scholarly journals Coordinate systems in the general relativistic framework

1986 ◽  
Vol 114 ◽  
pp. 145-168 ◽  
Author(s):  
T. Fukushima ◽  
M.-K Fujimoto ◽  
H. Kinoshita ◽  
S. Aoki

The treatment of the coordinate systems is briefly reviewed in the Newtonian mechanics, in the special theory of relativity, and in the general relativistic theory, respectively. Some reference frames and coordinate systems proposed within the general relativistic framework are introduced. With use of the ideas on which these coordinate systems are based, the proper reference frame comoving with a system of mass-points is defined as a general relativistic extension of the relative coordinate system in the Newtonian mechanics. The coordinate transformation connecting this and the background coordinate systems is presented explicitly in the post-Newtonian formalism. The conversion formulas of some physical quantities caused by this coordirate transformation are discussed. The concept of the rotating coordinate system is reexamined within the relativistic framework. A modification of the introduced proper reference frame is proposed as the basic coordinate system in the astrometry. The relation between the solar system barycentric coordinate system and the terrestrial coordinate system is given explicitly.

1990 ◽  
Vol 141 ◽  
pp. 99-110
Author(s):  
Han Chun-Hao ◽  
Huang Tian-Yi ◽  
Xu Bang-Xin

The concept of reference system, reference frame, coordinate system and celestial sphere in a relativistic framework are given. The problems on the choice of celestial coordinate systems and the definition of the light deflection are discussed. Our suggestions are listed in Sec. 5.


2017 ◽  
Vol 9 (2) ◽  
pp. 77
Author(s):  
Koshun Suto

This paper discusses the “triplet thought experiment” in which accelerated motion is eliminated from the famous twin paradox thought experiment of the special theory of relativity (STR). The author considers the coordinate systems of an inertial frame M and rocket A moving at constant speed relative to each other. First, an observer in inertial frame M performs the triplet thought experiment, and it is confirmed that the delay in time which elapses in the moving system agrees with the predictions of the STR. However, the delay in time predicted by the STR is observed even in the case when an observer A in rocket A carries out the triplet thought experiment. Before starting movement at constant velocity, rocket A experiences accelerated motion. The coordinate system of rocket A cannot be regarded physically as a stationary system. Even so, observer A observes the delay predicted by the STR. If the previous, traditional interpretation is assumed to be correct, observer A will never observe a delay in time agreeing with the predictions of the STR. To avoid paradox, the previously proposed traditional interpretation must be revised.


Author(s):  
Swami D. Nigam ◽  
James D. Guilford ◽  
Joshua U. Turner

Abstract Datum reference frames define coordinate systems for use in determining part compliance with geometric tolerances. A datum reference frame is specified based on the perfect nominal geometry of the part features called out as datums. However, the actual computation of a coordinate system frame of reference from the datum callouts becomes quite challenging when the features depart from nominal location, orientation, size, and form. We present a general method for representing datum reference frames (both partial and complete), and for computing a coordinate system from a simulated varianced part and a datum reference frame specification. The method makes use of built-in construction procedures, and derived or “virtual” geometry, in conjunction with a powerful parts positioning module that simulates the placement of the varianced part in a fixture represented by the datum surfaces. The reliance on virtual geometry as an intermediate representation, permits the concise representation of not only the datum reference frame types defined in the standard, but also allows for any arbitrary datum reference frames constructed by the user.


2021 ◽  
Vol 34 (3) ◽  
pp. 274-278
Author(s):  
Reiner Georg Ziefle

On Earth, we always measure the constant velocity c of electromagnetic radiation. Einstein assumed the velocity c of light to be constant in all inertial frames and developed his theory of special relativity by considering a light beam that moves back and forth, whereby he derived transformations between the coordinates of two reference frames: A moving reference frame represented by the coordinate system k and the coordinate system k that is at rest with respect to k. However, by applying Einstein’s theory of relativity, with its postulates of relativistic time dilation and length contraction, to electromagnetic radiation that moves only in one direction, either in the direction of or in the opposite direction to a moving inertial frame, it is demonstrated that the constancy of the velocity c of light is not compatible with Einstein’s theory of special relativity. It becomes obvious that Einstein’s relativistic physics must be an unrealistic theory, and consequently, we need an alternative, nonrelativistic, explanation of the constancy of the velocity c of electromagnetic radiation measured on Earth, and for the special and general “relativistic” phenomena.


2020 ◽  
Author(s):  
Douglas Michael Snyder

Though Einstein and other physicists recognized the importance of an observer being at rest in an inertial reference frame for the special theory of relativity, the supporting psychological structures were not discussed much by physicists. On the other hand, Rock wrote of the factors involved in the perception of motion, including one’s own motion. Rock thus came to discuss issues of significance to relativity theory, apparently without any significant understanding of how his theory might be related to relativity theory. In this paper, connections between Rock’s theory on the perception of one’s own motion, as well as empirical work supporting it, and relativity theory are explored. Paper available at: https://arxiv.org/abs/physics/9908025v1 .


2017 ◽  
Vol 75 (3) ◽  
pp. 263-269
Author(s):  
Özgür Özcan

Special theory of relativity is one of the difficult subjects of physics to be understood by the students. The current research designed as a qualitative research aim to determine the pre-service physics teachers’ understanding level and the alternative conceptions about three core concepts of special theory of relativity, such as time dilatation, length contraction and reference frames. The data were collected through semi structured interviews and were analyzed by using content analysis. At the end of the analysis process the understanding level of the students was determined to be “complete understanding”, “incomplete understanding” and “misunderstanding”. In order to achieve this, the students’ conceptual frameworks based on the operational definitions made by the students were determined firstly. The findings obtained in this research indicate that high school teachers as well as university instructors should take special care with some points in the teaching of the subjects related with special theory of relativity. This research might be useful to other studies to be done in the future, especially for investigating the students’ mental models related to special theory of relativity. Key words: Length contraction, reference frames, special relativity, time dilatation, understanding level.


2000 ◽  
Vol 180 ◽  
pp. 314-319 ◽  
Author(s):  
F. de Felice ◽  
A. Vecchiato ◽  
B. Bucciarelli ◽  
M.G. Lattanzi ◽  
M. Crosta

A non-perturbative general relativistic approach to global astrometry was developed by de Felice et al. (1998) to handle satellite astrometry data in a genuine relativistic framework. In this contribution, the framework above has been further exploited to account for stellar motions and parallax. Because of the relevance that accurate knowledge (to 10−5 or better) of the relativistic parameter γ has to fundamental physics, a Parametrized Post-Newtonian (PPN) model has also been implemented, which allows the direct estimation of γ along with the astrometric parameters. These models have been tested on end-to-end simulations of the mission GAIA. The results show that, within the limitation of the simulation and the assumptions of the adopted model, measurements accurate to 100 μarcsec of large arcs among stars repeated over a few years can be modelled to establish a dense reference frame with a precision of a few tens of μarcseconds. Moreover, our experiments indicate that γ can be estimated to better than 10−6.


Author(s):  
Steven Savitt

Restricted to special relativity, this chapter observes that the most significant change in the concept of time is certainly the relativity of simultaneity. What events are simultaneous with some event for one observer are different from those that are simultaneous with respect to an object traveling in a different inertial frame. Many believe that this relativity can play a role in an argument for eternalism. This chapter critically surveys these arguments before taking on the implications of relativity for the metaphysics of time. It also tackles the conventionality of simultaneity. Many philosophers of science, especially during the early days of relativity, felt that simultaneity is not only relative but also conventional—there is a crucial element of choice in deciding what events are simultaneous for any other in a given inertial reference frame, so that there is no fact of the matter about what is simultaneous.


2021 ◽  
Author(s):  
Dong Jun ◽  
Na Dong

Abstract In this paper, the special theory of relativity in different media is established, based on the fundamental invariant of the space-time four-dimensional space x2 + y2 + z2 - c2 t2 = x'2 + y'2 + z'2 - c' t'2 . First of all, the inertial coordinate system is strictly defined in mathematical language. The inertial coordinate system that uses the actual measured different speeds of light as the limit speed still retains its most basic characteristics as an inertial coordinate system. Then, the space-time coordinate transformation and velocity transformation formulas between inertial coordinate systems with different light velocity are derived. These results not only break through the limitation of "vacuum", but also all are exactly the same as the conclusions of the traditional special theory of relativity when c = c' ; and when c ≠ c' give the new physical content. This all lifted the threat of the theory of relativity by the speed of light experiment, making c = c' ; and c ≠ c' both inclusively under the basic point of view of the theory of relativity; which will inevitably broaden the way of using relativity to deal with physics problems and clarify many problems left over in the study of relativity. The article discusses the problem of relativistic kinematics involving the measurement of time and space, correctly interprets the effects of “ruler contraction” and “clock retardation”, and uncovers and correctly answers the “clock paradox” that accompanied the birth of relativity. For two motion systems S and S', that are separated from each other by constant velocity, at any time and where, the product of the proper time elapsed evenly and uniformly and the speed of light in the respective system are equal, cτ = c' τ'; and the product of the coordinates time read out in observing and recognizing the other party's proper time and the speed of light in the respective system are also equal, ct = c' t' . It is confirmed that the product of any moving individual's uniform disappearance proper time and its measured speed of light remain unchanged; and the proper time cannot be determined purely by the individual's subjective way. Deduced the uncertain relationship between the proper time and the coordinate time for an inertial coordinate system which was not noticed by the traditional special theory of relativity. Remind the practical astronomy workers who do the time measurement and the time service work to understand that it is impossible to equate practical scientific coordinate time and the proper time of ideal uniform disappearance (the so-called “Ephemeris Time”). Thereby pay attention to the impact of this uncertain relationship on the time measurement and the time service work, and propose ways to verify. Subsequent work will use this expanded special theory of relativity to conduct a comprehensive review of related physics, which will inevitably extend to issues that have not been or cannot be examined by traditional special theory of relativity.


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