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recent theoretical results show the existence of arbitrary speeds ($0\leq v <\infty$) solutions of the wave equations of mathematical physics. Some recent experiments confirm the results for sound waves. The question arises naturally: What…

General Relativity and Quantum Cosmology · Physics 2007-05-23 T. Matolcsi , W. A. Rodrigues

Astrophysical models developed to explain superluminal motion in beaming phenomena are shown to be incomplete and the correct kinematical expression in any case to predict projected velocities slower than the speed of light. The observed…

General Physics · Physics 2007-05-23 Ernst Karl Kunst

At present we have only the very successful but phenomenological Einstein geometrical modelling of the spacetime phenomenon. This geometrical model provides a `container' for other theories, in particular the quantum field theories. Here we…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Reginald T. Cahill , Christopher M. Klinger

While it is generally agreed that the nature of spacetime must be drastically different at the Planck scale, it has been a common practice to assume that spacetime is endowed with a full pseudo-Riemannian geometry regardless of the physical…

General Relativity and Quantum Cosmology · Physics 2011-03-29 Kaća Bradonjić

In present work the author presents a new set of spacetime measures for both, subluminal and superluminal motion regimes, which do not diverge for the speed of light in the former case and each regime has its own light-like cone which…

General Physics · Physics 2013-08-22 Benjamín Calvo-Mozo

A general relativistic description of a disk rotating at constant angular velocity is given. It is argued that conceptually this direct approach poses fewer problems than the special relativistic one. For observers on the disk, the geometry…

Popular Physics · Physics 2015-05-30 Klaus Kassner

New rigidity results for complete non-compact spacelike submanifolds of arbitrary codimension in plane fronted waves are obtained. Under appropriate assumptions, we prove that a complete spacelike submanifold in these spacetimes is…

Differential Geometry · Mathematics 2022-02-01 Francisco J. Palomo , José A. S. Pelegrín , Alfonso Romero

Einstein's theory of general relativity models the physical universe using spacetimes which satisfy Einstein's gravitational field equations. To date, Einstein's theory has been enormously successful in modeling observed gravitational…

General Relativity and Quantum Cosmology · Physics 2016-10-21 James Isenberg

One of the deepest insights from the general theory of relativity is the relational nature of spacetime. While it is a generally agreed on that the nature of spacetime must be drastically different at the Planck scale, it has been a common…

General Relativity and Quantum Cosmology · Physics 2009-05-30 Kaca Bradonjic

Close to the Planck energy scale, the quantum nature of space-time reveals itself and all forces, including gravity, should be unified so that all interactions correspond to just one underlying symmetry. In the absence of a full quantum…

High Energy Physics - Theory · Physics 2015-03-17 Mairi Sakellariadou

There is a possibility that spacetime itself is ultimately an emergent phenomenon, a near-universal "low-energy long-distance approximation", similar to the way in which fluid mechanics is the near-universal low-energy long-distance…

General Relativity and Quantum Cosmology · Physics 2008-01-04 Matt Visser

The paper uses geometrical arguments to derive equations with relevance for cosmology; 5-dimensional spacetime is assumed because it has been shown in other works to provide a setting for significant unification of different areas of…

General Physics · Physics 2008-01-29 Jose B. Almeida

First, we extend the special relativity into the superluminal case and put forward a superluminal theory of kinematics, in which we show that the temporal coordinate need exchanging with one of the spatial coordinates in a superluminal…

General Physics · Physics 2009-07-22 Z. C. Tu , Z. Y. Wan

It has long been considered that conformal superspace is the natural configuration space for canonical general relativity. However, this was never definitively demonstrated. We have found that the standard conformal method of solving the…

General Relativity and Quantum Cosmology · Physics 2010-09-21 Julian Barbour , Niall Ó Murchadha

We study the complete conformal geometry of shear-free spacetimes with spherical symmetry and do not specify the form of the matter content. The general conformal Killing symmetry is solved and we can explicitly exhibit the vector. The…

General Relativity and Quantum Cosmology · Physics 2013-10-02 S Moopanar , S. D. Maharaj

We consider the superfluid phase of a specific renormalizable relativistic quantum field theory. We prove that, within the regime of validity of perturbation theory and of the superfluid effective theory, there are consistent and regular…

High Energy Physics - Theory · Physics 2023-05-22 Ioanna Kourkoulou , Michael J. Landry , Alberto Nicolis , Klaas Parmentier

The notion of spacetime symmetry is essential to describe gravitating physical systems like planets, stars, black holes, or the universe as a whole, since they possess, at least to good approximation, spherical, axial, or spatially…

General Relativity and Quantum Cosmology · Physics 2022-12-01 Christian Pfeifer

We construct an idealized universe for didactic purposes. This universe is assumed to consist of absolute Euclidean space and to be filled with a classical medium which allows for sound waves. A known solution to the wave equation…

General Physics · Physics 2014-08-27 Manfred Schmid , Pavel Kroupa

We investigate the conformal geometry of spherically symmetric spacetimes in general without specifying the form of the matter distribution. The general conformal Killing symmetry is obtained subject to a number of integrability conditions.…

General Relativity and Quantum Cosmology · Physics 2016-11-15 S. Moopanar , S. D. Maharaj

The quantum mechanics description of a physical object stretched in space and stable in time from the relativistic space-time properties point of view, introduced in special theory of relativity, is considered and analysed. The mathematical…

Quantum Physics · Physics 2007-05-23 Andrey V. Novikov-Borodin
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