A SHORT COMMENT ON THE JUPITER TIME-DELAY CONTROVERSIES

2006 ◽  
Vol 15 (02) ◽  
pp. 291-293
Author(s):  
S. CARLIP
Keyword(s):  
Time Delay ◽  
Speed Of Light ◽  
Light Passing ◽  
Speed Of Gravity ◽  
Considerable Controversy ◽  
Short Comment

The observation of Shapiro time delay of quasar light passing near Jupiter1 generated considerable excitement, but also considerable controversy. The disagreements involve two distinct issues: (i) Is there a vJ/c term in the time delay that is large enough to detect? (ii) If so, is the factor of c in the delay the "speed of gravity" cg or the "speed of light" c? I will comment briefly on each.

scholarly journals COMMENTS ON "ON THE SPEED OF GRAVITY AND THE JUPITER/QUASAR MEASUREMENT" BY S. SAMUEL

2006 ◽  
Vol 15 (02) ◽  
pp. 273-288 ◽  
Author(s):  
SERGEI M. KOPEIKIN
Keyword(s):  
Time Delay ◽  
Review Article ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Speed Of Light ◽  
Propagation Of Light ◽  
Relativistic Time ◽  
Speed Of Gravity ◽  
General Relativistic ◽  
Recent Review Article

A recent review article by S. Samuel "On the Speed of Gravity and the Jupiter/Quasar Measurement" published as Int. J. Mod. Phys. D13, 1753 (2004), provides the reader with a misleading "theory" of the relativistic time delay in the general theory of relativity. Furthermore, it misquotes original publications by Kopeikin and Fomalont and Kopeikin related to the measurement of the speed of gravity by VLBI. We summarize the general relativistic principles of the Lorentz-invariant theory of the propagation of light in a time-dependent gravitational field, derive a Lorentz-invariant expression for the relativistic time delay, and finally explain why Samuel's "theory" is conceptually incorrect and confuses the speed of gravity with the speed of light.

scholarly journals A proposal to measure the speed of gravity

2013 ◽  
Vol 91 (6) ◽  
pp. 455-455 ◽  
Author(s):  
M.B. Paranjape
Keyword(s):  
Gravitational Field ◽  
Time Delay ◽  
Finite Time ◽  
Simple Experiment ◽  
Speed Of Gravity ◽  
Moving Body ◽  
Two Bodies

We propose a simple experiment to measure the speed of gravity in the laboratory. A moving body induces changes in the gravitational field that travel to the detector with a finite time delay. Moving two bodies causes changes to the gravitational field. These changes can add or subtract, and observing this interference allows for the measurement of the speed of gravity.

Time delay and the effect of the finite speed of light in atom gravimeters

2017 ◽  
Vol 96 (2) ◽  
Author(s):  
Yu-Jie Tan ◽  
Cheng-Gang Shao ◽  
Zhong-Kun Hu
Keyword(s):  
Time Delay ◽  
Speed Of Light ◽  
Finite Speed

scholarly journals Radar determination of the Astronomical Unit

1965 ◽  
Vol 21 ◽  
pp. 177-215
Author(s):  
Irwin Shapiro
Keyword(s):  
Time Delay ◽  
Astronomical Unit ◽  
Speed Of Light ◽  
Comprehensive Review ◽  
A Value ◽  
The Earth ◽  
Lincoln Laboratory ◽  
Data Yield ◽  
Shift Data

A comprehensive review is given of the Earth-Venus measurements made with the Lincoln Laboratory Millstone radar in 1959 and 1961. The time-delay and Doppler shift data yield a value for the Astronomical Unit of 499.0052 ± 0.001 light-sec. Using 299 792.5 km/s for the speed of light leads to an AU of 149 598 000 ± 300 km. With the radius of Earth taken as 6 378.15 km, the solar parallax then becomes 8″.79416 ± 0″.00002. This value is consistent with measurements made at various other laboratories to about one part in 105.

scholarly journals ON THE SPEED OF GRAVITY AND THE JUPITER/QUASAR MEASUREMENT

2004 ◽  
Vol 13 (09) ◽  
pp. 1753-1770 ◽  
Author(s):  
STUART SAMUEL
Keyword(s):  
Data Analysis ◽  
Time Delay ◽  
Speed Of Gravity ◽  
Delay Difference

I present the theory and analysis behind the experiment by Fomalont and Kopeikin involving Jupiter and quasar J0842+1845 that purported to measure the speed of gravity. The computation of the vJ/c correction to the gravitational time delay difference relevant to the experiment is derived, where vJ is the speed of Jupiter as measured from Earth. Since the vJ/c corrections are too small to have been measured in the Jupiter/quasar experiment, it is impossible that the speed of gravity was extracted from the data, and I explain what went wrong with the data analysis. Finally, mistakes are shown in papers by Fomalont and Kopeikin intended to rebut my work and the work of others.

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