Speed of Gravitation

Recently reported [Eur. Phys. J. C., 77, 549 (2017)] gravitoelectromagnetic equations of Ummarino and Gallerati (UG) in their linearized version of General Relativity (GR) are shown to match with (a) our previously reported special relativistic Maxwellian Gravity equations in the non-relativistic limit and with (b) the non-relativistic equations derived here, when the speed of gravity c g (an undetermined parameter of the theory here) is set equal to c (the speed of light in vacuum). Seen in the light of our new results, the UG equations satisfy the Correspondence Principle (CP), while many other versions of linearized GR equations that are being (or may be) used to interpret the experimental data defy the CP. Such new findings assume significance and relevance in the contexts of recent detection of gravita-tional waves and the gravitomagnetic field of the spinning earth and their interpretations. Being well-founded and self-consistent, the equations may be of interest and useful to researchers exploring the phenomenology of gravitomagnetism, gravitational waves and the novel interplay of gravity with different states of matter in flat space-time like UG's interesting work on supercon-ductors in weak gravitational fields.

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A connected discussion of Absolute Physics and modern cosmology emphasizing gravitation and inertia, with concluding remarks on the rageful “spiritus mundi” that is said to stalk the World.

We have determined the relativistic light deflection of the quasar J0842+1835 as Jupiter passed within 3.7 arcminutes
on 2002 September 8, by measuring the time delay using the Very Long Baseline Array (VLBA) and
Effelsberg radio telescopes at 8.4 GHz. At closest approach, general relativity (GR) predicts a radial (static)
deflection of 1190 microarcseconds and a tangential (retarded due to the speed of gravity) deflection in the direction of Jupiter’s motion of 51 microarcseconds. Our
experiment achieved an rms position error of
< 10 microarcseconds and measured this retarded deflection to be 0.98+/-0.19 (rms error) times that predicted by GR. The increased positional accuracy for this VLBI phase-referencing
experiment was achieved by using two calibrator sources. Comments on the interpretation of this experiment
are given.

It is shown that the finite speed of gravity affects very long baseline interferometric observations of quasars
during the time of their line-of-sight close angular encounter with Jupiter. The next such event will take place
in 2002 September 8. The present Letter suggests a new experimental test of general relativity in which the effect
of the propagation of gravity can be directly measured by very long baseline interferometry as an excess time
delay in addition to the logarithmic Shapiro time delay.