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Four-force

About: Four-force is a research topic. Over the lifetime, 3459 publications have been published within this topic receiving 87308 citations.


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01 Jan 2007

20 citations

Journal ArticleDOI
J. H. Field1
TL;DR: In this article, it was shown how all the mechanical equations of classical electromagnetism (CEM) may be derived from only Coulomb's inverse square force law, special relativity and Hamilton's principle.
Abstract: It is demonstrated how all the mechanical equations of classical electromagnetism (CEM) may be derived from only Coulomb's inverse square force law, special relativity and Hamilton's principle. The instantaneous nature of the Coulomb force in the centre-of-mass frame of two interacting charged objects, mediated by the exchange of space-like virtual photons, is predicted by quantum electrodynamics (QED). The interaction Lagrangian of QED is shown to be identical, in the appropriate limit, to the potential energy term in the Lorentz-invariant Lagrangian of CEM. A comparison is made with the Feynman–Wheeler action-at-a-distance formulation of CEM.

20 citations

Posted Content
TL;DR: In this paper, a review of the nature of time in physics is presented, both qualitatively and quantitatively, and it is interesting to note that general relativity is contaminated with non-trivial geometries that generate closed timelike curves, and thus violates causality.
Abstract: The conceptual definition and understanding of the nature of time, both qualitatively and quantitatively is of the utmost difficulty and importance, and plays a fundamental role in physics. Physical systems seem to evolve in paths of increasing entropy and of complexity, and thus, the arrow of time shall be explored in the context of thermodynamic irreversibility and quantum physics. In Newtonian physics, time flows at a constant rate, the same for all observers; however, it necessarily flows at different rates for different observers in special and general relativity. Special relativity provides important quantitative elucidations of the fundamental processes related to time dilation effects, and general relativity provides a deep analysis to effects of time flow, such as in the presence of gravitational fields. Through the special theory of relativity, time became intimately related with space, giving rise to the notion of spacetime, in which both parameters cannot be considered as separate entities. As time is incorporated into the proper structure of the fabric of spacetime, it is interesting to note that general relativity is contaminated with non-trivial geometries that generate closed timelike curves, and thus apparently violates causality. The notion of causality is fundamental in the construction of physical theories; therefore time travel and its associated paradoxes have to be treated with great caution. These issues are briefly analyzed in this review paper.

20 citations

Journal ArticleDOI
TL;DR: The existence of an invariant speed is not a necessary assumption and in fact is a consequence of the principle of relativity (though the finite value of this speed must, of course, be obtained from experiment) as discussed by the authors.
Abstract: The structure of the Lorentz transformations follows purely from the absence of privileged inertial reference frames and the group structure (closure under composition) of the transformations—two assumptions that are simple and physically necessary. The existence of an invariant speed is not a necessary assumption and in fact is a consequence of the principle of relativity (though the finite value of this speed must, of course, be obtained from experiment). Von Ignatowsky derived this result in 1911, but it is still not widely known and is absent from most textbooks. Here, we present a completely elementary proof of the result, suitable for use in an introductory course in special relativity.

20 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20239
202211
20208
20193
20185
201756