scholarly journals Interpolating the Schwarzschild and de Sitter metrics

2019 ◽  
Vol 28 (02) ◽  
pp. 1950038
Author(s):  
M. Halilsoy ◽  
S. Habib Mazharimousavi
Keyword(s):  
General Relativity ◽  
Acta Math ◽  
Finite Range ◽  
De Sitter ◽  
Sitter Solution ◽  
Common Parameter ◽  
Range Parameter ◽  
Alternative Approaches ◽  
High Level ◽  
The Way

The binary potential technique of interpolation (by [M. Riesz, Acta Math. 81 (1949) 1]) is applied to some well-known metrics of general relativity. These include Schwarzschild, de Sitter and [Formula: see text]-dimensional BTZ spacetimes. In particular, the Schwarzschild–de Sitter solution is analyzed in some detail with a finite range parameter. Reasoning by the high level of nonlinearity and absence of a superposition law necessitates searching for alternative approaches. We propose the method of interpolation between different spacetimes as one such possibility paving the way toward controling the two-metric system by a common parameter.

scholarly journals Driven black holes: from Kolmogorov scaling to turbulent wakes

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Tomas Andrade ◽  
Christiana Pantelidou ◽  
Julian Sonner ◽  
Benjamin Withers
Keyword(s):  
Nonlinear Dynamics ◽  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
De Sitter ◽  
Event Horizons ◽  
Binary Mergers ◽  
Tidal Deformations ◽  
Proof Of Principle

Abstract General relativity governs the nonlinear dynamics of spacetime, including black holes and their event horizons. We demonstrate that forced black hole horizons exhibit statistically steady turbulent spacetime dynamics consistent with Kolmogorov’s theory of 1941. As a proof of principle we focus on black holes in asymptotically anti-de Sitter spacetimes in a large number of dimensions, where greater analytic control is gained. We focus on cases where the effective horizon dynamics is restricted to 2+1 dimensions. We also demonstrate that tidal deformations of the horizon induce turbulent dynamics. When set in motion relative to the horizon a deformation develops a turbulent spacetime wake, indicating that turbulent spacetime dynamics may play a role in binary mergers and other strong-field phenomena.

scholarly journals General relativistic effects acting on the orbits of Galileo satellites

2021 ◽  
Vol 133 (4) ◽  
Author(s):  
K. Sośnica ◽  
G. Bury ◽  
R. Zajdel ◽  
K. Kazmierski ◽  
J. Ventura-Traveset ◽  
...  
Keyword(s):  
General Relativity ◽  
Orbit Determination ◽  
Final Height ◽  
Precise Orbit Determination ◽  
Satellite System ◽  
De Sitter ◽  
Circular Orbits ◽  
Precise Orbit ◽  
Artificial Earth Satellites ◽  
Artificial Earth

AbstractThe first pair of satellites belonging to the European Global Navigation Satellite System (GNSS)—Galileo—has been accidentally launched into highly eccentric, instead of circular, orbits. The final height of these two satellites varies between 17,180 and 26,020 km, making these satellites very suitable for the verification of the effects emerging from general relativity. We employ the post-Newtonian parameterization (PPN) for describing the perturbations acting on Keplerian orbit parameters of artificial Earth satellites caused by the Schwarzschild, Lense–Thirring, and de Sitter general relativity effects. The values emerging from PPN numerical simulations are compared with the approximations based on the Gaussian perturbations for the temporal variations of the Keplerian elements of Galileo satellites in nominal, near-circular orbits, as well as in the highly elliptical orbits. We discuss what kinds of perturbations are detectable using the current accuracy of precise orbit determination of artificial Earth satellites, including the expected secular and periodic variations, as well as the constant offsets of Keplerian parameters. We found that not only secular but also periodic variations of orbit parameters caused by general relativity effects exceed the value of 1 cm within 24 h; thus, they should be fully detectable using the current GNSS precise orbit determination methods. Many of the 1-PPN effects are detectable using the Galileo satellite system, but the Lense–Thirring effect is not.

Content and Language Integrated Learning: Panacea or Policy Borrowing Myth?

2013 ◽  
Vol 4 (2) ◽  
pp. 317-342 ◽  
Author(s):  
Amos Paran
Keyword(s):  
Second Language ◽  
High Achievers ◽  
Educational Policies ◽  
Student Selection ◽  
Integrated Learning ◽  
Policy Borrowing ◽  
Educational Transfer ◽  
High Level ◽  
The Way

AbstractThis paper examines the spread of Content and Language Integrated Learning (CLIL) through a number of lenses. It argues that the supporters and promoters of CLIL position it as a near-panacea and attribute to it a large number of benefits, not all of which are supported by research. Looking at the issues arising from recent attempts to define CLIL, the paper proposes a distinction between weak and strong CLIL. The paper points to the lacunae in the research into CLIL, and suggests that these gaps are the result of educational policies that privilege a second language over other curricular subjects. Looking at the contexts where CLIL seems to succeed, as well as places where such teaching has been acknowledged to fail, it emerges that success is often connected to a high level of student selection on a number of criteria, as well as a high level of investment in teachers and teaching, and that CLIL often privileges those students who are already high achievers both in language and content. The paper then looks at the way in which the spread of CLIL policies can be understood through theories of policy borrowing and educational transfer.

scholarly journals DUALITY AND SELF-DUAL TRIPLET SOLUTIONS IN EUCLIDEAN GRAVITY

1996 ◽  
Vol 11 (34) ◽  
pp. 2669-2679
Author(s):  
SWAPNA MAHAPATRA
Keyword(s):  
String Theory ◽  
The Self ◽  
Target Space ◽  
De Sitter ◽  
Gravitational Instanton ◽  
Duality Symmetry ◽  
Sitter Solution

Starting from the self-dual “triplet” of gravitational instanton solutions in Euclidean gravity, we obtain the corresponding instanton solutions in string theory by making use of the target space duality symmetry. We show that these dual triplet solutions can be obtained from the general dual Taub-NUT de Sitter solution through some limiting procedure as in the Euclidean gravity case. The dual gravitational instanton solutions obtained here are self-dual for some cases, with respect to certain isometries, but not always.

CHILDHOOD IN CHINA

PEDIATRICS ◽  
1977 ◽  
Vol 60 (6) ◽  
pp. 937-937
Author(s):  
W. Kessen
Keyword(s):  
Positive Reinforcement ◽  
Basic Problem ◽  
Chinese Child ◽  
Chinese Children ◽  
Chinese Teachers ◽  
Outstanding Feature ◽  
American Teacher ◽  
High Level ◽  
Problem Setting ◽  
The Way

If our observations were at all representative, the outstanding feature of childhood in China, and that which raises the lower basic problem, is the high level of concentration, orderliness, and competence of the children. The docility did not seem to us to be the docility of surrender and apathy; the Chinese children we saw were emotionally expressive, socially gracious, and adept. . . . Over and over we asked ourselves how the very young Chinese child was brought competence, social grace, and restraint. Put in its most simplifying form, Chinese children behave the way they do because that is the way children behave! The contrast with common American practice can be easily made. An American teacher (or parent) considers how he or she will effect a change in a child, what should be done with the child to make a difference. This attitude, which runs across many different theories of education, sees teaching as instrumental, as a set of procedures for the purpose of changing behavior. If the instruments of education, whether they are problem setting, positive reinforcement, or modeling, are ineffective, then change is difficult or distorted. Such a consciously instrumental attitude seems far less prevalent in Chinese schools. Rather, we formed the impression that Chinese teachers have uniform expectations of what children at one or another age can do and that they behave with the virtually certain knowledge that the children would come to behave in the expected way—and, critically, it did not much matter whether the children got there early or late.

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.

Appraisal, Coping and High Level Emotions Aspects of Computational Emotional Thinking

2015 ◽  
Vol 6 (1) ◽  
pp. 24-39 ◽  
Author(s):  
Max Talanov ◽  
Alexander Toschev
Keyword(s):  
Evolutionary Psychology ◽  
Emotional Response ◽  
Emotional State ◽  
Current Work ◽  
Computing Systems ◽  
Intelligent Machines ◽  
Thinking Processes ◽  
High Level ◽  
Computational Processes ◽  
The Way

Turing genius anticipated current research in AI field for 65 years and stated that idea of intelligent machines “cannot be wholly ignored, because the idea of 'intelligence' is itself emotional rather than mathematical” (). This is the second article dedicated to emotional thinking bases. In the first article, the authors () created overall picture and proposed framework for computational emotional thinking. They used 3 bases for their work: AI - six thinking levels model described in book “The emotion machine” (). Evolutionary psychology model: “Wheel of emotions” (). Neuroscience (neurotransmission) theory of emotions by Lovheim “Cube of emotions” (). Based on neurotransmitters impact the authors proposed to model emotional computing systems. Current work is dedicated to three aspects left not described in first article: appraisal: algorithm and predicates - how inbound stimulus is estimated to trigger proper emotional response, coping: the way human treat with emotional state triggered by stimulus appraisal and further thinking processes, high level emotions impact on system and its computational processes.

scholarly journals Energy conditions in non-local gravity

2019 ◽  
Vol 16 (10) ◽  
pp. 1950149 ◽  
Author(s):  
M. Ilyas
Keyword(s):  
Power Law ◽  
Arbitrary Function ◽  
Energy Conditions ◽  
De Sitter ◽  
Sitter Solution ◽  
Local Gravity ◽  
Non Local

We investigate the different energy conditions in non-local gravity, which is obtained by adding an arbitrary function of d’Alembertian operator, [Formula: see text], to the Hilbert–Einstein action. We analyze the validity of four different energy conditions and illustrate the different constraints over parameters of the power-law solution as well as de Sitter solution.

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