Source Of Gravity Research Articles

Energy Change of Particles or Photons at Crossing Gravity Fields of Galaxy Clusters or Single Stars: The Concept of Gravitons

We investigate the gravitational action of cosmic mass associations, like stars or stellar clusters, on moving massive objects. Hereby the relativistic effect of propagating field quanta communicating the position of gravity sources by means of so-called gravitons is taken into account. In case of moving objects this causes an aberration of the recognized actual location of the cosmic mass sources with respect to their positions in the cosmic rest frame. The astonishing effect of that position retardation is that a moving objekt, even if it moves right through the center of a centrally symmetric cluster mass association, experiences a net gravitational braking and energy loss. Applying this view to the problem of a planetary object orbiting around a central mass like the sun, then it turns out that the orbiting planet permanently reduces its orbital angular momentum, since permanently experiencing a gravitational force component antiparallel to its orbital motion. From that an orbital decay time can be derived which for a terrestrial planet would imply the spiralling-in period of only a few 103 years. Compared to the age of the planet earth of about 4. 5 Billion years this represents a big problem of understanding. In this article we cannot offer a rational solution of this problem and thus we simply end with the recommendation to perhaps reinvestigate the theoretical concept of gravitons thought to be the quantum messengers of gravitational fields.

The 6D Standing Wave Braneworld with Real Scalar Field

We introduce new non-static 6D braneworld model involving real 6D scalar field as the source of gravity. The brane is generated by the standing waves of gravity and real scalar field oscillating in the bulk. The oscillations are out of phase in time, so that the oscillation energy transfers back and forth between the standing waves of gravity and real scalar field. Underlying geometry of 6D spacetime has no horizons, the brane has one internal (on-brane) extra dimension which is compact and sufficiently small to describe our universe (hybrid compactification), and there is also one external to brane (off-brane) extra dimension, which is large or even infinite for the observers on the brane. We show that there are two different physical limits realizing the trapping of classical particles and light and also of massless scalar fields on the brane. In the first one, the amplitude of standing waves must be sufficiently large, while in the second one the amplitude of standing waves can be small enough. We show that in both cases particles and light, as well as massless scalar fields, are dynamically trapped on the brane by the pressure of bulk standing waves of gravity and real scalar field.

Linear and weakly nonlinear analysis of a ferrofluid layer for an LTNE model with variable gravity and internal heat source

A ferrofluid saturated porous layer convection problem is studied in the variable gravitational field for a local thermal nonequilibrium (LTNE) model. Internal heating and variation (increasing or decreasing) in gravity with distance through the layer affected the stability of the convective system. The Darcy model is employed for the momentum equation and the LTNE model for the energy equation. The boundaries are considered to be rigid-isothermal and paramagnetic. For the linear stability analysis of the three-dimensional problem, the normal mode has been applied and the eigenvalue problem is solved numerically using Chebyshev pseudospectral method, while weakly nonlinear analysis is carried out with a truncated Fourier series. The effect of different dimensionless parameters on the Rayleigh number has also been studied. We found that the system becomes unstable on the increasing value of nonlinearity index of magnetization ( $$M_3$$ ), porosity-modified conductivity ratio ( $$\beta $$ ), and internal heat parameter ( $$\xi $$ ). It is observed that the system is stabilized by increasing the value of the Langevin parameter ( $$\alpha _\mathrm{{L}}$$ ), variable gravity coefficient ( $$\delta $$ ), and effective heat transfer parameter ( $$H_1$$ ). Runge–Kutta–Gill method has been used for solving the finite-amplitude equations to study the transient behavior of the Nusselt number. Streamlines and isotherms patterns are determined for the steady case and are presented graphically.

Rotating Melvin-like Universes and Wormholes in General Relativity

We find a family of exact solutions to the Einstein–Maxwell equations for rotating cylindrically symmetric distributions of a perfect fluid with the equation of state p=wρ (|w|<1), carrying a circular electric current in the angular direction. This current creates a magnetic field along the z axis. Some of the solutions describe geometries resembling that of Melvin’s static magnetic universe and contain a regular symmetry axis, while some others (in the case w>0) describe traversable wormhole geometries which do not contain a symmetry axis. Unlike Melvin’s solution, those with rotation and a magnetic field cannot be vacuum and require a current. The wormhole solutions admit matching with flat-space regions on both sides of the throat, thus forming a cylindrical wormhole configuration potentially visible for distant observers residing in flat or weakly curved parts of space. The thin shells, located at junctions between the inner (wormhole) and outer (flat) regions, consist of matter satisfying the Weak Energy Condition under a proper choice of the free parameters of the model, which thus forms new examples of phantom-free wormhole models in general relativity. In the limit w→1, the magnetic field tends to zero, and the wormhole model tends to the one obtained previously, where the source of gravity is stiff matter with the equation of state p=ρ.

A comparative study on different filters for enhancing potential field source boundaries: synthetic examples and a case study from the Song Hong Trough (Vietnam)

Locating the horizontal boundaries of magnetic and gravity sources provides a fundamental tool for interpreting geological structures. Many filters for detecting the source boundaries have been proposed. These filters are generally constructed based on vertical and horizontal gradients of the magnetic and gravity data. This paper presents a comparative study of various boundary detection filters such as gradient amplitude, tilt derivative, gradient amplitude of tilt angle, theta map, horizontal tilt angle, hyperbolic tilt angle, and tilt angle of gradient amplitude. The applicability of each filter was tested on three synthetic gravity data sets. The results show that the use of the tilt angle of gradient amplitude can display the edges more clearly and precisely. Furthermore, the filters are also performed on a real gravity data set from the Song Hong Trough (Vietnam) where the result computed by the tilt angle of gradient amplitude is also in accord with the geology information.

The western São Francisco pericraton interpreted from crustal magnetic and gravity sources

The Neoproterozoic Brasiliano Orogeny shaped the former São Francisco paleocontinent into a preserved cratonic nucleus surrounded by a pericratonic region. In central Brazil, this pericraton crops out as the Goiás Massif, the basement of the northern Brasília Belt. The well-known difficulty of tracing suture zones on surface led to a longstanding dispute on whether the Rio Maranhão Thrust, a structure separating the Internal Zone and the External Zone of the Brasília Belt, marked the Brasiliano suture. This interpretation was largely based on regional gravimetric data showing a steep discontinuity at depth, between these zones. However, the Rio Maranhão Thrust separates two pericratonic domains of the Goiás Massif (Campinorte Domain and Cavalcante-Arraias Domain), which otherwise share similar Paleoproterozoic ages and geology. To properly address the main structural boundaries within the northern Brasília Belt, this work was focused on comparing shallow and deep gravity and magnetic data processed as enhanced anomalies and through matched filter analysis. Our results show that the large mafic-ultramafic complexes within the Internal Zone of the Brasília Belt are masking a smooth gravimetric transition into the External Zone. Additionally, the alleged suture zone is coincident with the Mesoproterozoic rift-related Juscelândia and Palmeirópolis volcano-sedimentary sequences, which have been largely ignored in their role as creating magnetic and gravity suture-like signatures. Along with previous structural and geochronological data, our results argue against the Rio Maranhão Thrust as a suture zone and, instead, support the alternative interpretation of the thrust as an intracontinental feature within a portion of the São Francisco pericraton. This pericratonic region, unliked the preserved cratonic core, was widely affected by Mesoproterozoic rifting and Neoproterozoic thick-skinned thrusting. The Rio Paranã Thrust, on the other hand, is unnoticeable below 8 km depth in gravity and magnetic data, suggesting thin-skinned tectonics also associated with the Brasiliano Orogeny. Finally, the relative crustal homogeneity from the São Francisco craton into the Goiás Massif evidenced by our gravity data and confirmed by first- and second-order magnetic lineaments confirms the nature of a pericraton with dominantly NE (N20-40E) trending lineaments. These lineaments were progressively overprinted by Brasiliano NNE (N45-70E) structures from the western margin of the External Zone into the Internal Zone.

Stamec-Gravitism: A Simple Theoretical Study to Inspire a Prototype Fabrication for Mobile Perpetual Electricity Generator

This novel research presents a theoretical work and its simple simulation as a breakthrough way to derive a mobile electricity apparatus with the weight of ~5 kg generated by an eternal gravity force on earth. The theoretical research was extracted in such a guide simply by incorporating statistical mechanics, classical mechanics and basic theory of electricity and magnetism. In the above-mentioned smart calculation, ones obtain the definition of a constant temperature particularly in isothermal enviromental nature. Furthermore, by solving the whole basic physics relationship with gravity source of power, the electrical energy formula was excerpted with the simplification through a Stamec-Gravitism: a simple theoretical study to inspire a prototype fabrication for mobile perpetual electricity generator. Furthermore, the work is sustained with its simulation results to find out the working physical parameters for normal use of alternating current (AC) electricity system with frequency of 50 Hz and electrical power of ~100 Watt for each proposed apparatus. This research suggests a bright future for the light mobile electricity generator for the needy and the poor in every different nations and tribes consisted of thousands of small islands because it does not need battery storage to work in any different conditions and weather so that such novel work can contribute in a large scale to mitigate natural disasters on earth by implementing it in all human being daily activities based energy uses.

Cluster Gravity – The Gravity Between Critical Masses, What Is the Source of Gravity?

This paper shows the concept of cluster gravity. The theme of cluster gravity comes as a result of the source of gravity and the movement of the bodies, pending accordingly to the vacuum and the space-time elasticity. It showed how a set of masses act as one mass of gravity to another set of masses with proportional mass. Then, for instance, two sets of masses act have the same behavior way as two masses.

On the Dimension of Tetrads in the Effective Gravity

Two different sources of emergent gravity lead to the inverse square of length dimension of metric field, $[g_{\mu\nu}]=1/[l]^2$, as distinct from the conventional dimensionless metric, $[g_{\mu\nu}]=1$, for $c = 1$. In both scenarios all the physical quantities, which obey diffeomorphism invariance, such as the Newton constant, the scalar curvature, the cosmological constant, particle masses, fermionic and scalar bosonic fields, etc., are dimensionless.

Basement faults deduction at a dumpsite using advanced analysis of gravity and magnetic anomalies

ABSTRACTA study of the fracture systems in the basement of the Matatlan urban waste dump of Guadalajara City, near the western edge of the Rio Grande de Santiago canyon (southwestern Mexico), is reported. The Matatlan dumpsite was developed on top of andesitic and rhyolitic rocks. Measurements at outcrops indicated that N–S (0°–15° and 165°–180°), N45–90E and N105–135E fracture systems affect the basement. Statistical analysis (micromagnetic method) of magnetic lineament azimuths indicated the presence of two lineament groups. The major one (N60–120E) has a maximum at N90–105E, and a secondary group (N120–165E). The gravity anomalies are featured by a major group (N60–120E, with maximums at N60–75E, and N105–120E) and a secondary group (N120–180E). Thus, a good to fair correlation exists between the measured fracture orientations and the lineaments featuring the gravity and magnetic anomalies. Horizontal derivative and tilt angle depicted horizontal limits of anomaly‐causative bodies. Results of the micromagnetic method are consistent with fracture orientations and with the limits established through edge‐detection techniques. Lineaments established by means of the gravity and magnetic Euler deconvolution are also consistent. Gravity and magnetic Euler deconvolution helped to estimate the depth extent of the limits of gravity and magnetic common sources. Euler deconvolution indicated the fault or contact nature of these lineaments. Furthermore, Euler deconvolution indicated slopes of the limits of gravity and magnetic sources. The fault or fracture nature of the major lineaments was finally confirmed by forward modelling (forward 2D cooperative modelling of gravity and magnetic profiles). For example, lineaments delimiting the northern depression could be characterized as normal faults. In general, this study indicates that it is possible, based on gravity and magnetic data, to characterize fractures affecting the basement of a dumpsite, a key parameter in hydrogeophysical studies. In particular, through this study, the inferred structures could be associated with regional tectonic faulting, which might provide migration paths to unhealthy lixiviate outside the dumpsite, giving rise to the contamination of the neighbouring environment. In particular, the study explains the presence of an unhealthy leachate waterfall to the northeast of the dumping site. Heavy metal contents in samples from this waterfall support that lixiviates originate at the dumpsite.

Delineation of shallow structures in Madawara igneous complex, Bundelkhand Craton, India using gravity–magnetic data: Implication to tectonic evolution and mineralization

An integrated gravity–magnetic study has been carried out over Madawara Igneous Complex (MIC) in southern part of Bundelkhand Craton with an aim to decipher shallow crustal configuration and mineralized zones, thereby to improve the understanding of tectonic evolution of the region. Derived gravity and magnetic anomaly maps show good correlation with known geology and have delineated continuity of mafic–ultramafic intrusive bodies in EW direction. Radially averaged power spectrum (2D) and solutions derived from 3D Euler deconvolution have revealed average basement depths for gravity sources as ~0.3, 1.2 and 3.2 km, whereas for magnetic sources as ~0.3 and 1.2 km. From this study, these interfaces could be attributed to sedimentary origin for shallowest layer, mafic–ultramafic intrusive for intermediate layer and changes within the granite–gneissic basement for deeper solutions. Two-dimensional inverse modelling of residual gravity anomaly has delineated intrusion of highly dense mafic–ultramafic rocks from deeper part within the granite gneissic complex. Deeper basement from gravity and shallower from magnetic data indicate presence of two-stage magmatism within a subduction setting where the second magmatic emplacement probably occurred with a magma that comprises high magnetic material. High gravity and magnetic anomalies are observed over the mafic and ultramafic rock samples which are already identified (based on previous geochemical studies) as prospective zones for Cr, Ni and PGE mineralization. Thus, it can be inferred from this study that the mafic–ultramafic intrusive bodies are favourable targets for Cr–Ni–PGE mineralisation which may be obtained between a depth range of around 300 m to 3 km. Thus, the study enhances the scope for further integrated geophysical investigation over the identified prospective zones as well as provides important clues on magmatic evolution of the region.

Classical double copy from color kinematics duality: A proof in the soft limit

Classical double copy is an intriguing relationship between classical solutions to a gravity theory and solutions to classical Yang-Mills equations. Although formally inspired by the double copy relation between (quantum) scattering amplitudes in QCD and perturbative gravity, a direct proof of the former from the latter continues to be under investigation. In this paper, we attempt to prove classical double copy from the color-kinematics duality symmetry of QCD amplitudes in a restricted setting. That is we consider radiative solutions with classical scattering sources in Yang-Mills theory and perturbative gravity in D > 4 spacetime dimensions. We show that when the frequency of radiation is much smaller than the characteristic frequency of the process, then at the subleading order in frequency, the classical double copy relating radiative gluon field to radiative gravitational field can be proved from the color-kinematics duality of QCD amplitudes.

Relativistic kinetic gases as direct sources of gravity

We propose a new model for the description of a gravitating multi particle system, viewed as a kinetic gas. The properties of the, colliding or non-colliding, particles are encoded into a so called one-particle distribution function, which is a density on the space of allowed particle positions and velocities, i.e. on the tangent bundle of the spacetime manifold. We argue that an appropriate theory of gravity, describing the gravitational field generated by a kinetic gas, must also be modeled on the tangent bundle. The most natural mathematical framework for this task is Finsler spacetime geometry. Following this line of argumentation, we construct a coupling between the kinetic gas and a recently proposed Finsler geometric extension of general relativity. Additionally, we explicitly show how the coordinate invariance of the action of the kinetic gas leads to a novel formulation of conservation of the energy-momentum distribution of the gas on the tangent bundle.

A possible semiclassical bounce instead of a Schwarzschild singularity

We have previously shown that the singularity in a Schwarzschild black hole of stellar or larger mass may be avoided in a semiclassical manner by using as a source of gravity the stress-energy tensor (SET) corresponding to vacuum polarization of quantum fields, with a minimum spherical radius a few orders of magnitude larger than the Planck length. In this note we estimate the nonlocal contribution to the total SET due to particle creation from vacuum. We show that this contribution is negligibly small as compared to vacuum polarization and does not affect the previously suggested scenario.

String clouds and radiation flows as sources of gravity in static or rotating cylinders

Static and stationary cylindrically symmetric space-times in general relativity are considered, supported by distributions of cosmic strings stretched in the azimuthal ([Formula: see text]), longitudinal ([Formula: see text]) or radial ([Formula: see text]) directions or and by pairs of mutually opposite radiation flows in any of these directions. For such systems, exact solutions are obtained and briefly discussed, except for radial strings (a stationary solution for them is not found); it is shown that static solutions with [Formula: see text]- and [Formula: see text]-directed radiation flows do not exist while for [Formula: see text]-directed strings a solution is only possible with negative energy density. Almost all solutions under discussion contain singularities, and all stationary solutions have regions with closed timelike curves, hence, most probably, only their well-behaved regions admit application to real physical situations.

ON DIMENSION OF TETRADS IN EffECTIVE GRAVITY

Two different sources of emergent gravity lead to the inverse square of length dimension of metric field, $[g_{\mu\nu}]=1/[l]^2$, as distinct from the conventional dimensionless metric, $[g_{\mu\nu}]=1$, for $c = 1$. In both scenarios all the physical quantities, which obey diffeomorphism invariance, such as the Newton constant, the scalar curvature, the cosmological constant, particle masses, fermionic and scalar bosonic fields, etc., are dimensionless.

Solution of Einstein’s Equations for a Closed Null String with Axial Symmetry that Is Radially Increasing Its Size

A solution to the Einstein equations for a closed null string with axial symmetry that is radially increases its size is found. The possibility of choosing the ideal gas of null strings as a dominant source of gravity is confirmed in the study of the null string inflation mechanism in Friedmann–Robertson–Walker spaces. The absence of a limit transition between the solution that is found and the solution for a closed circular null string that is radially changing its size is shown. This indicates the stability of the configuration of a closed circular null string during its motion in an external gravitational field. It is noted that part of the characteristics of the null string gas, such as the ability to form a domain structure and existence of stable polarized states (multi-string systems), are independent of the shape of null string, but the dynamics of the test null string in a field of such multi-string system has singularities.

On the gravitational field of a point-like body immersed in a quantum vacuum

ABSTRACT Quantum vacuum and the matter immersed in it interact through electromagnetic, strong and weak interactions. However, we have zero knowledge of the gravitational properties of the quantum vacuum. As an illustration of the possible fundamental gravitational impact of the quantum vacuum, we study the gravitational field of an immersed point-like body. This is done under the working hypothesis, that quantum vacuum fluctuations are virtual gravitational dipoles (i.e. two gravitational charges of the same magnitude but opposite sign); coincidentally, this hypothesis makes quantum vacuum free of the cosmological constant problem. The major result is that a point-like body creates a halo of polarized quantum vacuum around itself, which acts as an additional source of gravity. There is a maximal magnitude ${g_{\rm qv\max}}$ of gravitational acceleration that can be caused by a polarized quantum vacuum; the small size of this magnitude (${g_{\rm qv\max}} < 6\ \times {10^{ - 11}}\,\mathrm{ m\,s}{^{-2}}$) is the reason why in some cases (for instance within the Solar system) the quantum vacuum can be neglected. Advanced experiments at CERN and forthcoming astronomical observations will reveal if this is true or not, but we point to already existing empirical evidence that seemingly supports this fascinating possibility.

Efficient high order accurate staggered semi-implicit discontinuous Galerkin methods for natural convection problems

In this article we propose a new family of high order staggered semi-implicit discontinuous Galerkin (DG) methods for the simulation of natural convection problems. Assuming small temperature fluctuations, the Boussinesq approximation is valid and in this case the flow can simply be modeled by the incompressible Navier-Stokes equations coupled with a transport equation for the temperature and a buoyancy source term in the momentum equation. Our numerical scheme is developed starting from the work presented in [1, 2, 3], in which the spatial domain is discretized using a face-based staggered unstructured mesh. The pressure and temperature variables are defined on the primal simplex elements, while the velocity is assigned to the dual grid. For the computation of the advection and diffusion terms, two different algorithms are presented: i) a purely Eulerian upwind-type scheme and ii) an Eulerian-Lagrangian approach. The first methodology leads to a conservative scheme whose major drawback is the time step restriction imposed by the CFL stability condition due to the explicit discretization of the convective terms. On the contrary, computational efficiency can be notably improved relying on an Eulerian-Lagrangian approach in which the Lagrangian trajectories of the flow are tracked back. This method leads to an unconditionally stable scheme if the diffusive terms are discretized implicitly. Once the advection and diffusion contributions have been computed, the pressure Poisson equation is solved and the velocity is updated. As a second model for the computation of buoyancy-driven flows, in this paper we also consider the full compressible Navier-Stokes equations. The staggered semi-implicit DG method first proposed in [4] for all Mach number flows is properly extended to account for the gravity source terms arising in the momentum and energy conservation laws. In order to assess the validity and the robustness of our novel class of staggered semi-implicit DG schemes, several classical benchmark problems are considered, showing in all cases a good agreement with available numerical reference data. Furthermore, a detailed comparison between the incompressible and the compressible solver is presented. Finally, advantages and disadvantages of the Eulerian and the Eulerian-Lagrangian methods for the discretization of the nonlinear convective terms are carefully studied.

Antimatter gravity and the Universe

The aim of this brief review is twofold. First, we give an overview of the unprecedented experimental efforts to measure the gravitational acceleration of antimatter; with antihydrogen, in three competing experiments at CERN (AEGIS, ALPHA and GBAR), and with muonium and positronium in other laboratories in the world. Second, we present the 21st Century’s attempts to develop a new model of the Universe with the assumed gravitational repulsion between matter and antimatter; so far, three radically different and incompatible theoretical paradigms have been proposed. Two of these three models, Dirac–Milne Cosmology (that incorporates CPT violation) and the Lattice Universe (based on CPT symmetry), assume a symmetric Universe composed of equal amounts of matter and antimatter, with antimatter somehow “hidden” in cosmic voids; this hypothesis produced encouraging preliminary results. The heart of the third model is the hypothesis that quantum vacuum fluctuations are virtual gravitational dipoles; for the first time, this hypothesis makes possible and inevitable to include the quantum vacuum as a source of gravity. Standard Model matter is considered as the only content of the Universe, while phenomena usually attributed to dark matter and dark energy are explained as the local and global effects of the gravitational polarization of the quantum vacuum by the immersed baryonic matter. An additional feature is that we might live in a cyclic Universe alternatively dominated by matter and antimatter. In about three years, we will know if there is gravitational repulsion between matter and antimatter; a discovery that can forever change our understanding of the Universe.