The constancy of G and other gravitational experiments

1983 ◽  
Vol 310 (1512) ◽  
pp. 227-238 ◽  
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Relativistic Effects ◽  
Delay Effect ◽  
Data Set ◽  
Gravitomagnetic Field ◽  
Test Technology ◽  
Stringent Test ◽  
Data Yield ◽  
Time Delay Effect

Traditionally, theories of gravitation have received their most demanding tests in the solar-system laboratory. Today, electronic observing technology makes possible solar system tests of substantially increased accuracy. We consider how these technologies are being used to study gravitation with an emphasis on two questions: (i) Dirac and others have investigated theories in which the constant of gravitation, G , appears to change with time. Recent analyses using the Viking data yield | G / G | < 3 x 10 -11 per year. With further analysis, the currently available ensemble of data should permit an estimate of G/G with an uncertainty of 10 -11 per year. At this level it will become possible to distinguish among competitive theories. (ii) Shapiro’s time-delay effect has provided the most stringent solar-system test of general relativity. The effect has been measured to be consistent with the predictions of general relativity with a fractional uncertainty of 0.1%. An improved analysis of an enhanced data set should soon permit an even more stringent test. Technology now permits new kinds of tests to be performed. Among these are some that measure relativistic effects due to the square of the (solar) potential and others that detect the Earth’s ‘gravitomagnetic’ field (the Lense-Thirring effect). These experiments, and the use of astrophysical systems are among the experimental challenges for the coming decades.

scholarly journals Relativistic aspects of the JPL planetary ephemeris

2009 ◽  
Vol 5 (S261) ◽  
pp. 155-158 ◽  
Author(s):  
W. M. Folkner
Keyword(s):  
Solar System ◽  
Time Variation ◽  
Gravitational Constant ◽  
Equations Of Motion ◽  
Relativistic Effects ◽  
Radio Tracking ◽  
Data Set ◽  
Inverse Square Law ◽  
Radio Signals ◽  
Ppn Parameters

AbstractThe orbits of the planets as represented by the JPL planetary ephemerides are now primarily determined by radio tracking of spacecraft. Analysis of the data and propagation of the orbits relies on an internally consistent set of equations of motion and propagation of radio signals including relativistic effects at the centimeter level. The planetary ephemeris data set can be used to test some aspects of the underlying theory such as estimates of PPN parameters γ and β, time variation in the gravitational constant G, rotation of the solar system relative to distant objects (Mach's principle), and place stringent limits on the possible violation of the inverse-square law.

On claims that general relativity differs from Newtonian physics for self-gravitating dusts in the low velocity, weak field limit

2015 ◽  
Vol 24 (08) ◽  
pp. 1550065 ◽  
Author(s):  
David R. Rowland
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Relativistic Effects ◽  
Weak Field ◽  
Newtonian Gravity ◽  
Galactic Rotation ◽  
Low Velocity ◽  
Rotation Curves ◽  
Newtonian Physics ◽  
General Relativistic

Galaxy rotation curves are generally analyzed theoretically using Newtonian physics; however, two groups of authors have claimed that for self-gravitating dusts, general relativity (GR) makes significantly different predictions to Newtonian physics, even in the weak field, low velocity limit. One group has even gone so far as to claim that nonlinear general relativistic effects can explain flat galactic rotation curves without the need for cold dark matter. These claims seem to contradict the well-known fact that the weak field, low velocity, low pressure correspondence limit of GR is Newtonian gravity, as evidenced by solar system tests. Both groups of authors claim that their conclusions do not contradict this fact, with Cooperstock and Tieu arguing that the reason is that for the solar system, we have test particles orbiting a central gravitating body, whereas for a galaxy, each star is both an orbiting body and a contributor to the net gravitational field, and this supposedly makes a difference due to nonlinear general relativistic effects. Given the significance of these claims for analyses of the flat galactic rotation curve problem, this article compares the predictions of GR and Newtonian gravity for three cases of self-gravitating dusts for which the exact general relativistic solutions are known. These investigations reveal that GR and Newtonian gravity are in excellent agreement in the appropriate limits, thus supporting the conventional use of Newtonian physics to analyze galactic rotation curves. These analyses also reveal some sources of error in the referred to works.

scholarly journals RELATIVISTIC EFFECTS IN EXTRASOLAR PLANETARY SYSTEMS

2006 ◽  
Vol 15 (12) ◽  
pp. 2133-2140 ◽  
Author(s):  
FRED C. ADAMS ◽  
GREGORY LAUGHLIN
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Planetary Systems ◽  
Relativistic Effects ◽  
Interaction Theory ◽  
Orbital Elements ◽  
Secular Resonance ◽  
The Future ◽  
General Relativistic ◽  
Temporal Coverage

This paper considers general relativistic (GR) effects in currently observed extrasolar planetary systems. Although GR corrections are small, they can compete with secular interactions in these systems and thereby play an important role. Specifically, some of the observed multiple planet systems are close to secular resonance, where the dynamics is extremely sensitive to GR corrections, and these systems can be used as laboratories to test general relativity. For the three-planet solar system Upsilon Andromedae, secular interaction theory implies an 80% probability of finding the system with its observed orbital elements if GR is correct, compared with only a 2% probability in the absence of GR. In the future, tighter constraints can be obtained with increased temporal coverage.

scholarly journals Prospects for observations of relativistic effects in the solar system

1986 ◽  
Vol 114 ◽  
pp. 383-391
Author(s):  
R. D. Reasenberg ◽  
I. I. Shapiro
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Space Shuttle ◽  
Space Station ◽  
Relativistic Effects ◽  
Dramatic Improvement ◽  
Optical Interferometer ◽  
Theory Of Gravitation ◽  
Theories Of Gravitation ◽  
Solar Gravity

The solar system is the traditional laboratory for testing theories of gravitation. The results of all tests are consistent with the predictions of general relativity. The differences between these predictions and those of Newton's theory of gravitation have been confirmed with uncertainties as small as one part in a thousand. To enhance significantly the accuracy of such tests, one must investigate novel techniques. In this paper we concentrate on an experiment that promises a dramatic improvement in a classical test of general relativity – the deflection of light by solar gravity. The goal is to measure the post-post-Newtonian contribution of nearly 11 microarcseconds to this deflection. The technique we propose is based on use of an astrometric optical interferometer, POINTS, which could be operated from the bay of the Space Shuttle, mounted on the proposed Space Station, or supported by an independent spacecraft. POINTS should be able to measure the separation of stars about 90° apart with an uncertainty of only a few microarcseconds.

scholarly journals OPTICAL PHENOMENA IN THE FIELD OF BRANEWORLD KERR BLACK HOLES

2009 ◽  
Vol 18 (06) ◽  
pp. 983-1024 ◽  
Author(s):  
JAN SCHEE ◽  
ZDENĚK STUCHLÍK
Keyword(s):  
Black Hole ◽  
Hot Spot ◽  
Relativistic Effects ◽  
Delay Effect ◽  
Rotational Parameter ◽  
Rotating Black Hole ◽  
Optical Phenomena ◽  
Charge Parameter ◽  
Time Delay Effect ◽  
Free Falling

We study the influence of the tidal charge parameter of the braneworld models on some optical phenomena in rotating black hole space–times. The escape photon cones are determined for special families of locally nonrotating, circular geodetical and radially free-falling observers. The silhouette of a rotating black hole, the shape of an equatorial thin accretion disk and the time delay effect for direct and indirect images of a radiating hot spot orbiting the black hole are given and classified in terms of the black hole rotational and tidal parameters. It is shown that increase of the negatively valued tidal parameter, with the rotational parameter fixed, generally strengthens the relativistic effects and suppresses the rotation-induced asymmetries in the optical phenomena.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

scholarly journals Time delay effect in a three coupled oscillator system of the physarum plasmodium

2000 ◽  
Vol 40 (supplement) ◽  
pp. S100
Author(s):  
A. Takamatsu ◽  
T. Fujii ◽  
I. Endo
Keyword(s):  
Time Delay ◽  
Delay Effect ◽  
Coupled Oscillator ◽  
Oscillator System ◽  
Time Delay Effect

Structural Control Considering Time Delay Effect

1985 ◽  
Vol 9 (4) ◽  
pp. 224-227 ◽  
Author(s):  
Mohamed Abdel-Rohman
Keyword(s):  
Time Delay ◽  
Active Control ◽  
Theoretical Consideration ◽  
Structural Control ◽  
Control Mechanism ◽  
Structural Response ◽  
Delay Effect ◽  
Numerical Example ◽  
Control Forces ◽  
Time Delay Effect

The time delay between measuring the structural response, and applying the designed active control forces may affect the controlled response of the structure if not taken into consideration. In this paper it is shown how to design the control forces to compensate for the delay effect. It is also shown that the time delay effect can be used as a criterion to judge the effectiveness of the proposed control mechanism. As an illustration of the theoretical consideration, a numerical example in which a tall building is controlled by means of active tendons is presented.

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