We present the whole set of equations with regularity and matching conditions required for the description of physically meaningful static cylindrically symmmetric distributions of matter, smoothly matched to Levi-Civita vacuum spacetime. It is shown that the conformally flat solution with equal principal stresses represents an incompressible fluid. It is also proved that any conformally flat c...

We propose the generally covariant action for the theory of a self-coupled complex scalar field and electromagnetism which by virtue of constraints is equivalent, in the regime of long wavelengths, to perfect magnetohydrodynamics (MHD). We recover from it the Euler equation with Lorentz force, and the thermodynamic relations for a prefect fluid. The equation of state of the latter is related to...

We compute the static self-energy of SU(3) gauge theory in four spacetime dimensions to order α20 in the strong coupling constant α. We employ lattice regularization to enable a numerical simulation within the framework of stochastic perturbation theory. We find perfect agreement with the factorial growth of high order coefficients predicted by the conjectured renormalon picture based on the op...

Two possible interpretations of FRW cosmologies (perfect fluid or dissipative fluid) are considered as consecutive phases of the system. Necessary conditions are found, for the transition from perfect fluid to dissipative regime to occur, bringing out the conspicuous role played by a particular state of the system (the “critical point”).

In this article, we study small perturbations of the family of Friedmann-Lemâıtre-Robertson-Walker cosmological background solutions to the 1+ 3 dimensional Euler-Einstein system with a positive cosmological constant. These background solutions describe an initially uniform quiet fluid of positive energy density evolving in a spacetime undergoing accelerated expansion. Our nonlinear analysis sh...

The existence and nature of singularities in locally spatially homogeneous solutions of the Einstein equations coupled to various phenomenological matter models is investigated. It is shown that, under certain reasonable assumptions on the matter, there are no singularities in an expanding phase of the evolution and that unless the spacetime is empty a contracting phase always ends in a singula...

Drake and Szekeres have extended the Newman-Janis algorithm to produce stationary axisymmetric spacetimes from general static spherically symmetric solutions of Einstein equations. The mathematically generates an energy-momentum tensor for rotating solution, but nonrotating system may or not represent same physical system, in sense both being a perfect fluid, electromagnetic field, $\Lambda$-te...

Abstract The vanishing affine connections have been used solely while adopting the modified f ( Q ) gravity theory to cosmology. Consequently, researchers could not get beyond what is already known in T earlier. To alleviate this problem, present manuscript we investigate a recently proposed construction of using non-vanishing connection spatially flat FLRW spacetime. We then cosmological solut...

Abstract Spherically symmetric spacetimes are ambient spaces for models of stellar collapse and inhomogeneous cosmology. We obtain results the Weyl tensor covariant form Ricci on general doubly warped (DW) spacetimes. In a spherically metric, electric tensors become rank-2, built with metric tensor, velocity vector field its acceleration. Their structure dictates energy-momentum in Einstein equ...