Rest Energy Density Research Articles

An Investigation into LRS Bianchi I Universe in Brans-Dicke Theory

In this study, the homogenous and anisotropic locally rotationally symmetric (LRS) Bianchi type-I universe filled with the bulk viscous and the string cloud matter has been investigated in the Brans-Dicke (BD) scalar-tensor theory. The modified Einstein field equations of the constructed model have been solved by using the relation of the scale factors $A=B^m$ and considering the deceleration parameter to be $q=m-1$. It is found that the string does not survive for the model due to the obtained zero string energy density ($\rho_s=0$) and agrees with some studies in recent years. Moreover, it is possible to say that string matter may be turned into phantom energy over time, depending on the obtained negative rest energy density of the matter. When BD scalar field $\Phi$ is assumed constant, the attained solutions are reduced to General Relativity (GR) solutions for the static vacuum. Thus, the constructed model has not allowed the reduction of the BD solutions to GR solutions, including the matter distributions. In addition, some expansion models for choosing a value of constant $m$ have been obtained and provided. All the results have been analyzed in detail.

Example of negative energy density in a classical electron model

Classical models of the electron have been predicted to have negative rest energy density in certain regions. Using the model of the electron by Blinder we show that there are regions containing negative energy density, although the integral of the energy density over all space gives the electron rest mass. If the spin of the electron is ignored, then all regions of space have positive energy density with the Blinder model. The existence of Poincaré stress for the Blinder model is also demonstrated. The classical model for the electron discussed here admittedly does not involve quantum electrodynamics, where the infinite self energy is made finite with renormalization methods.

Anisotropic cloud string cosmological model with five-dimensional kaluza-klein space-time

Anisotropic cloud string cosmological models has been investigated in the context of five dimensional Kaluza- Klein space time. In this paper the energy momentum tensor is generated by rest energy density and tension density of the string with particle density attached to them. To obtained the exact solutions of the Einstein field equations we assumed a scale factor a(t)=e1β2βt+c where β and c are positive constant, which yields a variable deceleration parameter (DP) q=−aäȧ2=βH+α. The physical and geometrical behavior of the models is also discussed in detail.

Magnetized Bianchi Type-VI0 String Cosmological Model for Anti-Stiff Fluid in General Relativity

In this paper, we have investigated magnetized Bianchi type-VI0 string cosmological model for anti-stiff fluid in general relativity. We assume that F23 is the only survival component of electromagnetic field tensor Fij. For the absolute determination of the model, we assume the expansion in the model is proportional to the shear. The common measures of the Einstein’s field equations for the cosmological model have been acquired under the assumption of anti-stiff fluid i.e. p + ρ = 0, where ρ and p are the rest energy density and the pressure of the fluid, respectively. The physical and geometrical outcomes of the model in the presence of magnetic field are discussed.

Five Dimensional Bianchi Type-I Anisotropic Cloud String Cosmological Model With Electromagnetic Field in Saez-Ballester Theory

Within the context of Saez-Ballester theory, we explored the interaction of a five-dimensional Bianchi type-I anisotropic cloud string cosmological model Universe with an electromagnetic field. With an electromagnetic field, the energy momentum tensor is assumed to be the sum of the rest energy density and string tension density in this paper. We use the average scale factor as an integrating function of time to get exact answers to Saez-Ballester equations. The dynamics and importance of the model’s many physical parameters are also examined.

The matter Lagrangian of an ideal fluid

We show that the matter Lagrangian of an ideal fluid equals (up to a sign depending on its definition and on the chosen signature of the metric) the total energy density of the fluid, i.e. rest energy density plus internal energy density.

Interaction of Bianchi type-I anisotropic cloud string cosmological model universe with electromagnetic field

Here, we have investigated the interaction of Bianchi type-I anisotropic cloud string cosmological model universe with electromagnetic field in the context of general relativity. In this paper, the energy-momentum tensor is assumed to be the sum of the rest energy density and string tension density with an electromagnetic field. To obtain exact solution of Einstein’s field equations, we take the average scale factor as an integrating function of time. Also, the dynamics and significance of various physical parameters of model are discussed.

Kasner type magnetized string cosmological models in f(R,T) gravity

The Bianchi-I Kasner type metric with cosmic string and magnetic field in the framework of the f(R,T) theory of gravitation is considered. Three different functional forms of the function f(R,T) are chosen for investigation. We found that the strings exist in early stages of evolution of the Universe and they disappear as time increases. The variation of the equation of state (EoS) parameter ? = p/?<-1 may come from the effect of the string. We find that the string tension and rest energy density reduce in presence of magnetic field. The Universe is expanding and accelerating.

Rotating thin shells in (2 + 1)-dimensional asymptotically AdS spacetimes: Mechanical properties, machian effects, and energy conditions

In this paper, a rotating thin shell in a (2 + 1)-dimensional asymptotically AdS spacetime is studied. The spacetime exterior to the shell is the rotating BTZ spacetime and the interior is the empty spacetime with a cosmological constant. Through the Einstein equation in (2 + 1) dimensions and the corresponding junction conditions we calculate the dynamical relevant quantities, namely, the rest energy–density, the pressure, and the angular momentum flux density. We also analyze the matter in a frame where its energy–momentum tensor has a perfect fluid form. In addition, we show that Machian effects, such as the dragging of inertial frames, also occur in rotating (2 + 1)-dimensional spacetimes. The weak and the dominant energy condition for these shells are discussed.

Strange quark matter coupled to string cloud in Lyra geometry

Hypersurface homogeneous cosmological models for strange quark matter coupled to string cloud in the framework of Lyra geometry have been presented. Exact solution of the field equations are obtained by considering various forms of the deceleration parameter found in the literature. It is observed that the rest energy density, particle energy density and string tension density are affected by displacement vector β. Physical parameters of the investigated model are also discussed.

A higher-dimensional string cosmological model in a scalar-tensor theory of gravitation

A string cosmological model is obtained and presented by considering a five-dimensional Kaluza-Klein metric in the scalar-tensor theory of gravitation proposed by Brans and Dicke without taking any relation between rest energy density ρ and string tension density λ. Some physical and geometrical properties of the model are also discussed.

String cosmology in Bianchi type-VI0 space-time

In this paper we have constructed a spatially homogeneous and anisotropic Bianchi type-VI0 string cosmological model in general relativity. This model is expanding, shearing, non-rotating and has no initial singularity. Here it is interesting to note that string tension density (λ) is greater than half of rest energy density (ρ) and particle density (ρp) is less than half of rest energy density. Further some physical and kinematical properties of the model are discussed.

Bulk Viscous Bianchi-III Models with Time Dependent G and Λ

Bulk Viscous anisotropic Bianchi-III cosmological models are investigated with time dependent gravitational and cosmological constants in the framework of Einstein’s general relativity. In order to get some useful information about the time varying nature of G and Λ, we have assumed an exponentially decaying rest energy density of the universe. The extracted Newtonian gravitational constant G varies with time but its time varying nature depends on bulk viscosity and the anisotropic nature of the model. The cosmological constant Λ is found to decrease with time to a small but positive value for the models.

Bianchi Type-IX String Cosmological Models for Perfect Fluid Distribution in General Relativity

The present study deals with Bianchi type-IX string cosmological models for perfect fluid distribution. We consider two cases: (i) ρ + λ = 0, (ii) ρ – λ = 0, where ρ and λ are the rest energy density and the tension density of a string cloud, respectively. The physical and geometrical properties of the models are discussed.

Five-dimensional axially symmetric string cosmological model in Lyra manifold

In this paper we constructed five dimensional axially symmetric cosmological model generated by a cloud of strings with particles attached to them in Lyra manifold. Out of the two different cases obtained one case leads to the five dimensional vacuum universe in general theory of relativity while the other case yields a string cosmological model in Lyra manifold. In the cosmic string model we observed that the sum of tension density and rest energy density of strings vanishes and this model is also inflationary.

Multidimensional systems: Flow in electromagnetic fields and some fundamental implications

AbstractFor an electromagnetic (EM) field, local properties such as field velocity, rest field, and rest energy density are introduced. These are physically justified and mathematically defined by starting from what are the only assumptions on which this paper rests: the strict validity of Maxwell's equations and their inherent relativistic transformation rules. A variety of additional properties are presented that confirm the judiciousness of the chosen definitions. Based on these, flow equations of an EM field are derived, which offer remarkable analogies with equations of fluid dynamics and thus suggest attempting some mechanistic interpretation. Doing this by strictly adhering to the details of classical theories, however, is found to lead to incompatibilities, but a consistent interpretation is feasible in the context of some alternative relativistic results that have been presented in recent years and have originally been suggested by basic issues concerning passivity and losslessness in one‐ and multidimensional nonlinear Kirchhoff circuits and related areas of digital signal processing. In the light of these findings, available experimental evidence and original theoretical deductions are reassessed and shown not to contradict the present results. Potential models for electrons (rotating EM field) and photons (localized planar field that offers a natural solution to the wave‐particle duality) are obtained as rigorous solutions of Maxwell's equations, and possible consequences are discussed. Copyright © 2007 John Wiley & Sons, Ltd.

Some magnetized bulk viscous string cosmological models in General Relativity

Some Bianchi type-I viscous fluid string cosmological models with magnetic field are investigated. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density ξ(t)=ξ 0 ρ m , where ξ 0 and m are constants. To get a determinate model, we assume conditions ρ=(1+ω)λ, where ρ is rest energy density, ω a positive constant and λ the string tension density and expansion θ is proportional to eigen value σ 1 1 of the shear tensor σ j i . The behaviour of the models from physical and geometrical aspects in presence and absence of magnetic field is discussed.

Bianchi Type I Magnetized String Cosmological Model in General Relativity

Bianchi Type I magnetized string cosmological model following the techniques used by Letelier and Stachel, is investigated. To get a determinate model, we assume a condition ∊ = λ (geometric string) where ∊ is the rest energy density, λ the string tension density and expansion (θ) is proportional to eigen value σ11 of shear tensor (σ ji), which leads to A = l (BC)n where A, B, C are metric potentials and l and n are constants. The behaviour of the model in presence and absence of magnetic field is discussed. The physical and geometrical aspects of the model are also discussed.

Acceleration and Dissipation in Relativistic Winds

I argue that ideal MHD relativistic winds are always limited in practice to asymptotic 4-velocity γ∞ ≍ σ1/30 and asymptotic magnetization σ ∼ σ 2/30 ≫ 1, where σ0 is the wind magnetization with respect to the rest energy density, evaluated at the light cylinder of the rotating, magnetized compact object that drives the flow. This suggests that the observed low value of the asymptotic σ in the equatorial sectors of the winds driving pulsar wind nebulae and the associated high values of the asymptotic 4-velocity are a consequence of magnetic dissipation in the wind zone.

Bianchi type IX string cosmological model in general relativity

We have investigated Bianchi type IX string cosmological models in general relativity. To get a determinate solution, we have assumed a condition ρ=λ i.e. rest energy density for a cloud of strings is equal to the string tension density. The various physical and geometrical aspects of the models are also discussed.