Die Asymmetrie der kosmischen Zeit und RIEMANNS Gravitationstheorie1)     

Hans-Jürgen Treder 《Astronomische Nachrichten》1978,299(4):165-169

RIEMANN himself has considered his formulation of the differential geometry of curved spaces as a first step to a unified geometrical theory of “one ether of gravity, electricity and magnetism”. RIEMANN has pointed out that a fundamental point in such a theory of gravitation has to be the asymmetry of its sources: only positive masses exist. – According to RIEMANN this asymmetry of sources to be coupled with an asymmetry of gravitation field equation against the time-reversion t → - t. Therefore, the gravitation field equation is of the type of a continuity-equation of a velocity field v_i˜g^ikθ _k Φ. RIEMANN 's ether is incompressible in empty space-domains: θ _k (g^1/2v^k) = o. But, in domains with a massdensity σ > o it is θg^1/2/θt = −2 kcσ = − 2 kcg^1/2σ₀ (with a universal constant kc). The matter-density defines depressions of the ether. In a general-relativistic approach RIEMANN 's ansatz means that in empty space-time domains the world-geometry is the purely metrical “RIEMANN ian” geometry. However, in domains with a non-vanishing matter-tensor T_μ^v ≠ o the geometry becomes “non-RIEMANN ian” affine connecting and is of the type of WEYL 's geometry or of the “EINSTEIN -CARTAN theories of gravitation”. Especially, RIEMANN 's field equation for the empty space θ _k ((g^1/2g^ikθ _k Φ) = o. is the EINSTEIN equation (-|g_μv|)^1/2 R₀⁰ = o with g₀₀ = - Φ²c^-4.  相似文献   

Gravitation und weitreichende schwache Wechselwirkungen bei Neutrino-Feldern Gedanken zu einer Theorie der solaren Neutrinos     

H.-J. Treder 《Astronomische Nachrichten》1974,295(4):169-184

The strange non-evidence of the solar-neutrino current by the experiments of DAVIS et al. postulates a fundamental revision of the theory of weak interactions and of its relations to gravitation theory. (We assume that the astrophysical stellar models are not completely wrong.) – Our paper is based on PAULI 's grand hypothesis about the connection between weak and gravitational interactions. According to PAULI and BLACKETT the (dimensionless) gravitation constant is the square of the (dimensionless) FERMI -interaction constant and according to the hypotheses of PAULI, DE BROGLIE , and JORDAN the RIEMANN -EINSTEIN gravitational metric g_ik is fusioned by the four independent WEYL ian neutrino fields (β-neutrinos and β-antineutrinos, μ-neutrinos and μ-antineutrinos). This fusion gives four reference tetrads h_i^A(x^l) as neutrino-current vectors, firstly. Then, the metric g_ik is defined by the equation g_ik = η_AB h_i^Ah_η^B according to EINSTEIN 's theory of tele-parallelism in RIEMANN ian space-times. The relation of the gravitation field theory to FERMI 's theory of weak interactions becomes evident in our reference-tetrads theory of gravitation (TREDER 1967, 1971). – According to this theory the coupling of the gravitation potential h_i^A with the matter T_ιⁱ is given by a potential-like (FERMI -like) interaction term. In this interaction term two WEYL spinor-fields are operating on the matter-tensor, simultanously. Therefore, the gravitation coupling constant is PAULI 's square of the FERMI -constant. Besides of the fusion of the RIEMANN -EINSTEIN metric g_ik by four WEYL spinors we are able to construct a conformal flat metric ĝ_ik = ϕ²η_ik by fusion from each two WEYL spinors. (This hypothesis is in connection with our interpretation of EINSTEIN 's hermitian field theory as a unified field-theory of the gravitational metric g_ik and a WEYL spinor field [TREDER 1972].) Moreover, from the reference-tetrads theory is resulting that the WEYL spinors in the “new metric” ĝ_ik are interacting with the DIRAC matter current by a FERMI -like interaction term and that these WEYL spinors fulfil a wave equation in the vacuum. Therefore, we have a long-range interaction with the radiced gravitational constant \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {\frac{{tm^2 }}{{hc}}} $\end{document} as a coupling constant. That means, we have a long-range interaction which is 10¹⁸ times stronger than the gravitation interaction. – However, according to the algebraic structure of the conform-flat this long-range interaction is effective for the neutrino currents, only. And for these neutrinos the interaction is giving an EINSTEIN -like redshift of its frequences. The characteristic quantity of this “EINSTEIN shift” is a second gravitation radius â of each body: N = number of baryons, m = mass of a baryon.) This radius â is 10¹⁸ times larger than the EINSTEIN -SCHWARZSCHILD gravitation radius a = fM/c²: But, this big “weak radius” â has a meaning for the neutrinos, only.–The determination of the exterior and of the interior “metrics” ĝ_ik is given by an “ansatz” which is analogous to the ansatz for determination of strong gravitational fields in our tetrads theory. That is by an ansatz which includes the “self-absorption” of the field by the matter. For all celestial bodies the “weak radius” â is much greater than its geometrical dimension. Therefore, a total EINSTEIN redshift of the neutrino frequences v is resulting according to the geometrical meaning of our long-range weak interaction potential ĝ_ik = ϕ²η_ik. That means, the cosmic neutrino radiation becomes very weak and unable for nuclear reactions. Theoretically, our hypothesis means an ansatz for unitary theory of gravitation and of weak interaction. This unitary field theory is firstly based on EINSTEIN 's hermitian field theory and secondly based on our reference-tetrads theory of gravitation.  相似文献   

Some remarks about cosmology in brans and Dicke's theory     

G. Lessner 《Astrophysics and Space Science》1974,30(1):L5-L7

It is established that, in contrast to Einstein's theory, in the cosmological equations of the theory by Brans and Dicke the spatial component of the field equations follows from the remaining equations and the conservation lawT ^ik _jk=0 only if one excludes the power law R ^–2. Some consequences are discussed.  相似文献   

Programmed motion in the presence of homogeneity     

G. Bozis  M.‐C. Anisiu 《Astronomische Nachrichten》2009,330(8):791-796

In the framework of the inverse problem of dynamics, we face the following question with reference to the motion of one material point: Given a region T_orb of the xy plane, described by the inequality g (x, y) ≤ c₀, are there potentials V = V (x, y) which can produce monoparametric families of orbits f (x, y) = c (also to be found) lying exclusively in the region T_orb? As the relevant PDEs are nonlinear, an answer to this question (generally affirmative, but not with assurance) can be given by the procedure of the determination of certain constants specifying the pertinent functions. In this paper we ease the mathematics involved by making certain simplifying assumptions referring to the homogeneity of both the function g (x, y) (describing the boundary of T_orb) and of the slope function γ(x, y) = f_y/f_x (representing the required family f (x, y) = c). We develop the method to treat the so formulated problem and we show that, even under these restrictive assumptions, an affirmative answer is guaranteed provided that two algebraic equations have in common at least one solution (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

CO observations,geometry, and galactic structure     

B. J. Robinson  R. N. Manchester  W. H. McCutcheon 《Astrophysics and Space Science》1986,119(1):111-114

2.6 mm carbon monoxide and 21 cm hydrogen line observations of the Galaxy define six directions where gas is seen tangentially along a spiral feature and four directions where extended structures cross theR=R ₀ circle. These directions provide a geometrical framework for any spiral structure pattern. Also simple equations are derived to define the normalized radiusR/R ₀ of gas with a particular radial velocity in terms of the observed tangential velocity of gas with the sameR/R ₀=sinl _T, without specific knowledge of (R), ₀ orR ₀.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.  相似文献   

A nonlinear tensor field and the second metric tensor     

L. Sh. Grigorian  S. Gottlöber 《Astrophysics》1996,39(1):71-77

In our preceding paper {see [L. Sh. Grigorian and S. Gottlöber, Astrofizika (in press)]} we investigated a self-gravitating system consisting of a scalar field and a linear tensor field _ik= _ki with minimal coupling and with allowance for the action of vacuum polarization effects. In the present paper we investigate the case of a nonlinear tensor field _ik. The action S ⁽⁾ of the field _ik is determined by the difference R_ik — _ik, where R_ik is the space-time Ricci tensor and Rik is the analogous quantity constructed using the metric _ik=g_ik+_ik induced by _ik ( is a free parameter). Here S ⁽⁾ coincides with the previously known expression for the action of a linear field _ik. Equations of motion are derived for _ik in curved space-time. The energy-momentum metric tensor, determining the contribution of _ik to the gravitational field equations, is calculated.Translated from Astrofizika, Vol. 39, No. 1, pp. 135–144, January-March, 1996.  相似文献   

The Inversion of the EINSTEIN-STRAUS Theorem     

U. Kasper 《Astronomische Nachrichten》1976,297(3):127-129

We consider the inversion of a problem put by A. EINSTEIN and E. G. STRAUS , that is, we ask for restrictions on the scaling factor R(t) of the ROBERTSON WALKER metric and the functions H²(r') and A²(r') of a spherically symmetric and static vacuum metric, which are consequences of the requirement that the vacuum metric shall pass continuously differentiable into the ROBERTSON WALKER metric at a certain value r_b of the comoving radial coordinate r.  相似文献   

Stationary equations of hydrogen excitation and ionization in prominences     

Chultem  Ts.  Yakovkin  N. A. 《Solar physics》1974,34(1):133-150

The statistical equilibrium equations for the continuum and first 10 levels of a hydrogen atom show that the radiation of a bright prominence (the brightness of the H line has attained 56 mÅ of the disc centre spectrum) is completely due to scattering of the Sun radiation. The basic unknowns are separated with certainty: electron concentration (n _e = 3.0 × 10¹⁰ cm^–3), effective thickness (l = 4.2 × 10⁸ cm) and electron temperature (T _e = 5000 K).Radiation of a very bright prominence (A (H) = 213 mÅ; T _e = 7300 K; n _e = 5.0 × 10¹¹ cm^–3; l = 1.3 × 10⁷ cm) is on account of electron impacts (40%) and the Sun radiation scattering (60%).The parameters are shown to depend greatly on the prominence optical thickness in the lines of the first subordinate series of a hydrogen atom. In the course of determination all the parameters and 100 interconnected integral equations of the radiation diffusion have been thickness-averaged; the population of levels has been calculated by observations using the self-absorption factors.  相似文献   

Maximum temperatures for radiation from plasma waves     

D. F. Smith  P. A. Sturrock 《Astrophysics and Space Science》1971,12(2):411-414

We derive upper limits to the radiation temperaturesT ^t(k) for emission near the fundamental and second harmonic of the electron plasma frequency in terms of the effective temperature for plasma wavesT ^l(k). We findT ^t(k)(c/(3)^1/2 V _e)³ T ^l(k) for emission near the fundamental which differs from the result of Melrose (1970b) by the factor in parentheses. This factor can exceed 4×10⁴ in some plasmas. The conditions under which this limit could be reached are delinated. For emission near the second harmonicT ^t(k)T ^l(k) since the absorption coefficient in this case can only be positive.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   

Friedmann Models and Cosmological Solutions in the Bimetric Theory with a Quadratic Lagrangian     

A. H. Yeranyan 《Astrophysics》2001,44(1):137-142

Cosmological models are investigated within the framework of the bimetric theory of gravitation with a Lagrangian that is quadratic with respect to intensities g _ik|l . It is shown that the theory predicts not only singular but also nonsingular solutions.  相似文献   

Model atmosphere parameters of the binary systems COU1289 and COU1291     

M. A. Al‐Wardat 《Astronomische Nachrichten》2007,328(1):63-67

The spectral energy distributions between λ 3700 Å and λ 8100 Å of the binary systems COU1289 and COU1291 have been measured with the Carl‐Zeiss‐Jena 1 m telescope of the Special Astrophysical Observatory. Their B, V, R magnitudes and B – V colour indices were computed and compared with earlier investigations. Model atmospheres of both systems were constructed using a grid of Kurucz blanketed models, their spectral energy distributions in the continuous spectrum were computed and compared with the observational ones. The model atmosphere parameters for the components of COU1289 were derived as: T ^a_eff = 7100 K, T ^b_eff = 6300 K, log g _a = 4.22, log g _b = 4.22, R _a = 1.50 R_⊙, R _b = 1.40 R_⊙, and for the components of COU1291 as: T ^a_eff = 6400 K, T ^b_eff = 6100 K, log g _a = 4.20, log g _b = 4.35, R _a = 1.47 R_⊙, R _b = 1.12 R_⊙. The spectral types of both components of the system COU1289 were concluded as F1 and F7, and of the system COU1291 as F6 and F9. Finally the formation and evolution of the systems were discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Cosmological models with the variable gravitational and cosmological constants     

N. Ibotombi Singh  Anita Sorokhaibam 《Astrophysics and Space Science》2007,310(1-2):131-134

Cosmology with the gravitational and cosmological constants generalized as coupling scalars in Einsteins theory is considered. A general method of solving the field equations is given. Exact solution for Zeldovich fluid satisfying G=G ₀(R/R ₀) ⁿ is given.  相似文献   

The conformal potential of the stationary axisymmetric vacuum     

Z. Perjs 《Astronomische Nachrichten》1986,307(5):321-326

In a stationary axisymmetric vacuum gravitational field, the conformal structure of the 3-space is determined by the symmetric, trace free and divergence-less tensor Y_ir. Using the Killing vector Kⁱ of the axisymmetry, the conformal potential U can be defined by U,_i = _εijkKjY^krK_r. Conversely, the tensor Y_ik is given algebraically in terms of the gradient U,_i of the conformal potential. An attempt is made here to re-formulate the field equations R_λμ = 0 in terms of the conformal potential. Introducing the Ernst potential as a complex coordinate, the cylindrical radius can be eliminated from the field equations.  相似文献   

Cosmological models with generalised gravitational and cosmological constants     

N. Ibotombi Singh  S. Surendra Singh  S. Romaleima Devi  A. Sumati Devi 《Astrophysics and Space Science》2009,324(1):67-70

We consider cosmology with the gravitational and cosmological constants generalized as coupling scalars in Einstein’s theory. A general method of solving the field equations is given. We study here the exact solutions for negative pressure models satisfying G=G ₀(R/R ₀) ⁿ .  相似文献   

The most resonant pulsation frequency of δ Scuti stars     

S. V. Kotov  V. A. Kotov 《Astronomische Nachrichten》1997,318(2):121-128

Pulsation of the Sun with a period of P₀ ≈ 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this P₀ periodicity among other (short-period variable) stars, the pulsation frequencies of δ Sct stars are subjected to specific analysis. With a confidence level ≈ 3.8σ it is found that the frequency v₀ = P₀⁻¹ ≈ 104 m̈Hz, within the error limits, appears indeed to be the most “resonant” one for the total sample of 318 pulsating stars of δ Sct type (the most commensurable, or “synchronizing”, period for all these stars occurs to be 162 ± 4 min). We conjecture that a) the P₀ oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of δ Sct stars, reffected by this “ubiquitous” P₀ resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near-resonance with the “universal” v₀ frequency). The arguments are given favouring a cosmoogical nature of the P₀ oscillation.  相似文献   

Gravitation and inertia; a rearrangement of vacuum in gravity     

G. Ter-Kazarian 《Astrophysics and Space Science》2010,327(1):91-109

We address gravitation and inertia in the framework of a general gauge principle (GGP) which accounts for the gravitation gauge group G _R generated by a hidden local internal symmetry implemented on the flat space. Following the method of phenomenological Lagrangians, we connect the group G _R to a non-linear realization of the Lie group of the distortion G _D of the local internal properties of six-dimensional flat space, M ₆, which is assumed as a toy model underlying four-dimensional Minkowski space. We study the geometrical structure of the space of parameters and derive the Maurer–Cartan’s structure equations. We treat distortion fields as Goldstone fields, to which the metric and connection are related, and we infer the group invariants and calculate the conserved currents. The agreement between the proposed gravitational theory and available observational verifications is satisfactory. Unlike the GR, this theory is free of fictitious forces, which prompts us to address separately the inertia from a novel view point. We construct a relativistic field theory of inertia, which treats inertia as a distortion of local internal properties of flat space M ₂ conducted under the distortion inertial fields. We derive the relativistic law of inertia (RLI) and calculate the inertial force acting on the photon in a gravitating system. In spite of the totally different and independent physical sources of gravitation and inertia, the RLI furnishes a justification for the introduction of the Principle of Equivalence. Particular attention is given to the realization of the group G _R by the hidden local internal symmetry of the abelian group U ^loc=U(1) _Y ×diag[SU(2)], implemented on the space M ₆. This group has two generators, the third component T ³ of isospin and the hypercharge Y, implying Q ^d =T ³+Y/2, where Q ^d is the distortion charge operator assigning the number −1 to particles, but +1 to anti-particles. This entails two neutral gauge bosons that coupled to T ³ and Y. We address the rearrangement of the vacuum state in gravity resulting from these ideas. The neutral complex Higgs scalar breaks the vacuum symmetry leaving the gravitation subgroup intact. The resulting massive distortion field component may cause an additional change of properties of the spacetime continuum at huge energies above the threshold value.  相似文献   

Flare Plasma Cooling from 30 MK down to 1 MK modeled from Yohkoh,GOES, and TRACE observations during the Bastille Day Event (14 July 2000)     

Aschwanden  Markus J.  Alexander  David 《Solar physics》2001,204(1-2):91-120

We present an analysis of the evolution of the thermal flare plasma during the 14 July 2000, 10 UT, Bastille Day flare event, using spacecraft data from Yohkoh/HXT, Yohkoh/SXT, GOES, and TRACE. The spatial structure of this double-ribbon flare consists of a curved arcade with some 100 post-flare loops which brighten up in a sequential manner from highly-sheared low-lying to less-sheared higher-lying bipolar loops. We reconstruct an instrument-combined, average differential emission measure distribution dEM(T)/dT that ranges from T=1 MK to 40 MK and peaks at T ₀=10.9 MK. We find that the time profiles of the different instrument fluxes peak sequentially over 7 minutes with decreasing temperatures from T≈30 MK to 1 MK, indicating the systematic cooling of the flare plasma. From these temperature-dependent relative peak times t _peak(T) we reconstruct the average plasma cooling function T(t) for loops observed near the flare peak time, and find that their temperature decrease is initially controlled by conductive cooling during the first 188 s, T(t)∼[1+(t/τ_cond)]^−2/7, and then by radiative cooling during the next 592 s, T(t)∼[1−(t/τ_rad)]^3/5. From the radiative cooling phase we infer an average electron density of n _e=4.2×10¹¹ cm⁻³, which implies a filling factor near 100% for the brightest observed 23 loops with diameters of ∼1.8 Mm that appear simultaneously over the flare peak time and are fully resolved with TRACE. We reproduce the time delays and fluxes of the observed time profiles near the flare peak self-consistently with a forward-fitting method of a fully analytical model. The total integrated thermal energy of this flare amounts to E _thermal=2.6×10³¹ erg. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1014257826116  相似文献   

Strong and weak gravitational field in R+μ 4/R gravity     

K. Saaidi  A. Vajdi  S. W. Rabiei  A. Aghamohammadi  H. Sheikhahmadi 《Astrophysics and Space Science》2012,337(2):739-745

We introduce a new approach for investigating the weak field limit of vacuum field equations in f(R) gravity and we find the weak field limit of f(R)=R+μ ⁴/R gravity. Furthermore, we study the strong gravity regime in R+μ ⁴/R model of f(R) gravity. We show the existence of strong gravitational field in vacuum for such model. We find out in the limit μ→0, the weak field limit and the strong gravitational field can be regarded as a perturbed Schwarzschild metric.  相似文献   

Accelerated expansion from?a?modified-quadratic gravity     

El-Nabulsi Ahmad?Rami 《Astrophysics and Space Science》2011,332(2):491-495

We investigate the late-time dynamics of a four-dimensional universe based on modified scalar field gravity in which the standard Einstein-Hilbert action R is replaced by f(φ)R+f(R) where f(φ)=φ ² and f(R)=AR ²+BR _μν R ^μν,(A,B)∈ℝ. We discussed two independent cases: in the first model, the scalar field potential is quartic and for this special form it was shown that the universe is dominated by dark energy with equation of state parameter w≈−0.2 and is accelerated in time with a scale factor evolving like a(t)∝t ^5/3 and B+3A≈0.036. When, B+3A→∞ which corresponds for the purely quadratic theory, the scale factor evolves like a(t)∝t ^1/2 whereas when B+3A→0 which corresponds for the purely scalar tensor theory we found when a(t)∝t ^1.98. In the second model, we choose an exponential potential and we conjecture that the scalar curvature and the Hubble parameter vary respectively like R=hH[(f)\dot]/f,h ? \mathbbRR=\eta H\dot{\phi}/\phi,\eta\in\mathbb{R} and H=g[(f)\dot]^c,(g,c) ? \mathbbRH=\gamma\dot{\phi}^{\chi},(\gamma,\chi)\in\mathbb{R}. It was shown that for some special values of  χ, the universe is free from the initial singularity, accelerated in time, dominated by dark or phantom energy whereas the model is independent of the quadratic gravity corrections. Additional consequences are discussed.  相似文献   

Bianchi type-VI0 perfect fluid cosmological model in a modified theory of gravity     

V. U. M. Rao  D. Neelima 《Astrophysics and Space Science》2013,345(2):427-430

A spatially homogeneous and anisotropic Bianchi type-VI₀ space-time filled with perfect fluid in general relativity and also in the framework of f(R,T) gravity proposed by Harko et al. (in arXiv:1104.2669 [gr-qc], 2011) has been studied with an appropriate choice of the function f(R,T). The field equations have been solved by using the anisotropy feature of the universe in Bianchi type-VI₀ space time. Some important features of the models, thus obtained, have been discussed. We noticed that the involvement of new function f(R,T) doesn’t affect the geometry of the space-time but slightly changes the matter distribution.  相似文献