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Researchers in standard gravity theory and cosmology seldom take into account Lorentz relativistic mass. The dismissal of Lorentz relativistic mass by the research community has happened without first properly investigating what predictions incorporating it in gravity models have led to. We show that the inclusion of Lorentz relativistic mass in some gravity theories has a dramatic impact on the predicted redshift from objects with high gravitational field such as stellar objects fitting the mathematical properties of black holes. Taking into account Lorentz relativistic mass provides diverse interpretations of quasars and many other objects. As relevant example, it may explain the lack of observed velocity time dilation in quasars. [ABSTRACT FROM AUTHOR]

We demonstrate that the de Broglie wave of a particle in a gravitational field turns toward the region of lower gravitational potential, causing the particle to fall. This turning is caused by clocks running slower in the smaller potential. We use the analogy of ocean waves that are slower in shallower water and turn toward beaches. This approach implies that the motion is along a geodesic and explains the free fall qualitatively and quantitatively with only elementary algebra. [ABSTRACT FROM AUTHOR]

The principle of mental gravity contends that the mind uses physical gravity as a mental model or simulacrum to express the relation between the inner self and the outer world in terms of "UP"-ness and "DOWN"-ness. The simulation of increased gravity characterises a continuum of mental gravity which states includes depression as the paradigmatic example of being down, low, heavy, and slow. The physics of gravity can also be used to model spacetime curvature in depression, particularly gravitational time dilation as a property of MG analogous to subjective time dilation (i.e., the slowing of temporal flow in conscious experience). The principle has profound implications for the Temporo-spatial Theory of Consciousness (TTC) with regard to temporo-spatial alignment that establishes a "world-brain relation" that is centred on embodiment and the socialisation of conscious states. The principle of mental gravity provides the TTC with a way to incorporate the structure of the world into the structure of the brain, conscious experience, and thought. In concert with other theories of cognitive and neurobiological spacetime, the TTC can also work towards the "common currency" approach that also potentially connects the TTC to predictive processing frameworks such as free energy, neuronal gauge theories, and active inference accounts of depression. It gives the up/down dimension of space, as defined by the gravitational field, a unique status that is connected to both our embodied interaction with the physical world, and also the inverse, reflective, emotional but still embodied experience of ourselves. [ABSTRACT FROM AUTHOR]

The general theory of relativity (GTR) has proved to accurately describe all gravitational aspects of our universe. This theory was developed by Einstein under the premises of the principle of equivalence to describe the behavior of inertial systems in accelerated reference frames, but the physical basis for the principle of equivalence and for the existence of accelerated reference frames remains to be understood. Here, we postulate that the principle of equivalence could be explained in terms of an accelerated flow of space toward the origin of the gravitational field, which would explain the accelerated reference frames. We provide evidence that the gravitational constant predicts the observed increase in the Hubble constant from early to late universe. This suggests that gravity and accelerated expansion of the universe could derive from the same physical principle depending on the mass density operating in each process. Massinduced accelerated space expansion through a hypothetical fourth spatial dimension could explain the curvature of spacetime. It would be the projection of the expanded space to our threedimensional universe what would lead to relativistic gravitational effects such as time dilation, redshift, and black hole formation. Therefore, a gravitational theory can be envisioned, halfway between classical mechanics and GTR. [ABSTRACT FROM AUTHOR]

Recently, a static gravitational field, such as that of the Earth, was proposed as a new source of decoherence [1] . We study the conditions under which it becomes the dominant decoherence effect in typical interferometric experiments. The following competing sources are considered: spontaneous emission of light, absorption, scattering with the thermal photons and collisions with the residual gas. We quantify all these effects. As we will see, current experiments are off by several orders of magnitude. New ideas are needed in order to achieve the necessary requirements: having as large a system as possible, to increase gravitational decoherence, cool it and isolate well enough to reduce thermal and collisional decoherence, and resolve very small distances. [ABSTRACT FROM AUTHOR]

Two different forms of time dilation, namely, the kinematical time dilation of special relativity and gravitational red shift are coupled together during observations of a system travelling through a gravitational field. In the case of a Schwarzschild geometry these two effects are decoupled and in consequence they factorise. Such a factorization is not a universal feature. We define here a necessary and sufficient criterion for time dilation and gravitational red-shift decoupling. This property is manifested in a particular form of the frequency shift in a Schwarzschild geometry. [ABSTRACT FROM AUTHOR]

The twin paradox has played an important role in the history of special relativity (SR). A precise calculation would require the application of the general theory of relativity (GR) but, neglecting the acceleration phases of the traveling twin, even in SR it is possible to find the correct solution without logical contradictions. Nowadays it is well known that the twin thought experiment seems a paradox as a consequence of a naive application of time dilation and the principle of relativity. The twin who goes on space travel is the one who, returning to the twin at rest, finds the aged brother. Continuing in this pedagogical tradition, we want to add a further consideration. In fact, the experiment has always been explained by considering the two twins immersed in Minkowski's spacetime. It could be interesting, from a didactic point of view, to analyze the same thought experiment without neglecting the Earth's gravitational field. Indeed, under certain conditions, it may happen that the traveling brother can grow older than his brother at rest. [ABSTRACT FROM AUTHOR]

In this paper, we study the phenomenon of quantum interference in the presence of external gravitational fields described by alternative theories of gravity. We analyze both non-relativistic and relativistic effects induced by the underlying curved background on a superposed quantum system. In the non-relativistic regime, it is possible to come across a gravitational counterpart of the Bohm–Aharonov effect, which results in a phase shift proportional to the derivative of the modified Newtonian potential. On the other hand, beyond the Newtonian approximation, the relativistic nature of gravity plays a crucial rôle. Indeed, the existence of a gravitational time dilation between the two arms of the interferometer causes a loss of coherence that is in principle observable in quantum interference patterns. We work in the context of generalized quadratic theories of gravity to compare their physical predictions with the analogous outcomes in general relativity. In so doing, we show that the decoherence rate strongly depends on the gravitational model under investigation, which means that this approach turns out to be a promising test bench to probe and discriminate among all the extensions of Einstein's theory in future experiments. [ABSTRACT FROM AUTHOR]

Shows that the field treatment of gravitational fields allows the discovery of a new fundamental feature of gravitation, namely, the origination of effective repulsive forces caused by the time dilation of physical processes in strong gravitational fields. Absence of such forces in general relativity; Observation that the relativistic theory of gravitation exhibits a peculiar mechanism of gravitational self-regulation.

The concepts of a time ruler and space ruler are put forward, where the zoom of the space-time ruler provides for an intuitive explanation of the time dilation and length contraction effects associated with theory of relativity. Mass and energy can be regarded as measurements of matter by the time ruler, while momentum can be regarded as a measurement of matter by the space ruler. The space-time ruler can be divided into two kinds according to the causes of its deformation: a relative motion space-time ruler and a gravitational field space-time ruler. It is proved that there is equivalence between these two kinds of rulers under weak field conditions, with this amounting to another expression of the equivalence principle in general relativity. It is pointed out that the two kinds of space-time ruler can be superposed, with the formula for calculating the clock difference between satellites and ground stations being given by this superposition. A GPS satellite is used as an example to calculate clock difference in this way, and the calculation results are in agreement with the classical formula. [ABSTRACT FROM AUTHOR]

We present a Relativistic Newtonian Dynamics ( R N D ) for motion of objects in a gravitational field generated by a moving source. As in General Relativity ( G R ), we assume that objects move by a geodesic with respect to some metric, which is defined by the field. This metric is defined on flat lab spacetime and is derived using only symmetry, the fact that the field propagates with the speed of light, and the Newtonian limit. For a field of a single source, the influenced direction of the field at spacetime point x is defined as the direction from x to the to the position of the source at the retarded time. The metric depends only on this direction and the strength of the field at x. We show that for a static source, the R N D metric is of the same form as the Whitehead metric, and the Schwarzschild metric in Eddington–Finkelstein coordinates. Motion predicted under this model passes all classical tests of G R . Moreover, in this model, the total time for a round trip of light is as predicted by G R , but velocities of light and object and time dilation differ from the G R predictions. For example, light rays propagating toward the massive object do not slow down. The new time dilation prediction could be observed by measuring the relativistic redshift for stars near a black hole and for sungrazing comets. Terrestrial experiments to test speed of light predictions and the relativistic redshift are proposed. The R N D model is similar to Whitehead's gravitation model for a static field, but its proposed extension to the non-static case is different. This extension uses a complex four-potential description of fields propagating with the speed of light. [ABSTRACT FROM AUTHOR]

The gedanken experiment of the clock paradox is solved exactly using the general relativistic equations for a static homogeneous gravitational field. We demonstrate that the general and special relativistic clock paradox solutions are identical and in particular that they are identical for finite acceleration. Practical expressions are obtained for proper time and coordinate time by using the destination distance as the key observable parameter. This solution provides a formal demonstration of the identity between the special and general relativistic clock paradox with finite acceleration and where proper time is assumed to be the same in both formalisms. By solving the equations of motion for a freely falling clock in a static homogeneous field elapsed times are calculated for realistic journeys to the stars. [ABSTRACT FROM AUTHOR]

Quantum theory and relativity offer different conceptions of time. To explore the conflict between them, we study a quantum version of the light-clock commonly used to illustrate relativistic time dilation. This semiclassical model combines elements of both theories. We show for Gaussian states of the light field that the clock time is independent of the initial state. We calculate the discrepancy between two such clocks when one is held in a gravitational field and the other is left to fall a certain distance. Contrasting our results with the case of pointlike observers in general relativity, as well as classical light-clocks, we find both quantitative and qualitative differences. We find that the quantum contribution to the discrepancy between the two clocks increases with the gravitational field strength, and results in a minimum resolution of the dropped clock (distinct from the quantum uncertainty in its measurement). [ABSTRACT FROM AUTHOR]

The gedanken experiment of the clock paradox is solved exactly using the general relativistic equations for a static homogeneous gravitational field. We demonstrate that the general and special relativistic clock paradox solutions are identical and in particular that they are identical for finite acceleration. Practical expressions are obtained for proper time and coordinate time by using the destination distance as the key observable parameter. This solution provides a formal demonstration of the identity between the special and general relativistic clock paradox with finite acceleration and where proper time is assumed to be the same in both formalisms. By solving the equations of motion for a freely falling clock in a static homogeneous field elapsed times are calculated for realistic journeys to the stars. [ABSTRACT FROM AUTHOR]

The article presents information on the difference between the physical properties of the general theory of relativity and relativistic theory of gravity (RTG) in a strong gravitational field. The analysis of the exact internal Schwarzschild solution shows that the physical gravitational field in the RTG stops the process of gravitational contraction due to the boundedness of the admissible dilation of time by the gravitational field.

Gravity bends light. One can argue this by reasoning that a beam of light should travel in a curved path when viewed from within an accelerating frame of reference, and then invoking Einstein's principle of equivalence, which asserts that the effects observed in an accelerating frame of reference are indistinguishable from the effects observed in a uniform gravitational field. If light bends in an accelerating reference frame, it must also bend in a gravitational field. [ABSTRACT FROM AUTHOR]

This paper shows that gravitational results of general relativity (GR) can be reached by using special relativity (SR) via a SR Lagrangian that derives from the corresponding GR time dilation and vice versa. It also presents a new SR gravitational central scalar generalized potential V = V (r , r. , ϕ.) , where r is the distance from the center of gravity and r. , ϕ. are the radial and angular velocity, respectively. This is associated with the Schwarzschild GR time dilation from where a SR scalar generalized potential is obtained, which is exactly equivalent to the Schwarzschild metric. Thus, the Precession of Mercury's Perihelion, the Gravitational Deflection of Light, the Shapiro time delay, the Gravitational Red Shift, etc., are explained with the use of SR only. The techniques used in this paper can be applied to any GR spacetime metric, Teleparallel Gravity, etc., in order to obtain the corresponding SR gravitational scalar generalized potential and vice versa. Thus, the case study of Newtonian Gravitational Potential according to SR leads to the corresponding non-Riemannian metric of GR. Finally, it is shown that the mainstream consideration of the Gravitational Red Shift contains two approximations, which are valid in weak gravitational fields only. [ABSTRACT FROM AUTHOR]

Abstract: The time scale for cooling of the gravitationally bound gaseous intracluster medium (ICM) is not determined by radiative processes alone. If the ICM is in quasi-hydrostatic equilibrium in the fixed gravitational field of the dark matter halo then energy losses incurred by the gravitational potential energy of the gas should also be taken into account. This “gravitational heating” has been known for a while using explicit solutions to the equations of motion. Here, we re-visit this effect by applying the virial theorem to gas in quasi-hydrostatic equilibrium in an external gravitational field, neglecting the gravity of the gas. For a standard NFW form of halo profiles and for a finite gas density, the response of the gas temperature to changes in the total energy is significantly delayed. The effective cooling time could be prolonged by more than an order of magnitude inside the scale radius of the halo. Gas lying at a distance twice the scale radius, has negative heat capacity so that the temperature increases as a result of energy losses. Although external heating (e.g. by AGN activity) is still required to explain the lack of cool ICM near the center, the analysis here may circumvent the need for heating in farther out regions where the effective cooling time could be prolonged to become larger than the cluster age and also explains the increase of temperature with radius in these regions. [Copyright &y& Elsevier]

The article presents information on the field theory of gravitation. The theory states if the formula for the dilation of time are correct, then the physical laws would cease at the center of the universe, for, at that point, time will not advance. The theory contradicts the general theory of relativity. The article also discusses the extremely rigid equation of state for matter.

The Brillouin sphere is defined as the smallest sphere, centered at the origin of the geocentric coordinate system, that incorporates all the condensed matter composing the planet. The Brillouin sphere touches the Earth at a single point, and the radial line that begins at the origin and passes through that point is called the singular radial line. For about 60 years there has been a persistent anxiety about whether or not a spherical harmonic (SH) expansion of the external gravitational potential, V, will converge beneath the Brillouin sphere. Recently, it was proven that the probability of such convergence is zero. One of these proofs provided an asymptotic relation, called Costin's formula, for the upper bound, EN, on the absolute value of the prediction error, eN, of a SH series model, V N (θ , λ , r) , truncated at some maximum degree, N = n max . When the SH series is restricted to (or projected onto) a particular radial line, it reduces to a Taylor series (TS) in 1 / r . Costin's formula is E N ≃ B N − b (R / r) N , where R is the radius of the Brillouin sphere. This formula depends on two positive parameters: b, which controls the decay of error amplitude as a function of N when r is fixed, and a scale factor B. We show here that Costin's formula derives from a similar asymptotic relation for the upper bound, An on the absolute value of the TS coefficients, an, for the same radial line. This formula, A n ≃ K n − k , depends on degree, n, and two positive parameters, k and K, that are analogous to b and B. We use synthetic planets, for which we can compute the potential, V, and also the radial component of gravitational acceleration, g r = ∂ V / ∂ r , to hundreds of significant digits, to validate both of these asymptotic formulas. Let superscript V refer to asymptotic parameters associated with the coefficients and prediction errors for gravitational potential, and superscript g to the coefficients and predictions errors associated with gr. For polyhedral planets of uniform density we show that b V = k V = 7 / 2 and b g = k g = 5 / 2 almost everywhere. We show that the frequency of oscillation (around zero) of the TS coefficients and the series prediction errors, for a given radial line, is controlled by the geocentric angle, α, between that radial line and the singular radial line. We also derive useful identities connecting K V , B V , K g , and Bg. These identities are expressed in terms of quotients of the various scale factors. The only other quantities involved in these identities are α and R. The phenomenology of 'series divergence' and prediction error (when r < R) can be described as a function of the truncation degree, N, or the depth, d, beneath the Brillouin sphere. For a fixed r ⩽ R , as N increases from very low values, the upper error bound EN shrinks until it reaches its minimum (best) value when N reaches some particular or optimum value, N opt . When N > N opt , prediction error grows as N continues to increase. Eventually, when N ≫ N opt , prediction errors increase exponentially with rising N. If we fix the value of N and allow R / r to vary, then we find that prediction error in free space beneath the Brillouin sphere increases exponentially with depth, d, beneath the Brillouin sphere. Because b g = b V − 1 everywhere, divergence driven prediction error intensifies more rapidly for gr than for V, both in terms of its dependence on N and d. If we fix both N and d, and focus on the 'lateral' variations in prediction error, we observe that divergence and prediction error tend to increase (as does B) as we approach high-amplitude topography. [ABSTRACT FROM AUTHOR]

There are discernible and fundamental differences between clocks, waves and physical states in classical physics. These fundamental concepts find a common expression in the context of quantum physics in gravitational fields; matter and light waves, quantum states and oscillator clocks become quantum synonymous through the Planck-Einstein-de Broglie relations and the equivalence principle. With this insight, gravitational effects on quantum systems can be simply and accurately analyzed. Apart from providing a transparent framework for conceptual and quantitative thinking on matter waves and quantum states in a gravitational field, we address and resolve with clarity the recent controversial discussions on the important issue of the relation and the crucial difference between gravimetery using atom interferometers and the measurement of gravitational time dilation. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Physics is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We study matter accretion in a static, axially symmetric and vacuum geometry describing the exterior gravitational field of a black hole mimicker called the γ metric. We evaluate the thermal and optical properties of thin accretion disks, including the emission rate, luminosity and shadow, in the g a m m a spacetime. Also, we explore the radial accretion of polytropic matter fields onto the central source and evaluate the thermal and optical properties of the infalling gas, such as temperature and luminosity. The results are discussed in the context of evaluating the possibility that the true nature of astrophysical black hole candidates may not be a black hole but some exotic compact object possessing a non-vanishing mass quadrupole moment. [ABSTRACT FROM AUTHOR]

The gravitational redshift forms the central part of the majority of the classical tests for the general theory of relativity. It could be successfully checked even in laboratory experiments on the earth's surface. The standard derivation of this effect is based on the distortion of the local structure of spacetime induced by large masses. The resulting gravitational time dilation near these masses gives rise to a frequency change of any periodic process, including electromagnetic oscillations as the wave propagates across the gravitational field. This phenomenon can be tackled with classical electrodynamics assuming a curved spacetime background and Maxwell's equations in a generally covariant form. In this paper, we show that in a classical field theoretical context the gravitational redshift can be interpreted as the propagation of electromagnetic waves in a medium with corresponding conductivity σ = g/(μ0c³), where g is the gravitational acceleration and μ0 is the vacuum magnetic permeability. Moreover, the energy density of the wave remains proportional to its frequency in agreement with Planck's postulate. [ABSTRACT FROM AUTHOR]

Copyright of Physics Essays is the property of Physics Essays Publication and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We propose a model describing spin-half quantum particles in curved spacetime in the framework of quantum field theory. Our model is based on embodying Einstein's equivalence principle and general covariance in the definition of quantum-particle states. With this model at hand, we compute several observables which characterise spin-half quantum particles in a gravitational field. In particular, we find that spin precesses in a normal Fermi frame, even in the absence of torsion. The effect appears to be complementary to free-fall non-universality we have recently reported about for spinless quantum particles. Furthermore, we find that quantum-particle gravitational-potential energy is insensitive to wave-packet spreading in the Earth's gravitational field, that is responsible for the non-universality of free fall in quantum theory. This theoretical result provides another channel for the experimental study of our quantum-particle model by using gravitational spectrometers. Finally, we also find that (elementary) fermions and antifermions are indistinguishable in gravity. [ABSTRACT FROM AUTHOR]

The possibility of determining the difference in gravitational potentials and orthometric heights in the Earth's field based on measurements of the phase difference of laser radiation in an optical fiber is proposed and investigated in this study. Such a phase difference is attributed to the effect of the gravitational delay of light waves. A block diagram of a measuring complex designed to measure the phase difference of light waves caused by this effect is proposed. The measurements use two coherent light waves from a single laser, each propagating along a separate fiber-optic communication line. The composition of each fiber-optic communication line includes the same coils of a long optical fiber, spaced apart in height. The analysis of the factors influencing the phase relations of waves propagating along two communication lines of the measuring complex is performed. The phase effects of the delay, caused by the influence of the true gravitational field of the Earth, and the influence of the fields of inertial forces and gyroscopic effects due to the Earth's rotation are determined. Methods for suppressing interfering effects are proposed. The achievable errors in measuring the differences in gravitational potentials and corresponding orthometric heights are estimated. With a fiber length in coils of 100 km and a height difference of 100 m, the errors are 0.2 m2/s2 and 2 cm, respectively. The measuring complex under study is called a laser gravipotentiometer. It is an optical analog of the well-known radio-frequency quantum-level unit, but it does not require ultrastable frequency and time standards. The research results of the proposed measuring complex are relevant for the development and improvement of measuring instruments for the parameters of the Earth's gravitational field and a means of the high-precision synchronization of time scales of remote standards. [ABSTRACT FROM AUTHOR]

Good clocks are of importance both to fundamental physics and for applications in astronomy, metrology and global positioning systems. In a recent technological breakthrough, researchers at NIST have been able to achieve a stability of one part in 1018 using an ytterbium clock. This naturally raises the question of whether there are fundamental limits to time keeping. In this article we point out that gravity and quantum mechanics set a fundamental limit on the fractional frequency uncertainty of clocks. This limit comes from a combination of the uncertainty relation, the gravitational redshift and the relativistic time dilation effect. For example, a single ion aluminium clock in a terrestrial gravitational field cannot achieve a fractional frequency uncertainty better than one part in 1022. This fundamental limit explores the interaction between gravity and quantum mechanics on a laboratory scale. [ABSTRACT FROM AUTHOR]

The equivalence principle (EP) is at the heart of general relativity (GR), tested in many aspects. In discussion, it is often referred to explaining qualitatively the influence of gravity on physical phenomena, but is this qualitative approach supported by the theory? We compare clock rates, frequency shifts, light deflection, and time delay in simple static spacetimes to the analogous phenomena seen by accelerated observers in Minkowski space. In contrast to previous studies, we do not assume that the gravitational field is weak and see, as we proceed, how the field is constrained by the EP. Special care is taken that results are only observer-, but not coordinate-dependent. By this, we clarify some of the issues raised in the literature and show which gravitational effects can and which cannot be simulated by acceleration. The paper may also serve as a starting point for discussions on the implications of the EP. [ABSTRACT FROM AUTHOR]

We propose an approach that allows to systematically take into account gravity in quantum particle physics. It is based on quantum field theory and the general principle of relativity. These are used to build a model for quantum particles in curved spacetime. We compute by its means a deviation from a classical geodesic in the Earth's gravitational field. This shows that free fall depends on quantum- matter properties. Specifically, we find that the free-fall universality and the wave-packet spreading are mutually exclusive phenomena. We then estimate the Eötvös parameter for a pair of atoms freely falling near the Earth's surface, provided that the wave-packet spreading is more fundamental than the weak equivalence principle. [ABSTRACT FROM AUTHOR]

Einstein's general relativity postulates that, at each position within a gravitational field, we must measure the same frequency f0, but seen from a distance, the frequency at the position of another gravitational potential is different from f0. As gravity decreases with the increase in the distance from Earth, in the Pound-Rebka experiment at the top of the tower, the frequency of electromagnetic radiation must be higher than at the bottom. If electromagnetic radiation was able to have the same frequency f0 at the top of the tower as at the bottom of the tower, an observer at the top of the tower would have to be able to increase gravity to the same level that gravity has at the bottom. But the decrease in gravity with an increase in the altitude cannot be reversed. It is demonstrated that the relativistic interpretation of the Pound-Rekba experiment showing a doubling of the gravitational frequency shift for "two-way" observations violates the principle of energy conservation, whereas the classical interpretation of the experiment identifies the doubling of the gravitational frequency shift as a pure mathematical effect that has no physical reality, which always occurs when we subtract relative differences with opposite algebraic signs from each other. It is shown that Einstein's general relativity only seemingly corresponds with reality; thus, gravitational frequency (time) shifts must be interpreted according to classical considerations. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between energy, time and space is still not solved in an appropriate manner. According to Newton''s concept of time and space, both have to be taken as absolute. If we follow Leibniz and his arguments, space and time are relative. Since Einstein''s theory of relativity we know at least that energy, time and space are deeply related. Albert Einstein originally predicted that time is nothing absolute but something relative, time changes and can change. Especially, time and gravitational field are related somehow even in detail if we still don’t know how. According to the gravitational time dilation, the lower the gravitational potential, the more slowly time passes and vice versa. Somehow, it appears to be that the behaviour of time is directly linked to the behaviour of the gravitational field. The aim of this publication is to work out the interior logic between time and gravitational field and to make the proof that time is equivalent to the gravitational field and vice versa. [Copyright &y& Elsevier]

We describe the quantum mechanical rotation of a photon state, the Wigner rotation—a quantum effect that couples a transformation of a reference frame to a particle's spin, to investigate geometric phases induced by Earth's gravitational field for observers in various orbits. We find a potentially measurable quantum phase of the Wigner rotation angle in addition to the rotation of standard fame, the latter of which is computed and agrees well with the geodetic rotation. When an observer is in either a circular or a spiraling orbit containing non-zero angular momentum, the additional quantum phase contributes 10−6 degree to 10−4 degree respectively, depending on the altitude of the Earth orbit. In the former case, the additional quantum phase is dominant over the near-zero classical geodetic rotation. Our results show that the Wigner rotation represents a non-trivial semi-classical effect of quantum field theory on a background classical gravitational field. [ABSTRACT FROM AUTHOR]

The neutral time-like particle's bound orbits around modified Hayward black holes have been investigated. We find that both in the marginally bound orbits (MBO) and the innermost stable circular orbits (ISCO), the test particle's radius and its angular momentum are all more sensitive to one of the parameters β. Especially, modified Hayward black holes with β = 1 0 could mimic the same ISCO radius around the Kerr black hole with the spin parameter up to a / M ≈ 0. 9 9. Small β could mimic the ISCO of small-spinning test particles around Schwarzschild black holes. Meanwhile, rational (periodic) orbits around modified Hayward black holes have also been studied. The epicyclic frequencies of the quasi-circular motion around modified Hayward black holes are calculated and discussed with respect to the observed Quasi-periodic oscillations (QPOs) frequencies. Our results show that rational orbits around modified Hayward black holes have different values of the energy from the ones of Schwarzschild black holes. The epicyclic frequencies in modified Hayward black holes have different frequencies from Schwarzschild and Kerr ones. These might provide hints for distinguishing modified Hayward black holes from Schwarzschild and Kerr ones by using the dynamics of time-like particles around the strong gravitational field. [ABSTRACT FROM AUTHOR]

In (Zych et al 2011 Nat. Commun. 2 505), the authors predicted that the interferometric visibility is affected by a gravitational field in way that cannot be explained without the general relativistic notion of proper time. In this work, we take a different route and start deriving the same effect using the unitary representation of the local Lorentz transformation in the Newtonian limit. In addition, we show that the effect on the interferometric visibility due to gravity persists in different spacetime geometries. However, the influence is not necessarily due to the notion of proper time. For instance, by constructing a 'astronomical' Mach–Zehnder interferometer in the Schwarzschild spacetime, the influence on the interferometric visibility can be due to another general relativistic effect, the geodetic precession. Besides, by using the unitary representation of the local Lorentz transformation, we show that this behavior of the interferometric visibility is general for an arbitrary spacetime, provided that we restrict the motion of the quanton to a two-dimensional spacial plane. [ABSTRACT FROM AUTHOR]

By using the concept of a space-time ruler, the clock difference between the clocks on two aircraft flying around the world, one east and one west, along the equator and a clock fixed on the equator is calculated (Hafele–Keating experiment). The calculated results are consistent with the classical formula associated with Einstein's theory of relativity. A generalized Hamiltonian, which can characterize the energy properties of matter, is given by using the space-time ruler. It is proved that the Hamiltonian in classical mechanics is an approximation of the generalized Hamiltonian under the conditions of low speed and a weak gravitational field. By using the generalized Hamiltonian, a new formula for gravitational redshift is obtained. Under the condition of a weak gravitational field, the new formula for gravitational redshift enables two classical formulas on gravitational redshift to be derived, both of which have been experimentally proven. [ABSTRACT FROM AUTHOR]

Copyright of Physics Essays is the property of Physics Essays Publication and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The technological refinement of experimental techniques has recently allowed the generation of two-photon polarization-entangled states at low Earth orbit, which has been subsequently applied to quantum communications. This achievement paves the way to study the interplay between general relativity and quantum mechanics in new setups. Here, we study the generation of two-photon energy-time entangled states via large scale Franson and Hugged interferometric arrays in the presence of a weak gravitational field. We show that for certain configurations of the arrays, an entangled state emerges as a consequence of the gravitational time delay. We also show that the aforementioned arrays generate entanglement and violate the Clauser–Horne–Shymony–Holt inequality under suitable conditions even in the presence of frequency dispersion. [ABSTRACT FROM AUTHOR]

The state of an ensemble of three-level atoms after absorption of a single photon and subsequent spontaneous decays in the presence of a weak gravitational field is shown to lose the phase matching of the emitted photons with the wave vector of the absorbed photon, similar to the case of an ensemble of two-level atoms. However, the spatial distribution of a second photon coincides with the result for a space without a gravitational field when averaging over the state of one of the emitted photons. [ABSTRACT FROM AUTHOR]

Witnessing quantum effects in the gravitational field is found to be exceptionally difficult in practice due to the lack of empirical evidence. Hence, a debate is going on among physicists whether gravity has a quantum domain or not. To date, no convincing experimental proposal was put forward until two recent independent works by Bose et al. (Phys Rev Lett 119:240401, 2017) and Marletto and Vedral (Phys Rev Lett 119:240402, 2017). The authors have proposed schemes to test the quantumness of gravity in two small test masses by entangling two spatially separated objects using gravitational interactions. They have provided a method to witness the entanglement using spin correlation measurements, which could imply evidence for gravity being a quantum coherent mediator. Here we have proposed a simulational model by providing a new quantum circuit for verifying the above schemes. We have simulated the schemes for the first time in IBM's 5-qubit quantum chip 'ibmqx4' by developing a quantum system which shows effects analogous to quantum gravity and calculates the degree of entanglement of the spin correlation. The entanglement witness over a range is obtained for different experimental parameters. [ABSTRACT FROM AUTHOR]