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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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Journal ArticleDOI
TL;DR: In this paper, the authors describe a theory of gravity in (1 + 1) dimensions that can be thought of as a toy model of general relativity, and derive the theory from fundamental physical principles using two different methods.
Abstract: We describe a theory of gravity in (1 + 1) dimensions that can be thought of as a toy model of general relativity. The theory should be a useful pedagogical tool, because it is mathematically much simpler than general relativity but shares much of the same conceptual structure; in particular, it gives a simple illustration of how gravity arises from spacetime curvature. We derive the theory from fundamental physical principles using two different methods, one based on extrapolating from Newtonian gravity and one based on the equivalence principle, and present several exact solutions.

16 citations

Journal ArticleDOI
11 Apr 1970-Nature
TL;DR: To answer the question, the most successful theory of symmetry that has emerged in twentieth century physics—the theory of relativity is referred to.
Abstract: THE question I wish to discuss is: what is the most general mathematical representation of a given theory that is based on a symmetry principle ? To answer the question, I refer to the most successful theory of symmetry that has emerged in twentieth century physics—the theory of relativity.

16 citations

Journal ArticleDOI
TL;DR: In this article, the authors argue that perfect inertial dragging may save the principle of relativity, and that this requires a new model of the Minkowski spacetime where the cosmic mass is represented by a massive shell with radius equal to its own Schwarzschild radius.
Abstract: The twin paradox is intimately related to the principle of relativity. Two twins A and B meet, travel away from each other and meet again. From the point of view of A, B is the traveller. Thus, A predicts B to be younger than A herself, and vice versa. Both cannot be correct. The special relativistic solution is to say that if one of the twins, say A, was inertial during the separation, she will be the older one. Since the principle of relativity is not valid for accelerated motion according to the special theory of relativity B cannot consider herself as at rest permanently because she must accelerate in order to return to her sister. A general relativistic solution is to say that due to the principle of equivalence B can consider herself as at rest, but she must invoke the gravitational change of time in order to predict correctly the age of A during their separation. However one may argue that the fact that B is younger than A shows that B was accelerated, not A, and hence the principle of relativity is not valid for accelerated motion in the general theory of relativity either. I here argue that perfect inertial dragging may save the principle of relativity, and that this requires a new model of the Minkowski spacetime where the cosmic mass is represented by a massive shell with radius equal to its own Schwarzschild radius.

16 citations

Book ChapterDOI
Michel Paty1
01 Jan 1992
TL;DR: In this article, a reevaluation of Poincare's conception of the relation between Geometry and physics, quite at variance with the received view, is presented, which is an adaptation of his previous implicit conception, at work with Special Relativity, to the requirements of the general theory.
Abstract: The problem of the relation between Geometry and Physics has been the object of extensive discussions, through the present century, by mathematicians, physicists and philosophers of science, who have considered the possibility to decide which geometry corresponds to physical space, with respect to the General Theory of Relativity. At first sight, the Special Theory of Relativity seems to be independent from this problem. In this debate, which made reference to Poincare's philosophy of Geometry, Einstein has been directly involved. Although he concludes positively about the decidability of Geometry, he is not a rejoinder of empiricism. He himself invokes frequently Poincare in his arguments against empiricists, in particular Poincare's alleged "indissociability between Geometry and Physics", which sounds like Poincare's indissociability between space and dynamics contrary to Einstein's separation of kinematics from dynamics in Special Relativity. It is thus tempting to compare his own position to Poincare's one before and after his elaboration of the General Theory of Relativity. We would like to know, in particular, whether Einstein's conception of the relations between Geometry and Physics has drastically changed when he has passed from Special to General Theory of Relativity, adopting henceafter the essential of Poincare's conception which he did not share at the time of Special Relativity. This inquiry has led us to a reevaluation of Poincare's conception of the relation between Geometry and Physics, quite at variance with the received view. It also has led us to consider again the problem of why Poincare did not fully develop Special Relativity as we now understand it, i.e. in Einstein's sense, and to show evidence for a strong influence of his conception of Geometry when dealing with classical and relativistic Mechanics. Finally we show what has been actually - in our view - the evolution of Einstein's thought concerning the relations of Physics and Geometry, which is indeed an adaptation of his previous implicit conception, at work with Special Relativity, to the requirements of the general theory. This adaptation revealed to him the complexity of a problem he had considered previously in a simplified way, and made him conscious of the well-foundedness of important aspects of Poincare's conceptions, which he translated, then adapted, for the use of his own physical thinking.

16 citations

Journal ArticleDOI
TL;DR: It is desirable to investigate the proper method of extending the ordinary principles of thermodynamics so as to make them hold for considerations in curved space-time where the methods of general relativity must be employed.
Abstract: Introduction. The recent interesting article of Lenz(1) on the equilibrium between radiation and matter in Einstein's closed universe makes it desirable to investigate the proper method of extending the ordinary principles of thermodynamics so as to make them hold for considerations in curved space-time where the methods of general relativity must be employed.

16 citations


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