A New Theory of Gravity: Overcoming Problems with General Relativity.

2007 ◽  
Vol 20 (1) ◽  
pp. 83-100 ◽  
Author(s):  
Ronald R. Hatch
Keyword(s):  
General Relativity ◽  
Theory Of Gravity

scholarly journals What are the wild waves saying? Yet another meditation on the predictions, searches for, and detections of gravitational waves

2018 ◽  
Vol 27 (14) ◽  
pp. 1830009
Author(s):  
Virginia Trimble
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Point Of View ◽  
Large Majority ◽  
Laboratory Apparatus ◽  
New Information ◽  
Theory Of Gravity ◽  
To Come ◽  
The Universe

A large majority of the physics and astronomy communities are now sure that gravitational waves exist, can be looked for, and can be studied via their effects on laboratory apparatus as well as on astronomical objects. So far, everything found out has agreed with the predictions of general relativity, but hopes are high for new information about the universe and its contents and perhaps for hints of a better theory of gravity than general relativity (which even Einstein expected to come eventually). This is one version of the story, from 1905 to the present, told from an unusual point of view, because the author was, for 28.5 years, married to Joseph Weber, who built the first detectors starting in the early 1960s and operated one or more until his death on 30 September 2000.

scholarly journals Foundations of a Theory of Gravity with a Constraint and Its Canonical Quantization

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Alexander P. Sobolev
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Early Universe ◽  
Canonical Quantization ◽  
Entropy Density ◽  
Maximum Temperature ◽  
Past Century ◽  
Physical Point ◽  
Theory Of Gravity ◽  
The Universe

AbstractThe gravitational equations were derived in general relativity (GR) using the assumption of their covariance relative to arbitrary transformations of coordinates. It has been repeatedly expressed an opinion over the past century that such equality of all coordinate systems may not correspond to reality. Nevertheless, no actual verification of the necessity of this assumption has been made to date. The paper proposes a theory of gravity with a constraint, the degenerate variants of which are general relativity (GR) and the unimodular theory of gravity. This constraint is interpreted from a physical point of view as a sufficient condition for the adiabaticity of the process of the evolution of the space–time metric. The original equations of the theory of gravity with the constraint are formulated. On this basis, a unified model of the evolution of the modern, early, and very early Universe is constructed that is consistent with the observational astronomical data but does not require the hypotheses of the existence of dark energy, dark matter or inflatons. It is claimed that: physical time is anisotropic, the gravitational field is the main source of energy of the Universe, the maximum global energy density in the Universe was 64 orders of magnitude smaller the Planckian one, and the entropy density is 18 orders of magnitude higher the value predicted by GR. The value of the relative density of neutrinos at the present time and the maximum temperature of matter in the early Universe are calculated. The wave equation of the gravitational field is formulated, its solution is found, and the nonstationary wave function of the very early Universe is constructed. It is shown that the birth of the Universe was random.

A brief survey of general relativity

2019 ◽  
pp. 25-50
Author(s):  
Nils Andersson
Keyword(s):  
General Relativity ◽  
Geometric Theory ◽  
Einstein’S Field Equations ◽  
Curved Spacetime ◽  
Field Equations ◽  
Einstein's Field Equations ◽  
Theory Of Gravity

This chapter provides an overview of Einstein’s geometric theory of gravity – general relativity. It introduces the mathematics required to model the motion of objects in a curved spacetime and provides an intuitive derivation of Einstein’s field equations.

scholarly journals Asymptotically flat vacuum solution in modified theory of Einstein’s gravity

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Surajit Kalita ◽  
Banibrata Mukhopadhyay
Keyword(s):  
General Relativity ◽  
Vacuum Solution ◽  
Compact Objects ◽  
Schwarzschild Solution ◽  
Asymptotically Flat ◽  
Symmetric Vacuum ◽  
Theory Of Gravity ◽  
Bound Orbits ◽  
Vacuum Spacetime ◽  
The Universe

Abstract A number of recent observations have suggested that the Einstein’s theory of general relativity may not be the ultimate theory of gravity. The f(R) gravity model with R being the scalar curvature turns out to be one of the best bet to surpass the general relativity which explains a number of phenomena where Einstein’s theory of gravity fails. In the f(R) gravity, behaviour of the spacetime is modified as compared to that of given by the Einstein’s theory of general relativity. This theory has already been explored for understanding various compact objects such as neutron stars, white dwarfs etc. and also describing evolution of the universe. Although researchers have already found the vacuum spacetime solutions for the f(R) gravity, yet there is a caveat that the metric does have some diverging terms and hence these solutions are not asymptotically flat. We show that it is possible to have asymptotically flat spherically symmetric vacuum solution for the f(R) gravity, which is different from the Schwarzschild solution. We use this solution for explaining various bound orbits around the black hole and eventually, as an immediate application, in the spherical accretion flow around it.

Solar Eclipses as a Teaching Opportunity in Relativity

2020 ◽  
Vol 02 (02) ◽  
pp. 2050010
Author(s):  
James Overduin ◽  
Kelsey Glazer ◽  
Keri McClelland ◽  
Amelia Genus ◽  
Chris Miskiewicz
Keyword(s):  
General Relativity ◽  
Gravitational Lensing ◽  
Pivotal Role ◽  
Light Deflection ◽  
British Government ◽  
Composite Image ◽  
Theory Of Gravity ◽  
Solar Eclipses

Total solar eclipses represent a challenging but spectacular opportunity to introduce curious students to the wonders of general relativity through the phenomenon of light deflection (gravitational lensing). During the Great American Eclipse of 2017, we were among a small number of teams attempting to repeat Eddington’s iconic observations of 1919, which played a pivotal role in establishing Einstein’s theory as the governing theory of gravity. We were not quite successful on the observational front, but acquired an excellent composite image from a fellow astronomer. Analysis of this image allowed us to obtain a result consistent with Einstein’s theory. It is remarkable that such an experiment, which once required the resources of the British government, can now be attempted with reasonable hope of success by teachers and their students. We look forward to our next chance in 2024.

scholarly journals Black Holes and Wormholes in Extended Gravity

Universe ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 25 ◽  
Author(s):  
Stanislav Alexeyev ◽  
Maxim Sendyuk
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Quantum Theory ◽  
Gravity Models ◽  
Astrophysical Data ◽  
Effective Gravity ◽  
Extended Gravity ◽  
Theory Of Gravity ◽  
Hawking Evaporation

We discuss black hole type solutions and wormhole type ones in the effective gravity models. Such models appear during the attempts to construct the quantum theory of gravity. The mentioned solutions, being, mostly, the perturbative generalisations of well-known ones in general relativity, carry out additional set of parameters and, therefore could help, for example, in the studying of the last stages of Hawking evaporation, in extracting the possibilities for the experimental or observational search and in helping to constrain by astrophysical data.

scholarly journals Gravitomagnetic Time Delay and the Lense–Thirring Effect in Brans–Dicke Theory of Gravity

2003 ◽  
Vol 18 (30) ◽  
pp. 2117-2124 ◽  
Author(s):  
A. Barros ◽  
C. Romero
Keyword(s):  
General Relativity ◽  
Time Delay ◽  
Theory Of Gravity ◽  
Theoretical Results

We discuss the gravitomagnetic time delay and the Lense–Thirring effect in the context of Brans–Dicke theory of gravity. We compare the theoretical results obtained with those predicted by general relativity. We show that within the accuracy of experiments designed to measure these effects both theories predict essentially the same results.

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