Speed of Gravity?

You posted the following above:for the speed of gravity and for relativity were published in: “Experimental Repeal of the Speed Limit for Gravitational, Electrodynamic, and Quantum Field Interactions”, T. Van Flandern and J.P. Vigier, Found.Phys. 32(#7), 1031-1068 (2002). I don't recall seeing any front page news about it, do you?
There is zero data or proof in your writing but if it can be proven that the two centers 20" apart are real points it would be front page news according to USNO. Why no post the proof that this is real and not something from science fiction? The posting you have done here is not data either.

Jim,

I have some experience in doing astronomical calculations (by hand!), and I can confirm the 20" difference.

When calculating the position of the Sun, all of the tables of periodic terms give the <i>gravitational</i> position of the Sun, since it is gravity (the pull of the planets) that effects the position of the Sun.

Once you have the gravitational position of the Sun, though, you have to make corrections to obtain the <i>apparent</i> position of the Sun. Since the speed of light is finite, there is an ~8-minute delay between the time that the Sun is actually at a point in the sky and the time that observers on Earth see the Sun at that point. During those 8 minutes, the Earth moves, rotating on its axis and revolving in its orbit. Hence the apparent position of the Sun in the sky is not its actual instantaneous position.

This difference in position is the quantity called aberration. Aberration is the angular distance which separates the Sun's apparent position from its actual position. Aberration varies very slightly over time, because the Earth is not always exactly the same distance from the Sun and is not always moving at exactly the same speed, and there are even smaller variations over thousands of years due to the variation of the eccentricity of Earth's orbit. However, the aberration always stays close to 20.49".

When you calculate the position of the Sun, you first use tables of periodic terms to determine the Sun's gravitational position. Then you must calculate the aberration (~20.49") and subtract that from the Sun's gravitational position in order to get the Sun's apparent position.

You can find all of this in any book of astronomical formulae or mathematical astronomy theory.


Tom,

I've been told by one relativity supporter that general relativity can make the speed of gravity equal to the speed of light and still account for aberration. Do you know anything about this?


--Astro

Astro, I have no problem with the result you have posted above about the location of the sun and the fact that 8.3 minutes makes the sun appear 20" from where it is actually is. The question is where the GRAVITY is centered. If the gravity is focused at one center rather than the other(and I see no data indicating which point is the focus) then it speaks volumes about the topic. And by the way the gravity center has to be focused somewhere so the question is where.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Astrodelugeologist</i>
<br />I've been told by one relativity supporter that general relativity can make the speed of gravity equal to the speed of light and still account for aberration. Do you know anything about this?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It all depends on what that person thinks "the speed of gravity" means. Kopeikin (who did the Jupiter-quasar experiment) and even Nobel laureate Joe Taylor mistakenly thought that the expression meant the speed of gravitational waves, which certainly is the speed of light. But that has nothing to do with gravitational force. In fact, gravitational waves are not yet officially discovered, and no trace of one has ever been detected in our solar system.

This person probably has the same confusion. But if he doesn't, then he (or she) is quite mistaken. Any computer experiment will show that, if gravitational force is delayed by the same amount as light, planetary orbits become outward spirals. The Earth would double its distance from the Sun in just 1200 years.

As we say in our two published papers on this topic in Phys.Lett.A and Found.Phys., all six experiments that bear on the speed of gravitational force indicate strongly FTL speeds, and no experiment is consistent with speeds as slow as light within the experimental errors. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />Astro, I have no problem with the result you have posted above about the location of the sun and the fact that 8.3 minutes makes the sun appear 20" from where it is actually is. The question is where the GRAVITY is centered. If the gravity is focused at one center rather than the other(and I see no data indicating which point is the focus) then it speaks volumes about the topic. And by the way the gravity center has to be focused somewhere so the question is where.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I think you're confusing two unrelated issues here.

The solar system's center of gravity is not at Sun or at the Sun's apparent position 20" away. The center of gravity is another concept entirely. It's the point which all of the objects in the solar system (including the Sun) orbit. Naturally, the Sun's orbit around the center of gravity is very small; because the mass of the Sun is so great in proportion to the rest of the solar system, the center of gravity is very close to the Sun.

This is how extrasolar planets are detected--by the wobble of their parent star, which is the orbit of the star around the system's center of gravity.

The 20" displacement is an entirely different concept altogether. The Sun's position, determined gravitationally from tables of periodic terms, is a real, physical, observable point. If you could "teleport" to that location instantaneously, you would find the Sun there. The Sun's apparent position, determined observationally by detecting its electromagnetic radiation or calculated by correcting its gravitational position for aberration, is also an observable point. You can point to it and say, "That's where the Sun was eight minutes ago when it emitted the light we're seeing right now". The center of gravity, on the other hand, is a fictitious point; if you went there in a spaceship, you would find nothing but empty space.

--Astro

Astro, I understand what you are saying and I'm not confusing two points at all. The barycenter is yet another point in the model. I am not talking about models here but real stuff. The center of gravity is not at the barycenter as was decided several times on other threads and above if you care to look back there.