and Einstein gravity.
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Gravity Without Newton’s Gravitational Constant and no Knowledge of Mass Size
viXra, 2018Co-Authors: Espen Gaarder HaugAbstract:In this paper, we show that the Schwarzschild Radius can be extracted easily from any gravitationally-linked phenomena without having knowledge of Newton's gravitational constant or the mass size of the gravitational object. Further, the Schwarzschild Radius can be used to predict any gravity phenomena accurately, again without knowledge of Newton's gravitational constant and also without knowledge of the size of the mass, although this may seem surprising at first. Hidden within the Schwarzschild Radius are the mass of the gravitational object, the Planck mass, and the Planck length, which we will assert contain the secret essence related to gravity, in addition to the speed of light, (the speed of gravity). This seems to indicate that gravity is quantized, even at the cosmological scale, and this quantization is directly linked to the Planck units. This also supports our view that Newton's gravitational constant is a universal composite constant of the form G=l_p^2c^3/hbar, rather than relying on the Planck units as a function of G. This does not mean that Newton's gravitational constant is not a universal constant, but rather that it is a composite universal constant, which depends on the Planck length, the speed of light, and the Planck constant. This is, to our knowledge, the first paper that shows how a long series of major gravity predictions and measurements can be completed without any knowledge of the mass size of the object, or Newton's gravitational constant. As a minimum, we think it provides an interesting new angle for evaluating existing theories of gravitation, and it may even provide a hint on how to combine quantum gravity with Newton and Einstein gravity.
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Is the Schwarzschild Radius Truly a Radius
viXra, 2016Co-Authors: Espen Gaarder HaugAbstract:This paper questions the assumption that the Schwarzschild Radius actually represents a Radius. It has recently been shown by Haug (2016) that the Schwarzschild Radius for any object can simply be written as N2l_p, where N is the number of Planck masses into which we can ``hypothetically" pack an object of interest and l_p is the well known Planck length. The Schwarzschild Radius seems to represent the length of the number of Planck mass objects we can ``hypothetically" pack a planet or star into and then we can place them in perfect alignment along a single strand (of single particles) in a straight line.
