scholarly journals Generating solutions of Ricci-Based Gravity theories from General Relativity

2020 ◽  
Vol 29 (11) ◽  
pp. 2041010
Author(s):  
Emanuele Orazi
Keyword(s):  
General Relativity ◽  
Electromagnetic Fields ◽  
Scalar Fields ◽  
Gravity Theories ◽  
Anisotropic Fluids ◽  
Matter Sector ◽  
The Way

We generalize the algorithm that establishes the correspondence between metric-affine Eddington-inspired Born-Infeld (EiBI) gravity and General Relativity (GR) to any bosonic matter sector. Along the way, a polished version of the proof of existence of a metric compatible frame associated to any metric-affine Ricci-Based Gravity (RBG) is presented. Particular attention is given to the problem of generating solutions of a RBG from the GR counterpart, providing a general recipe for the EiBI case. This extends previous results obtained for specific matter that included anisotropic fluids, scalar fields and electromagnetic fields.

scholarly journals Plane Symmetric Solutions of a Scalar-Tensor Theory of Gravitation

1977 ◽  
Vol 30 (1) ◽  
pp. 109 ◽  
Author(s):  
DRK Reddy
Keyword(s):  
General Relativity ◽  
Empty Space ◽  
Scalar Fields ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Plane Symmetric ◽  
Zero Mass ◽  
Tensor Theory ◽  
Special Cases ◽  
Theory Of Gravitation

Plane symmetric solutions of a scalar-tensor theory proposed by Dunn have been obtained. These solutions are observed to be similar to the plane symmetric solutions of the field equations corresponding to zero mass scalar fields obtained by Patel. It is found that the empty space-times of general relativity discussed by Taub and by Bera are obtained as special cases.

Physics as an Art Form

2018 ◽  
pp. 1-4
Author(s):  
Alvaro De Rújula
Keyword(s):  
General Relativity ◽  
Laws Of Nature ◽  
Space Time ◽  
Einstein’S Equations ◽  
Einstein's Equations ◽  
Ockham’S Razor ◽  
Art Form ◽  
Ockham's Razor ◽  
The Universe ◽  
The Way

Beauty and simplicity, a scientist’s view. A first encounter with Einstein’s equations of General Relativity, space-time, and Gravity. Ockham’s Razor. Why the Universe is the way it is: The origin of the laws of Nature.

Canonical quantization of free fields

2021 ◽  
pp. 70-98
Author(s):  
Iosif L. Buchbinder ◽  
Ilya L. Shapiro
Keyword(s):  
Field Theory ◽  
Quantum Theory ◽  
Electromagnetic Fields ◽  
Classical Theory ◽  
Canonical Quantization ◽  
Classical Mechanics ◽  
Scalar Fields ◽  
Complex Scalar ◽  
Spinor Fields ◽  
Free Fields

This chapter discusses canonical quantization in field theory and shows how the notion of a particle arises within the framework of the concept of a field. Canonical quantization is the process of constructing a quantum theory on the basis of a classical theory. The chapter briefly considers the main elements of this procedure, starting from its simplest version in classical mechanics. It first describes the general principles of canonical quantization and then provides concrete examples. The examples include the canonical quantization of free real scalar fields, free complex scalar fields, free spinor fields and free electromagnetic fields.

On Almost Contingent Manifolds of Second Class with Applications in Relativity

1978 ◽  
Vol 21 (3) ◽  
pp. 289-295 ◽  
Author(s):  
K. L. Duggal
Keyword(s):  
General Relativity ◽  
Electromagnetic Fields ◽  
Vector Fields ◽  
Killing Vector ◽  
Positive Definite ◽  
Geometric Proof ◽  
Sasakian Manifolds ◽  
Killing Vector Fields ◽  
Degenerate Metric ◽  
Frame Work

D. E. Blair [1] has introduced the notion of K-manifolds as an analogue of the even dimensional Kähler manifolds and of the odd dimensional quasi-Sasakian manifolds. These manifolds have been studied with respect to a positive definite metric. In this paper, we study a more general case of if-manifolds carrying an arbitrary non-degenerate metric, in particular, a metric of Lorentz signature. This theory is then applied within the frame-work of general relativity. Using the Ruse-Synge classification [8, 9] of non-null electromagnetic fields with source, we develop a geometric proof for the existence of either two space like or one space like and one time like Killing vector fields on the space-time manifold.

scholarly journals PRINCIPLES OF EINSTEIN–FINSLER GRAVITY AND PERSPECTIVES IN MODERN COSMOLOGY

2012 ◽  
Vol 21 (09) ◽  
pp. 1250072 ◽  
Author(s):  
SERGIU I. VACARU
Keyword(s):  
General Relativity ◽  
Lorentz Invariance ◽  
Frame Structure ◽  
Relativity Theory ◽  
Finsler Metrics ◽  
Finsler Spaces ◽  
Modern Cosmology ◽  
Gravity Theories ◽  
Tangent Bundles ◽  
Local Lorentz Invariance

We study the geometric and physical foundations of Finsler gravity theories with metric compatible connections defined on tangent bundles, or (pseudo) Riemannian manifolds, endowed with nonholonomic frame structure. Several generalizations and alternatives to Einstein gravity are considered, including modifications with broken local Lorentz invariance. It is also shown how such theories (and general relativity) can be equivalently re-formulated in Finsler like variables. We focus on prospects in modern cosmology and Finsler acceleration of Universe. Einstein–Finsler gravity theories are elaborated following almost the same principles as in the general relativity theory but extended to Finsler metrics and connections. Finally, some examples of generic off-diagonal metrics and generalized connections, defining anisotropic cosmological Einstein–Finsler spaces are analyzed; certain criteria for the Finsler accelerating evolution are formulated.

scholarly journals Cosmological bounce in Horndeski theory and beyond

2018 ◽  
Vol 191 ◽  
pp. 07013 ◽  
Author(s):  
R. Kolevatov ◽  
S. Mironov ◽  
V. Rubakov ◽  
N. Sukhov ◽  
V. Volkova
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Cosmological Solutions ◽  
The Stability ◽  
The Way

We discuss the stability of the classical bouncing solutions in the general Horndeski theory and beyond Horndeski theory. We restate the no-go theorem, showing that in the general Horndeski theory there are no spatially flat non-singular cosmological solutions which are stable during entire evolution. We show the way to evade the no-go in beyond Horndeski theory and give two specific examples of bouncing solutions, whose asymptotic past and future or both are described by General Relativity (GR) with a conventional massless scalar field. Both solutions are free of any pathologies at all times.

Some wave solutions in general relativity

1974 ◽  
Vol 75 (2) ◽  
pp. 261-267
Author(s):  
L. K. Patel
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Electromagnetic Fields ◽  
General Scheme ◽  
Wave Solutions ◽  
Particular Solution

AbstractA general scheme for the derivation of wave solutions in general relativity is developed. Some solutions describing the flow of gravitational waves are discussed. Singular electromagnetic fields corresponding to one particular solution are also discussed.

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