Science topic

Gravitation - Science topic

Acceleration produced by the mutual attraction of two masses, and of magnitude inversely proportional to the square of the distance between the two centers of mass. It is also the force imparted by the earth, moon, or a planet to an object near its surface. (From NASA Thesaurus, 1988)
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Publications related to Gravitation (10,000)
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The advantages of eddy current dampers over conventional fluid dampers include the ability to produce resistive forces with no contact between the components wherein damping forces are generated, resulting in a less degradable mechanism. Thus far, the apparent mass effect, referred to as inertance, in an eddy current damper employing rotational mot...
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The present research represents a new, fast and easy-to-apply semi-inversion technique for the direct separation of the Bouguer gravity anomaly to its corresponding depths or thicknesses of the prior known rock formations from a borehole (as a control point). As well as the possibility of tracing these formations on the profile points to the Bougue...
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From a theoretical viewpoint, dark matter is a prerequisite entity in the formation processes of large-scale structures on the cosmological (galactic) scales of space and time. The behaviours of Jeans modes for gravitational systems composed of dark and baryonic matters are restudied in the framework of Kaniadakis' statistics and kinetic theory. Th...
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Purpose: In the acute respiratory distress syndrome (ARDS), decreasing Ventilation-Perfusion [Formula: see text] mismatch might enhance lung protection. We investigated the regional effects of higher Positive End Expiratory Pressure (PEEP) on [Formula: see text] mismatch and their correlation with recruitability. We aimed to verify whether PEEP im...
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The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundament...
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Background: In the management of a trauma patient with cervical spine injury, the need for accurate diagnostic imaging is key to ensure correct management. Different classification systems have been developed including the Subaxial Injury Classification (SLIC) system and AO cervical spine fracture classification. Through a multicentre study, we hav...
Article
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The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundament...
Article
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Satellite geodesy uses the measurement of the motion of one or more satellites to infer precise information about the Earth’s gravitational field. In this work, we consider the achievable precision limits on such measurements by examining approximate models for the three main noise sources in the measurement process of the current Gravitational Rec...
Preprint
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Definition Gravitational curvature boundary value problem. Boundary value problem of the potential theory which relates third-order gradients of the gravitational potential known at the spherical boundary with the gravitational potential in its mass-free exterior.
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Our body has evolved in terrestrial gravity and altered gravitational conditions may affect the sense of body ownership (SBO). By means of the rubber hand illusion (RHI), we investigated the SBO during water immersion and parabolic flights, where unconventional gravity is experienced. Our results show that unconventional gravity conditions remodula...
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The design of a globally convergent position observer for feature points from visual information is a challenging problem, especially for the case with only inertial measurements and without assumptions of uniform observability, which remained open for a long time. We give a solution to the problem in this paper assuming that only the bearing of a...
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Linear cities where activity is spread out along a transportation line, aim to offer the highest levels of accessibility to their adjacent populations as well as to the countryside. These city forms are popular amongst architects and planners in envisioning ideal cities but they are difficult to implement as they involve strict controls on developm...
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Oil spillage and industrial discharge of oily wastewater threaten the health of the human beings and the environmental life. To perform oil cleaning from the water bodies, several physicochemical methods have been employed. However, these methods experience various challenges hindering their absolute usage. To curb these problems, smart materials a...
Book
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In this research we developed and applied a novel data-driven approach to investigate Rayleigh-Bernard convection in a two-phase cryogenic tank under varying gravity levels. In the initial simulation, a joint CFD-multinodal technique (CMT) was employed to simulate a pressurized cryogenic tank, with the gas section developed by a multinode model and...
Article
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The holographic principle, theorized to be a property of quantum gravity, postulates that the description of a volume of space can be encoded on a lower-dimensional boundary. The anti-de Sitter (AdS)/conformal field theory correspondence or duality¹ is the principal example of holography. The Sachdev–Ye–Kitaev (SYK) model of N ≫ 1 Majorana fermions...
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In our previous work (Paper I), we demonstrated that coagulation instability results in dust concentration against depletion due to the radial drift and accelerates dust growth locally. In this work (Paper II), we perform numerical simulations of coagulation instability taking into account effects of backreaction to gas and collisional fragmentatio...
Article
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In this work, we have discussed a spatially homogeneous and anisotropic Bianchi type-I space–time in the presence of Barrow holographic dark energy (infrared cut-off is the Hubble’s horizon) proposed by Barrow recently [J. D. Barrow, Phys. Lett. B 808, 135643 (2020).] and matter in the framework of [Formula: see text] gravity where the nonmetricity...
Article
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A minimum length scale of the order of Planck length is a feature of many models of quantum gravity that seek to unify quantum mechanics and gravitation. Recently, Perivolaropoulos in his seminal work (Perivolaropoulos in Phys. Rev. D 95:103523, 2017) predicted the simultaneous existence of minimal and maximal length measurements of quantum gravity...
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An overwhelming number of the scientists assume today that the general relativity theory describes the gravity correctly. Here, another description of gravitation is presented. This new description is based on three pillars: 1. an extended mechanical view based on Newton's equations, 2. an electromagnetic view based on Maxwell's equations, 3. a qua...
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We investigate the dynamics of two quantum mechanical oscillator system-bath toy models obtained by truncating to zero spatial dimensions linearized gravity coupled to a massive scalar field and scalar QED. The scalar-gravity toy model maps onto the phase damped oscillator, while the scalar QED toy model approximately maps onto an oscillator system...
Article
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We study neutrinos gravitationally scattered off a rotating supermassive black hole which is surrounded by a thin accretion disk with a realistic magnetic field. Neutrinos are supposed to be Dirac particles having a nonzero magnetic moment. Neutrinos move along arbitrary trajectories, with the incoming flux being parallel to the equatorial plane. W...
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We examine the modulus stabilization mechanism of a warped geometry model with nested warping. Such a model with multiple moduli is known to offer a possible resolution of the fermion mass hierarchy problem in the Standard Model. A six dimensional doubly warped braneworld model under consideration admits two distinct moduli, with the associated war...
Article
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Sea level changes in coastal areas significantly influence port activities (e.g., the safety of navigation). Along Italian coastlines, sea level variations are mainly due to astronomical tides (well known, due to gravitational attraction between Earth, Moon and Sun); however, during the last fifteen years, a high number of “anomalous” tides has bee...
Preprint
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In this paper, we propose a high order semi-implicit well-balanced finite difference scheme for all Mach Euler equations with a gravitational source term. To obtain the asymptotic preserving property, we start from the conservative form of full compressible Euler equations and add the evolution equation of the perturbation of potential temperature....
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We show that large gauge transformations modify the structure of momentum conservation leading to non-vanishing three-point amplitudes in a simple toy model of a gravitational wave event. This phenomenon resolves an apparent tension between perturbative scattering amplitude computations and exact methods in field theory. The tension is resolved to...
Article
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Neste trabalho analisamos a formação das ondas gigantes no planeta Miller, descrito no filme de ficção científica Interestelar. Este planeta orbita um buraco negro supermassivo chamado Gargântua, estando sujeito a uma enorme atração gravitacional, o que ocasiona gigantescas forças de maré. A partir do conceito de potencial gravitacional, foi deriva...
Article
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Unimodular Gravity is an alternative to General Relativity (GR) which, however, is so closely related to the latter that one can wonder to what extent they are different. The different behavior of the cosmological constant in the semiclassical regimes of both frameworks suggests the possible existence of additional contrasting features. UG and GR are...
Preprint
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In this VERTICO science paper we aim to study how the star formation process depends on galactic environment and gravitational interactions in the context of galaxy evolution. We explore the scaling relation between the star formation rate (SFR) surface density and the molecular gas surface density, also known as the Kennicutt-Schmidt (KS) relation...
Preprint
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The energy-momentum-stress tensor of the Riemannian space in general relativity is found and determined as a function of the metric tensor. Within the limits of non-inertial space this tensor is equal to zero however under the Newtonian limit its value is calculated in the general theory of relativity. This allows us to include the field energy ten...
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We investigate the dynamics and electromagnetic (EM) signatures of neutron star–neutron star (NS–NS) or neutron star–black hole (NS–BH) merger ejecta that occur in the accretion disk of an active galactic nucleus (AGN). We find that the interaction between ejecta and disk gas leads to important effects on the dynamics and radiation. We show five st...
Article
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Neste trabalho, apresentamos alguns conceitos e aspectos interessantes acerca dos efeitos sofridos por uma partícula imersa em um campo gravitacional provocado por um buraco negro. Primeiro, explicamos como é definido o campo gravitacional na concepção da Gravitação Universal Newtoniana. Damos uma rápida introdução aos conceitos de geodésica e curv...
Article
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The torsion models have stood out among the proposals for an alternative description of gravity. The simplest of them, the Teleparallel theory, is equivalent to General Relativity and there are many studies dealing with its extension to more general functions of the torsion T. The purpose of our study is to consider a family of f(T) models and appl...
Article
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The existence of black holes (BHs) with masses in the range between stellar remnants and supermassive BHs has only recently become unambiguously established. GW190521, a gravitational wave signal detected by the LIGO/Virgo Collaboration, provides the first direct evidence for the existence of such intermediate-mass BHs (IMBHs). This event sparked a...
Article
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We study a perturbation theory for embedding gravity equations in a background for which corrections to the embedding function are linear with respect to corrections to the flat metric. The remaining arbitrariness after solving the linearized field equations is fixed by an assumption that the solution is static in the second order. A nonlinear diff...
Preprint
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The center-of-mass energy can be arbitrarily high in Schwarzschild spacetime if one considers the front collision of two particles, one of which moves along so-called white hole geodesics and another one along a black hole geodesic. This process can take place if one considers the gravitational collapse model. In this paper, we consider the well-kn...
Article
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A bstract A long-lived scalar field (Φ) which couples weakly to the right-handed (RH) neutrinos ( N Ri ), generates small RH neutrino masses ( M i ) in Low-Scale-Leptogenesis (LSL) mechanisms, despite having a large vacuum expectation value v Φ . In this case, the correlation shared by the M i s and the duration of the non-standard cosmic history d...
Preprint
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Binary solar system objects are common and range from satellite systems with very large mass ratios $M_1/M_2$ to mass ratios very close to unity. A well-known example of a binary is the Pluto-Charon system. With Charon only eight times less massive than Pluto the question arises as for many other systems, why the mass-ratio is still close to unity....
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We suggest a new explanation of the flatness of galaxies rotation curves without invoking dark matter. For this purpose, a new gravitational tensor field is introduced in addition to the metric tensor.
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Long-distance communication protocols cannot ignore the existence of the Earth’s gravitational field and its effects on quantum states. In this work, we show a very general method to consider the effects of the Earth’s gravitational field on continuous-variable quantum key distribution protocols. Our results show that the Earth’s gravitational fiel...
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We derive new functional renormalization group flows for quantum gravity, in any dimension. The key new achievement is that the equations apply for any theory of gravity whose underlying Lagrangian∼f(Rμνρσ) is a function of the Riemann tensor and the inverse metric. The results centrally exploit the benefits of maximally symmetric spaces for the ev...
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The melting process of two-dimensional (2D) Yukawa crystals for dusty plasma medium induced by external perturbations has been explored using molecular dynamics simulations. A 2D monolayer of particles interacting via Yukawa pair potential is formed in the presence of an external confinement potential. The confinement potential is a combined effect...
Preprint
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The study of indefinite causal order has seen rapid development, both theoretically and experimentally, in recent years. While classically the causal order of two timelike separated events A and B is fixed - either A before B or B before A - this is no longer true in quantum theory. There, it is possible to encounter superpositions of causal orders...
Article
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In this study, an integrated system of winch driving and potential energy recovery using a four-quadrant pump was proposed, aimed at the large amount of recoverable gravitational potential energy in a winch system. The proposed system changed the original open system into a closed-structure part, using a four-quadrant pump to drive the winch, and a...
Article
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Barrow proposed that the area law of the horizon entropy might receive a “fractal correction” $$S\propto A^{1+\Delta /2}$$ S ∝ A 1 + Δ / 2 due to quantum gravitational effects, with $$0\leqslant \Delta \leqslant 1$$ 0 ⩽ Δ ⩽ 1 measures the deviation from the standard area law. While such a modification has been widely studied in the literature, its...
Preprint
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Abstract: In the dialogues, The Timaeus and The Critias, Plato enumerates the dimensions of the mythological island and city of Atlantis. The dimensions of this ancient and technologically advanced city correspond directly to the orbits of the inner planets of the solar system. Furthermore, the stated dimensions for the entire island of Atlantis c...
Preprint
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The longest recognized stellar stream in the Milky Way Galaxy has an expanse of over more than half the north sky. There was a physical disturbance within the stream, 500 million years ago, which could have been the scar of a dark matter collision. Due to its proximity to the galactic center, the GD-1 stellar stream can act as an antenna for gravit...
Preprint
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We study the spherically symmetric collapse of a cloud of dust in VCDM, a class of gravitational theories with two local physical degrees of freedom. We find that the collapse corresponds to a particular foliation of the Oppenheimer-Snyder solution in general relativity (GR) which is endowed with a constant trace for the extrinsic curvature relativ...
Presentation
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Riemannian formulation of classical fluctuation theory appears after imposing the principle of general covariance, which requires a reformulation of Einstein postulate of classical fluctuation theory and Ruppeiner geometry of thermodynamics. This proposal predicts thermo-statistical counterparts of Hamilton-Jacobi equation of classical mechanics an...
Article
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We present here solutions of a non-linear Schrödinger equation in presence of an arbitrary linear external potential. The non-linearity expresses a self-focusing interaction. These solutions are the product of the pilot wave with peaked solitons the velocity of which obeys the guidance equation derived by Louis de Broglie in 1926. The degree of val...
Article
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We have recently developed a new understanding of probability in quantum gravity. In this paper we provide an overview of this new approach and its implications. Adopting the de Broglie–Bohm pilot-wave formulation of quantum physics, we argue that there is no Born rule at the fundamental level of quantum gravity with a non-normalisable Wheeler–DeWi...
Book
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In this paper in an elegant way will be present that the gravitational fine-structure constant is a simple analogy between atomic physics and cosmology. We will find the expression that connects the gravitational fine-structure constant with the four coupling constants. Perhaps the gravitational fine-structure constant is the coupling constant for...
Article
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The generalized Brans–Dicke theory (GBD), as one of the modified gravitational theories, was proposed previously and some interesting properties were found in this theory. Here we investigate the traversable-wormhole physics for GBD theory. Firstly, we derive the gravitational field equation in the framework of GBD wormhole geometry. The traversabl...
Article
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The use of transparent test/source masses can benefit future measurements of Newton’s gravitational constant G. Such transparent test mass materials can enable nondestructive, quantitative internal density gradient measurements using optical interferometry and allow in-situ optical metrology methods to be realized for the critical distance measureme...
Article
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Stars are born in dense molecular filaments irrespective of their mass. Compression of the interstellar medium by shocks causes filament formation in molecular clouds. Observations show that a massive star cluster formation occurs where the peak of gas column density in a cloud exceeds 10 ²³ cm ⁻² . In this study, we investigate the effect of the s...
Preprint
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The ability to represent perturbative expansions of interacting quantum field theories in terms of simple diagrammatic rules has revolutionized calculations in particle physics (and elsewhere). Moreover, these rules are readily automated, a process that has catalysed the rise of symbolic algebra packages. However, in the case of extended theories o...
Article
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The three-body problem is famously chaotic, with no closed-form analytical solutions. However, hierarchical systems of three or more bodies can be stable over indefinite timescales. A system is considered hierarchical if the bodies can be divided into separate two-body orbits with distinct time and length scales, such that one orbit is only mildly...
Preprint
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Motivated by the fermionic Berry's phase in momentum space, we study a local Abelian phase in momentum space, also known as the momentum gauge, coupled to electromagnetism, for complex scalars in the phase-space worldline formalism. The interaction of both Abelian fields is shown to give rise to a momentum gauge dependant emergent spacetime. As a c...
Article
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A bstract We consider the fuzzy 4-sphere $$ {S}_N^4 $$ S N 4 as a background in the IKKT matrix model, and explore the relation between $$ {S}_N^4 $$ S N 4 and fuzzy twistor space in the semi-classical limit. A novel description for the IKKT-matrix model in terms of spinorial indices is given, which is reminiscent of $$ \mathcal{N} $$ N = 4 super-s...
Preprint
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We derive and establish the new precision frontier at the fifth PN (5PN) order, and put forward a broader picture of the effective theory of a spinning particle within the EFT of spinning gravitating objects. This precision frontier includes higher-spin sectors, quadratic and quartic in the spin, which both display novel physical effects, from the...
Preprint
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Dense stellar environments as hosts of ongoing star formation increase the probability of gravitational encounters among stellar systems during the early stages of evolution. Stellar interaction may occur through non-recurring, hyperbolic or parabolic passages (a so-called 'fly-by'), through secular binary evolution, or through binary capture. In a...
Article
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In this manuscript, we construct a spherical thin shell wormhole in the background of the minimally coupled $f(R,~T)$ model. In this gravitational theory, $f$ is an arbitrary functional form that depends on the Ricci scalar $(R)$ as well as the trace of stress-energy tensor $(T)$. To continue our systematic analysis, we use a cut and paste approach...
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We study the effects of velocity dispersion on the formation of primordial black holes~(PBHs) in a matter-dominated era. The velocity dispersion is generated through the nonlinear growth of perturbations and has the potential to impede the gravitational collapse and thereby the formation of PBHs. To make discussions clear, we consider two distinct...
Article
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The combined effect of the solar radiation pressure and the oblateness of the planets on the position and stability of the Lagrangian points within the restricted elliptic three-body problem was studied. We found that the solar radiation pressure and planet oblateness slightly changed the location of the Lagrangian points. New formulas for the loca...
Article
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In this paper, we study the inflationary scenario in logarithmic f(R) gravity, where the rate of inflation roll is constant. On the other hand, our gravitational f(R) model is a polynomial plus a logarithmic term. We take advantage of constant-roll conditions and investigate the cosmic evolution of the logarithmic f(R) gravity. We present a numeric...