Quasi-local mass and angular momentum in general relativity

1982 ◽  
Vol 381 (1780) ◽  
pp. 53-63 ◽  
Keyword(s):  
General Relativity ◽  
Angular Momentum ◽  
Twistor Space ◽  
New Approach ◽  
Local Mass ◽  
Bondi Mass ◽  
Definition Of

A new approach to defining energy-momentum and angular momentum in general relativity is presented which avoids some of the difficulties of previous definitions and which can be applied quasi-locally. It depends on the construction of a twistor space T α ( S ) associated with any spacelike topological 2-sphere S . Though several problems of interpretation remain to be solved, the new definition works well at I + , reproducing the Bondi-mass-momentum as four of the ten precisely determined quantities at each cut of I + . The remaining six quantities provide a definition of angular momentum which appears to be new.

2-Surface twistors, embeddings and symmetries

1987 ◽  
Vol 411 (1840) ◽  
pp. 59-83 ◽  
Keyword(s):  
General Relativity ◽  
Angular Momentum ◽  
Twistor Space ◽  
Conformally Flat ◽  
Definition Of

2-Surface twistor space (Penrose, Proc. R. Soc. Lond . A 381, 53 (1982)) was introduced in connection with a proposal for a quasi-local definition of mass and angular momentum within general relativity. Properties of the 2-surface twistor space are related to the possibilities for embedding the 2-surface in real and complex conformally flat spaces. The additional properties of the twistor space resulting from symmetries of the 2-surface are discussed, with particular detail on axisymmetric 2-surfaces.

scholarly journals Gravitational memory effects and Bondi-Metzner-Sachs symmetries in scalar-tensor theories

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shaoqi Hou ◽  
Zong-Hong Zhu
Keyword(s):  
General Relativity ◽  
Angular Momentum ◽  
Evolution Equations ◽  
Equations Of Motion ◽  
Memory Effects ◽  
Scalar Tensor Theory ◽  
Null Infinity ◽  
Infinite Dimensional ◽  
Tensor Theory ◽  
Bondi Mass

Abstract The relation between gravitational memory effects and Bondi-Metzner-Sachs symmetries of the asymptotically flat spacetimes is studied in the scalar-tensor theory. For this purpose, the solutions to the equations of motion near the future null infinity are obtained in the generalized Bondi-Sachs coordinates with a suitable determinant condition. It turns out that the Bondi-Metzner-Sachs group is also a semi-direct product of an infinite dimensional supertranslation group and the Lorentz group as in general relativity. There are also degenerate vacua in both the tensor and the scalar sectors in the scalar-tensor theory. The supertranslation relates the vacua in the tensor sector, while in the scalar sector, it is the Lorentz transformation that transforms the vacua to each other. So there are the tensor memory effects similar to the ones in general relativity, and the scalar memory effect, which is new. The evolution equations for the Bondi mass and angular momentum aspects suggest that the null energy fluxes and the angular momentum fluxes across the null infinity induce the transition among the vacua in the tensor and the scalar sectors, respectively.

scholarly journals On the Validity of the Definition of Angular Momentum in General Relativity

2015 ◽  
Vol 17 (2) ◽  
pp. 253-270 ◽  
Author(s):  
Po-Ning Chen ◽  
Lan-Hsuan Huang ◽  
Mu-Tao Wang ◽  
Shing-Tung Yau
Keyword(s):  
General Relativity ◽  
Angular Momentum ◽  
Definition Of

Twistor theory and the energy—momentum and angular momentum of the gravitational field at spatial infinity

1983 ◽  
Vol 390 (1798) ◽  
pp. 191-215 ◽  
Keyword(s):  
General Relativity ◽  
Angular Momentum ◽  
Twistor Space ◽  
Conserved Quantities ◽  
Twistor Theory ◽  
Coordinate Transformations ◽  
Spatial Infinity ◽  
Weyl Curvature ◽  
Linearized Theory ◽  
Math Phys

Penrose’s ‘quasi-local mass and angular momentum’ (Penrose, Proc. R. Soc. Lond . A 381, 53 (1982)) is investigated for 2-surfaces near spatial infinity in both linearized theory on Minkowski space and full general relativity. It is shown that for space-times that are radially smooth of order one in the sense of Beig & Schmidt ( Communs math. Phys . 87, 65 (1982)), with asymptotically electric Weyl curvature, there exists a global concept of a twistor space at spatial infinity. Global conservation laws for the energy—momentum and angular momentum are obtained, and the ten conserved quantities are shown to be invariant under asymptotic coordinate transformations. The relation to other definitions is discussed briefly.

Seeing, imagined, and lived

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Anandi Silva Knuppel
Keyword(s):  
Sensory Experience ◽  
Religious Practices ◽  
Daily Lives ◽  
New Approach ◽  
Theories Of Practice ◽  
Sources Of Authority ◽  
Definition Of

Scholarship on Hindu traditions and practices proposes the practice of darshan as fundamental to Hindu traditions, particularly in temple worship, observing that devotees seek out images of deities primarily to see them and “receive” their darshan. These works typically gloss the definition of darshan with a sentence or two about seeing, exchanging glances, and/or receiving blessings. In this paper, I focus on the ways in which darshan is ideally imagined in conjunction with other bodily sensory practices through sources of authority, such as texts and senior devotees, to create a specific sensory experience and expectation in the transnational Gaudiya Vaishnava community. I then look to the lived realitiesof darshan in this tradition, specifically how devotees negotiate the structures created through sources of authority in their daily lives. Through this juxtaposition of idealized and lived darshan, I argue that we need a new approach towards theories of practice to take into account the complexities of darshanic moments in this and other religious practices.

scholarly journals Off-Shell Noether Currents and Potentials for First-Order General Relativity

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 348
Author(s):  
Merced Montesinos ◽  
Diego Gonzalez ◽  
Rodrigo Romero ◽  
Mariano Celada
Keyword(s):  
General Relativity ◽  
Vector Fields ◽  
Killing Vector ◽  
Spherically Symmetric ◽  
Killing Vector Fields ◽  
Arbitrary Vector ◽  
Four Dimensions ◽  
First Order ◽  
Direct Form ◽  
Definition Of

We report off-shell Noether currents obtained from off-shell Noether potentials for first-order general relativity described by n-dimensional Palatini and Holst Lagrangians including the cosmological constant. These off-shell currents and potentials are achieved by using the corresponding Lagrangian and the off-shell Noether identities satisfied by diffeomorphisms generated by arbitrary vector fields, local SO(n) or SO(n−1,1) transformations, ‘improved diffeomorphisms’, and the ‘generalization of local translations’ of the orthonormal frame and the connection. A remarkable aspect of our approach is that we do not use Noether’s theorem in its direct form. By construction, the currents are off-shell conserved and lead naturally to the definition of off-shell Noether charges. We also study what we call the ‘half off-shell’ case for both Palatini and Holst Lagrangians. In particular, we find that the resulting diffeomorphism and local SO(3,1) or SO(4) off-shell Noether currents and potentials for the Holst Lagrangian generically depend on the Immirzi parameter, which holds even in the ‘half off-shell’ and on-shell cases. We also study Killing vector fields in the ‘half off-shell’ and on-shell cases. The current theoretical framework is illustrated for the ‘half off-shell’ case in static spherically symmetric and Friedmann–Lemaitre–Robertson–Walker spacetimes in four dimensions.

Coercive Persuasion As a Specific Type of Violence in Criminal Law

2020 ◽  
Vol 1 (1) ◽  
pp. 61-72
Author(s):  
Carlos Bardavío Antón
Keyword(s):  
Criminal Law ◽  
Comparative Law ◽  
Third Parties ◽  
Physical Injury ◽  
Comprehensive Understanding ◽  
Legal Doctrine ◽  
New Approach ◽  
Freedom Of Will ◽  
Definition Of ◽  
Regulatory Problems

The field of cults, and that of destructive or coercive cults in particular, has received little attention from the perspective of criminal law doctrine. Supporters of such groups often claim to be victims of a violation related to freedom of will. In this article, I consider various methodologies and manipulation techniques used by such groups and suggest that comparative law, criminal definitions, and regulatory problems provide the basis for a more comprehensive understanding of criminal phenomenology that includes these concerns: the loss of freedom through coercive persuasion, and thus being the victim of a crime, or through becoming an instrument for the commission of crimes ordered by third parties. Research shows that the conventional definition of crime against freedom of will and physical injury is inadequate. I posit that a new approach to legal doctrine and criminal classification is required to fight against new crime phenomenology. I propose a criminal classification aimed at considering coercive persuasion as a crime, and a definition for the criminalization of certain organizations that engage in willful misconduct or reckless conduct.

scholarly journals A Reconsideration on the Theory of Beauty: Previous Views and a New Approach Following Maslow's Theory (Part II)

2021 ◽  
Author(s):  
Iulia-Adina Lehene
Keyword(s):  
Nineteenth Century ◽  
Urban Planning ◽  
Civil Engineering ◽  
Philosophical Perspective ◽  
New Approach ◽  
Human Motivation ◽  
Definition Of ◽  
Concept Of Beauty

This paper is the second part of a work that aims to rethink the concept of beauty as close as possible to its essence and in a way that integrates the science of aesthetics with the field of construction. Within other theoretical and practical works, this study may be further used to physically reflect the definition of beauty in areas such as architecture, civil engineering or urban planning and support professionals in designing and building beautiful objects and constructions. However, it has to be added that the assumption that there must be a particular original aspect related to beauty that leads a human-made object to success, needs to be further identified. The approach to the concept of beauty is through a general philosophical perspective and partially through the areas mentioned above.The second part of the study includes the synthesised guidance provided by Monroe Beardsley through the theories on beauty from the nineteenth century until today. In addition, it comprises the scheme of concepts that characterised the beautiful in this time, including the lines that guided its study, previous ideas that support our later views on presented theory, and a brief exposition of Maslow's theory of human motivation followed by our theory on beauty and the conclusions.

scholarly journals Modern vision for critical flow in an egg-shaped section

2021 ◽  
Author(s):  
Hachemi Rachedi Lamia ◽  
Lakehal Moussa ◽  
Achour Bachir
Keyword(s):  
Froude Number ◽  
Critical Regime ◽  
Critical Flow ◽  
New Approach ◽  
Smooth Channel ◽  
Critical Flow Regime ◽  
Modern Vision ◽  
The One ◽  
Definition Of ◽  
Steep Slopes

Abstract The critical regime plays a primordial role in the study of gradually varying flows by classifying flow regimes and slopes. Through this work, a new approach is proposed to analyze critical flow regime in an egg-shaped channel. Based on both the definition of Froude number and Achour and Bedjaoui general discharge relationship, a relation between critical and normal depths is derived and then graphically represented for the particular case of a smooth channel characterized by a generating diameter equal to one meter. The results show the influence of the slope on the frequency of occurrence of the critical regime. At the same time and independently of the flow rate, a very advantageous approach for the calculation of the Froude number has been proposed. The study shows that there are six zones to differentiate the various flow states, namely: on the one hand for steep slopes two subcritical zones interspersed by a supercritical zone and on the other hand for mild slopes a zone corresponding to uniform flow, an area where the flow is probably gradually varied and finally an area where the flow is abruptly varied. Based on the specific energy equation, a validation process concluded that the proposed relationships were reliable.

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