相关论文: The twin paradox on the photon sphere
We consider a class of static and spherically symmetric black hole geometries endowed with a photon sphere. On the one hand, we show that close to the photon sphere, a massless scalar field theory exhibits a simple dynamical…
Einstein's theory of special relativity(SR) and the principle of causality imply that the speed of any moving object can not exceed that of light in a vacuum($c$).However,there were many attempts in literature discussing the particle moving…
In this article we extend a recent theorem proven by Hod (Phys. Lett. B, {\bf 727}, 345--348, 2013) to $n$-dimensional Einstein and Einstein-Gauss-Bonnet theories, which gives an upper bound for the photon sphere radii of spherically…
In a spherically symmetric and static spacetime of a compact object, such as that of a Schwarzschild black hole, the light-ring is a 2-sphere where photons experience the only possible circular orbits. As a "Gedankenexperiment", we imagine…
We investigate local and global properties of timelike geodesics in three static spherically symmetric spacetimes. These properties are of its own mathematical relevance and provide a solution of the physical `twin paradox' problem. The…
Light that grazes a black-hole event horizon can loop around one or more times before escaping again, resulting for distance observers in an infinite sequence of ever fainter and more delayed images near the black hole shadow. In the case…
We demonstrate that at the rim of photon sphere of a black hole the quantum collective transition takes place in any multiparticle system of indistinguishable particles at passing inward this limiting sphere. This transition is related to…
We discuss a general feature of Freund Rubin compactifications that was previously overlooked. It consist in a curious pairing, which we call a shadow relation, of completely different (in terms of spin and mass) fields of the dimensionally…
This research delves into the optical characteristics of stationary, spherically symmetric black holes. These black holes follow the Konoplya-Zhidenko deformation rule in arbitrary gravity theories. This research finds that the effects of…
We consider the effect of the \emph{Varying Speed of Light} theory on non-rotating black holes. We show that in any varying-$c$ theory, the Schwarzschild solution is neither static nor stationary. For a no-charged black hole, the…
In this work we postulate that Schwinger's threshold for a dynamic electric field intensity to induce spatial nonlinearity is a special case and, more generally, it is the threshold field for both static and dynamic electric fields. Fields…
The motion of a massive particle in Rindler space has been studied and obtained the geodesics of motion. The orbits in Rindler space are found to be quite different from that of Schwarzschild case. The paths are not like the Perihelion…
One of the best ways to understand the gravitation of a massive object is by studying the photon's motion around it. We study the null geodesic of a regular black hole in anti-de Sitter spacetime, including a Gaussian matter distribution.…
Starting from a Hamiltonian description of the photon within the set of Bargmann-Wigner equations we derive new semiclassical equations of motion for the photon propagating in static gravitational field. These equations which are obtained…
Photons propagating in curved spacetime may, depending on their direction and polarisation, have velocities exceeding the ``speed of light'' c. This phenomenon arises through vacuum polarisation in QED and is a tidal gravitational effect…
In principle, the twin paradox offers the possibility to go on a trip to the center of our galaxy or even to the end of our universe within life time. In order to be a most comfortable journey the voyaging twin accelerates with Earth's…
The motion of superluminal particles in the gravitational field of a non-rotating black hole is analyzed. The relativistic Hamilton-Jacobi equation is solved for particles with imaginary rest mass. It is shown that there are no stable…
A new paradox in superluminal signaling is presented. In contrast to the Tolman paradox with tachyon exchange between two parties, the new paradox appears already in a one-way signaling, even without creating the time loop. As shown in the…
Motivated by detections of hypervelocity stars that may originate from the Galactic Center, we revist the problem of a binary disruption by a passage near a much more massive point mass. The six order of magnitude mass ratio between the…
Among modified theories of gravity, the teleparallel $f(T)$ gravity is an intensively discussed modelin the literature. The best way to investigate its viabilityis to derive observable predictions which yield evidence or constraints for the…