共查询到20条相似文献,搜索用时 31 毫秒
1.
Emilio Santos 《Physics letters. A》2010,374(5):709-712
It is pointed out that quantum vacuum fluctuations may give rise to a curvature of space-time equivalent to the curvature currently attributed to dark energy. A simple calculation is made, involving plausible assumptions within the framework of quantized gravity, which suggests that the value of the dark energy density is roughly given by the product of Newton's constant times the quantity m6c4?−4, m being a typical mass of elementary particles. The estimate is compatible with observations. 相似文献
2.
It is shown that a solution of the form R(ν)=0 (R is the space-time curvature) exists for a vacuum solution (the field fluctuations
are assumed zero, and only the ground state with the minimum effective potential energy remains) in the initial stage with
consideration of the effect of spontaneous symmetry breaking for a scalar field with the “wrong sign” of the mass term and
the conformal factor. For a spherically symmetric metric in vacuum, a solution increasing as a square of the distance and
proportional to the square of the Higgs boson mass exists.
A. A. Fridman Theoretical Physics Laboratory. Translated from Izvestiya Vysshikh Uchebhykh Zavedenii, Fizika, No. 4, pp. 34–38,
April, 2000. 相似文献
3.
Under the flat Minkowski space-time background, using the perturbative expansion of the metric density, we calculate the expressions of the leading terms of several two-point curvature vacuum correlation functions in N-dimensional R-gravity, resulting in that the contributions of the leading terms of the curvature vacuum correlation functions are all vanishing. 相似文献
4.
A. F. Yukin 《Russian Physics Journal》2006,49(7):699-705
A scalar field Lagrangian is considered in the curved space-time to which a Hamiltonian determining nonzero vacuum field value
is added. The initial Lagrangian can be expressed as a sum of Lagrangians for the constant scalar field component and perturbation.
The first Lagrangian can be considered as a Lagrangian for the Einstein gravitational field in vacuum. The problem of renormalization
of the constant scalar field component is investigated. It is demonstrated that in the case of conformal relation of the scalar
field to the space-time curvature, there exists a unique value of the scalar space curvature for which the field can be considered
constant (field perturbations do not result in renormalization of the constant component). This curvature value determines
the unique value of the equilibrium nuclide density. A correlation of the examined Lagrangian parameters with the integral
parameters of the Solar system is discussed.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 18–34, July, 2006. 相似文献
5.
We argue that quantum-gravitational fluctuations in the space-time background give the vacuum non-trivial optical properties that include diffusion and consequent uncertainties in the arrival times of photons, causing stochastic fluctuations in the velocity of light in vacuo. Our proposal is motivated within a Liouville string formulation of quantum gravity that also suggests a frequency-dependent refractive index of the particle vacuum. We construct an explicit realization by treating photon propagation through quantum excitations of D-brane fluctuations in the space-time foam. These are described by higher-genus string effects, that lead to stochastic fluctuations in couplings, and hence in the velocity of light. We discuss the possibilities of constraining or measuring photon diffusion in vacuo via -ray observations of distant astrophysical sources. 相似文献
6.
The propagation of electromagnetic waves in the vacuum is considered taking into account quantum fluctuations in the limits
of Maxwell-Langevin (ML) equations. For a model of “white noise” fluctuations, using ML equations, a second order partial
differential equation is found which describes the quantum distribution of virtual particles in vacuum. It is proved that
in order to satisfy observed facts, the Lamb Shift etc, the virtual particles should be quantized in unperturbed vacuum. It
is shown that the quantized virtual particles in toto (approximately 86 percent) are condensed on the “ground state” energy
level. It is proved that the extension of Maxwell electrodynamics with inclusion of the vacuum quantum field fluctuations
may be constructed on a 6D space-time continuum with a 2D compactified subspace. Their influence on the refraction indexes
of vacuum is studied. 相似文献
7.
The effect of spectral broadening of electromagnetic radiation propagating in a four-dimensional space-time with fluctuations in the space curvature caused by relict gravitational radiation is predicted. It is demonstrated that distortion of spectral line profiles of electromagnetic radiation caused by the fluctuating metric is at the level of resolution of the available spectral instrumentation. 相似文献
8.
We analyze the quantum fluctuations of vacuum stress tensors and spacetime curvatures, using the framework of linear response theory which connects these fluctuations to dissipation mechanisms arising when stress tensors and spacetime metric are coupled. Vacuum fluctuations of spacetime curvatures are shown to be a sum of two contributions at lowest orders; the first one corresponds to vacuum gravitational waves and is restricted to light-like wavevectors and vanishing Einstein curvature, while the second one arises from gravity of vacuum stress tensors. From these fluctuations, we deduce noise spectra for geodesic deviations registered by probe fields which determine ultimate limits in length or time measurements. In particular, a relation between noise spectra characterizing spacetime fluctuations and the number of massless neutrino fields is obtained. 相似文献
9.
Stefan Haesen 《General Relativity and Gravitation》2004,36(8):1791-1804
We study Kerr-Schild type perturbations with a non-null perturbation vector in the vacuum case. The perturbation equations are derived and it is shown that they lead to constraints on the background space-time which can be interpreted in terms of the curvature of 3-spaces. The first order perturbation equations are used to construct new Petrov type D solutions tangent to the Schwarzschild metric. 相似文献
10.
Howard E. Brandt 《Foundations of Physics Letters》1992,5(1):43-55
The maximum possible proper acceleration relative to the vacuum determines much of the differential geometric structure of the space-time tangent bundle. By working in an anholonomic basis adapted to the spacetime affine connection, one derives a useful expression for the Riemann curvature scalar of the bundle manifold. The explicit documentation of the proof is important because of the central role of the curvature scalar in the formulation of an action with resulting field equations and associated solutions to physical problems. 相似文献
11.
《Nuclear Physics B》1995,454(3):541-560
We propose a new formulation of the space-time interpretation of the c = 1 matrix model. Our formulation uses the well-known leg-pole factor that relates the matrix model amplitudes to that of the 2-dimensional string theory, but includes fluctuations around the Fermi vacuum on both sides of the inverted harmonic oscillator potential of the double-scaled model, even when the fluctuations are small and confined entirely within the asymptotes in the phase plane. We argue that including fluctuations on both sides of the potential is essential for a consistent interpretation of the leg-pole transformed theory as a theory of space-time gravity. We reproduce the known results for the string theory tree-level scattering amplitudes for flat space and linear dilaton background as a special case. We show that the generic case corresponds to more general space-time backgrounds. In particular, we identify the parameter corresponding to background metric perturbation in string theory (black-hole mass) in terms of the matrix model variables. Possible implications of our work for a consistent non-perturbative definition of string theory as well as for quantized gravity and black-hole physics are discussed. 相似文献
12.
G. F. Torres Del Castillo 《General Relativity and Gravitation》1999,31(2):205-212
It is shown that in a space-time that admits ageodetic and shear-free null vector field which is aprincipal direction of the conformal curvature(therefore, in any algebraically special solution of the Einstein vacuum field equations), any self-dualelectromagnetic field is locally given by a scalar(Debye) potential which obeys a second-orderdifferential equation and, similarly, that any self-dualYang-Mills field is locally given by a matrix-valuedpotential governed by a nonlinear second-orderdifferential equation. Using the fact that any self-dualelectromagnetic field is the self-dual part of a realsolution of the source-free Maxwell equations, it isshown that in any space-time of this class, the solutionof the source-free Maxwell equations is locally given bya Debye potential. 相似文献
13.
The cosmological constant problem is examined within the context of the covariant brane-world gravity, based on Nash’s embedding
theorem for Riemannian geometries. We show that the vacuum structure of the brane-world is more complex than General Relativity’s
because it involves extrinsic elements, in specific, the extrinsic curvature. In other words, the shape (or local curvature)
of an object becomes a relative concept, instead of the “absolute shape” of General Relativity. We point out that the immediate
consequence is that the cosmological constant and the energy density of the vacuum quantum fluctuations have different physical
meanings: while the vacuum energy density remains confined to the four-dimensional brane-world, the cosmological constant
is a property of the bulk’s gravitational field that leads to the conclusion that these quantities cannot be compared, as
it is usually done in General Relativity. Instead, the vacuum energy density contributes to the extrinsic curvature, which
in turn generates Nash’s perturbation of the gravitational field. On the other hand, the cosmological constant problem ceases
to be in the brane-world geometry, reappearing only in the limit where the extrinsic curvature vanishes. 相似文献
14.
In brane inflationary scenarios, the cosmological perturbations are supposed to originate from the vacuum fluctuations of the inflaton field corresponding to the position of the brane. We show that a significant, and possibly dominant, contribution to the curvature perturbation is generated at the end of inflation through the vacuum fluctuations of fields, other than the inflaton, which are light during the inflationary trajectory and become heavy at the brane-antibrane annihilation. These fields appear generically in string compactifications where the background geometry has exact or approximate isometries and parametrize the internal angular directions of the brane. 相似文献
15.
Janet E. Jones 《Annals of Physics》1976,101(2):380-393
It is shown for the case of a conformally flat vacuum that the curvature of space-time may be viewed as the observable consequence of particle interactions involving a scalar field φ, rather than the independent agency of the gravitational field by itself. The quantum nature of gravity comes in as a consequence of the quantum properties of the φ-field (“vacuum fluctuation”), and a direct analogy is drawn between the renormalizations of charge and mass. Cosmological solutions are derived: These being just the conventional Friedmann solutions, or the de Sitter solution. It is pointed out that a totally empty universe must be Minkowskian. 相似文献
16.
Michael Redhead 《Foundations of Physics》1995,25(1):123-137
In this paper questions about vacuum fluctuations in local measurements, and the correlations between such fluctuations, are discussed. It is shown that maximal correlations always exist between suitably chosen local projection operators associated with spacelike separated regions of space-time, however far apart these regions may be. The connection of this result with the well-known Fregenhagen bound showing exponential decay of correlations with distance is explained, and the relevance of the discussion to the question “What do particle detectors detect?” is addressed. 相似文献
17.
It is shown that Minkowski space is unstable in the context of semiclassical gravity. There exists a threshold mass, of the quantized matter field, which marks the dividing line between stable and unstable vacuum fluctuations of matter in flat space-time. The Minkowski vacuum gravitational-matter system undergoes a phase transition above this critical point, the new phase being a self-consistently generated de Sitter Euclidean cosmology. Its total energy is degenerate with respect to that of empty Minkowski space-time. It represents an appropriate candidate for the primeval configuration of an inflationarylike universe.This essay received the fourth award from the Gravity Research Foundation for the year 1983 [Ed.]. 相似文献
18.
Federico Demartin Fabio Maltoni Kentarou Mawatari Ben Page Marco Zaro 《The European Physical Journal C - Particles and Fields》2014,74(9):1-19
We evaluate the Wightman function, the mean field squared and the vacuum expectation value of the energy–momentum tensor for a scalar field with the Robin boundary condition on a spherical shell in the background of a constant negative curvature space. For the coefficient in the boundary condition there is a critical value above which the scalar vacuum becomes unstable. In both the interior and the exterior regions, the vacuum expectation values are decomposed into the boundary-free and sphere-induced contributions. For the latter, rapidly convergent integral representations are provided. In the region inside the sphere, the eigenvalues are expressed in terms of the zeros of the combination of the associated Legendre function and its derivative and the decomposition is achieved by making use of the Abel–Plana type summation formula for the series over these zeros. The sphere-induced contribution to the vacuum expectation value of the field squared is negative for the Dirichlet boundary condition and positive for the Neumann one. At distances from the sphere larger than the curvature scale of the background space the suppression of the vacuum fluctuations in the gravitational field corresponding to the negative curvature space is stronger compared with the case of the Minkowskian bulk. In particular, the decay of the vacuum expectation values with the distance is exponential for both massive and massless fields. The corresponding results are generalized for spaces with spherical bubbles and for cosmological models with negative curvature spaces. 相似文献
19.
20.
Gerald E. Marsh 《Foundations of Physics》2008,38(10):959-968
It has been shown that for the Reissner-Nordström solution to the vacuum Einstein field equations charge, like mass, has a unique space-time signature (Marsh, Found. Phys. 38:293–300, 2008). The presence of charge results in a negative curvature. This work, which includes a discussion of effective mass, is extended here to the Kerr-Newman solution. 相似文献