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51.
Taking into account the violation of the equivalence principle, we analyze the propagation of neutrinos in the gravitational field generated by wormholes. The analysis is performed for massive and massless neutrinos. By using the constraints on the (negative) mass of wormholes, which is of the order of stellar-substellar masses, we determine constraints on f which characterizes the degree of violation of the equivalence principle. 相似文献
52.
Marco Matone 《Foundations of Physics Letters》2002,15(4):311-328
We suggest that quantum mechanics and gravity are intimately related. In particular, we investigate the quantum Hamilton–Jacobi equation in the case of two free particles and show that the quantum potential, which is attractive, may generate the gravitational potential. The investigation, related to the formulation of quantum mechanics based on the equivalence postulate, is based on the analysis of the reduced action. A consequence of this approach is that the quantum potential is always non-trivial even in the case of the free particle. It plays the role of intrinsic energy and may in fact be at the origin of fundamental interactions. We pursue this idea, by making a preliminary investigation of whether there exists a set of solutions for which the quantum potential can be expressed with a gravitational potential leading term which alone would remain in the limit 0. A number of questions are raised for further investigation. 相似文献
53.
研究墙体对微波脉冲的衰减特性,测量了微波脉冲垂直入射墙体后的脉冲信号,经过计算得到普通砖混墙、普通钢筋混凝土墙、钢筋网混凝土墙对窄带微波和超宽带微波的衰减值;分析了微波脉冲穿越不同墙体的频谱变化。研究结果表明,普通钢筋混凝土墙和普通砖混墙对窄带微波脉冲的衰减为0.342~0.699 dB/cm,对超宽带信号的衰减为0.134~0.183 dB/cm。钢筋网混凝土墙(厚65 cm)对超宽带信号的衰减较大(29.07~45.79 dB),同时使穿透墙体的超宽带信号频率分布向高频位移。 相似文献
54.
Ibrahim I. A. ElSersy H. H. Abadir M. F. 《Journal of Thermal Analysis and Calorimetry》2004,76(3):713-718
Thermal analysis was first used to investigate the pattern of dissociation of hydrated ordinary Portland cement. Portlandite
(Ca(OH)2) decomposes at about 500°C. This was confirmed by kinetic calculations. Thermal analysis was then performed to establish
the effect of varying the cement content on the percent mass loss associated with the decomposition of Ca(OH)2 in cement mortar cured for 28 days. An increasing relation was obtained. Standard concrete cubes were then prepared with
cement contents ranging from 200 to 450 kg m-3. The loss in mass on heating, up to 750°C, of concrete samples cured for 28 days was then related to the cement content in
concrete. The relation obtained was tested for concrete cubes of known cement content and found to be in better agreement
than the results obtained by conventional chemical analysis. This method can be used for an approximate determination of the
cement content in concrete.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
55.
The paper outlines a case for taking greater interest in the bottomless, or infinitely deep, dam model in Hydrology. It then shows that for such a model with unit withdrawals and an ergodic Markov chain input process the limiting distribution of depletion, when this exists, is a zero modified geometric distribution. This result generalises the well known result for independent inputs. The technical conditions required for the proof are satisfied for finite state space input processes and are shown to be satisfied by certain infinite state space input processes. These include as special cases examples which have a negative binomial limiting input distribution. 相似文献
56.
In this paperwewill derive a generalized uncertainty principle (GUP) in a simple varying speed of light (VSL) model. First
we will show that VSL is an immediate consequence of GUP. Then, within the framework of a simple VSL model, we will show that
GUP can be expressed as a function of cosmological scale factor. This expression gives two main results: uncertainties in
position and momentum are actually cosmological models dependent and these uncertainties depend on mass and momentum of the
particle under consideration. The relationship between matter content of the Universe and the values of uncertainties in early
stages of the evolution of the Universe will be discussed in a mini-superspace approach. 相似文献
57.
Surajit?Dasgupta Neven?Bilic Tapas?K.?DasEmail author 《General Relativity and Gravitation》2005,37(11):1877-1890
We demonstrate that a spherical accretion onto astrophysical black holes, under the influence of Newtonian or various post-Newtonian
pseudo-Schwarzschild gravitational potentials, may constitute a concrete example of classical analogue gravity naturally found
in the Universe. We analytically calculate the corresponding analogue Hawking temperature as a function of the minimum number
of physical parameters governing the accretion flow. We study both the polytropic and the isothermal accretion. We show that
unlike in a general relativistic spherical accretion, analogue white hole solutions can never be obtained in such post-Newtonian
systems. We also show that an isothermal spherical accretion is a remarkably simple example in which the only one information–the
temperature of the fluid, is sufficient to completely describe an analogue gravity system. For both types of accretion, the
analogue Hawking temperature may become higher than the usual Hawking temperature. However, the analogue Hawking temperature
for accreting astrophysical black holes is considerably lower compared with the temperature of the accreting fluid. 相似文献
58.
Relativistic Brownian Motion and Gravity as an Eikonal Approximation to a Quantum Evolution Equation
We solve the problem of formulating Brownian motion in a relativistically covariant framework in 3+1 dimensions. We obtain
covariant Fokker–Planck equations with (for the isotropic case) a differential operator of invariant d’Alembert form. Treating
the spacelike and timelike fluctuations separately in order to maintain the covariance property, we show that it is essential
to take into account the analytic continuation of “unphysical” fluctuations. 相似文献
59.
Helmholtz electrically induced extra mass inside a charged hollow sphere, recently evidenced by Mikhailov, is analogous to Machs inertial mass. Existence of a corresponding magnetically induced extra mass in an electron flying around an autistic magnet is derived. The overall electro-magnetic effect can be covariantly expressed. 相似文献
60.
I discuss the experiments of Joseph Weber (1919-2000) of the University of Maryland between
1960 and 1973 that were aimed at the detection of gravity waves. He used throughout a quadratic
detector to demodulate his antenna signal, which I analyze and compare to a linear detector.The
latter was used by all of the other groups that entered the field. Of these, Richard Garwin and I at
IBM were one of the first groups to publish, and I discuss in detail our experiments between 1973
and 1975. I then discuss the experiments that were carried out at Bell Labs-Rochester, Glasgow,
Munich-Frascati,Moscow, and Tokyo. I compare the results, all of which were negative, with Webers
claimed detection of large numbers of gravity-wave events, as many as seven per day. I conclude
that these were not in fact gravity waves, but artifacts of his extremely hands-on data-analysis procedures,
which I discuss in detail. Finally, I speculate on how this came about. 相似文献