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Special relativity (alternative formulations)
About: Special relativity (alternative formulations) is a research topic. Over the lifetime, 3102 publications have been published within this topic receiving 55015 citations.
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TL;DR: In this paper, a variational principle was applied to the general relativity case, using a tetrad to express the spin density and the four-velocity of the fluid. And an energy-momentum tensor was defined for a spinning fluid.
Abstract: General relativity field equations are employed to examine a continuous medium with internal spin. A variational principle formerly applied in the special relativity case is extended to the general relativity case, using a tetrad to express the spin density and the four-velocity of the fluid. An energy-momentum tensor is subsequently defined for a spinning fluid. The equations of motion of the fluid are suggested to be useful in analytical studies of galaxies, for anisotropic Bianchi universes, and for turbulent eddies.
33 citations
TL;DR: In this article, the authors show that the correct bound on the Standard Model Extension photon-sector parameter is in fact $2.2\times 10^{-7} = 0.
Abstract: In an earlier paper [1] (hep-ph/0408006), the bound on the Standard Model Extension photon-sector parameter $\tilde{\kappa}_{tr}$ [2] (hep-ph/0205211) set by the heavy-ion storage-ring experiment of Saathoff et al. [3] was incorrectly reported. We show that the correct bound on $\tilde{\kappa}_{tr}$ which resulted from this experiment is in fact $2.2\times 10^{-7}$.
33 citations
33 citations
TL;DR: In this article, the families of effective actions considered by Jacobson et al. to study Lorentz invariance violations contain a class of models that represent pure general relativity with a Euclidean signature.
Abstract: We show that the families of effective actions considered by Jacobson et al. to study Lorentz invariance violations contain a class of models that represent pure general relativity with a Euclidean signature. We also point out that some members of this family of actions preserve Lorentz invariance in a generalized sense.
33 citations
TL;DR: In this paper, the authors present a method to find the apparent horizon (AH) on a special family of 3D spacelike hypersurfaces which has a symmetry around the $z$ axis as well as the reflection one with respect to the equatorial plane.
Abstract: We present a method to find the apparent horizon (AH) on a special family of three-dimensional (3D) spacelike hypersurfaces which has $\ensuremath{\pi}$-rotation symmetry around the $z$ axis as well as the reflection one with respect to the equatorial plane. In a nonaxisymmetric 3D hypersurface, the AH, if it exists, is determined by solving a 2D elliptic-type equation. In the present method, we solve the elliptic-type equation as a boundary value problem. To test this method, we apply it to a variety of nonaxisymmetric 3D hypersurfaces which can be obtained by solving the constraint equations in general relativity. We find that the present method works well in all cases.
33 citations