Nonlocal Transformations for Accelerated Observers

According to the locality postulate of special relativity, the measurements of physical fields by accelerated observers at a given event in Minkowski spacetime are related to each other by the representations of the Lorentz group. Nonlocal extensions of these representations are necessary, however, once acceleration-induced nonlocality is taken into account. The particular case of Dirac spinors is treated in detail and the corresponding nonlocal transformation group is studied.Comment: 8 pages, accepted for publication in Ann. Phys. (Berlin

Vacuum Electrodynamics of Accelerated Systems: Nonlocal Maxwell's Equations

The nonlocal electrodynamics of accelerated systems is discussed in connection with the development of Lorentz-invariant nonlocal field equations. Nonlocal Maxwell's equations are presented explicitly for certain linearly accelerated systems. In general, the field equations remain nonlocal even after accelerated motion has ceased.Comment: LaTeX file, 23 pages, no figures, accepted for publication in Annalen der Physi

On the spin-rotation-gravity coupling

The inertial and gravitational properties of intrinsic spin are discussed and some of the recent work in this area is briefly reviewed. The extension of relativistic wave equations to accelerated systems and gravitational fields is critically examined. A nonlocal theory of accelerated observers is presented and its predictions are compared with observation.Comment: LaTeX, 13 pages, no figures. Submitted to Hehl festschrift (GRG, to appear

Necessity of Acceleration-Induced Nonlocality

The purpose of this paper is to explain clearly why nonlocality must be an essential part of the theory of relativity. In the standard local version of this theory, Lorentz invariance is extended to accelerated observers by assuming that they are pointwise inertial. This locality postulate is exact when dealing with phenomena involving classical point particles and rays of radiation, but breaks down for electromagnetic fields, as field properties in general cannot be measured instantaneously. The problem is corrected in nonlocal relativity by supplementing the locality postulate with a certain average over the past world line of the observer.Comment: 12 pages; v2: improved version accepted for publication in Ann. Phys. (Berlin

Gravitoelectromagnetism

Gravitoelectromagnetism is briefly reviewed and some recent developments in this topic are discussed. The stress-energy content of the gravitoelectromagnetic field is described from different standpoints. In particular, the gravitational Poynting flux is analyzed and it is shown that there exists a steady flow of gravitational energy circulating around a rotating mass.Comment: LaTeX file, no figures, 12 pages, Plenary talk given at EREs2000 (Valladolid, Spain, 6-9 September 2000); to be published in Proc. Spanish Relativity Meeting, edited by J.-F. Pascual-S\'anchez, L. Flor\'ia, A. San Miguel, and F. Vicente (World Scientific, 2001

Gravitation and Nonlocality

The physical basis of the standard theory of general relativity is examined and a nonlocal theory of accelerated observers is described that involves a natural generalization of the hypothesis of locality. The nonlocal theory is confronted with experiment via an indirect approach. The implications of the results for gravitation are briefly discussed.Comment: LaTeX file, no figures, 12 pages. To be published in: Proc. 25th Johns Hopkins Workshop "2001: A Relativistic Spacetime Odyssey" (World Scientific, Singapore

Nonlocal Electrodynamics of Linearly Accelerated Systems

The measurement of an electromagnetic radiation field by a linearly accelerated observer is discussed. The nonlocality of this process is emphasized. The nonlocal theory of accelerated observers is briefly described and the consequences of this theory are illustrated using a concrete example involving the measurement of an incident pulse of radiation by an observer that experiences uniform acceleration during a limited interval of time.Comment: 24 pages, no figures, expanded version accepted for publication in Physical Review

Gravitoelectromagnetism: A Brief Review

The main theoretical aspects of gravitoelectromagnetism ("GEM") are presented. Two basic approaches to this subject are described and the role of the gravitational Larmor theorem is emphasized. Some of the consequences of GEM are briefly mentioned.Comment: 15 pages, no figures; v2: slightly improved version published as the third chapter of The Measurement of Gravitomagnetism: A Challenging Enterprise, edited by L. Iorio (Nova Science, New York, 2007), pp. 29-3

Modification of the Doppler Effect due to the Helicity-Rotation Coupling

The helicity-rotation coupling and its current empirical basis are examined. The modification of the Doppler effect due to the coupling of photon spin with the rotation of the observer is considered in detail in connection with its applications in the Doppler tracking of spacecraft. Further implications of this coupling and the possibility of searching for it in the intensity response of a rotating detector are briefly discussed.Comment: LaTeX file, no figures, 15 pages, amended versio

Acceleration-Induced Nonlocality

The standard relativistic theory of accelerated reference frames in Minkowski spacetime is described. The measurements of accelerated observers are considered and the limitations of the standard theory, based on the hypothesis of locality, are pointed out. The physical principles of the nonlocal theory of accelerated observers are presented. The implications of the nonlocal theory are briefly discussed.Comment: LaTeX file, no figures, 9 pages, to appear in: "Advances in General Relativity and Cosmology", edited by G. Ferrarese, Pitagora (Bologna), 200