Mathematical Models of Spacetime in Contemporary Physics and Essential Issues of the Ontology of Spacetime

1998 ◽  
pp. 1-5
Author(s):  
Maciej Gos
Keyword(s):  
Field Theory ◽  
Mathematical Models ◽  
Space Time ◽  
Theory Of Relativity ◽  
Time Arrow ◽  
Time Singularities ◽  
Time Quantum ◽  
Theory Of Gravitation ◽  
The Difference ◽  
Definition Of

The general theory of relativity and field theory of matter generate an interesting ontology of space-time and, generally, of nature. It is a monistic, anti-atomistic and geometrized ontology — in which the substance is the metric field — to which all physical events are reducible. Such ontology refers to the Cartesian definition of corporeality and to Plato's ontology of nature presented in the Timaeus. This ontology provides a solution to the dispute between Clark and Leibniz on the issue of the ontological independence of space-time from distribution of events. However, mathematical models of space-time in physics do not solve the problem of the difference between time and space dimensions (invariance of equations with regard to the inversion of time arrow). Recent research on space-time singularities and asymmetrical in time quantum theory of gravitation will perhaps allow for the solution of this problem based on the structure of space-time and not merely on thermodynamics.

Momentum space techniques for curved space–time quantum field theory

1979 ◽  
Vol 367 (1728) ◽  
pp. 123-141 ◽  
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Momentum Space ◽  
Nuclear Physics ◽  
Space Time ◽  
Coordinate Space ◽  
Quantum Field ◽  
Curved Space ◽  
Time Quantum ◽  
Space Formulation

A momentum space formulation of curved space–time quantum field theory is presented. Such a formulation allows the riches of momentum space calculational techniques already existing in nuclear physics to be exploited in the application of quantum field theory to cosmology and astrophysics. It is demonstrated that one such technique can allow exact, or very accu­rate approximate, results to be obtained in cases which are intractable in coordinate space. An efficient method of numerical solution is also described.

Propagation of electromagnetic wave in gravitational field

2021 ◽  
Vol 34 (1) ◽  
pp. 89-96
Author(s):  
Yan Yi
Keyword(s):  
Electromagnetic Wave ◽  
Gravitational Field ◽  
Photoelectric Effect ◽  
Space Time ◽  
Propagation Path ◽  
Propagation Characteristics ◽  
Propagation Law ◽  
The Difference ◽  
Definition Of ◽  
Wave Properties

This paper is the third part of the induction theory of gravitational field. It mainly discusses some propagation characteristics of electromagnetic wave in the space-time constructed in the first paper [Y. Yi, Phys. Essays 33, 219 (2020)]. In this paper, a new definition of the basic properties of electromagnetic wave is given at first. Second, the photoelectric effect is explained by the new electromagnetic wave properties. Then, the propagation law of electromagnetic wave in space-time is discussed. Finally, the propagation law of electromagnetic wave in axisymmetric gravitational field is analyzed. According to the analysis in this paper, the propagation path of electromagnetic wave is unique in the spherical symmetric gravitational field, while the propagation path of electromagnetic wave in the axisymmetric gravitational field is related to the wavelength. This is the difference between the induction theory of gravitational field and the existing theory, which can be used to verify the theory of gravitational field induction.

General introduction

1979 ◽  
Vol 368 (1732) ◽  
pp. 3-4
Keyword(s):  
Initial Period ◽  
Space Time ◽  
Relativistic Astrophysics ◽  
Theory Of Relativity ◽  
Kerr Geometry ◽  
Time Singularities ◽  
General Relativistic ◽  
The Subject ◽  
Insight Into ◽  
Theoretical Side

It is now over 60 years since Einstein first put forward his General theory of Relativity, providing what was, at that time, a daring new view of the geometry of the world and an extraordinary insight into the nature of the gravitational field - perhaps the single most strikingly original contribution to the scientific thought of recent times. But despite an initial period of active development both in the observational and theoretical sides of the subject, there followed a long period of comparative quiescence during which the subject had seemed to have little contact with the rest of physics and even less with feasible observations or experiments. In recent years, however, this situation has changed dramatically. On the theoretical side, for example, there has been much clarification of the nature of gravitational waves and of the fact that these waves carry positive mass-energy. Much more is known concerning exact solutions of Einstein’s equations. The space-time singularities that had been previously suspected as being features only of special symmetrical solutions are now known to be inevitable for wide classes of space-times. The theory of black holes has arisen and has led to a remarkably complete picture with a detailed and well-understood space-time geometry (the Kerr geometry). The relation to quantum theory, while still enigmatic, has made significant advances (e.g. Hawking radiation). The subject of General-Relativistic astrophysics has been born and has flourished.

scholarly journals Foundations of fundamental mechanics (1)

2019 ◽  
Author(s):  
Thomas Blommaert ◽  
Michael Appleby
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
General Theory ◽  
Potential Field ◽  
Quantum Physics ◽  
Space Time ◽  
Quantum Field ◽  
Theory Of Relativity ◽  
General Theory Of Relativity

The following paper presents a description on the fundamental mechanics of nature.This is the first of a set of papers entitled Foundations of fundamental mechanics, in which this first paper is specifically on the nature of gravity.For all intents and purposes this paper is NOT intended to be a replacement for the General theory of Relativity (GR) (A. Einstein 1915–1916), rather it is intended to be a complimentary extension of its work, with the purpose of extending it into quantum physics. Most notably, to relate it to quantum field theory (QFT), by quantizing the metric of space-time into a potential field theory.

scholarly journals Special relativity: Interpretation and implications for space-time geometry

2005 ◽  
Vol 219 (2) ◽  
pp. 133-146 ◽  
Author(s):  
H Rahnejat
Keyword(s):  
Special Relativity ◽  
Light Cone ◽  
Small Variation ◽  
Special Theory ◽  
Space Time ◽  
Matter Field ◽  
Theory Of Relativity ◽  
Speed Of Light ◽  
Calculus Of Variation ◽  
Definition Of

The paper commemorates the centenary of the special theory of relativity, which effectively sets the limit for the structure of space-time to that of the stationary system. The long lasting debate for definition of concepts of instantaneity and simultaneity was thus resolved by the declaration of constancy of speed of light in vacuo as a law of physics. All motions were thus bounded by the light cone and described by the properties of differential geometry, firmly anchored in the calculus of variations. The key contribution underpinning the theory was the resolution of the contradiction imposed by the Galilean transformation through physical explanation and the adoption of the Lorentzian transformation. This highlighted the relative nature of both space and time and the linkage of these to preserve the sanctity of the light cone. The resulting space-time geometry was then founded on the traditional calculus of variation with the addition of this transformation. This retains the time as an independent coordinate and its linkage to space in an explicit form. One implication of this approach has been the retention of the concept of infinitum for some physical quantities as a drawback for use of the Lorentzian transformation. The paper shows that this singular behaviour need not arise if the explicit linkage in space-time is abandoned in favour of the implicit inclusion of time as a link between the curved structure of space and the speed of light, thus restating the calculus of variation in line with special relativity. This points to a closed loop space-matter field, which may belie the fabric of the continuum. One implication of this interpretation is that a small variation in speed of light within the field would be required to dispense with the aforementioned singular nature of the Lorentzian boost, while still remaining within the spirit of special relativity.

scholarly journals Gravitational Collapse

1974 ◽  
Vol 64 ◽  
pp. 82-91 ◽  
Author(s):  
R. Penrose
Keyword(s):  
Black Hole ◽  
Gravitational Collapse ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Space Time ◽  
Local Version ◽  
Time Singularities ◽  
Standard Picture ◽  
Cosmic Censorship Hypothesis ◽  
Definition Of

In the standard picture of gravitational collapse to a black hole, a key role is played by the hypothesis of cosmic censorship – according to which no naked space-time singularities can result from any collapse. A precise definition of a naked singularity is given here which leads to a strong ‘local’ version of the cosmic censorship hypothesis. This is equivalent to the proposition that a Cauchy hypersurface exits for the space-time. The principle that the surface area of a black hole can never decrease with time is presented in a new and simplified form which generalizes the earlier statements. A discussion of the relevance of recent work to the naked singularity problem is also given.

scholarly journals The Pioneer anomaly in covariant theory of gravitation

2015 ◽  
Vol 93 (11) ◽  
pp. 1335-1342 ◽  
Author(s):  
Sergey G. Fedosin
Keyword(s):  
General Theory ◽  
Equations Of Motion ◽  
Covariant Theory ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Pioneer Anomaly ◽  
Theory Of Gravitation ◽  
The Difference

The difference of equations of motion in the covariant theory of gravitation and in the general theory of relativity is used to explain the Pioneer anomaly. Calculation shows that the velocities of a spacecraft in both theories at equal distances can differ by several centimetres per second. This leads also to a possible explanation of the flyby anomaly and comet disturbances, which are not taken into account by the general theory of relativity.

scholarly journals An Approach to Colliding Plane Waves in General Relativity

2021 ◽  
Vol 9 (12) ◽  
pp. 981-988
Author(s):  
Dr. Shailendra Kumar Srivastava
Keyword(s):  
General Relativity ◽  
Plane Waves ◽  
Space Time ◽  
Theory Of Relativity ◽  
Field Equations ◽  
Vast Number ◽  
Gravitational Fields ◽  
Time Singularities ◽  
Linearized Theory ◽  
High Degree

Abstract: For many years after Einstein proposed his general theory of relativity, only a few exact solutions were known. Today the situation is completely different, and we now have a vast number of such solutions. However, very few are well understood in the sense that they can be clearly interpreted as the fields of real physical sources. The obvious exceptions are the Schwarzschild and Kerr solutions. These have been very thoroughly analysed, and clearly describe the gravitational fields surrounding static and rotating black holes respectively. In practice, one of the great difficulties of relating the particular features of general relativity to real physical problems, arises from the high degree of non-linearity of the field equations. Although the linearized theory has been used in some applications, its use is severely limited. Many of the most interesting properties of space-time, such as the occurrence of singularities, are consequences of the non-linearity of the equations. Keywords: General Relativity , Space-Time, Singularities, Non-linearity of the Equations.

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