# Talk:Speed of gravity

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## Definition

I read this, and found that Josh Gross had totally removed the content that had been there. I have put back, so information wouldn't be lost. (I hope I haven't stepped on Ben Baker's toes...) Having read the article in the external links section, it was clear Josh was confusing speed of gravity with the speed of gravity waves. (A distinction pointed out in the external link page).

What the heck is the speed of gravity supposed to be, so that we can quantify it at all? Asking because I don't know. --LMS

The speed of gravity is the speed at which changes in the location of an object propagate to all other objects that are affected by the gravity of that object. (essentially the rest of the universe) A gravity wave is a fluctuation in the gravity field around an object, as I understand it.

Why didn't you just put that in the article, if it's correct? :LMS

Okay, I will. but I don't want to get in between a battle between Josh and Ben...

Is the [citation needed] necessary on "Formally, c is a conversion factor for changing the unit of time to the unit of space.[citation needed]" That's a really fundamental way that c is used, and 'formally' already implies 'can be thought of as.' It has units of m/s and we're talking about 'formally.' No citation is needed for basic dimensional analysis. The discussion on this sentence should be about whether it should be in the opening paragraph or not, rather than if a citation can be found. 2/4/2011 Anonymous —Preceding unsigned comment added by 96.255.65.164 (talk) 18:42, 4 February 2011 (UTC)

"In a more physically correct sense, the "speed of gravity" refers to the speed of a gravitational wave." this statement seems problematic to me considering there is yet to be any supporting evidence proving the existence of gravitational waves.Norlesh (talk) 12:05, 19 August 2015 (UTC)

## Transmission

The changes in the location of an object are transmited by the interactions, graviational or electromagnetic. And for most anybody that is the speed of light.

I modified the article not removing the claims, but minimazing its importance (in my years of BS in physics, MS in Astronomy and PhD in Astronomy, never heard of this competing theories, except, I think to remember, as an historic thing). That doesn't by itself mean that it can not be correct, but it is far far away from mainstream science. --AN

## Van Flandern

Did you read Van Flandern's article ? I'd certainly like to see what flaws you detect in it. He seems to have thought about this a great deal. And yes, he does seem to address your concerns.

I don't think he agrees with you that those changes are transmitted by gravitational waves, nor electromagnetic waves.

I have left in the bit about a supernova, even though he argues they are irrelevant to this issue since the matter distribution from the explosion is symmetric.

Oh, we also need to decide if the link should be to gravitational wave or gravity wave. The article uses both, and they are presumably the same thing.

O.K. I read the article, and I found nothing obviously wrong, what doesn't mean there isn't. I removed the bit about SNe, because the author makes the distinction between gravitational waves (radiation) and the propagation of gravity, and accepts that propagation of radiation has speed c, so that will not prove anything. Still, this seems to be in the fringe of science, the site where the article is hosted has some other weird bits like the one about the "face" on Mars... It is clearly not the most accepted view, and apparently, not one that more that one person accepts. I don't see any of this published in Physics Reviews or any other peer refereed Jornal. This, again, doesn't mean by itself it is wrong, but it can be considered an instance of expert testimony. I will leave the article as it is now, but i'm not sure i want to leave the link in gravity. --AN

Does the electric field even propogate? from what I understand of it, electromagnetic waves broadcast changes in velocity, not position. If acceleration = 0, there are no waves produced, and thus no propogation. The way I found best to think of it was that the electric field does not propogate, it is like a structure, when it changes velocity, however, the relativity induced length expansion/contraction changes the form of the field, and that change needs to propogate out. Sort of like when you stop a car quickly, you get thrown forward because the message of a change in speed needs to reach your body. Not the best analogy, since it isn't exact, but it's what I could come up with. Would gravitational waves work differently? I don't know enough about general relativity to answer, but my gut says they work the same.

They're supposed to work the same. As for the general acceptance of Flandern's work, it didn't take long to find that at one point he was a poster on sci.physics.relativity - many people who disagree with relativity are - and like most of them did not much impress the various people there who actually know what they are talking about. The first thing that came up is this dejanews article and you are welcome to agree or to disagree with it, but all in all I think the evidence establishes the Flandern does not have any credibility with workers in the field, and his material has not been peer-reviewed. Permission to remove discussion of his material, from special relativity at least? --Josh Grosse

I've come into this discussion cold, but I find it very frustrating that y'all are discussing an article that someone keeps removing the link to. I finally found it after looking through ump-teen versions. (And if they had been purged, I would have had NO way to find it... Would people just leave this link here, for the next soul who has some interest in it ?

Sigh. Van Flandern has been refuted *many* times. Most notably by Steve Carlip (an expert in General Relativity, and one of the editors of Classical and Quantum Gravity, the leading journal in the field). His most recent rebuttal of van Flandern's nonsense is at

You can find tonnes more with a bit of searching: for example the Salon.com article

or Chris Hillman's excellent rebuttal

Frankly the idea of even having an article on the speed of gravity is a bit silly, at best it deserves a minor mention in a full article on general relativity. -M. Nobes

Comment: This ignores that Carlip's paper was challenged and critiqued in the referenced Foundations of Physics paper; the salon article was journalistic trash, as called out by readers in http://salon.com/people/letters/2001/07/23/hughes/index.html; and that "Hillman's excellent rebuttal" (even if he does say so himself) was oblivious to the entire issue being debated. Tomvf 03:00, 25 March 2006 (UTC)

_____

Well, the question comes down to: Is the speed of gravity c (as a limit), or instantaneous? That should be easy enough to determine experimentally, yet nobody has, that I know of.

Carlip expounding on Van Flandern I'll read, he's a genuine practictioner of this stuff.

Hillman, OTOH, is suspected to be a simulacrum constructed for the purpose of opposing and confounding the undergrads. He's purportedly been graduated from U.W. for something like three years now, hasn't announced gainful employment, which is a nasty state of affairs for most PhD's. If he doesn't announce something -- like a Job -- in the next year or two, I'm going to have to conclude that the 'computer construct' thesis is correct, and that Chris Hillman doesn't -- in human terms -- exist.

-- Stranger

What's with this gratuitous slam of Chris Hillman? He's a perfectly nice guy and has spent an inordinate amount of time arguing against the crazies on sci.relativity. He left academics after he got his Ph.D. which, as you may know, is allowed. I'm tempted to delete this comment. -- Walt Pohl 02:12, 19 Mar 2004 (UTC)

It doesn't matter whether he is or not, though I've been on the physics newsgroups many times and never saw any evidence of him opposing and confounding undergrads. What matter is whether his arguments are reasonable or not, since from what I can tell, he's made every possible appeal for people to learn the material and check the sources for themselves.

I expounded Van Flandern's argument, and why most physicists who look at it think it's wrong. It's really a subtle and interesting counterintuitive brain-twister. Also, I summarized the rebutals and moved them to the end. Also I removed the attributions to the rebutals since it smelled too much like argument from authority (journal editors have been known to be wrong and it's much more important to give a simple synopsis of *why* Van Flandern appears to be wrong).

I also added a reference to MOND since this is an interesting contrast between non-standard and crankish and non-standard and non-crankish.

### Removed this statement

It is well known that the speed of gravity can't be appreciably less than the speed of light, since that could be detected by changes in the angular momentum of the planets.

It's far from well known, and it's not obvious to me that it is even correct. If it's well known, then it should be easy to find a cite.

Moved the statement about gravity moving less than the speed of light to Van Flandern believes. I've thought about it, and that statement seems to be the very issue that Van Flandern seems to disagree with the scientific consensus. If the "speed of gravity" were small, it would

• not* necessarily violate angular momentum. If it *did* violate

angular momentum there would be a problem with gravity moving at the speed of light since even a small difference is in one direction and the angular momentum would build up and cause the planets to fly off.

This is precisely Van Flandern's argument that gravity moves instantaneously, and most scientists think that he is wrong precisely because they don't believe that finite speed of gravity implies non-conservation of angular momentum.

...Van Flandern does NOT argue that gravity moves instantaneously. He argues that it moves at >= 2x10^10 c.
Erikmartin (talk) 20:52, 19 August 2008 (UTC)

Where do I go to find the name of the author? And why should anyone have to run the maze with their mouse to find it? Sign the article. Although, in the case of "Speed of Gravity," I can see why the reluctance. Terrible writing, unsupported claims, etc., etc. Compare this to Van Flandern's clear, concise, experimentally supported claims. The fact that there is a universe of competent physicists who can reproduce his results does not exonerate the incompetent who cannot. Frederick George Wilson - "Samizdat"

## Gravitons

Just want to posit a thought or two here. Gravitons are one of the most elusive objectives in physics. Anyone ever find one? It seems apparent to me that there's something wrong in the way that we're looking for them, and I personally suspect that it's related to the four-dimension space-time continuum, which I think is probably a wrong -- well, actually insufficient -- construct. I'm not talking about the extra dimensions of, say, string theory, but rather, specifically, extra dimensions of time, and that perhaps time is a dimensional continuum other than, but interacting with, the spacial continuum. What this is all leading up to is that the "speed" of gravity could be simply not what we have assumed that it is; it may be involved with more dimensions of time (possibly less of space?). That would not make it necessarily "instantaneous" but could enable an apparent speed faster than that of light/emr. Food for thought, at least. --user:jaknouse

Where do I go to find the name of the author? And why should anyone have to run the maze with their mouse to find it? Sign the article. Although, in the case of "Speed of Gravity," I can see why the reluctance. Terrible writing, unsupported claims, etc., etc. Compare this to Van Flandern's clear, concise, experimentally supported claims. The fact that there is a universe of competent physicists who can reproduce his results does not exonerate the incompetent who cannot. Frederick George Wilson - "Samizdat"

Mecklen once said that there is always a

answer that is simple, clear, and wrong. Most every physicist I know of thinks that Von Flandern is just wrong. The problem is that it takes some effort to come up with a picture that explains exactly why he is wrong without a huge amount of mathematics. I've tried, but if the explanation doesn't make any sense, let me know. It's much easier if you have a blackboard.

Basically the answer is that its not the force that is delayed, its the potential.

Imagine a ball on a rubber sheet. Now imagine the ball moving. If the rubber sheet doesn't transmit the depression immediately, the indentation in the sheet will become distorted, and non-circular. Now look at the line of steepest descent of that indentation. It will point to where the ball is *now* not where the ball was earlier. -- User:Roadrunner

There is a link in each article called "history". Click on that and each edit ever made to the article, when they made and who made it is all there. This is how we "sign" our work. Welcome BTW. Somebody else will have to answer the other part of your statement. --mav
Most definitely the rubber sheet cannot transmit the depression immediately. In order to transmit the depression, the rubber sheet need distort its physical structure. It's known that massive objects cannot move instantly, nor even at the speed of light. Thus, there is no way that this depression could be transmitted immediately. For effect, place a ball on a surface of water. Now move the ball. You will immediately notice that the disruption of the water's surface is most definitely non-circular. The same follows for the ball on a rubber sheet, except the speed of sound is faster in a solid object than in a liquid object, so you're less likely to see the distortion, but that doesn't mean that it's there. (Why is it the speed of sound? Because you're exerting momentum to the rubber sheet, that momentum is then carried through the surface, the same as a sound wave. Only at a very very low Hertz) --Puellanivis 12:51, 16 November 2007 (UTC)

## Van Flandern

Whoa, geez, what's going on here guys? This is an ENCYLOPEDIA, not a science debating forum. I don't see the majority of the AIDS article taken up by discussions of the various people who claim its a bioweapon or that HIV doesn't cause it. By the same token, this HUGE section on Van Flandern certainly does NOT belong here, and I am moving it to a different article.

As to his theory specifically, I can't answer because I can't get to the article. *&%&^ surf-blocker software. However one way or the other the description of it here is either weong, or his "theory" is sophmoric. No one believes gravity propagates instantly, in fact, the belief that it does not is one of the best pieces of evidence FOR traditional GR! If Van Flandern's problem actually IS based on the claim that he thinks everyone else believes this, it can be dismissed out of hand.

jaknouse, I will write an article on gravitons for you.

I think it doesnt really matter whos right and wrong; More important that most views should at least have a mention, as to have a complete reference (on the term 'speed of gravity')

On reading some of the discussions above, it seems some the people who are dismissing Tom Van Flandern views have not read what he had to say properly.

It is the effect of a meme propagation that says: "Tom Van Flandern is a crank, so don't bother to read anything that he wrote and to try to actually understands his points, because I already did it for you and his papers are all wrong according to me and all relativists experts". It may take a hundread of years for people to recognize that gravity travels much faster than light (200.161.55.3 (talk) 03:27, 11 July 2008 (UTC))
While I don't mean to be at odds with anyone over this, surely you don't literally mean that it doesn't matter whether or not something is actually scientifically correct for it to be published here at Wikipedia? When you say "I think it doesnt really matter whos right and wrong" it's hard for me to take it another way, though. Moritheil (talk) 22:38, 1 May 2009 (UTC)

## on the definition of the speed of gravity

Constant, c, in Maxwell's theory has three different facets: (1) the speed of propagation of electromagnetic waves (light), c_l, (2) the constant linking electric and magnetic fields in Farady's law, c_{em}, (3) the coupling constant between electric current and magnetic field, c{m}, ( subscrpt m stands for Maxwell). These constants could be different, but the experiments prove they are equal to certain degree of accuracy. Thus, one uses a connotation c to denote these constants and call it "the speed of light".

Analogously, the constant, c, in Einstein's theory of relativity has three different facets: (1) the speed of propagation of gravitational waves, c_{gw}, (2) the constant linking gravito-electric and gravito-magnetic fields, c_{gem}, (3) the coupling constant between matter (stress-energy tensor) and gravitational field, c{e}, ( subscrpt e stands for Einstein). These constants could be different in arbitrary theory of gravity, but Einstein postulated that they are equal in General Relativity. I have used connotation c_g to denote these constant and call it "the speed of gravity" following the analogy with Maxwell's theory. General relativity has enormous predictive power to propose experiments in which various facets of c_g could be measured. VLBI experiment I have designed and conducted on September 8, 2002 along with Dr. Ed Fomalont from NRAO uncovered that c_g=c with 20%.

If an alternative theory of gravity rather than General Relativity is used the three facets of c_g are not united and each of c_g-s must be called by its own name. If such an alternative theory of gravity is used for interpretation of the experiment, the accuracy of our experiment sets the upper limit on c_{gem} only.

It is clear that "the speed of light" plays no role in the interpretation of the experiment. Critics of C. Will against my interpretation was based on the postulate that c_{gem}=c. From this he concluded that I and Fomalont measured the speed of light. That postulate is invalid from the first principles. It is our experiment that provides a direct test that c_{gem}=c under assumption that test particles move along geodesics which is described by the same equation as in General Relativity.

## Essay pasted here in apparent violation of WP:NOR

Hi Alfonso,

I don't believe that the talk pages of WP are an appropriate place to publish original research. Surely you can find some other website in which to publish these thoughts? linas 02:16, 5 December 2005 (UTC)

I agree with Linas (see next comment) and have moved this essay here. Alfonso, please don't do this again! TIA---CH 23:25, 24 December 2005 (UTC)
Note. User essay article was deleted in March 2007. - DVdm (talk) 19:34, 6 January 2012 (UTC)

## 02/28/05 version is awful

This article is terrible! The whole thing about electromagnetism has no place here. The article also doesn't really say that the idea "speed of gravity=speed of light" is extremely well accepted. It makes it sound like it's up in the air in the same way that, say "is the universe infinite?" is up in the air. And what's all that about Newton's philosophical problems and conservation of angular momentum? ugh.

(unsigned comment by 128.135.152.163)

I agree! I've done a bit of clean up, slightly improved the organization, added a todo list. ---CH 00:30, 28 February 2006 (UTC)

## Pseudoscience infobox

In the new version, I have used the infobox from Wikipedia:WikiProject Pseudoscience. This is specifically for pseudoscience, so I deliberately did not add a similar infobox regarding the Kopeikin controversy, which should at present perhaps be regarded as a legitimate controversy in mainstream physics, although I would agree with those who feel this characterization is becoming strained. As long as we link to Van Flandern's website, I think we can keep discussion to a minimum. In my view, this is the preferred option with all pseudoscience at WP: in case of controversies, describe the issue briefly and WP:NPOV and link to a few pro and con websites.---CH 00:41, 28 February 2006 (UTC)

## Should I provide a synopsis of Carlip's arguments against Van Flandern?

Hi, guys, I'm a Ph.D. student in physics at UC Davis (coincidentally Carlip taught my gen rel class!), and I was wondering if it would be good for this page to provide a nice summary of Carlip's arguments here. Here's a basic outline of what I'd write:

1. Simplification of Flandern's argument: gravitational position vs. opitical position of objects, and why it has to be the way Flandern describes it.

2. How one can see that this instant location doesn't actually give us any new information about the object: information is not propagating faster than the speed of light.

3. Explain how when one does the calculations properly, including the velocity terms in the metric, one finds that the gravitational position is indeed not exactly the instantaneous position, but rather a position extrapolated from the velocity and acceleration that was there when the gravitons were emitted.

4. Reiterate why one expects the above result.

Anyway, I'll probably throw it together in a week or two, and if anybody else thinks it'd be a good idea, I'll post it. What I have above would include no more than what people could already glean from looking at Carlip's rebuttal linked in the page. ---Jason Dick 08:33, 2 March 2006 (UTC)

Hi, Jason. I think this summary would be useful, but maybe not at WP.
I have experimented with a number of strategies for dealing with cranks at WP, including
1. proposing to delete articles outright,
2. trying to negotiate with cranks regarding detailed arguments,
3. (most recently): agreeing to keep "notable crank" articles, but trying to persuade those pushing/opposing a controversial POV to shove detailed arguments off onto personal websites, anti-crank websites, etc.
My concern in this case is that if you put in this overview in this article, you will simply awaken Van Flandern's many devoted fans, who can cause a lot of grief simply by persistence in edit wars. AFAIK, TVF has actually been much less noisy in recent years, which would be a welcome development.
However, it would be useful to have both my very long compendium of Carlip's posts addressing TVF over many years, and your summary. I am currently considering a revision of Relativity on the World Wide Web. If you create the summary in your own user space and give me permission, I will include this in the new RWWW. ---CH 18:35, 3 March 2006 (UTC)

Wikipedia should provide all points of view which are notable.Just label it pseudoscience or alternative views.I would like to see sceptic and detractors full arguments for values of speed of gravity and not a brief summary: speed of gravity=C,proof abcd,the end.

## Improved citations

I have formatted the citations using standard Wikipedia citation templates.

User:Kopeikins changed Kopeikin continues to vigorously argue his case to Kopeikin continues to vigorously argue this case through publications in peer review physics journals. I reverted this because that change was awkward, and the apparent point (that Kopeikin has continued to publish rebuttals to his critics in respectable research journals) is now clear without further comment from the formatted citations.

However, as I feared would happen, the list of citations regarding the Kopeikin controversy is growing too long. This is an encyclopedia article, not a review article! User:Kopeikins, I assume you are Sergei Kopeikin. Can you propose below a pruned list which would be acceptable to you? Note that Clifford Will's web page seems to have a comprehensive list of papers on this issue. If you put up your own website, I can add that to the external links. I feel there should only be one or two pro and con papers listed as references on this issue.---CH 13:46, 10 March 2006 (UTC)

Reference to Samuel was the wrong "Samuel". I corrected this. Also clarified what the work in PhysRevLett.90.231101 says based on its abstract.--- December 11, 2013. — Preceding unsigned comment added by Drscientific (talkcontribs) 22:00, 11 December 2013 (UTC)

## Description of Kopeikin controversy

I had written in the article that the current mainstream view is that Kopkeikin has simply misinterpreted Fomalont's results. I feel this characterization is amply borne out by the citations listed in the article.

However, it seems that even this mild statement was too controversial for one editor. So I have removed all description of the nature of the arguments pro and con and simply the interested reader to the citations. If the editor in question disagrees, I hope he will make his case on this talk page (and address my concern about a direct participant in the controversy apparently editing an encyclopedia article describing this controversy). TIA---CH 19:46, 15 March 2006 (UTC)

Kopkeikin = Kopeikin (avoid misspelling). Kopeikin and Fomalont formed and still form a single team, so that Kopeikin could not misinterpret the results of Fomalont or vice versa - they proposed the experiment, did observations, processed the data, and analyzed them together. Please, do not break the team. This confuses the readers. Best regards. Sergei Kopeikin TIA---CH 19:26, 16 March 2006 (UTC)

Er, in my sig [[User:Hillman|CH]], the "CH" represents my initials, not wikicode :-/ To sign your user name, you need only write ~~~~ (four tildes) at the end of your comment. When you save the edit, your user name and a time stamp will appear automatically, something like User:Kopeikins 19:26, 16 March 2006 (UTC). If you wrote [[User:Kopeikins|Sergei]] it will look like Sergei (no time stamp, just an internal link to your user page). You can modify your User Preferences page to give yourself a "nickname" in signatures. See this and this for more hints.
(My chronic misspelling: sorry about that, I seem to find your name difficult. I'll try not to do it again.)
You wrote Kopeikin and Fomalont formed and still form a single team, so that Kopeikin could not misinterpret the results of Fomalont . This conclusion is patently disingenous. The issue is whether the observations have been interpreted correctly in various papers by yourself. Some but not all of the "pro" papers also had contributions from coauthors, but it seems to me that yours is the only name which is on all of the "pro" papers. This (plus laziness) probably explains why I wrote Kopeikin claims rather than Kopeikin-Fomalont claims, but I wouldn't have any objection to making this change.
As far as I can tell, Will is correct when he states (on his website) that the mainstream view about the controversy is that the observations in question have not been correctly interpreted. At this point I assume that you agree that this is indeed the mainstream view, but not (obviously) that the mainstream view is valid. If so, I think the article currently expresses this. In any case, I think WP readers (of the article) should not be mislead either way about the current scientific status of the Kopeikin/Fomalont claims, and that's what I am concerned to avoid.
Again, I stress that so far I do think that your edits to the article have been fairly restrained--- I really hope you will keep it that way! Again, the point is that since you are editing an encyclopedia article on a controversy in which you are direct participant, most Wikipedians would probably feel that you bear a special version to be very judicious in any changes you make, to avoid any appearance of POV pushing. (This kind of thing has proven to be real problem in other cases, which explains why I am acting so concerned, so forgive me if it seems you are suffering as a result of the prior misbehavior of other users. I think you're still fairly new to WP; once you've been here for a while you will appreciate better why users can behave proactively at times.)
If you feel that something in the article is factually inaccurate or imbalanced, e.g. slanted too heavily against your interpretation of the observations (I am assuming that you are indeed the same Sergei Kopeikin at the center of the controversy, of course), I would prefer that rather than editing the article yourself, you express such concerns here in this talk page. I expect that other users, who are hopefully neutral but who may feel you have made a good case in this talk page, would then be happy to try to promptly adjust the article itself. This would be preferable because one can hope that editors of the article itself will be reasonably neutral. I think this approach will work best for everyone concerned.---CH 10:14, 18 March 2006 (UTC)

## Edits by anon 24.113.28.179

The anon from Kirkland

1. removed the expert flag
2. Added to In mathematical physics, particularly in the context of classical theories of gravitation, the speed of gravity refers to the speed at which gravitational radiation propagates. This is the speed at which news or field updating information is propagated as a wave. the sentence
• However, in common parlance, the speed of gravity refers to the speed at which gravitational force propagates, where force retains its classical meaning of the time rate of change of 3-space momentum. This meaning is used, for example, in orbital dynamics even in a relativistic context, where one must work in 3-space plus time (as opposed to Minkowski 4-space) to compare theory with observations.
3. Added to If no other theory is specified, it is generally understood that the theory in question is our current gold standard theory of gravitation, namely general relativity. the sentences
• Relativists then tend to assume that the speed of gravity is the speed of gravitational waves, which is undisputedly the speed of light. By contrast, dynamicists and laypersons tend to assume that the speed of gravity is the speed of gravitational force, which is approximated as infinite (no retardation of sources) in both Newtonian gravity and in general relativity. That is why the latter can reduce to the former for weak-field, low-velocity cases, such as most of those encountered in astronomy. For such practical applications, gravitational radiation (aka gravitational waves) rarely needs any consideration, and it has yet to be detected (directly or indirectly) anywhere in our solar system.
4. Made further changes which I at least would regard as contradicting mainstream scientific views, and thus as controversial POV-pushing; see this.

These are characteristic of Van Flandern's views, as such are regarded as controversial. Such changes should be discussed on the talk page rather than simply executed in defiance of Wikipedia custom.

However, I lack energy for an edit war, particularly with the TVF crowd, so I'll have to leave it to others to argue about this, if they wish. I just wanted to point out the problem. ---CH 21:45, 19 March 2006 (UTC)

Added 3/21 by T. Van Flandern: The changes referenced above were approved by me before posting. They deal mostly with the definition of the term speed of gravity. It meant the speed at which gravitational force propagates long before the concepts of gravitational fields or gravitational waves were conceived, and it still means that today to most people. To not understand that two different meanings are in use is to not understand the controversy, much less its resolution. No one disputes that the speed of gravitational radiation is the speed of light. But it has nothing to do with ordinary gravitational force either, and in fact has never been detected in any form in the solar system. This article is not about that concept. It is about the speed at which changes in the relative position of a source mass begin to affect the (3-space) acceleration of the target body. And as theory, observations, and simple computer experiments unambiguously show, that speed cannot possibly be as slow as the speed of light because that would destroy angular momentum conservation and turn elliptical orbits into outward spirals. Tomvf 21:10, 21 March 2006 (UTC)

Definitions can be abused. If something is disputed in the scientific community, it should not be presented as fact on Wikipedia, eh? - mako 01:28, 24 March 2006 (UTC)
Reverted back per WP:NOR. --EMS | Talk 05:06, 24 March 2006 (UTC)

WP:NOR states: "Articles may not contain any unpublished theories, data, statements, concepts, arguments, analyses or ideas; nor may they promote any novel synthesis of published material, without a verifiable source." So the reversion was in defiance of those criteria, not in accord with them. Everything I said above meets those requirements and appears in the Van Flandern-Vigier 2002 paper in Foundations of Physics -- the last word on this subject in any official forum. Grousing by those with contrary personal views that cannot meet journalistic requirements for publication, and apparently cannot even be articulated here, should not dictate content of Wikipedia articles. Tomvf 03:00, 25 March 2006 (UTC)

IMO, there is a more relevant part of WP:NOR that applies here. From the section "Disputes over how established a view is":
• If a viewpoint is in the majority, then it should be easy to substantiate it with reference to commonly accepted reference texts;
• If a viewpoint is held by a significant minority, then it should be easy to name prominent adherents;
• If a viewpoint is held by an extremely small (or vastly limited) minority, it doesn't belong in Wikipedia (except perhaps in some ancillary article) regardless of whether it's true or not; and regardless of whether you can prove it or not. [bolding is mine].
I don't see that Tomvf's edits meet either of the first two tests. Instead, as best I can tell, his views fall into the later category of being "an extremely small (or vastly limited) minority". To make matters worse, his reference is to an article that he has co-authored, which raises issues involving WP:AUTO and WP:NPOV. The point is that Tom Van Flandern cannot be expected to be neutral about the work of Tom Van Flandern. Finally, WP:CITE calls for the use of both primary and secondary sources. Even allowing the Van Flandern-Vigier 2002 paper in Foundations of Physics as a permisible primary source, there is no body of other articles which comment on and/or expand on that work. Without those, the conclusion must be that this work is of extremely limited interest, and is therefore inappropriate to cite as an authoritative work on this subject. --EMS | Talk 04:25, 25 March 2006 (UTC)
:::: In the reference list we have: "Farrell, John (2006), “Was Einstein a fake?”, Cosmos 11, <http://www.cosmosmagazine.com/node/1162> . This article includes some blunt assessments from relativity experts. Steve Carlip says: "As far as I can tell, Van Flandern simply doesn't understand the Einstein field equations." Flandern does not accept this assessment."

I wonder why put this Steve Carlip's personal opnion about what TVF does or does not understand. This is absurd and out of context. The published peer reviewed articles by TVF are there for anyone who wants to check them. Let's not transform wikipedia in a kind of brainwashing. People does not need to find such a personal biased opnion in a wikipedia article. It seems to be a flagrant tentative of ridicuralize TVF's work and to tell the reader that he/she should not bother reading his material. Also, TVF's 1998 paper should be cited in the reference list because that paper is one of the few papers that deals specifically with the very issue this entry is proposed to deal. (EPLeite 19:15, 10 July 2008 (UTC))

The first two criteria from WP:NOR seem more relevant to me: • “By insisting that only facts, assertions, theories, ideas, claims, opinions, and arguments that have already been published by a reputable publisher may be published in Wikipedia, the no-original-research and verifiability policies reinforce one another. The threshold for inclusion in Wikipedia is verifiability, not truth.” COMMENT: The cited set of published papers on this subject from 1994 forward in Astrophysics & Space Science, Physics Letters A, and Foundations of Physics certainly constitute verifiability for the point of view recently added to the article. The reversions attempt to take away some of this verifiability. And as the criterion states, verifiability is more important than trying to establish “truth”. • “The prohibition against original research limits the possibility of an editor presenting his or her own point of view in an article. Moreover, by reinforcing the importance of including verifiable research produced by others, this policy promotes the inclusion of multiple points of view in an article. Consequently, this policy reinforces our neutral point of view policy.” COMMENT: The Wikipedia article called for assistance from experts. Experts are all presumably people who have published on the subject in reputable, peer-reviewed journals. I feel certain it was not the intent of this “neutrality” paragraph to exclude comments from any experts who have ever published on the subject because they are “not neutral”. When I reviewed and commented on the previous Wikipedia text shown to me from the main article, I insisted that the other points of view expressed there remain intact, which they still are. I simply assisted with adding the point of view expressed in some of the most recent journal articles since 1994. EMS and Mako098765 appear to be advocating a non-neutral point of view by reversions to a previous, very one-sided article that does not present the current viewpoint in these papers.

EMS says: “Even allowing the Van Flandern-Vigier 2002 paper in Foundations of Physics as a permissible primary source, there is no body of other articles which comment on and/or expand on that work.” COMMENT: This puts the cart before the horse. The sequence of journal publications is presented just below, and the list is not inflated with the citations therein dealing with the eight major relevant experiments. The Van Flandern-Vigier 2002 article comments and expands on those previous papers, and deals definitively with every objection yet raised by anyone. The final reference is a recent 20-author book that carries on the work into many new areas of applicability.

• Van Flandern, T. (1996). "Possible new properties of gravity". Astrophys. & Space Sci. 244: 249–261.
• Van Flandern, T. (1998). "The speed of gravity – What the experiments say". Phys. Lett. A. 250: 1–11.
• Marsch, G.E. & Nissim-Sabat, C. (1999). "Comments on 'The speed of gravity'". Phys. Lett. A. 262: 103–106.
• Van Flandern, T. (1999). "Reply to comments on 'The speed of gravity'". Phys. Lett. A. 262: 261–263.
• Carlip, S. (2000). "Aberration and the Speed of Gravity". Phys. Lett. A. 267: 81–87.
• Van Flandern, T. & Vigier, J.P. (2002). "Experimental Repeal of the Speed Limit for Gravitational, Electrodynamic, and Quantum Field Interactions". Phys. Lett. A. 32: 1031–1068.
• Edwards, M., ed. (2002). Pushing Gravity: new perspectives on Le Sage’s theory of gravitation. Apeiron Press. pp. 93–128. Unknown parameter |city= ignored (help)

EMS says: “I don't see that Tomvf's edits meet either of the first two tests [for an established point of view]. Instead, as best I can tell, his views fall into the later category of being "an extremely small (or vastly limited) minority". COMMENT: That opinion is analogous to polling only Republicans to determine Bush’s favorability rating. Among relativists, the point of view I expressed in those journal articles is still a minority viewpoint. But very few dynamical astronomers (my own field) would find any statements in my articles to disagree with. And ultimately, the “speed of gravity” (meaning the propagation speed of gravitational force) is the main “meat and potatoes” of dynamical astronomy. But it is merely a sideline for relativists, many of whom have never ventured beyond the field equations and their solutions (where only the speed of light enters) into the dynamical equations of motion (expressions for gravitational 3-space acceleration) where the propagation speed of gravitational force is crucial. I would cite R. Moulton, Brouwer & Clemence, Danby, Szebehely, or any major celestial mechanics or orbit theory textbook to see that gravitational force in a relativistic context must be taken as near-instantaneous, or the orbits become spirals. These will also show the equations of motion (as do Misner, Thorne & Wheeler on p. 1095 of “Gravitation”), where anyone can, by inspection, see that they contain no propagation delay terms and nothing traveling at the speed of light.

So there is no question that the viewpoint I expressed is an established one. The cited papers show that much. Opinion polls about whether or not it is the correct viewpoint are irrelevant to whether the viewpoint is an established one now under widespread consideration by scientists all over the world, as my daily inbox continually reminds me. Yet no one has raised any new objection not already refuted by our 2002 paper. Tomvf 08:40, 25 March 2006 (UTC)

The problem is that you've placed your minority view front and center, starting with the introduction. You've injected material into the general relativity section that is not consistent with what GTR theorists are saying. You say you are not a relativist, so why do you modify that section? We have separate sections in order to partition the page between the various theories. - mako 09:49, 25 March 2006 (UTC)
As I explained, it is only "a minority view" among relativists, but not dynamicists. And the subject here, the propagation speed of gravitational force, is the province of dynamicists, not relativists. Relativists study the gravitational field, usually to the exclusion of gravitational force; and they use the speed of gravitational waves (disturbances of the gravitational potential field), which is clearly the speed of light. But because gravitational waves have nothing to do with ordinary gravitational force, their speed is not what either dynamicists or laypersons mean by the speed of gravity.
As for the introduction, it seems neutral and balanced to me because not even relativists (at least those who are familiar with this issue and have read the papers) can claim there is anything factually incorrect there, and it points out the dual usage of the term by the respective fields. Which particular point or points are causing you difficulty? Tomvf 18:50, 25 March 2006 (UTC)
For one, terms like relativists and dynamicists seem to be neologisms. (I assume that dynamicists are those who share your views.) My main objection to the introduction is the tone. I'll make some changes to the article and await your comments. - mako 23:36, 25 March 2006 (UTC)
"Dynamicists" are most of the members of the American Astronomical Society's "Division on Dynamical Astronomy" and their international colleagues, as well as most of the authors publishing in the journal "Celestial Mechanics and Dynamical Astronomy", and most people employed in aeordynamics who work on orbits. That you don't already know this is a problem here, and would seem on its face to make you unqualified to edit this article, which is mainly the province of dynamicists and not relativists. I am thoroughly familiar with both the dynamicist and the relativist points of view, and probably meet most objective criteria to be called either one professionally, which qualifies me to at least try to write a balanced article. By contrast, you seem to think I'm presenting a personal or extreme minority viewpoint because of your complete unfamiliarity with astrodynamics, which apparently causes you take a one-sided and somewhat extremist position of your own on the issues we are discussing.
I simplified the introduction and removed your interjections from the general relativity section, as they are not mainstream views. I moved some to the 'superluminal gravity' section, but had to leave some out for lack of context. You can expand that section, keeping WP:AUTO and WP:NPOV in mind. I hope this partitioned approach makes sense to you. - mako 01:09, 26 March 2006 (UTC)
Well, I liked the idea that you objected mainly to the tone and planned to reword things to be more balanced. But what you actually did was change the substance of the article to your personal, extremist position and make it not just unbalanced, but demonstrably wrong on several key points. These points you tried to advocate were falsified in the most recent (2002) and complete journal publication on this subject -- ironically, the main one you omitted from the bibliography.
I should probably insist that the Wikipedia article be in accord with the publications, because I can provide observations, experiments, argumentation, and citations for the key points and you mostly cannot. But I'd much rather we reached some sort of agreement here. So I have a suggestion. I recommend you read the 2002 Van Flandern-Vigier article in Foundations of Physics 32, 1031-1068, making notes of any important points you don't understand or think may be wrong. (If you don't have access to the journal, drop me an email and I'll email you back with an MS Word or PDF version.) That way, you will be up-to-speed on the issues and what is published in the journals these days. We can then discuss those points of dispute -- here, off-line, over coffee, or in any venue you like. I don't even mind appearing before a hostile crowd of old-time relativists. You and companions can show me my errors. With what's left, we don't need to agree on which view is right, but only how to word a balanced presentation of both viewpoints, as long as both are "verifiable" by Wikipedia's definition.
I'll await your response to this before proposing what we should do with the article while working through these issues. Otherwise, I fear we are probably headed for a Wikipedia management intervention that will probably not make either of us happy, or possibly to two different articles (relativist version and dynamicist version) that reference one another. Tomvf 02:00, 26 March 2006 (UTC)
It's a mistake to call this my personal, extremist position. I'm not here to debate the merits of your theory, and talk pages are not for that either; you yourself agree that a balanced article is the ultimate objective. However, given that your theory is a minority view, it does not merit equal attention and standing, and there is no reason why the overall article should focus on it. And POV forks are not acceptable.
You say that the current article is "demonstrably wrong on several key points". Care to elaborate? - mako 07:56, 26 March 2006 (UTC)
I cannot abide by the current edits and will revert them back. They admit as important a claim that as best I can tell falls under the "small enough minority" criteria, and I am going to rest on that.
With respect to bias: I will not claim to be unbiased in this matter at all. What I am biased to towards is a fair exposition of the mainstream viewpoint and of any significant minority viewpoints. My understanding of the situation is that general relativity works fine with the speed of gravity being finite, in part because GR lacks a global conservation of energy/momentum, and in part because the gravitational field can hold energy/momentum of its own (as gravitational waves). In any case, there is no need in general relativity for any object to respond to events outside of its light-cone, and Tom Van Flandern suggests.
Beyond that, TomVF's references need to be checked out, especially the two by Carlip and Marsch. I would not be surprised to find that they are less than complimentary of of TomVF's work.
Mako098765 - Please be advised that it is normal for people like TomVF to seek to redefine the purpose and focus of Wikipedia to suit their own needs, and to hold up publications records that often are even more limited that TomVF's as "proof" of the acceptability of their views. Lacking any backing from other editors, people like Tom need to be held at bay, and their views not allowed to be given an inappropriate importance in Wikipedia. To do so simply would not be encyclopedic. So I am going to hold the line here, and ask that you do the same. If this keeps up, there are tools that can be used to rule on disputes like that, such as WP:RfC and WP:RfAr. --EMS | Talk 04:03, 26 March 2006 (UTC)
I have also removed the added part on "superluminal gravity". (I missed that before.) Let's just say that if something is not worth mentioning, then it is just plain is not worth mentioning. That section was just a pie-in-the-face, and not NPOV at all. --EMS | Talk 04:13, 26 March 2006 (UTC)

[mak]:[EMS]: Lacking any backing from other editors, people like Tom need to be held at bay, and their views not allowed to be given an inappropriate importance in Wikipedia. [Tomvf]: I see that the gloves are off and all pretense to neutrality is gone.

[mak]: given that your theory is a minority view, it does not merit equal attention and standing, and there is no reason why the overall article should focus on it. [EMS]: I cannot abide by the current edits and will revert them back. They admit as important a claim that as best I can tell falls under the "small enough minority" criteria, and I am going to rest on that. [Tomvf]: EMS wasn’t paying attention and overwrote mak’s edits, not mine. I don’t have any “theory” here, just a published POV about the physical interpretation of general relativity. And Wikipedia does not require a majority, but does insist that editors be neutral and respectful. Ignoring what is said here in Talk, as both of you have done (especially about your “minority” claims) is not in accord with Wiki guidelines for dispute resolution.

[mak]: You say that the current article is "demonstrably wrong on several key points". Care to elaborate? [Tomvf]: That would be more courtesy than you have yet to extent to my edits; but I will nonetheless mention a few specifics:

• “the slowly evolving ‘Coulomb component’ of the gravitational field can not transfer information about position of the source of the gravitational field with the speed faster than the speed of light.” Comment. That is contrary to the fundamental reason why this issue exists in the first place. In both astronomical experiments and in computer simulations, target bodies in a gravitational field must accelerate toward the true, instantaneous positions of a source mass even when the source mass accelerates. The light-time-retarded position or even the extrapolated retarded position one light-time ahead is entirely insufficient to give closed orbits. Once you discover this basic fact that dynamicists, celestial mechanisms, many astronomers, and all relativists in the know (including Steve Carlip) are aware of, you will for the first time begin to appreciate why the old position of relativists (that gravity simply propagates at the speed of light, no qualifiers needed) is no longer viable.
• “This finite speed of gravitational interaction in general relativity may at first seem to lead to exactly the same sorts of problems with aberration of gravity … one can show that general relativity does not suffer from these problems…” Comment: No such showing is possible with respect to the speed of gravitational interactions. To get around the aforementioned difficulty, Carlip had to postulate a new, velocity-dependent force to cancel aberration. And even that doesn’t work for all cases, as our refutation of Carlip shows. Retarded Lienard-Wiechert potential theory is also addressed in the papers, and applies only to the fields, but not to the resulting field gradients or forces for moving target bodies, which have no such retardation.
• “It is not very easy to construct a self-consistent gravity theory in which gravitational interaction propagates at a speed other than the speed of light” Comment. General relativity already has instantaneous gravitational interaction built in. If you doubt it, please see the derivation in our 2002 paper, or point to the retardation term in the GR equations of motion shown on p. 1095 of MTW.
• General comment. Your editing makes no sense unless gravitational radiation has something to do with gravitational interactions. But this is not the case. Please carefully note these three points: (1) When I walk into a room, a gravimeter can track changes in the gravitational acceleration I produce. These are not gravitational waves being detected. No evidence for gravitational waves anywhere in the solar system has yet been detected. (2) The GR equations of motion are expressions for accelerations of bodies as a function of location, velocity, and potential. As such, they describe changes in acceleration through second order in potential or fourth order in velocity, which covers about 16 digits of precision for solar system applications. There is plenty of gravitational acceleration and changes in acceleration but no gravitational wave component in these equations. (3) In a static potential field, an orbiting test body is continually changing its acceleration. We can easily measure these changes. Yet no gravitational waves exist in this scenario. Conclusion: Gravitational waves have nothing to do with ordinary gravitational acceleration or with changes therein. They were not even part of general relativity as Einstein originally presented it.

[mak]: And POV forks are not acceptable. [Tomvf]: In that case, we are obligated to do a better job of representing both viewpoints fairly. The rules clearly state that you can’t just engage in a reversion war to suppress a frequently discussed and published POV that is not to your liking.

[EMS]: My understanding of the situation is that general relativity works fine with the speed of gravity being finite, in part because GR lacks a global conservation of energy/momentum, and in part because the gravitational field can hold energy/momentum of its own (as gravitational waves). In any case, there is no need in general relativity for any object to respond to events outside of its light-cone, and Tom Van Flandern suggests. [Tomvf]: Need or not, objects do respond to positions that won’t become visible until one light-time into the future. Look at it this way: Light and gravity from the Sun travel from the same source to the same target along the same linear path, yet arrive at Earth from different directions on the sky. (They differ by the angle of aberration, which is 20 arc seconds for retarded light and zero for gravitational force/acceleration.) Gravity affects us now from a position that it outside the light-cone. Your understanding is incorrect. Tomvf 09:45, 26 March 2006 (UTC)

To Tomvf - I will give you credit for both a throughful respose and more importantly for not persuing an edit war. You seem to be much more cooperative than the average POV-pusher. However, I will hold to my position at this time. I still have no reason to believe that your views have any serious following in the scientific community (or amongst relativists in particular). If I should find that the group the you call "dynamicists" is of a substantial size and that your views are widely supported by them, then I certainly will change my tune regarding whether your views on the speed of gravity are encyclopdic. I may be operating from a pro-relativity POV, but in Wikipedia I understand that my job is to enhance this encyclopedia and not to blindly push relativity or unfairly censor alternate views.
Let me put it to you this way: Ideas should not be presented in Wikipedia if they are not getting attention elsewhere. However, given some ongoing currency in either scientific or lay circles for your ideas, then it become incumbent on Wikipedia to report it. (So the "it doesn't matter if you are right" business is a two-edged sword, since if the idea is controversial enough then it must be reported on even if it is dead wrong.) Beyond that, there is the issue of how this should be reported on if it is mentioned here. IMO, the lack of acceptance in the scientific community must be mentioned, but I don't want to see your views slammed as simple "pseudoscience" either. (Being right is not a prerequisite for doing a scientific investigation. However, blind dogmatism is not science either.) --EMS | Talk 03:29, 27 March 2006 (UTC)
To EMS - I also appreciate your tone of moderation. If we work at it, I'm sure we can reach a resolution. And I have no problem at all with true statements such as that the viewpoint in my papers is still not widely known or accepted in the relativity community. But new ideas are normally slow to catch on unless something dramatic happens, such as the historic 1833 meteor storm over the Eastern U.S., which literally overnight disposed of the entrenched mainstream paradigm that rocks cannot fall from the sky. Here, I have no carrot to get relativists to read the published papers on this, the arguments in which would seem likely to bring about similar overnight change, as judged by reports in my inbox from many who have read the papers. And unlike what happened after my 1998 and 2000 papers in PLA, when many relativists wrote me and the journals with objections, no new objections have arisen in nearly four years now.
So what should be the next step? Should I rally the troops and get people to email you or put comments in this Talk so you can see these views are not isolated? Shall I prepare a collection of comments from my inbox? Your comments make it seem that numbers are more important than quality of evidence, the reverse of the usual situation in science. Or are there any important issues that still need clarification, or where you need to check with other relativists to see if any problems do exist with this new perspective? Please advise on how to proceed. Tomvf 08:30, 28 March 2006 (UTC)
You must realize that Wikipedia is not a soapbox. Most scientists do not appear to support your assertions (I was indeed wrong to call it a theory), regardless of whether they have raised objections of late, and regardless of how strong you feel your evidence is. Therefore at this point, your views on this matter cannot take center stage in this article. If you can accept that, we basically come to a resolution. But if you insist on having your views be the focus of the article, you first need to, quite frankly, have prominent members of the scientific community speak out in support.
Speaking to your comments above, your edits were flagged as questionable by Chris Hillman, so the onus is on you to defend them. Your objections to the original article seem to be, pretty much, what is contained in your papers. So it's the same problem.
The statement at the top of this section was misattributed to me; I have fixed it. As I have midterms coming up, I do not have time to be active in this debate. Hopefully you and EMS can come to terms. - mako 01:41, 29 March 2006 (UTC)
Tom - I must second mak's comment above about Wikipedia not being a soapbox. I know that you have supporters. I also know that they are a small but vocal group, and that you and they are not very much respected in the scientific community as a whole. In fact, you seem to tread near the line which separated science from pseudoscience, but see that questions you ask as being valid even if I join many others in dismissing the answers you give them.
If your ideas are to be mentioned, it will be in a section on "alternate views" at the end of the article, and the mention will be short, sweet, and respectable; but also firm on how your ideas stand in the view of the mainstream of physics. I will not permit your ideas to be labelled "pseudoscience" here, but am willing to support documentation of its being labelled that way elsewhere. (Wikipedia cannot by its own rules act as a primary or secondary source, but can be quite liberal in reporting on such sources.) For now, I ask you to be patient and not to expect too much from me. I need to get a better sense of how significant the awareness of your concepts is. --EMS | Talk 05:55, 29 March 2006 (UTC)

## Mentioning Tom Van Flandern's work

I now have an opinion on whether Tomvf's work is encyclopedic. Overall, it is. So the issue now is to fit it into this article in an appropriate manner. My sense right now is to let Tom propose either here or (preferably) in his user space (for example by starting the article User:Tom Van Flandern/speed of gravity edit) how he wants his work in this area to be described, and then I will add in the refutation and note that it is the view held by mainstream theorists. I kindly request this this be kept to a paragraph or two at most. (Note that it is fair to reference one's web site in this context.) In any case, the goal will be to at least semi-refine the wording and get it into this article ASAP. --EMS | Talk 04:25, 30 March 2006 (UTC)

I'm very new to Wiki and don't fully understand the procedures you describe. I also will be away for much of the coming week, with uncertain access to Wiki during that time. But I will try to work with you on this as my time permits. Questions: (1) Are you associated with Wikipedia in any formal capacity, or are we on an equal level as editors even if very unequal in experience with Wiki, its style and goals? (2) In the various referenced publications, a dozen referees tried through several rounds to find a "refutation" of these ideas without success. Each would-be refutation was easily rebutted to the satisfaction of neutral editors. So why should the refutation you propose be the final word here? If a rebuttal exists, it should be added too, shouldn't it? (3) In the hope of simplifying this task for both of us, but at the risk of complicating it, may I point out that a biographical entry already exists for me at Tom Van Flandern?
I have no idea who started this biography, but it was the first place where I was asked to comment on Wiki entries, and it contains material similar to what you requested on the "speed of gravity" subject. (In any representative biography, that material would not play a large, much less exclusive, roll.) I therefore suggst that, as a first approximation to the task you assigned me, we take over the material in that biography on the "speed of gravity" (which is most of it), along with the existing rebuttals and counter-rebuttals. We then have a condensed representation of views on both sides, which we can use as a first draft here for the purpose you propose. The vacated biography can then just reference my resume and bibliography at the Meta Research web site. Does that work for you? Tomvf 07:48, 30 March 2006 (UTC)
If you are happy to let me work off of the Tom Van Flandern article, then I am happy to do so. Do note that I want the discussion of your views to be relatively short, but to also portray as accurately as possible what you are proposing. The same for the description of the rebuttals. (Note that the details of your ideas and of the rebuttals may be found in other web sites and publications.) Also please be aware that it is the opinion of relativists in general it is you that has failed to make your case, not them. Your personal refusal to accept the presented refutations does not mean that others are not satisfied with them. The bottom line is the goal of Wikipedia is to document current human knowledge. So the issue for an article like this one is not what is correct, but rather that which is believed to be correct. The ovewhelming consensus is that you are not correct. Yet at the same time, your views are prominent enough to be worth mentioning as a noticed minority view. My goal will be to treat you in the way Alfred Wegener and his continental drift ideas would have deserved to be treated here in the 1920s. Do note that Wikipedia is not a crystal ball!! I will treat your ideas with some respect, but their lack of acceptance (be it proper or not) will be solidly noted. After all, that lack of acceptance is part of current human knowledge. --EMS | Talk 21:45, 30 March 2006 (UTC)
You say: "please be aware that it is the opinion of relativists in general it is you that has failed to make your case, not them. Your personal refusal to accept the presented refutations does not mean that others are not satisfied with them." I've been hearing the cheap, sound-byte dismissal "Van Flandern just doesn't understand" a lot since the joint 2002 paper with Vigier, which comprehensively addressed all objections raised to date to the satisfaction of neutral referees. Before 2002, there was always some specific objection attached to that dismissal. But now that all available arguments are rebutted in print, I just hear the put down with conspicuously absent specifics.
However, posturing means nothing. I already agreed that this viewpoint is a minority position among relativists, though not among physicists in general who have informed themselves on the subject, and especially not among dynamicists. But raise your very best rebuttal arguments in consultation with the top relativity experts, and we'll see what happens when I get back. Tomvf 07:48, 31 March 2006 (UTC)
The goal is not to formally rebut you here, but to state how relativists like myself consider you to be rebutted. That you and your supporters find the rebuttals inadequate will be mentioned, but this is not the place for the highly detailed specifics of the rebuttal and counter-rebuttals. (Even what you are claiming will need to be expressed in a reasonably brief form). Perhaps we can work together to create a Research of Tom Van Flandern or a Speculations of Tom Van Flandern page. (I prefer the later title, but doubt that it is NPOV.) BTW - To start either article, just click on the red link and get to work. Its start probably should be text exported from the Tom Van Flandern article, but with each thesis in a seperate section and the rebuttals and counter-rebuttals listed in a properly wikified format.
In any case, I see your role as making sure that what I claim you are saying is as accurate as possible given the space constraints. You may also feel free to question the POV, but do realize that an overly pro-TomVF slant is as bad here as an overly anti-TomVF slant. My goals are to be fair and to avoid being blatantly derogatory towards you, but to still express how you are seen in the eyes of mainstream physicists. --EMS | Talk 18:09, 31 March 2006 (UTC)

## The Kansas City Library anon

An anon using IP 204.56.7.1 (talk · contribs), aka the Linda Hall Library anon in Kansas City, MO made an odd minor edit, which may have been well intentioned but which I reverted because it didn't seem to improve the article but in fact seemed to make it slightly uglier.

I request other editors to help me monitor this article closely, since this user (and more generally an individual who edits from other libraries in Kansas City, e.g. the kc.umkc.edu anon) has been causing problems (disruptive POV-pushing) in a number of other articles dealing with relativistic physics. ---CH 22:37, 2 June 2006 (UTC)

## Removal of Van Flandern mentions

Cj67 - A lot of head scratching and soul-searching was done before deciding that this article should mention TVF. Now you come along and decide that it should not be there. For now, I will restore that material. Beyond that, please read the above discussions, and then make your case for removing it. I must admit that I am totally unsympathetic to its removal, but as Tom Van Flandern is a notable enough person to have his own article, then is not his work mentionable here? Be advised that the basic issues are ones of fairness: Fairness to Wikipedia and its mission, fairness to the readers, and fairness to the topic. --EMS | Talk 03:03, 3 June 2006 (UTC)

It is not so clear to me what the standards here are, but, for example, I am willing to bet that no usual reputable encyclopedia mentions TVF. The reason is simple -- there is really no controversy regarding the speed of gravity, just a guy claiming that gravity is 20 x 10^9 times faster than light. Find a reputable text on general relativity that mentions TVF -- I really doubt one exists. So, in such a short article, to mention TVF is extremely misleading regarding the general acceptance of general relativity and the state of the art (Cj67 04:56, 3 June 2006 (UTC)).
Hang on, Cj67 (talk · contribs)! I made the change and I doubt that you could find a more severe critic of Tom Van Flandern's various cranky claims than myself. I entirely agree that there is no scientific controversy here, but the problem is that TVF insists on trying to manufacture a kind of media controversy. There are in fact quite a few cranky websites which mention his claims. When I first came to WP almost a year ago I also tended to favor deleting stuff like Tom Van Flandern (this current wikibiography is mostly written by himself and of course far longer and far more biased in his favor than is really appropriate in a general encyclopedia), but even though it is a huge pain (and often seems like a waste of time), on balance I have come to believe that attempting to write (and maintain against crank edits) brief NPOV descriptions of even manufactured "controversies" is best, since (if well maintained) this can help random invidividuals quickly find information on some topic concerning which they have heard some snatch of misinformation. ---CH 05:22, 3 June 2006 (UTC)
I pretty much agree with Chris. At first with this page I figured that the TVF stuff had to go also, but as I got more familiar with the issues the question came up not of whether there is any scientific validity to it but instead of whether people may reasonably be expected to come here looking for info on TVF's views. The conclusion that I came to is that being encyclopedic is a matter of awareness within a relevant community and/or the population as a whole. TVF's idea seen to have low but notable level of awareness amongst the population in general. Hence it is reasonable to mention it here.
You need to realize that Wikipedia is not constrained by the space requirements of a normal encyclopedia, and that gives an extra level of flexibility to the medium. Even so, it is a poilicy the "Wikipedia is not an indiscriminate collector of information". Hence my willingness to consider the removal of the TVF material. So far, I am not convinced about that, but this is a somewhat grey area. However, I don't forsee its being decided that TVF and his ideas are not encyclopedic. --EMS | Talk 18:42, 3 June 2006 (UTC)

## Todo list and students beware

As a courtesy, I have removed the todo list. I am leaving WP and doubt anyone else will care to implement the suggested improvements.

Good luck in your search for information, regardless!---CH 17:36, 1 July 2006 (UTC)

## Historical sections

I thought it's necessary to include some hisorical information in the artice. So I added 2 sections on Laplace and field theories. --D.H 20:12, 12 March 2007 (UTC)

## Quantification, even if only hypothetical - it's important information.

Somewhere in the earliest part of this article belongs a statement on what the speed actually IS (or is thought to be). One shouldn't have to carefully read all the way to the relativity and experimentation sections before discovering that THIS is where it's written that the speed of gravity is thought to be the same as the speed of light. 198.49.180.40 00:44, 6 April 2007 (UTC)

## Removed Flandern response to Kopeikin

I have removed from the external links a link to a response by Flandern to Kopeikin. The Clifford Will citation gives a more authoritative response, and the problem with the Flandern citation is that is mixes up issues. Flandern is most noted for his own ideas -- also conventionally considered to involve basic theoretical errors in handling general relativity. There's already a citation to Flandern which will suffice. -- Duae Quartunciae (t|c) 04:29, 20 July 2007 (UTC)

Flandern's response to Kopeikin is perfectly adequate and should be cited, in my opnion. Also, there are no "basic theoretical errors" in TVF's papers dealing with any aspect of General Relativity. This is simply a myth. —Preceding unsigned comment added by Epleite (talkcontribs) 02:34, 9 July 2008 (UTC)
Also, in relation to Flandern, switched around the order of comments in the aberration section, and added a citation. It is appropriate to give the conventional explanation of relativity experts first, with a brief mention of dissenters coming later if at all. Frankly, I think the small mention of Flandern here could be removed altogether. But hey. I've left it for the time being, with a reference to give the rather blunt reaction of more conventional physicists. -- Duae Quartunciae (t|c) 05:15, 20 July 2007 (UTC)

## Why no direct experimental measurement?

The speed of light (in air or partial vacuum) can and has been measured by simple experiments involving creating pulses of light and using electronics to measure the time between sending and receiving the pulse. I'll call this a "direct" experiment, as all astronomical effects used for deducing the speed of light require additional assumptions.

In looking at the article, I notice that no similar simple experiment has been suggested or conducted for measuring the speed of gravity. Now, I realize that gravity is much more difficult to detect than a light pulse. Nevertheless, can someone please explain why the following experiment would not work?: there is a "source" mass and a "target" mass, separated by a fixed distance. The source mass is moved quickly by a spring-loaded release mechanism (such as a slingshot). Photoelectric sensors monitor the position of the source and target. The time lag of the correlation of their positions (corrected, if necessary, for the inertia of the masses) gives the propagation time of gravity, from which the speed of gravity is a simple calculation. Setups using different masses and separations between the masses would then be used to confirm that the speed is a constant. Mounting the experiment on a moving platform could then be used to confirm that the speed of gravity is independent of reference frame. David spector (talk) 03:00, 27 October 2009 (UTC)

## Laplace section is incomprehensible and possibly wrong

Please, someone write a more coherent section on Laplace's efforts to assess gravity's minimum speed. Besides, in the very same sentence where he (Laplace) mentions the 7 million * c speed, he mentions other data (RE the moon) which shows that it must be at least 100 million times c. I get lost in trying to follow his pages upon pages of derivations, but I'm pretty sure he looks at both drag on celestial bodies (such as the moon) induced by their moving through a sea of sunlight particles (or Fatio/LeSage-type gravitational particles), and also, as discussed here, orbital stability (gravitational aberration). I'd have to study it much more thoroughly to know what calculations he uses in each of the two minimal speeds he mentions. Hopefully, some reviewer here will know. hkyriazi (talk) 00:53, 16 January 2010 (UTC)

I have sometimes wondered myself about the speed of gravitational fields, but it seems to be rarely discussed even though it seems to me at least to be a meaningful question to ask. Perhaps it would be helpful to first answer the same question with regards to electric fields and magnetic fields. If an electromagnet was instantly magnetised I believe that the magnetic field would be detected at various distances from the electromagnet at time delays determined by the speed of light. Similarly if a Van de Graff generator was instantly charged to a high voltage the electric field would be detected again also depending on the speed of light. If a change in mass of some object or objects occured then in the same way I would also expect the gravitational field strength to be detected at distances away depending on the speed of light. Gravitational fields are different to gravitational waves in the same way that electric and magnetic fields are different to electromagnetic waves. Perhaps for a gravtiational wave to exist it would also have to "oscillate" between two fundermental forces in the same way that electromagnetism does? —Preceding unsigned comment added by 65.116.131.6 (talk) 20:22, 1 June 2010 (UTC)

## False Premise

The Practical mathematics of Orbital mathematics ignore the time factor when calculating the effects of gravity.

From:Orbital mechanics Formulae for free orbits Orbits are conic sections, so, naturally, the formula for the distance of a body for a given angle corresponds to the formula for that curve in polar coordinates, which is: (offsite image of formula here)

The parameter θ is known as the true anomaly, p is the semi-latus rectum, while e is the eccentricity, all obtainable from the various forms of the six independent orbital elements.

Circular orbits All bounded orbits where the gravity of a central body dominates are elliptical in nature. A special case of this is the circular orbit, which is an ellipse of zero eccentricity. The formula for the velocity of a body in a circular orbit at distance r from the center of gravity of mass M is: (offsite image of formula here)

Both formulas ignore any Time constraint.

A semi random, (English only, verbiage appears to relate to speed of gravity,) sampling of authors references and citations found only articles refuting authors writings. 6: 14, 16,

An examintation of the citations most cited author, Kopeikin, Sergei M, reveal that the mojority are pay for view articles costing on the order of $40.00 each, which is beyond this writers budget. The remainder are links to abstracts to articles dicussing the Jovian Deflection Experiment, both before and after it occured. Again, there is a similarity in a majority of the articles in the they link to articles by Kopeikin, Sergei M. The very few articles or comprehensive abstracts cited also refute the authors' premise that Gc = C. Due to the cost of merely the pay for few citations mentioned above, >$400.00 and the probability that there are several other PFV citations, this writer wonders if the author himself has read all of them.

## Speed of gravity

I don't know if its by omission or whatever but this article does seem to avoid anything that criticizes the view that the speed of gravity is restricted to c making it appear a little bit as a puff piece for General Relativity.
I am talking about gravitation involving black holes. Put bluntly the escape velocity within the event horizon of a black hole is greater than the speed of light, it seems as far as I can tell that its quite widely acknowledged that general relativity breaks down at this point. If gravitational forces really moved at the speed of light then the field (and the space time) should collapse in on itself and from the outside the black hole should appear completely massless. (this contradicts observation)
Now I know about the solution called gravitational red-shifting but it does seem to me to be a little thin. Effectively its allowing the field (and space time) to travel faster than light while pretending that its not by allowing the wavefront to move slower. Worse though is that its invoking the wave properties of light for gravity, the waves implying that gravity is mediated by a particle - pretty much the end for space time curvature as the cause of gravity - and pretty bad news for general relativity itself.
Sorry if this is not very well written, been working half the night, hope it helps. Lucien86 (talk) 06:07, 16 August 2010 (UTC)

You are spot-on. This article was originally written highlighting theories of scientific "dissidents" such as Tom Van Flandern and you should take a look at the archived discussion pages. There was a consensus, eons ago, to present these ideas but it has, over time, been white-washed by protectors of GR and those ideas have been edited out. You're right, without those ideas, this isn't much of an article, is it? Akuvar (talk) 16:02, 16 August 2010 (UTC)

## Static field do propagate

I think thet the followig sentences are questionable, under General Relativity - Background, and I ask for a proper references:

1. "Since the gravitoelectric field is, by definition, static and continuous, it does not propagate."
2. "Every Planckian moment of time, the static configuration of the universe's gravitoelectric field instantaneously changes."
3. "The gravitoelectric field of the universe does not exist in time. It is time itself."
4. "so that no meaningful information about the new position would be transmitted faster than the speed of light."
1. about 1: here : [[1]| WP:Parallels_between_electrostatics_and_gravity] :4 . Both propagate with finite speed c, the speed of light."
2. about 2: there are none "instantaneously change". A no null interaction time must be observed.
3. about 3: A field..."It is time itself"? why not include an entry here [[2]]?
4. about 4: No meaningful information can...? Information (and energy) can not be transmited at speeds superior to 'c', meaningful or not.

Heldervelez (talk) 22:25, 9 October 2010 (UTC)

In accordance with the uncertainty principle, a field, whose intensity is below the Planck constant, is nonlocal (omnipresent) and has no room for propagation. 89.110.15.136 (talk) 05:44, 11 October 2010 (UTC)

## Word-for-word copy of another article

Having noticed two related (or even identical) edits by Antichristos in two diferent articles (–see [3] and [4]–), I had removed per wp:COPYWITHIN, a part of this article that is a word-for-word copy of Action at a distance (physics)#Quantum mechanics. Upon this Antichristos reverted my edit because "This paragraph substantiates the next paragraph". I don't really agree with that, but surely it should be possible to replace the duplicated text with a short one-sentence synopsis with a wikilink to the section in question as an introduction to the next paragraph. This has two benefits: there is no wp:COPYWITHIN-attribution problem, and (2) when something changes in one article, there's no need to go and change it in the other. Thoughts? DVdm (talk) 10:30, 16 January 2011 (UTC)

You had no right to remove the paragraph per wp:COPYWITHIN. The paragraph was originally written in Speed of gravity and later copied by its author to Action at a distance (physics)#Quantum mechanics. Antichristos (talk) 12:45, 16 January 2011 (UTC)
It looks like the opening line was indeed created by anon 89.110.20.164 (talk · contribs) on 1-Dec-2010, with this edit. After some work on it, it was copied to the other article with this edit by anon 89.110.9.221 (talk · contribs). I had assumed that it was the other way around, since the content seems a bit off topic here.

Please note that this is not a question of rights to remove, just one of common sense, trying to avoid having duplicate content accross different articles. I notice that you have done a lot of work on both articles, so do you know of some neat way to solve this little redundancy problem? Cheers - DVdm (talk) 17:07, 16 January 2011 (UTC)

This paragraph is crucial to understanding why ultraweak fields, such as the gravitoelectric field, are nonlocal. Wikipedia should provide understanding, not just blind knowledge. I will try to shorten the paragraph without detriment to its purport, but I do not know how much time it will take. Cheers — Antichristos (talk) 17:44, 16 January 2011 (UTC)
No rush—after all, this is not a wp:BLP issue :-) Thanks - DVdm (talk) 18:11, 16 January 2011 (UTC)

## so what is the speed of gravity?

I came here on wiki to find this the answer to this q and what did I found?
λ = hc/E
what the hell dudes?
is it the same with the speed of light?
is it instantanious?
is it aproximatelly 1 million faster than light?
or nobody knows?
your page brings more confusion to a casual user than if it would have not entered this page at all.
for the god sake just tell on the first line an aproximation.
just say it is comonnly acepted that the speed of gravity is fukin x

—Preceding unsigned comment added by 86.3.114.216 (talk) 20:13, 18 January 2011 (UTC)

Well put. Even to a well-informed reader like me, this paragraph (which is the subject of the previous section's discussion, if I'm not mistaken) is rather hard to follow, and so does not belong in the introductory part of the article. Furthermore, it seems to constitute original research, since the argument does not seem to be summarizing any of the references; therefore it does not belong on Wikipedia at all. I also think that the conclusion doesn't follow from the argument, but that's for another time.
So, I will momentarily replace it with something more suitable. Rafaelgr (talk) 10:21, 19 January 2011 (UTC)
Note—This is currently also being discussed at Wikipedia_talk:WikiProject_Physics#Speed_of_gravity. - DVdm (talk) 10:24, 19 January 2011 (UTC)

Cheers guys. that is much better. Anyway it says the "In general relativity, gravitation is regarded as the static curvature of space, to which the notion of speed is inapplicable (in plain words, gravitation does not propagate at all)" but the effect of the curvature is what is seen as gravity (right?) so is the curvature propagating with any speed? or do we need a new page with what is the speed of the curvature propagating?Raffethefirst (talk)

Starting off again, I think that the lead paragraph as you describe it (which I've just changed again) is again quite difficult to follow. The key word in Antichristos' reformulation is actually static: if gravity is understood as static (i.e. unchanging) curvature, then anything which propagates is not gravity; however this is not a reasonable formulation of what is meant by gravity, and the idea of propagation of gravity is not nonsense. It is however a very complicated business, not least because what is curving is spacetime, which can make it very difficult to say exactly what we mean by how far something takes to travel a certain distance.
I also want to reiterate that what was the second paragraph of the lead and is now the section on measurement of the speed of gravity is original research and does not belong on Wikipedia. If someone wishes to change my mind, the best place to start would be by indicating an appropriate source which draws the conclusion that gravitational radiation (as opposed to the quantization of gravitational radiation, which is what Antichristos' sources are mostly about) is necessarily unobservable.Rafaelgr (talk) 12:57, 19 January 2011 (UTC)
Antichristos, let me reiterate that the issue is not just whether you are right (although I'm pretty sure you're not), but whether you are introducing a conclusion that's not in your references. Rafaelgr (talk) 14:39, 19 January 2011 (UTC)

At a minimum, the lead should follow MOS:BOLDTITLE. --Kkmurray (talk) 18:43, 19 January 2011 (UTC)

## Suggestion

I suggest that the article be restored to this revision. It may not be perfect, but at least it contained a well sourced discussion of various attempts to measure/estimate the speed of gravity. More importantly, the sources actually discuss that subject. (Unlike the sources, used for the current synthesis in the article.TimothyRias (talk) 20:19, 19 January 2011 (UTC)

Agree. Maybe the Kopeikin refs should be removed again. User User:Kopeikins has been removing some stuff, but I have no idea what this was about. DVdm (talk) 20:36, 19 January 2011 (UTC)
I agree that TimothyRias's suggested revision is much better than the version as revised by Antichristos. Same reasons as everyone else mentioned: The sources discuss the subject, no significant synthesis or original research, basically consistent with the literature, no bizarre misunderstandings of wave-particle duality, etc. --Steve (talk) 22:30, 19 January 2011 (UTC)
Agree with above. Xxanthippe (talk) 23:08, 19 January 2011 (UTC).
As I wrote at WP:NORN#Speed of gravity I believe all the stuff by Antichristos should be reverted. They have been doing this to some other articles too I believe. Dmcq (talk) 15:33, 20 January 2011 (UTC)

## Speed of static gravity or gravity waves??

This is not an idle distinction. Gravitational waves move at the speed of light, but static gravitational effects "appear" to take instantaneous effect over infinite distance, at least for objects moving at constant transverse velocity. The same is true for electromagnetic waves vs. an electrostatic field.

It will help if people joining in who don't immediately agree with the above, will first read the following discussion and references to Feynman's texts and others, if they want to talk about the similar effects of electrostatics and gravitostatics: http://www.physicsforums.com/showthread.php?t=149794

Consider a distant "charge" or charged-object AT REST. Does it show "abberation" in its location (direction of its static field lines) to an observer in transverse motion, with respect to it? Answer: Clearly no, since the static field lines are already in place thoughout the universe, and the motion of the observer doesn't change their direction back to the source. They don't show any abberation to a moving observer, precisely BECAUSE they are static, and not "moving" radially outward, like a ray of light, from source to observer. They just "exist" everywhere, timelessly. Once one accepts this (no abberation for static fields), it's easy to turn the situation around with Lorentz invariance and say that the observation must be the same if the situation is the same, but we choose a frame in which the OBSERVER is at rest, but now the distant charged object is moving. It's the same physical situation but we've only changed frames. Doing this ALSO cannot change the direction from which the observer "feels" or detects the pull of the charge, so therefore a steadily-moving charge (no velocity changes) must appear to be, not where the charge WAS with a speed of light retardation-delay, but instead exactly where the charge is NOW (its "true position") with no correction for any "signal" delays! Thus, the electrostatic field of a steadily-moving charge points directly at it, no matter how far away from it you are, since the static field is "updated" (a retarded time extrapolation correction) at distances. The field "extrapolates" for constant velocity, and corrects the retardation effects for it. This all happens with no speed of light delay.

Now, none of this can be used to send signals faster than c, because the direction to a static source isn't a signal. The extrapolation term breaks down if the transverse velocity is NOT constant. To send a signal you need to make change in your source, and to do that, you need to accelerate a charge (or a mass) by wiggling it, and that acceleration is NOT updated instantly, at distance. Instead, it moves outward from the accelerated source with a speed-of-light retardation delay, exactly as we're used to, with light. The static field is updated instantaniously at distance, but a changing field (be it EM wave or gravity wave) is updated only at the speed of light. A moving observer DOES see abberation in any outwardly moving waves (EM or gravity), or signals, because they DO propagate from source to observer with a limited velocity of c. "Acceleration" for the source breaks the symmetry of the previous situation, and now we see intuitively why source-acceleration is necessary to generate EM or gravitational waves. Constant-velocity doesn't do it, because you can't tell who the velocity belongs to.

Thus, we see abberation in light from the Sun (its called "annual solar abberation"). It means the Sun appears optically 8.3 arcseconds "behind" (west, since the Sun moves west->east against the Zodiac) of its "true" position against the stars. However, the Sun's pull on the Earth (fortunately) points exactly to its true position, not its (false) optical position. If this didn't happen (as the article itself points out), there would be a retarding force on the Earth's orbit and it would spiral inward-- static effects help preserve conservation of momentum and angular momentum, even over long distances. If the Sun had a static electric charge, of course the pull from THAT would also point to its true position, not its mere optical position. But that doesn't mean static fields move faster than light. They don't "move" at all-- that's why they're called static fields.

So-- most of what's in this article about the speed of gravity, is nonsense. Static gravity is (in this sense) instantaneous. Gravity waves travel at c. The stuff about gravity waves above one Hz being nonexistant, and waves below 1 Hz traveling faster than light, is all nonsense (mainly due to Antichristos and a bunch of Tom Van Flandern followers) and should be reverted at once. I don't know how far you have to go back to get a "good" version of this article, but most of it needs to go. SBHarris 04:01, 27 January 2011 (UTC)

Looks good, if you can reference it, feel free to add it to the article. PlantRunner (talk) 18:25, 28 February 2011 (UTC)
I would support rewriting the article to remove the errors pointed out by Sbharris. Martin Hogbin (talk) 18:27, 6 January 2012 (UTC)
Does the effect on space-time due to acceleration of mass in someway dwarf the other effect on space-time due to the position of the mass? If not, then I do not see how this could fail to result in allowing for super-luminal communication, provided that the tidal stresses are detectable by a reasonably sensitive strain gauge. I understand that without tidal forces, you could not in a sense detect how far away this mass could be, because the detector would be in freefall provided that no other mass exists.
Even if acceleration of mass did have a larger effect on space-time, it appears that accelerations of mass, for the most part, are irrelevant for determining the space-time, as it is apparent that calculating orbits based on positions pretty much gives you the right answer.
Of course, finding enough gravity that we can manipulate in order to do this test experimentally is out of the question (let alone allow for economical communication of information), but in principle, the same test for "tidal" forces (as it were) should work with electrostatic fields as well.siNkarma86—Expert Sectioneer of Wikipedia
86 = 19+9+14 + karma = 19+9+14 + talk
02:21, 21 November 2013 (UTC)
It also appears that "spooky action at a distance" has already long been shown to be possible in quantum physics theories. Sure, you cannot communicate two-way faster than the speed of light using only two entangled particles, but if you have two clusters of entangled particles that respond asynchronously, you should be able to preserve enough information to close the communication loop. If you are guessing that I just made that up, you would be correct, but to my surprise, I checked 1 minute ago on this information, and sure enough, someone else already thought of it:

https://en.wikipedia.org/w/index.php?title=Superluminal_communication&diff=576700390&oldid=575273736
Although such communication is prohibited in the thought experiment described above, some argue that superluminal communication could be achieved via quantum entanglement using other methods that don't rely on cloning a quantum system. One suggested method would use an ensemble of entangled particles to transmit information,[10] similar to a type of quantum eraser experiments.[11][12][13] As the quantum eraser experiments rely on a classical, subluminal channel for coincidence detection, it is unclear whether superluminal communication would be possible by this method. Physicist John G. Cramer at the University of Washington is attempting to replicate one of these experiments and demonstrate whether or not it can produce superluminal communication.[14][15]

Perhaps this was no accident. I did look at that page before today, though I currently don't know how long ago was that. I would have to check an old archive of my Firefox Browser History to see when I did that.siNkarma86—Expert Sectioneer of Wikipedia
86 = 19+9+14 + karma = 19+9+14 + talk
02:49, 21 November 2013 (UTC)

## Speed gravity + Inflation of Space

There should be some easy way to estimate the speed of gravity knowing the rate of inflation of space and the dimension of a large galaxy. The gravity near the outer edge of a galaxy should appear to be much stronger in the direction of the center of the galaxy because the space was "smaller" between the edge and the center when the gravity from the center started toward the edge. So does Newton's inverse square law of gravitation need a rate of inflation term? Have any of these effects be calculated? Are they consistent with observations? Does anyone really know? Is it worth commenting in this article or at least cross referencing explanations in other pages? I am raising these questions because I am curious what the answers might be. —Preceding unsigned comment added by 97.65.82.66 (talk) 21:59, 14 March 2011 (UTC)

What do you mean "when the gravity from the center started toward the edge?" Unless you're talking about a change in gravity (a change in quadrupole moment, as happens when stars rotate about each other, see Hulse-Taylor binary, ther is no "change in gravity" to move anywhere. Gravitationally, a system looks the same when when it merely contracts symmetrically, or expands. There's no "change" in the field to "travel." SBHarris 01:54, 15 March 2011 (UTC)

If changes propagate at finite speeds but when it is static the information is instantaneous, wouldn't that make the gravity for an object that is suddenly stopped appear to come from two different points in space simultaneously? Why would gravity somtimes propagate instantaneously and somtimes propagate at speed of light? Doesn't make sense... --TiagoTiago (talk) 05:54, 31 October 2011 (UTC)

"Suddenly stopping" is a change. If that happens, people far away do not see the stop (that inforamtion propagates at the speed of light). Instead the people far away, for the intervening time, see the object continue as though it hadn't stopped. They see it from one place, but now it's the wrong place. As soon as the change catches up to them, they see it at the correct place. That also applies to changing speeds. So long as it has moved at constant velocity since the change in speed, people at all distances see it at the true direction, AFTER the change gets to them, but see it at the wrong place before that. SBHarris 07:47, 31 October 2011 (UTC)

## Lorentz covariant models

I added following statement in the section "Lorentz covariant models" (which was removed):

The Whitehead's theory of gravitation (1922) explains gravitational red shift, light bending, perihelion shift and Shapiro delay.[16]

1. ^ http://iopscience.iop.org/0264-9381/21/13/010/
3. ^ http://www.hbci.com/~wenonah/new/gravity2.htm
4. ^ http://www.gravitywarpdrive.com/Speed_of_Gravity.htm
5. ^ http://cosmicdarkmatter.com/Speed_of_gravity.html
6. ^ http://fascistsoup.com/2010/05/14/the-speed-of-gravity-why-einstein-was-wrong/
7. ^ http://www.ldolphin.org/vanFlandern/gravityspeed.html
9. ^ http://wugrav.wustl.edu/people/CMW/SpeedofGravity.html
10. ^ Millis, M.G.; Davis, E.W., eds. (2009). Frontiers of Propulsion Science. Progress in astronautics and aeronautics. American Institute of Aeronautics and Astronautics. pp. 509–530.
11. ^ Strekalov, D.; Sergienko, A.; Klyshko, D.; Shih, Y. (1 May 1995). "Observation of Two-Photon "Ghost" Interference and Diffraction" (PDF). Physical Review Letters. 74 (18): 3600–3603. Bibcode:1995PhRvL..74.3600S. doi:10.1103/PhysRevLett.74.3600. PMID 10058246.
12. ^ Dopfer, Birgit (1998). PhD Thesis. Univ. Innsbruck.
13. ^ Zeilinger, Anton (1999). "Experiment and the foundations of quantum physics" (PDF). Reviews of Modern Physics. 71 (2): 288–297. Bibcode:1999RvMPS..71..288Z. doi:10.1103/RevModPhys.71.S288.
14. ^ Paulson, Tom (14 November 2006). "Going for a blast into the real past". Seattle Post-Intelligencer. Retrieved 11 July 2011.
15. ^ Barry, Patrick (September 30, 2006). "What's done is done… or is it?". New Scientist. 191 (2571): 36–39. (subscription required)
16. ^ Will, Clifford & Gibbons, Gary. "On the Multiple Deaths of Whitehead's Theory of Gravity", to be submitted to Studies In History And Philosophy Of Modern Physics (2006).

It is historically true, but DVdm and Neo. want to dicsuss it. The Whitehead's theory uses retardation (by the speed of gravity equal to the speed of light) and it can explain several effects like GTR. 195.113.87.138 (talk) 12:07, 31 May 2013 (UTC)

Note - I don't really want to discuss this. I reverted two edits of yours that were not properly sourced ([5] and [6]). Then Neo suggested ([7]) that you bring another kind of edit (with a source this time) to this talk page for discussion. I don't know whether the source indeed backs the added content or whether the statement is worth adding to the article. Perhaps others? Cheers, 195. - DVdm (talk) 13:05, 31 May 2013 (UTC)
In On the Multiple Deaths of Whitehead's Theory of Gravity is In 1922, the distinguished mathematician and philosopher Alfred North Whitehead (1861-1947) , then in his 60th year, published a relativistic theory of gravity with the property, which it shares with Einstein’s theory, of containing no arbitrary parameters. Furthermore, when suitably interpreted, it yields the same predictions as General Relativity (GR), not only for the three classic tests of light bending, gravitational redshift and the precession of the perihelion of Mercury, but also for the Shapiro time delay effect (Shapiro 1964), recently confirmed to one part in 105 (Bertotti et al. 2003). and the version proposed here is sufficient. I think. 195.113.87.138 (talk) 07:44, 3 June 2013 (UTC)
Your own reference says it's been experimentally disproven. If it was never a mainstream theory and isn't currently accepted, does it really add anything to this particular article? Laura Scudder | talk 14:32, 11 June 2013 (UTC)
This theory was not "disproven" until 70s (nevertheless in 70s somebody still prefer Whitehead: value of the gravitational constant is not a function of the prior geometry as Will and Ariel claim ... Since Whitehead’s formulae as they stand have not been disconfirmed ... Currently there is considerable interest in correlating relativity theory with quantum mechanics. The efforts made in this direction tend to support Whitehead rather than Einstein. [8]). It was a good educational example and shows, that the four main experiments (used for a confirmation of the general relativity) can be explained as retarded gravitation (with the speed of gravity exactly equal to the speed of light).195.113.87.138 (talk) 06:06, 12 June 2013 (UTC)

While I have not read the argumentation in this section in detail, I would simply observe that the statement "The Whitehead's theory of gravitation (1922) explains gravitational red shift, light bending, perihelion shift and Shapiro delay" is inappropriate unless some sort of connecting reasoning links this statement to the surrounding discussion. Was it considered valid once upon a time, but no longer is? If still not falsified, is it proposed to be equivalent to GR? If not, what distinguishes it? This is confusing; I wish it could be clarified, as it seems to be an significant and interesting historical side note, if nothing else. — Preceding unsigned comment added by 75.161.40.5 (talk) 04:37, 16 January 2014 (UTC)

## Removed the statement about a research team in China

The result of a research team in China is faked and wrong

In Ref.[1], it is pointed out that Tang and coworkers’ result cannot be obtained from normal process and their result is faked.

In Ref.[2] it is concluded that their result seems to be drawn based on the misinterpreting of the known formula and the less careful data analysis.

Reference [1] Y. Zhu, Measurement of the speed of gravity, arXiv:1108.3761 [2] C. G. Huang, The observation of the Earth tide is irrelevant to the speed of gravity, Chin Sci Bull, 2013, 58: 3291–3294 — Preceding unsigned comment added by Zhuyin (talkcontribs) 06:41, 10 October 2013 (UTC)

## Yan Zhou ?

Why is there a section on something from a Yan Zhou ? It seems he is from Agriculture Department of Hubei Province in China, not a physicist. I can't find anything else about him on google, nor his article on arXiv.org. And the pdf in the arXiv.org has a lot of references, but none that proves those variations on satellite orbits. — Preceding unsigned comment added by 77.119.131.141 (talk) 08:52, 4 July 2014 (UTC)

Note: https://independent.academia.edu/YinZhu talk2siNkarma86—Expert Sectioneer of Wikipedia 15:05, 4 July 2014 (UTC)

The dear unsigned,

I tried to link the arXiv:1108.3761v8 through the reference [28] here and I succeeded. Please try again if you failed to open this link before.

You are welcome to comment my article entitled “Measurement of the speed of gravity”, arXiv:1108.3761v8.

But, I don’t think it is a rational way to say that “none that proves those variations on satellite orbits” without a scientific comment on the article.

I addition, my name is Yin Zhu, not Yan Zhou. — Preceding unsigned comment added by Zhuyin (talkcontribs) 07:40, 14 July 2014 (UTC)

The dear unsigned, More than 8 weeks passed, have you had some of comments on my article entitled “Measurement of the speed of gravity”, arXiv:1108.3761v8. If you have, you are welcomed to show them. I hope you could show some of significant views about it.

If you could not have a scientific comment on it, I hope you should not have non- scientific comment on it. — Preceding unsigned comment added by Zhuyin (talkcontribs) 02:44, 9 September 2014 (UTC)

## Chinese measurement

In the Gravitation article, a subsection entitled Speed of gravity has something to say about a 2012 Chinese measurement, whereas the main article here says nothing about it. Seems like Speed of gravity should say something about it, if it is reputable. Conversely, the Gravitation article seems to give the Chinese measurement a great deal of undue weight, given that it has nothing whatever to say about the topic except for the Chinese measurement. Could someone more familiar with this topic either take this on, or advise what ought to be done here (and there)?

In December 2012, a research team in China announced that it had produced measurements of the phase lag of Earth tides during full and new moons which seem to prove that the speed of gravity is equal to the speed of light.[1] The team's findings were released in the Chinese Science Bulletin in February 2013.[2]

### Reflist for snippet above

1. ^ Chinese scientists find evidence for speed of gravity, astrowatch.com, 12/28/12.
2. ^ TANG, Ke Yun; HUA ChangCai; WEN Wu; CHI ShunLiang; YOU QingYu; YU Dan (February 2013). "Observational evidences for the speed of the gravity based on the Earth tide" (PDF). Chinese Science Bulletin. 58 (4–5): 474–477. doi:10.1007/s11434-012-5603-3. Retrieved 12 June 2013.

Mathglot (talk) 06:08, 24 July 2014 (UTC)

I am not an expert on the subject but, as far as I can see, the above paper claims to show a phase shift (lag) between the action of the Moon's gravity on the Earth compared with that predicted by the Moon's position in space relative to the Earth. Although it might appear that this result confirms the generally accepted theory of gravitation (GR), quite the reverse is true as GR predicts no such phase shift and such a phase shift would make the Earth's orbit unstable. Martin Hogbin (talk) 08:58, 24 July 2014 (UTC)

Dear Sir Hogbin, If you should read “Measurement of the speed of gravity”, arXiv:1108.3761v8, you might get some of answers. — Preceding unsigned comment added by Zhuyin (talkcontribs) 02:50, 9 September 2014 (UTC)

## How does one get the speed of gravity?

From Maxwell's Equations we can get the speed of electromagnetic radiation by multiplying μ0 with ε0, is there a way to get the speed of gravity from similar equations.

For example, replacing the differential form fo Newton's law ${\displaystyle \nabla \cdot \mathbf {g} =-4\pi G\rho ,}$ with Gauss's law (the differential form of Coulomb's Law) ${\displaystyle \nabla \cdot \mathbf {E} ={\frac {\rho }{\varepsilon _{0}}}}$ — Preceding unsigned comment added by 195.194.89.201 (talk) 15:04, 8 September 2014 (UTC)

## Possible observations

In November 2013, Y. Zhu announced that he observed the speed of gravitational force, calculating the variations of the orbit of the geosynchronous satellites perturbed by the Sun. It is shown that the gravitational force of the Sun acting on the satellite is from the present position of the Sun. It indicates that the speed of gravitational force is much larger than the speed of light in a vacuum. From this observation and the recent experiments, the structure of the fields of a moving source (a body or a charge) is studied. A method to measure the speed of gravitational force in laboratory and a line to indirectly test the wavelengths of gravitational waves are presented. [1]

References

1. ^ Yin Zhu (2011). "Measurement of the Speed of Gravity". arXiv:1108.3761.
This looks like a rehash of an old argument. ArXiv is not a reliable source unless published elsewhere. Martin Hogbin (talk) 08:49, 25 September 2014 (UTC)
To be fair this has been published elsewhere. (For future reference, the Arxiv abstract page will usually contain a link to the published version. Many journals require this as a condition for the worj being on ArXiv.) However, looking at the revision history of the arxiv entry it seems that this paper may have been rejected quite a few times before getting accepted somewhere. (Which usually happens eventually if you are persistent.)TR 10:55, 25 September 2014 (UTC)
From what I can see, this looks like a rehash of the Laplace argument, discussed in the article. Martin Hogbin (talk) 11:55, 25 September 2014 (UTC)
This observation is based on the satellite motions. A detailed calculation is presented for the result. Did Laplace have some argument about the satellite motions?

Laplace presented some line for the speed of gravity. But, I proved that the gravitational force between two planets is certainly directed to the present positions of the two planets, not the retarded positions of them.

If you are able to understand how the orbit of a satellite is designed, you shall understand the result in my article.

Your theory is therefore in accordance with the current generally accepted theory of gravitation, general relativity. Martin Hogbin (talk) 09:25, 26 September 2014 (UTC)

First, I think, the purpose of the wiki is for spreading information and knowledge quickly, not for stopping this spreading. It can solve some problem in the traditional way, such as monopolization and domination of message and knowledge. If it cannot be discussed or argued, science shall cannot be developed. In this sense, I do not think that it is in accordant with the purpose of the wiki to remove Tom van Flandern’s works from here.

Second, my result is an observation. The theory of gravity need be in accordant with an observation or experiment. If a theory is not accordant with the observation or experiment, it is invalid.

Third, if the result in my article is mistake, it is certain this mistake shall be pointed out by someone. Before no one is certain that the result in my article is mistake, it has to be regarded as valid.

Your observations need to be published in a reliable source where they are actively peer reviewed. --NeilN talk to me 15:15, 3 December 2014 (UTC)

## Some problems in the “Speed of Gravity”

1.The Static fields

It is clear and certain, both the electromagnetic and gravitational field can transfer energy. For example, for two interacting charges A and B, as soon as A is moved, the B is moved by the motion of A. And, it is well known, the gravitational field can cause the tides which is a very big energy.

Therefore, it is nonesense to state that a static field cannot transfer energy.

2.Steve Carlip’s "Aberration and the Speed of Gravity" may be wrong

In "Aberration and the Speed of Gravity", Carlip obtained the equation (2.4). But, now we know that equation (2.4) is a fundamental equation for both the electrodynamics and the general relativity. Please see: Jackson, J. D.(1998) Classic Electrodynamics, 3rdEd., chapter 14, John Wiley 7 Sons, Inc. & Ryder L. (2009) Introduction to General Relativity, Cambridge University Press, chapter 9. In Jackson’s “Classic Electrodynamics”, it is explained that the interactive term in the equation (2.4) is the same as a static field, the speed of it is infinite.

3.Thus, Flandern’s result in his paper “The speed of gravity: what the experiments say?” has not been negated by Steve Carlip. — Preceding unsigned comment added by Zhuyin (talkcontribs) 08:37, 3 December 2014 (UTC)

## Orphaned references in Speed of gravity

I check pages listed in Category:Pages with incorrect ref formatting to try to fix reference errors. One of the things I do is look for content for orphaned references in wikilinked articles. I have found content for some of Speed of gravity's orphans, the problem is that I found more than one version. I can't determine which (if any) is correct for this article, so I am asking for a sentient editor to look it over and copy the correct ref content into this article.

Reference named "PRL-20160211":

Reference named "Nature_11Feb16":

I apologize if any of the above are effectively identical; I am just a simple computer program, so I can't determine whether minor differences are significant or not. AnomieBOT 07:30, 20 February 2016 (UTC)

Create also a page titled: Speed of quantum information.
Then merge the pages:

1. Speed of quantum information (or quantum transmission)
2. Speed of light in the classical void
3. Speed of gravity

under the general name: Speed of color (the chromodynamic chroma) and maintain the subarticles as parts of that new page. — Preceding unsigned comment added by talk) 18:22, 26 April 2016 (UTC)

## Assessment comment

The comment(s) below were originally left at Talk:Speed of gravity/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

 This article is currently a hodge-podge of views on the issue, all covered breifly. The lead is pathetic, and Van Flandern's views take up too much of the article (although this is because the rest of the article needs expanding). --EMS

Last edited at 05:41, 29 November 2006 (UTC). Substituted at 06:40, 30 April 2016 (UTC)