Talk:Frame-dragging

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Help with this template Comments: edit – history – watch – refresh The point is very simple: while the references of a researcher have not been ever censored and have always properly cited, the ones by the other researcher have often-and now too!!-been censored. As a result, the reader of Wikipedia has not the possibility of getting informed about the attempts with the Sun and those with Mars and MGS. What is this?

This is a controversial topic, which may be under dispute. Please read this talk page and discuss substantial changes here before making them. Make sure you supply full citations when adding information to highly controversial articles.

Contents 1 document ancestry 2 linked from slashdot 3 Removed comment 4 frame dragging due to simple acceleration 5 Accelerational frame-dragging and warp fields 6 Recent controversy 7 The disputed sections 8 Mathematical treatment of frame-dragging 9 Semi-protecting 10 To the anonymous editors of this article 11 Lose discussion of SR from the intro section?

[edit] document ancestry

An early version of this article was adapted from public domain material from http://science.msfc.nasa.gov/newhome/headlines/ast06nov97_1.htm

This currently is mostly press-release journalese, but it will do for now to stimulate the development of a proper article in due course. -- The Anome 23:36, 13 Apr 2004 (UTC)

[edit] linked from slashdot

http://science.slashdot.org/science/04/04/19/232237.shtml?tid=134&tid=160 -- Finlay McWalter | Talk 11:53, 20 Apr 2004 (UTC) http://science.slashdot.org/science/05/11/19/077220.shtml?tid=236&tid=14 -- 19 Nov 2005

[edit] Removed comment

I removed this comment about Gravity Probe B:

Note: The experiment was completed supporting frame-dragging.

as I can't find any evidence of a preliminary result from the Gravity Probe B team to back this up. -- The Anome 13:02, 24 Oct 2004 (UTC)

[edit] frame dragging due to simple acceleration

The principle of relativity, applied to acceleration and rotation, requires that both effects distort spacetime (basically, if an object is made to feel gee-forces, there's a back-reaction on the shape of the region). So, if you forcibly-accelerate a mass, you create a distortion that tends to pull other nearby objects along with it (as, when you rotate a mass, it tends to pull other nearby objects around with it).

This page only seemed to mention the "rotational" effect (which is probably the better known of the two), so I took the liberty of squeezing a few words into the intro to acknowledge the existence of the the "acceleration" version. ErkDemon 00:57, 17 July 2005 (UTC)

[edit] Accelerational frame-dragging and warp fields

PS: if you forcibly accelerate a hollow spherical mass, the gravitomagnetic field created inside it looks awfully like an Alcubierre warpdrive field. ErkDemon 00:56, 17 July 2005 (UTC)

[edit] Recent controversy

This article has recently been subject to some highly POV editing between two competing points of view, with accusations of censorship and other name-calling in the other article text. See, for example, recent edits by User:87.17.229.141, and various other Italian IP addresses beginning with 87, some of the most recent of which accuse other editors of censorship, with accusations that they are mentally ill (see this edit and this edit). It has also grown a rather large bibliography, yet currently lacks any specific supporting citations or attributions for any of the controversial opinions in the article.

Since most of the content of this article seems to be the disputed content, I have now removed all the disputed content, reducing the article to a very brief but (I hope) uncontentious stub. This article now needs to be rebuilt, with serious attention to WP:NPOV and WP:CITE, to bring it up to date with current scientific knowledge, explicitly mentioning which areas are the subject of current scientific controversy. -- The Anome 12:27, 29 January 2007 (UTC)

OK, I've made a start on this: the LAGEOS stuff is now a small part of the article, and just references the supporting references given in the earlier version of the article, without going into great detail: this article is about frame-dragging, not just this particular experiment. -- The Anome 13:23, 29 January 2007 (UTC)

(Next time), can you copy the disputed content to the talk page? This makes it more readily visible, and allows it to be discussed, point by point. linas 01:13, 30 January 2007 (UTC)

[edit] The disputed sections

The edit war appears mostly to be over the following text, and the papers listed in the references. The issue appears to be Iorio's et. al's criticism of Ciufolini et al's re-analysis of the LAGEOS data. As just a very small sample of what has being going on, in this edit various mentions to papers by L. Iorio disappear, and in this edit, the disputed text is restored, along with the addition of a large number of papers by L. Iorio.

The disputed text and references are batted to and fro, over and over again, with no attempt at a neutral point of view by representing both sides' views, and the tone is far too technical for an encyclopedia article. This needs to stop, and the anonymous participants in the edit war need to collaborate on the article. If this detailed level of scientific discussion is to be incorporated in the article, it should first be introduced with an introduction that will allow it to be understood by readers not already familiar with the discussion.

BEGIN DISPUTED TEXT

Another consequence of the gravitomagnetic field of a central rotating body is the so-called Lense-Thirring effect (Lense and Thirring 1918). It consists of small secular precessions of the longitude of the ascending node Ω and the argument of pericenter ω of the path of a test mass freely orbiting the spinning main body. de Sitter (1916) worked out the gravitomagnetic pericentre precession in the particular case of equatorial orbits. Lense and Thirring (1918) originally proposed to use the natural satellites of the gaseous giant planets of the Solar System, especially Jupiter, to detect their effect, but such a possibility is not yet viable today (Iorio and Lainey 2005). In regard to the Earth's gravitational field, Cugusi and Proverbio (1978) proposed for the first time to use the LAGEOS satellite, just launched at that time, along with the other existing terrestrial artifical satellites to measure the Lense-Thirring effect with the Satellite Laser Ranging (SLR) technique. Later, Ciufolini (1986) proposed to built and launch a new SLR satellite of LAGEOS-type in supplementary orbital configuration with respect to LAGEOS, but, to date, no effective plans have yet been approved to implement such a proposal. For the nodes of the LAGEOS and LAGEOS II satellites the Lense-Thirring node rates amount to ~30 milliarcseconds per year (ms/yr or ms yr ^{− 1}). Such tiny precessions would totally be swamped by the much larger classical precessions induced by the even zonal harmonic coefficients of the multipolar expansion of the Newtonian part of the terrestrial gravitational potential. Even the most recent Earth gravity models from the dedicated CHAMP and GRACE missions would not allow to know the even zonal harmonics to a sufficiently high degree of accuracy in order to extract the Lense-Thirring effect from the analysis of the node of only one satellite.

Ciufolini (1996) proposed to overcome this problem by suitably combining the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II in order to cancel out all the static and time-dependent perturbations due to the first two even zonal harmonics . Various analyses with the pre-CHAMP/GRACE JGM-3 and EGM96 Earth gravity models were performed by Ciufolini et al. over observational time spans of some years (Ciufolini et al. 1996; 1997; 1998). The claimed total accuracies were in the range of 20-25% (Ciufolini 2004). However, subsequent analyses by Ries et al. (2003a; 2003b) and Iorio (2003) showed that such estimates are largely optimistic. Indeed, a more conservative and realistic evaluation of the impact of the uncancelled even zonal harmonics , according to the adopted EGM96 model, yield a systematic error of about 80% at 1-sigma level. Moreover, also the systematic error due to the non-gravitational perturbations mainly affecting the perigee of LAGEOS II was underestimated.

The opportunities offered by the new generation of Earth gravity models from CHAMP and, especially, GRACE allowed to discard the perigee of LAGEOS II, as pointed out by Ries et al. (2003a; 2003b). In 2003 Iorio, following the strategy put forth by Ciufolini (1996), put explicitly forth a suitable linear combination of the nodes of LAGEOS and LAGEOS II which cancels out the first even zonal harmonic J₂ (Iorio and Morea 2004). Such an observable was used by Ciufolini and Pavlis in a test performed with the 2nd generation GRACE-only EIGEN-GRACE02S Earth gravity model over a time span of 11 years (Ciufolini and Pavlis 2004). The claimed total error budget is 5% at 1-sigma level and 10% at 3-sigma level. However, Iorio (2005a; 2005b; 2006a; 2006b) criticized such results because of the neglected impact of the secular variations of the uncancelled even zonal harmonics which would amount to about 13%. This would yield a total error of 20% at 1-sigma level. Moreover, the latest CHAMP/GRACE-based Earth gravity models do not yet allow for a model-independent measurement. Indeed, the systematic error due to the static part of the even zonal harmonics amounts to 4% for EIGEN-GRACE02S, 6% for EIGEN-CG01C and 9% for GGM02S at 1-sigma level. Another potential source of additional systematic bias may be represented by the cross-coupling among J₂ and the residuals of the inclination δi, as pointed out by Iorio (2006b). Other papers on such a long-lasting, sometimes harsh, controversy are (Ciufolini and Pavlis 2005; Lucchesi 2005).

By the way, such a controversial test has recently been superseded by an unexpected result in the gravitational field of Mars. Indeed, by suitably interpreting the RMS orbit overlap differences of the out-of-plane portion (Konopliv et al. 2006) of the orbit of the Mars Global Surveyor (MGS) spacecraft which orbited the red planet along a nearly polar orbit until November 2006, Iorio (2006c) reported a 6% measurement, on average, of the Lense-Thirring effect. A further analysis (Iorio 2007a), based on a more detailed calculation, extended time span and error analysis, has pushed the precision level of such a test below the 1% level. A lively debate about such finding can be found in (Krogh 2007; Iorio 2007b; Sindoni et al. 2007; Iorio 2007c).

Other preliminary tests of the Lense-Thirring effect induced by the Sun's gravitomagnetic field on the orbital motions of the inner planets of the Solar System can be found in (Iorio 2005c). The predictions of general relativity for the Lense-Thirring perihelion precessions are, in fact, in agreement with the latest determinations of the extra-perihelion advances of the inner planets (Pitjeva 2005a) obtained with the EPM2004 ephemerides (Pitjeva 2005b), but the errors are still large.

END DISPUTED TEXT

-- The Anome 14:55, 4 February 2007 (UTC)

[edit] Mathematical treatment of frame-dragging

I've now added an empty section to the article, tagged with a request for expansion. Perhaps we could first have a mathematical treatment of what frame-dragging actually is, before we have detailed arguments about whether or not one particular group have observed it? -- The Anome 15:40, 4 February 2007 (UTC)

Nope. Apparently we can't -- one of the previous IP editors has just banged the disputed material right back in by reverting to a previous version of the article, removing the in-text cites, and any other work on the article. (see diff) Since they react to any editing that touches their text by reverting the article in its entirety, I'll try another approach.

I've now tagged the disputed text with {{NPOV}}, re-added the in-text citations to Lense, Thirring and Einstein, and re-added the empty mathematical treatment section, together with an {{expand}} tag. Let's see if this helps. -- The Anome 09:33, 5 February 2007 (UTC)

[edit] Semi-protecting

The combatting IP editors are at it again: see, for example, [1]. Wikipedia is not a venue for argumentation. I've removed the endlessly-edited experimental observation section for now, semi-protected the article for two weeks (with a note that disputes should be discussed here), and will wait to see whether they can be persuaded to create accounts and/or discuss any changes here. -- The Anome 10:53, 5 February 2007 (UTC)

[edit] To the anonymous editors of this article

This article is primarily for discussion of frame-dragging, not disputes over interpretations of particular experiments. In particular, it is not a venue for name-calling, or for communication between editors. If you wish to discuss amendments to the article, please do so here: this page is the correct place to discuss changes to the article.

Please, before you go any further:

• read the neutral point of view policy
• read the civility policy
• consider adding a detailed treatment of the predictions of frame-dragging in the theory of general relativity, before you start discussing experimental observations: without first having an understanding of what is predicted by theory, other readers cannot begin to understand the details of any analysis of experimental observations as tests of the hypothesis of frame-dragging.

-- The Anome 10:58, 5 February 2007 (UTC)

[edit] Lose discussion of SR from the intro section?

The article's intro says (in part):

"More familiar and already-proven effects of special relativity include the equivalence of mass and energy (as seen in matter-antimatter reactions) , and the Lorentz transformations which make objects near lightspeed seem to grow shorter and heavier from the point of view of an outside observer.

It's not a bad sentence, but it doesn't seem to have anything obvious to do with frame-dragging. Perhaps it strayed in from another article?

The "frame-dragging" effect in question happens under general relativity, and doesn't exist under special relativity. Frame-dragging involves curved spacetime; special relativity depends on flat spacetime. Frame dragging is a gravitomagnetic effect that describes how the motion of a body warps lightbeam geometry; special relativity depends for its internal consistency on the idea that we know that the motion of bodies has ==zero effect== on the propagation of light.

Does anyone have any objection to the quiet removal of this sentence? I understand that sometimes some background context or historical context for an article can sometimes be valuable, but in this case, special relativity isn't the correct context (or even _a_ valid context) for the effect being described. SR may have some relevance as a building block for Einstein's general theory, but for this topic it seems to be an irrelevant building block. Frame dragging is a consequence of the general application of the principle of relativity to noninertial motion, it isn't inhertited from the the "SR" side of GR1915's family tree. SR doesn't have a lot to say on the subject, since it is partly founded on the assumption that these sorts of complicating effects don't exist ... anything that it did say on the subject would tend to be negative.

Delete sentence? ErkDemon 20:40, 5 February 2007 (UTC)

Done. I saw less use for it than you did. I also updated the description of rotation frame dragging, and am seriously considering removing the "velocity frame dragging" part. (I don't see that this article needs to include controversial items at this stage.) —The preceding unsigned comment was added by Ems57fcva (talk • contribs) 21:50, 5 February 2007 (UTC).

okey-doke ErkDemon 02:02, 26 February 2007 (UTC)