Talk:Gravity/Archive 7

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Opening sentence

Gravitation is a natural phenomenon by which all objects with mass attract each other in a way that conserves angular momentum, and is one of the fundamental forces of physics.

To me, the fact that gravity conserves angular momentum is a subsidiary point that should not be mentioned in the opening sentence. The prominence of this detail here is likely to just raise unnecessary doubts in the reader's mind. It almost sounds as if the definition is distinguishing gravity from other phenomena that cause objects with mass to attract each other but which happen not to conserve angular momentum. Angular momentum is always conserved, so it's no big deal (at this point in the article) that gravity does also.

If others agree then perhaps someone who is able to edit this article could move it? —Preceding unsigned comment added by 86.138.105.113 (talk) 12:39, 17 July 2008 (UTC)

 Done (by Rracecarr, and I also endorse). - Eldereft (cont.) 19:07, 17 July 2008 (UTC) If you are a universe designer and want to put a quantity of matter (mass) into an existing physical system there are a number of associated physical properties of the matter that you need to specify in order to adequately include it. There's position, and velocity, and direction, and any forces and/or force differencials per unit direction that you know about, plus the unknown potential future activities of the universe and/or any of its subsidiaries. So let's face it, there must be an easier line of endeavor.WFPMWFPM (talk) 02:39, 8 September 2008 (UTC) And now in place of a universal fixed distance and time unit universe we have distance-time transformations which make it impossible to describe simultaneity and or time increment values between moving frames of reference. And so if you work it right and move around fast enough, you can become younger than your son or maybe even your grandson. But I wouldn't recommend it. WFPMWFPM (talk) 03:19, 8 September 2008 (UTC) --Gravitation may also described as the result of a process of Energy Conversion whereby the constituents of an initial system of mass concentration of matter are presumed to have an initial quantity of "Potential Energy" as the result of their position, and to subsequently move and gain an equivalent amount of "Kinetic Energy of motion" as the result of the process. This Concept was proposed by Maxwell in his article "Atom" in 9th edit. EB as the method of identifying systems of concentration versus systems of disassociation. WFPMWFPM (talk) 17:09, 30 September 2008 (UTC)

Solar System Photo

Despite the fact that Pluto was declassified as a major planet, we shouldn't be going around and removing it from everything. In this context, I'm sure it is still a mass, affected by the Sun's gravity and exerting its own force of gravity.

Reinstate Solar sys.jpg instead of the vandalized one. (same photo, but with Pluto still in it) —Preceding unsigned comment added by Heerojyuy (talk • contribs) 18:47, 30 July 2008 (UTC)

References

Reference for the apocryphal nature of the story of the experiment to show the nature of gravity is more properly cited as: Nature News (13 Jun 2005), doi: 10.1038/news050613-10 or some variant thereof. Can someone please change this? Also, could someone rewrite the sentence to not include the word 'apocryphal', such that it is less obsfucatory for those readers who are less versed in the language. I've met plenty of adults who don't know the meaning of the word 'apocryphal', and I imagine there are very few grade-school children who do either. My intention here is to make it very clear that the veracity of this story is highly disputed. Cheers Sander roy (talk) 21:18, 4 August 2008 (UTC)

Done, thank you for pointing this out. I disagree about apocryphal, but I would have no problem with someone else rewriting the point. - Eldereft (cont.) 07:24, 5 August 2008 (UTC)

Opening statement revisited

Gravitation is a natural phenomenon by which objects with mass attract one another.

The above statement is false. What I propose instead is to make it true by stating Gravitation is a natural phenomenon by which objects with mass look like attracting one another. Then, besides possibly awaking the curiosity why they look like attracting one another, there is a room for explaining why in the real world they don't attract one another but only look like they do. Room for explaining why the whole Newtonian gravitation is just a magic, pure math without much physics behind it even if it is taught in physics classes. Otherwise we may be forced at some point to have to admit that we knew that they don't attract one another and that we were simply lying.

"Attraction" is an illusion that people still use to "explain" gravitational phenomena to people they consider dummies. Phenomena that are a bit more complex than a simple attraction but considered by some professors too complex to be explained to "dummies" like high school kids. They turn out to be too complex mostly to those professors who don't understand them themselves. My survey among professors indicated that none of them was able to explain the true mechanism of gravitatonal force despite their scientific degrees in physics. Yet all of them knew it isn't attraction.

The main difference between reality and attraction is that attraction acts at the distance while in reality the "gravitational action at the distance" is mediated by the curvature of spacetime in which the important thing is the local curvature of space. In flat space there wouldn't be any gravitation. Ironically, the Newtonian gravitation is a theory in which space is flat. In the real gravitation though (not just in a magical mathematical theory that simulates the real thing) the spacetime may be flat and the space must be curved to produce gravitational effects (it also makes the whole theory simpler by allowing a flat spacetime).

The whole confusion about gravitation comes from the fact that despite that in the Newtonian gravitation the space is flat there is something called gravitational time dilation that saves the Newtonian gravitation from being completely wrong. So it is only half wrong by missing the curvature of space. And that's why it is not exact. Since the curvature of space acts visibly only when velocities are near speed of light or masses are real big (many orders of magnitude bigger than what we see around in our solar system). Otherwise it acts behind the scene to cause gravitational time dilation to make those gravitational phenomena that we may see happening.

That's why it is important to understand the real gravitation before writing articles for high school kids. They may never know more physics than it can be found in wikipedia. So they shouldn't learn as physics things that are merely figures of speech. Jim (talk) 15:03, 13 September 2008 (UTC)

The objection to "attract" is valid. I would be interested, however, in your method of separating the "curvature of space" from the curvature of spacetime because it seems to be inseparable in the context of GR. Fairandbalanced (talk) 21:38, 15 September 2008 (UTC) I'm afraid that I just dont understand how "space" is wraped so tight around the earth that it is possible for two objects on oppisite sides of the earth to accelerate directly at each other, WFPMWFPM (talk) 11:20, 26 September 2008 (UTC) In scientific subject matter communication it can be said that there are 2 (Not necessarily mutually exclusive) sets of scientic information that can be communicated, and 1 set can be called "agreed facts" and the other set can be called "Opinions". And so if you're going to talk about gravitation in both the Newton and the Relativity concepts then the statement that units of matter "attract each other" should probably be expressed as an opinion and not as a definition of the subject matter. WFPMWFPM (talk) 19:40, 27 September 2008 (UTC).WFPMWFPM (talk) 19:43, 27 September 2008 (UTC)

And the distinction is...?

The terms gravitation and gravity are mostly interchangeable in everyday use, but in scientific usage a distinction may be made. "Gravitation" is [...]. By contrast, in general relativity gravitation is [...].

The last paragraph of the introduction seems about to explain a distiction between gravitation and gravity (such as the one given here [1]), but then forgets how it began, and provides instead a distinction between two uses of the term gravitation! Dependent Variable (talk) 17:44, 13 September 2008 (UTC)

Gravity and Quantum Mechanics

The article states that theory breaks down at the Planck scale. Is there any reason to believe that gravity applies at all at the Planck scale? Why can't it be a far-field effect? Fairandbalanced (talk) 21:30, 15 September 2008 (UTC)

That's what the debate is all about. Anyway...lately I just feel that gravity is keeping me down. —Preceding unsigned comment added by 137.186.237.158 (talk) 20:36, 23 September 2008 (UTC)

Yeah, it's not evolution. There is a debate: http://arxiv.org/abs/0809.4218v1 Fairandbalanced (talk) 04:36, 26 September 2008 (UTC) You have to start out with a net balance of force at the small(Planck) distances. Then you have to propose a cause for an unbalance of these forces in some direction of mass concentration.WFPMWFPM (talk) 11:09, 26 September 2008 (UTC)Then you can get into the argument about the velocity of propogation of these net delta forces through the spacial volume. WFPMWFPM (talk) 11:52, 26 September 2008 (UTC)

Last sentence

By contrast, in general relativity gravity is due to spacetime curvatures which cause inertially moving objects to accelerate towards each other.

This is false. Curvature of spacetime does not cause inertially moving objects to accelerate. That doesn't even make sense: how could things be inertial and non-inertial at the same time? Objects that travel along the geodesics of spacetime are, and will always be, inertial. Space-time tells matter how to move. If you throw an apple in the air, it follows its geodesic as it rises and falls; it falls because space-time is curved. Of course, you've just observed the curving of space-time. Why does the falling apple accelerate? That's because relative to you, the non-inertial observer (on the ground being exerted by an upward force, thus upward proper acceleration), the inertial apple (along the geodesics) seems to accelerate. If we undergo a transformation of reference frame, an inertial observer will see the falling apple traveling at constant velocity in curved space-time (refer to the free-falling elevator experiment). In other words, since the observer is non-inertial and the object is inertial, there is an observable acceleration. That's the point of relativity; motion is relative.

Therefore, this sentence needs to be changed. For me, it should be written as: "By contrast, gravitation, in general relativity, is defined as the curvature of space-time which governs the motion of inertial objects."

Oh, and this article still haven't explained the distinction between gravitation and gravity. —Preceding unsigned comment added by Persistent76 (talk) 08:59, 28 September 2008 (UTC) ---Let's Change this scenario to the case of the hammer versus the feather experiment carried out on the moon. The astraunaut releases the hammer and the feather above the moon's surface. You say the hammer and the feather then become inertial but the moon and the rest isn't. I contest that. What we have now are two independent inertial systems. And the the question becomes as to which system is being accelerated. And why do you vote for the massive moon versus the hammer and the feather? WFPHWFPM (talk) 18:10, 28 September 2008 (UTC)PS: In the last argument I should have used the word "interdependent" rather than independent for the relationship of the two inertial systems, and it has been my experience concerning the interaction of large and small systems, that whereas both systems receive the same delta MV from the interaction, the smaller mass always gets the most energy change from the exchange due to its smaller mass and necessarily higher delta V value. WFPMWFPM (talk) 18:57, 28 September 2008 (UTC) And the net unbalanced accelerating force on the loose (inertial) hammer and feather entities would have to be functioning on a per nucleon basis, otherwise we would wind up with the hammer accelerating faster than the feather. WFPMWFPM (talk) 03:50, 29 September 2008 (UTC)WFPMWFPM (talk) 14:56, 29 September 2008 (UTC)

I agree with the 'interpendent' characterization. It ought to be possible to fall back on John Wheeler's quotation: "matter tells spacetime how to curve, and spacetime tells matter how to move." If we look at astronaut David Scott's hammer and feather experiment on the Moon, we have another example of Galileo's cargo experiment, where the cargo (hammer and feather) is moved slightly, but the ship (Moon) doesn't notice the perturbation (Scott lets go) at all. --Ancheta Wis (talk) 19:32, 28 September 2008 (UTC)

Hi, WFPM: I am afraid you did not really understand my previous comment. Your example still does not prove how curvature of spacetime can cause acceleration. The geometry of spacetime tells matter how to move; things fall because spacetime is curved. The golf ball and the feather are inertial because they are following the geodesics of space-time, but, relative to the non-inertial astronaut (noninertial due to upward proper acceleration by an upward force on the ground), both the golf ball and the feather are seen accelerating. Motion is relative: do you understand that? Both objects hits the ground at the same time due to the lack of drag on the moon. Guess what? Attach an accelerometer on both falling objects and it reads zero acceleration. Attach one on the astronaut standing on the ground and it reads a value. For your question, the observer in both systems are non-inertial (accelerating upward), but the falling objects are not. General relativity states that force of gravity does not exist, thus, since the falling objects are not affected by such force, they are inertial. General relativity also states that objects follow the geodesics of spacetime unless there is a force applied. It has nothing to do with the systems being accelerated. Relative, remember, relative. Now, why do both observers not shooting up into the sky due to the upward acceleration while standing? Curvature of spacetime. Why are both objects inertial and the rest are not (your question)? As stated before, the objects are following geodesics but the astronauts are not due to the mechanical resistance of the moon (thus, upward force). Is the moon accelerating around the Earth? Yes, relative to a non-inertial observer. Since the moon is basically traveling along the geodesics of the Earth's curved space-time (circling by following the geodesics around it, bringing it back to the same point), the moon's orbital motion is inertial. Unless, you want to argue that following geodesics is not classified as an inertial motion.

"And the net unbalanced accelerating force on the loose (inertial) golf ball and feather entities" ...??

Curvature of spacetime does not cause objects to accelerate. Rather, it causes objects to fall or orbit, for example. I still believe my sentence makes more sense: "By contrast, gravitation, in general relativity, is defined as the curvature of space-time which governs the motion of inertial objects."

I suggest you to read this article:

http://www.black-holes.org/relativity6.html comment added by Persistent76 (talk) 09:09, 29 September 2008 (UTC)

---Let's see, an accelerometer consists of a lightly restrained mass inside a box with a capabillity of measuring the relative spacial acceleration of the mass with respect to the box, or vice versa And you say that while I'm holding the box steady it will still register the existence of an acceleration. But when I release the box and it begins to presumably fall, the mass will be displaced from its original position and change to a new position that you choose to call the "zero acceleration position". So far so good. Now when we get to the end of this experiment we need to find out what entity there is that has acquired the kinetic energy that was released therein, and we will find that it was acquired by the so called "inertial mass" inside the instrument. Which leads me to the conclusion that it was the inertial mass that was being accelerated thereby towards the center of the local gravitational mass system, which was the moon. WFPMWFPM (talk) 16:17, 29 September 2008 (UTC) .WFPM .WFPMWFPM (talk) 09:49, 30 September 2008 (UTC)WFPMWFPM (talk) 09:54, 30 September 2008 (UTC)

Hi, WFPM:In General Relativity, we are not accelerating down; we are accelerating up on the ground. Falling objects are inertial because they are following geodesics of space-time. Thus, in our frame of reference, the falling objects are seen accelerating as motion is relative. It is a mistake to think that "since the geodesics are 'curved', there has to be acceleration." Hold an apple in mid-air and there is an upward force (exerted by you) to prevent it from falling. Now, why does the apple not accelerate up because of the upward force? That's not because you are holding it, but because spacetime is curved; the path of the apple is basically circling around the geometry of curved spacetime. This brings the apple back to the same point.

Now, throw the apple straight up. The apple rises and falls because the shape of spacetime influences the path of the apple. http://fy.chalmers.se/~rico/Theses/tesx.pdf Chp 2.4-2.6 explains it quite clearly of the whole apple scenario (Oh, "a picture explains a thousand words" the path of the apple in curved spacetime). The geometry of spacetime is a very important concept. The moon's orbit is another example of how the geometry of spacetime governs our motion. No matter how fast it orbits, the geodesics in spacetime will eventually bring the moon back to the same point in space (circling along the geodesics around the Earth). Thanks. comment added by Persistent76 (talk) 08:23:55, 30 September 2008 (UTC)

I have to agree with Persistent76 - while it is completely reasonable to use the mantra "Matter tells spacetime how to curve, spacetime tells matter how to move", it is vital to avoid saying that curvature accelerates objects. This can cause confusion since, as Persistent has already said above, you must consider proper acceleration in General Relativity, which is zero when following a geodesic. This consistency of definition has to maintained across the site or it will cause people to misunderstand basic notions of relative motion and the concepts of what an inertial and non-inertial observer are. I support the re-wording as suggested by Persistent76. (Mattrixx (talk) 08:32, 29 September 2008 (UTC)) ---If you are describing the activity of the accelerating ball toward the earth as shown in the article, which are you going to say? "I am watching the acceleration of the ball towards the earth". Or "I and the earth are accelerating upwards and watching a stationary ball"? WFPMWFPM (talk) 11:04, 30 September 2008 (UTC)

Hi, WFPM:This "I and the earth are accelerating upwards and watching a stationary ball", but it is actually not "stationary". When we travel along the geodesics in spacetime, we are undergoing inertial motion. Thus, relative to an inertial observer, the falling ball is traveling at constant velocity. Since we are actually non-inertial, the inertial ball is accelerating relative to us. Persistent76 (talk) 06:59:44, 02 October 2008 (UTC)

Let's consider this as an energy conversion process. A massive system is involved in a gravitational interaction with a small constituent thereof (lets say a released accelerometer). The result of this

process is for the constituents of the combined system to acquire the increased kinetic energy (delta v squared) as the result of the process. And science tells us that in an interchange of an equal amount on momentum between a large and a small mass, the small mass always does most of the accelerating and gets the vast majority of the increase in kinetic energy. WFPMWFPM (talk) 18:16, 2 October 2008 (UTC).WFPMWFPM (talk) 17:03, 11 October 2008 (UTC)

Who is Mr. Kassner

Wednesday, October 8, 2008

Who is Mr. Kassner? It appears the phrase Mr. Kassner has being inserted in many places where gravitation should appear. Has this article been vandalised? —Preceding unsigned comment added by 206.67.217.20 (talk) 16:26, 8 October 2008 (UTC)

Alternative Gravity Theory

This is a new theory published in a physics journal... just a month early. I have not violated any policy by posting it as I wrote without personal views and keep on topics discussed in the theory. There is no reason this should be removed when it is a legitimate paper. Slipinski (talk) 20:44, 8 October 2008 (UTC)

First of all, as the author of the paper, you should defer to the judgment of other editors to decide whether the new theory belongs in the article. As I see it, there are three things that count against the inclusion of this in the article. First of all, the paper appears in a fairly obscure physics journal. Secondly, the author is not an especially notable physicist. Third, there are apparently no physics reviews (or any third-party treatment) of this "new theory". Now, in terms of policy, Wikipedia strictly discourages dissemination of original research. Everything an article reports should have appeared elsewhere, and ideally in multiple third-party sources. Another item to consider is WP:WEIGHT. There are hundreds if not thousands of "alternative theories", many published, most unpublished, of varying degrees of plausibility. What you need to establish is that your theory has received on the same order of magnitude of discussion as some of the other theories listed here, such as Brans-Dicke theory, MOND, Heim theory, or the Rosen bi-metric theory. However, as far as I can tell there has been zero third-party coverage of this. Please correct me if I am wrong. siℓℓy rabbit (talk) 20:55, 8 October 2008 (UTC)

As far as your first two points I am not concerned with them as this is published in a peer reviewed physics journal. Additionally, if you would take the time to check it out, this theory meets all the same rigorous tests as GR and even has a derivation of the Coulomb force which is not present in any other gravity theory. There are third person reviews, however they have requested to remain anonymous so my hands are tied. However the fact remains this theory can complete all the GR tests including the binary pulsars. Once again I state I am in no violation of policy as this theory is equal to GR in the experimental tests. Slipinski (talk) 21:16, 8 October 2008 (UTC)

Gentlemen, you are both verging towards being accused either of edit warring or of 3RR violation. I am not a physicist, and make no claim personally to decide the merits of the Alternative Theory; but it does not appear at present to be supported by a meaningful body of opinion, as far as is claimed or admitted. And I appreciate that new theories displace old - for many years general relativity was held to be the last word. So was Newtonian mechanics. But would it be reasonable, given the current status of the theory, to rewrite the article to highlight this newness, rather than presenting it, as at present, as a theory which is given as much weight as is quantum mechanics? --Anthony.bradbury^"talk" 21:33, 8 October 2008 (UTC)

Ummm... we are talking about a crank theory here only just published in an obscure physics journal with minimal if any editorial oversight. This isn't about alternative theories in general, just this one. Which is covered zero third party sources or physics reviews. That said, I have no problem with alternative theories supplanting new ones, but an encyclopedia article is not the place for this to happen, and certainly not until the purported theories have gained some traction in the scientific community. Read WP:OR, which was specifically crafted to guard against this sort of thing. And, by the way, Slipinski is well over the 3rr limit here: a total of three editors have reverted his contributions. He should be blocked, but I don't have the time to fill out a 3rr report. siℓℓy rabbit (talk) 21:46, 8 October 2008 (UTC)

I have removed it yet again. The basic threshold for inclusion is that of WP:WEIGHT. A COMPARABLE NUMBER OF SOURCES should discuss this new theory as do the Brans-Dicke theory, and other established alternative theories of gravitation. So far there is only ONE source, in an obscure physics journal which is probably not peer-reviewed. (IMO, the new theory is a complete load of rubbish. Some physics journals must publish anything they come across.) When this new theory has received substantial coverage by third-party published sources then it may be considered for inclusion. Until then, keep your blatant self-promotion of original research out of the article. siℓℓy rabbit (talk) 03:24, 9 October 2008 (UTC)

A remark/position like "Added a section on a new theory of gravity which is equal if not better than General Relativity" is indeed going to need a massive amount of third party coverage. - DVdm (talk) 10:04, 9 October 2008 (UTC)

Dark Matter

"Stars in galaxies follow a distribution of velocities where stars on the outskirts are moving faster than they should according to the observed distributions of normal matter. Galaxies within galaxy clusters show a similar pattern. Dark matter, which would interact gravitationally but not electromagnetically, would account for the discrepancy."

This statement is almost entirely untrue, and against current theoritical ideas. The conentration of dark matter INSIDE of galixies is would cause a larger central aggrate mass, and would have no effect on the speed of the outer stars. The theory for the effect of the speed on the outer stars is that because of the gravity of the galixy as a whole is larger because of dark matter, they experence a larger time dialation due to the effects of Einstienan physics. They appear to be moving faster in respect to a stationary observer outside the galixy, but their local time frame appears to them unchanged. i.e. They see no effect due to dark matter. If anyone has seen this idea in print or refrenced other places, then please provide a refrence. —Preceding unsigned comment added by 99.185.0.29 (talk) 22:58, 22 October 2008 (UTC)

Gravity and gravitation

"Gravity", on the other hand, is described as the theoretical force responsible for the apparent attraction between a mass and the Earth.

This seems too specific. It is common, for example, to talk of "gravity" on other bodies such as the Moon or the planets. Also, "described" seems the wrong word here. Did the author mean "defined" perhaps? 14:56, 30 October 2008 (UTC).

This might addressed by fixing up the sentence -- use "Earth's gravity" instead. --Ancheta Wis (talk) 13:40, 2 November 2008 (UTC)

I think the paragraph was better as it was a few months ago. I don't remember the exact wording, and it's too tiresome to trawl back through hundreds and hundreds of edits, but I think the gist of it was something like:

The terms gravitation and gravity are mostly interchangeable in everyday use, but a distinction may be made in scientific usage: "gravitation" is a general term describing the phenomenon by which masses are attracted to one another, while "gravity" is a force which in certain theories (such as Newton's) is responsible for this attraction. In general relativity, in contrast, gravitation is a consequence of the curvature of spacetime which governs the motion of inertial objects.

Any objections to this wording? Any better suggestions? Matt 00:28, 5 November 2008 (UTC)~. —Preceding unsigned comment added by 86.152.243.89 (talk)

• Having looked into this some more, I can't find any references that support the statements in the original wording -- even though that accords better with my preconceptions. In fact, I found several other sources that more-or-less agree with the current wording. What I have done is just rearranged some of the sentences in the intro, and made one or two minor alterations to the wording, to improve the flow, as it seems to me. For good measure I also added another reference for the "gravity = earth's gravitational force" claim. Another Matt (talk) 00:36, 11 November 2008 (UTC) (btw, it was me above; I just didn't bother to sign in).

Scientific revolution

Newton Is also used in the popular lunch snack, Fig Newtons. This is because if you throw a Fig Newton at a fat person, they will revolve around them.

Why has this not been removed? —Preceding unsigned comment added by 85.24.201.147 (talk) 14:54, 21 November 2008 (UTC)

Fixed. User requested to edit constructively. - Eldereft (cont.) 16:57, 21 November 2008 (UTC)

Did Newton predict gravitational lensing, and did Eddington refute Newton and confirm Einstein ?

Was the prediction of gravitational lensing historically novel to Einstein's theory of gravity and did the 1919 Eddington eclipse experiments really confirm Einstein's GTR against Newton ?

In its Section 1.3 ‘General relativity’ section the article currently claims

"General relativity has enjoyed much success because of how its predictions of phenomena which are not called for by the theory of gravity have been regularly confirmed. For example: ... The prediction of the deflection of light was first confirmed by Arthur Eddington in 1919, and has more recently been strongly confirmed through the use of a quasar which passes behind the Sun as seen from the Earth."

And indeed it is a standard claim of positivist history of science that (i) Einstein's GTR made a historically novel prediction of gravitational lensing and (ii) that Eddington's 1919 eclipse experiments on Principe and Sobral then confirmed it.

However, in the first instance, contrary to the above claim, gravitational lensing is called for by the Newtonian theory of gravity insofar as it is obviously also predicted by any corpuscular theory of light, such as Newton's, and actually was predicted in the early 19th century.

Moreover a Newtonian gravitation prediction of a solar bending of starlight was also made for the 1919 eclipse experiments, namely a deflection of 0.87", whilst Einstein's theory predicted a deflection of 1.74".

But secondly, on the evidence of Earman & Glymour's 1980 paper Relativity and Eclipses: The British Eclipse Expeditions of 1919 and Their Predecessors in Historical Studies in the Physical Sciences, 11, pp. 49-85, either the outcome of the readings of all three telescopic instruments in the 1919 eclipse experiments on Principe and Sobral confirmed both the Newtonian and Einsteinian predictions of bending within experimental error, or else on the best result, which was obtained on Sobral, it refuted them both. Earman & Glymour write as follows:

"The natural conclusion from these results is that gravity definitely affects light, and that the gravitational deflection at the limb of the sun is somewhere between a little below 0.87" and a little above 2.0". If one kept the data from all three instruments, the best estimate of the deflection would have to be somewhere between the Newtonian value and the Einstein value. If one kept only the results of the Sobral 4-inch instrument [whose plates are unequivocally the best], the best estimate of the deflection would be 1.98", significantly above even Einstein's value. The conclusion that the Astronomer Royal announced...on November 6, 1919, was stronger: Einstein's prediction had been confirmed." [p76 Earman & Glymour 1980]

Thus I hereby flag the article's claim that the 1919 eclipse experiments confirmed Einstein against Newton, at least for further clarification pro tem, and for eventual removal if it cannot be substantiated.

--Logicus (talk) 19:05, 25 November 2008 (UTC)

Citation of 1919 experiment added. [Thanks for that] Note that this was the first experimental corroboration of Einsteins's 1907 formulation of the Principle of Equvalence. [Why ?] Of course, the precession of the perihelion of Mercury was already known, as an consequence of GR. [So what ?] --Ancheta Wis (talk) 20:44, 25 November 2008 (UTC)

Eddington et al come to the conclusion that the experiment confirms Einstein's theory and disconfirms Newton. It seems the above Earman & Glymour quote may have missed some of the context. Apparently the data from the Sobral observatory was excluded because of several systematic errors. Anyway, as the article notes, much better astronomical observations of lensing have subsequently confirmed Einstein's theory and disconfirmed Newton. siℓℓy rabbit (talk) 20:56, 25 November 2008 (UTC)

Logicus to Ancheta & Silly:Given the doubts about whether Eddington confirmed Einstein and refuted Newton raised by Earman & Glymour 1980, surely what is required here, in compliance with Wikipedia etiquette stated in footnotes 1 & 2 of Wikipedia:Verifiability, is the provision of a quotation that demonstrates a valid outcome expressed in a statement of the estimated deflection, also stating its boundaries of experimental error, and whereby the Newtonian prediction (of 0.87" ?) was outside of experimental error and the Einsteinian prediction (of 1.74" ?) was within it. Could either of you two gentlemen possibly provide one ?

Also please see my inserts above

--Logicus (talk) 17:30, 28 November 2008 (UTC)

Have you examined the above referenced Eddington et al paper? If so, do you still need clarification on the above points? If not, please do so. siℓℓy rabbit (talk) 17:50, 28 November 2008 (UTC)

Logicus to Silly:

Have you examined the above referenced Eddington et al paper? If so, can you please now confirm it refuted the Newtonian predicted deflection and confirmed Einstein's ? If not, please do so.

But note that referring to such a primary source and using it in the article as Ancheta has done apparently constitutes Wiki Original Research, albeit I have no personal objection to it. But of course I would hate to be accused of committing such myself (-:

By the way, note that Earman & Glymour refer to Dyson's November 1919 announcement and not the 1920 paper, which may have reported a different agreed outcome. I wonder what Peter Galison says on this episode.

As I see the Wiki correct procedure here, in compliance with Wiki Verification policy, Ancheta (or anybody else) should now be be supplying the quotation requested from the 1920 Dyson et al paper that verifies the agreed outcome refuted the Newtonian prediction of a 0.87" deflection and confirmed the GTR prediction of 1.74", notably just double the Newtonian prediction.

Here I present my (edited) edit of your above 25 November contribution that you deleted:

"Eddington et al come to the conclusion that the experiment confirms Einstein's theory and disconfirms Newton. [So what ? Did it actually do so ?] It seems the above Earman & Glymour quote may have missed some of the context. Apparently the data from the Sobral observatory was excluded because of several systematic errors. [Interesting. Could you kindly provide further detail and evidence on this please ?] Anyway, as the article notes, much better astronomical observations of lensing have subsequently confirmed Einstein's theory and disconfirmed Newton. [But the issue here is not whether GTR was ever confirmed and Newton refuted, but whether the Eddington eclipse experiment confirmed GTR but refuted Newton.] siℓℓy rabbit (talk) 20:56, 25 November 2008 (UTC)"

--Logicus (talk) 17:48, 7 December 2008 (UTC)

Logicus to Ancheta:Re your above contribution of 25 November, would you please kindly supply the requested verification that the 1920 Dyson et al paper you reference confirmed GTR and refuted the Newtonian prediction. Also please note your following claim

"Of course, the precession of the perihelion of Mercury was already known, as an consequence of GR."

is false. It was not already known as a consequence of GR, but rather had been known at least since the early 19th century. And as I recall (from reading), most of it was already explained by Newtonian theory. --Logicus (talk) 17:59, 7 December 2008 (UTC)

Logicus to Silly: Thanks you for providing quotations from the Dyson, Eddington & Davidson 1920 Royal Society paper, and also from Weinberg. If you now care to read this material logically and critically, I hope you will now agree with me and Earman & Glymour that on the most rigorous Sobral result both the Newtonian and Einsteinian predictions were refuted, where the refutation of a prediction means it falls outside the experimental error of the outcome, and on the most liberal interpretation both were confirmed.

The conclusion of the 1920 paper you quote:

“Thus the results of the expeditions to Sobral and Principe can leave little doubt that a deflection of light takes place in the neighbourhood of the sun and that it is of the amount demanded by Einstein's generalised theory of relativity, as attributable to the sun's gravitational field."

was clearly invalid in respect of its second conjunct on the basis of its declared 1.98” +- 0.12 best outcome and GTR’s 1.75” prediction, at least if you can agree that 1.98 – 0.12 = 1.86 and that 1.75 < 1.86 ?

This refutation is also evident from Weinberg’s bizarre statement you quote, which throws in the less satisfactory Principe result claimed in the 1920 paper as follows

“About a dozen stars in all were studied, and yielded values 1.98 ± 0.11" and 1.61 ± 0.31", in substantial agreement with Einstein's prediction θʘ = 1.75"."

But the first result he states clearly refuted the GTR prediction. The single relatively unreliable Principe result here was the only one that refuted Newton but confirmed GTR.

Do we have a classical case here of Feyerabend’s thesis that modern physics frequently interprets refutations as confirmations ?

By the way, what is the basis in the 1920 paper, if any, for your apparently mistaken earlier 25 November claim above that "It seems the above Earman & Glymour quote may have missed some of the context. Apparently the data from the Sobral observatory was excluded because of several systematic errors." ?

--Logicus (talk) 19:58, 8 December 2008 (UTC)

I provisionally conclude from this that the claim that Eddington's eclipse experiment refuted Newton but confirmed Einstein is mistaken and must be deleted. This is in addition to the fact that it must be deleted from where it is because it was clearly not an example of a phenomenon that was not predicted by Newtonian theory. --Logicus (talk) 20:02, 8 December 2008 (UTC)

I reject your preliminary conclusion, as it is entirely based on original research. The conclusion of the Eddington et al paper is one made by three of the most eminent astronomers of the era. The Weinberg quote establishes that these results have been accepted by the mainstream of the modern physics community as confirmatory of the predictions of the general theory of relativity. Surely other such quotes can be produced, if you would care to consult your local library. As I have already indicated, the results of the Sobral astrographic plates were rejected (contrary to your inexplicable claim that this was mistaken). From Eddington et al; e.g., p. 331: "There remain the Sobral astrographic plates which gave the deflection of 0".93 discordant by an amount much beyond the limits of its accidental error. For the reasons already described, not much weight is attached to this determination." Finally, the quote from Earman & Glymour is quite weak, since it is in the form of a conditional. I could truthfully say, "If it were the case that 1=0, then all pigs would have wings" without lending any weight to either the antecedent or the consequent of such a statement. You are free to "provisionally conclude" whatever suits your fancy. But before you make changes to the article based on your conclusion, may I suggest that you solicit more outside input on the matter? An RfC may help to bring in more expert input. siℓℓy rabbit (talk) 00:15, 9 December 2008 (UTC)

Cutting to the chase. It is quite public knowledge that the actual data of the 1919 expedition didn't quite back up the strong conclusions made by Eddington et al. (it is for example mentioned in Sean Carroll's Spacetime and Geometry on page 292) The trouble is with the fact the Eddington quite arbitrarily deleted data points as being 'systematic errors' in order to obtain his result. This is (literally!) a textbook example of bad science.

That being said Eddington's results have since then been confirmed many times by much more precise measurements, that completely refute the Newtonian theory, while agreeing with GR.

The sentence in question should probably be slightly altered to reflect the fact that the Eddington result was later doubted. I'll give it a go in a second. (TimothyRias (talk) 08:54, 9 December 2008 (UTC))

The present wording suits me just fine. I would just like to remark on the charge of "bad science". According to the following recent reassessment in Scientific American [2] Eddigton et al acted properly in rejecting the data of the Sobral astrographic plates. As the chief point made by those who call it bad science is that it seemed to reject the data which didn't fit the desired conclusion, this examination would seem to obviate such objections. siℓℓy rabbit (talk) 12:12, 9 December 2008 (UTC)

I actual had a look at the Kennefick article earlier today. He doesn't make a very strong case. In the end what should have happend is that Eddington should have presented his results with the suspect data point included. They could have discussed their reservation about that point in the article. But the final conclusion of their paper should have been that the result was indicative of Einstainian GR, but not conclusive and that better measurements where warrented. Instead they jumped the gun and declared that there result decisively confirmed GR. That is bad science by today's standard. For example, CERN has a policy of requiring 5 sigma certainty on results before declaring the discovery of a new particle of new phenomenon. (TimothyRias (talk) 14:47, 9 December 2008 (UTC))

Point taken. Results from stellar deflection data have apparently always been quite poor because they are apparently quite hard to calibrate. Weinberg has a table summarizing some of these results through the first half of the 20th century, and there isn't much if any improvement over the 1919 expedition. Declaring it a decisive confirmation is clearly a stretch by contemporary standards. Interferometric results from the latter half of the 20th century were much more accurate and consistent. siℓℓy rabbit (talk) 15:01, 9 December 2008 (UTC)

Logicus on just one quick logical point: Before we sort out the issue of whether or not Eddington 1919 confirmed Einstein AND also refuted Newton and how to express the outcome, the prior more basic question raised in the next discussion topic is whether gravitational lensing was a phenomenon not predicted by Newtonian theory as the article currently claims it was, and thus an example of a phenomenon to be included in this list of such phenomena. Since the phenomenon was also predicted by Newtonian theory, as the 1920 Dyson et al paper makes abundantly clear on its very first page, it must therefore be deleted from this particular list. Discussion of it may of course and indeed should be included elsewhere, with the invaluable contributions of TimothyRias. I shall perhaps comment on various invalid points made by Silly in the wider discussion later.--Logicus (talk) 22:56, 9 December 2008 (UTC)

That last comment is not very good form, Logicus. Let's try to keep things civil, ok? I stand by my assertion that this bullet point still belongs in this list. If you believe otherwise, please file an RfC. I am finished here. siℓℓy rabbit (talk) 23:27, 9 December 2008 (UTC)

Logicus to Silly: Contrary to your implication, no incivility was committed nor intended here. To refer to points as ‘invalid’ is not to be uncivil anymore than describing an argument as invalid is. For example, my provisional conclusion was not based “entirely on original research” as you claim it was, if indeed at all, but at least partly on the Weinberg secondary source that you quote. Thus at least this point of yours was invalid, as are many others. Such as, for another example, your 25 November claim that

“Apparently the data from the Sobral observatory was excluded because of several systematic errors.”

Which is apparently flatly contradicted and invalidated by the very first sentence of the ‘General Conclusions’ section of the 1920 paper on its page 330, which is as follows:

“In summarising the results of the two expeditions, the greatest weight must be attached to those obtained with the 4-inch lense at Sobral. “

And finally, it remains the case that gravitational lensing was not a phenomenon not also predicted by Newtonian theory, as the article still mistakenly claims.

--Logicus (talk) 20:21, 10 December 2008 (UTC)

Logicus's summary of the discussion:

I propose the outcome of the foregoing learned discussion and its referenced literature on whether the Eddington eclipse experiments on gravitational lensing confirmed the GTR prediction of a 1.75" deflection and refuted the Newtonian prediction of a 0.87" deflection may be summarised as follows.

(The Sobral1 and Sobral2 results refer to those of the Sobral 4-inch and Sobral 13-inch telescopes respectively.)

The Sobral1 result of 1.98" +- 0.12" refuted both the Newtonian and GTR predictions, but obviously the latter much less so. This was the most reliable result. The Principe result of 1.61" +- 0.3" confirmed GTR and refuted Newton. The Sobral2 result of 0.93" refuted GTR and confirmed Newton.

The Principe result was the only one that confirmed GTR and refuted Newton.

As Earman and Glymour [1980] point out, the joint range of all three results confirmed both GTR and Newton, and the most reliable result - Sobral1 - refuted both of them.

The stated conclusion of the 1920 Dyson, Eddington & Davidson Royal Society paper was that the Sobral1 and Principe results confirmed GTR and refuted Newton, thus both discounting the Sobral2 result, and also interpreting the Sobral1 refutation of GTR as a confirmation of it against Newton, presumably turning a refutation into a confirmation because it was a much better approximation than the Newtonian prediction, in spite of being refuted.

So the 1920 Royal Society paper understandably created the impression of illegitimate cherry-picking of experimental results and interpretations that confirmed GTR. So whilst the outcomes of the Eddington eclipse experiments were regarded as confirming gravitational lensing, on the other hand it seems they were regarded as indecisive as crucial experiments that decided between GTR and Newtonian theory. Thus they cannot be counted as experiments whose estimated outcomes would have justified the acceptance of GTR and the rejection of the Newtonian theory of gravity in 1920.

But subsequent computer analysis of the Sobral2 data by Greenwich Royal Observatory in 1978 corrected its result to 1.55" +- 0.34" [See Minkel's article in Scientific American 6 March 2008.]. Hence on this analysis all three results had refuted Newton, two of them had in fact confirmed GTR (Principe & Sobral2), and the most reliable refuted GTR and also Newton (Sobral1). And the whole range of all three results now confirmed the GTR prediction and refuted the Newtonian prediction.

However, it seems that by 1978 GTR was already generally accepted as replacing the Newtonian theory of gravity.

Hence in conclusion, whilst the Eddington eclipse experiments confirmed gravitational lensing in 1919, they were not amongst those experiments whose outcomes should have caused the rejection of the Newtonian theory of gravity in favour of the general acceptance of GTR by the scientific community since they were indecisive on that particular issue. Nor has any evidence been presented that they actually did so at that time, or that GTR replaced Newtonian gravity theory in the 1920s.

It remains to determine (from the literature) by when at least the majority conversion of the scientific community from Newtonian gravity theory to GTR occurred, and what experimental result(s), if any, caused that conversion. By what date did the Newtonian theory of gravity come to be largely regarded as refuted by experiment and GTR as confirmed by experiment ? And by what experiment(s) ? The literature seems to imply the range of this date lies somewhere between 1915 and 1975.

This must be established to determine whether the article’s following methodologically interesting current claim is true or not:

“General relativity has enjoyed much success because it predicted new phenomena that other theories of gravitation could not account for,…”

if “has enjoyed much success” means ‘has been largely accepted by the scientific community’.

Incidentally it is by way perhaps noteworthy that the 1920 paper made no account nor even any mention whatever of any lunar gravitational deflection, which might presumably have increased the deflection, but only of the solar deflection ? Was its presumption maybe that lunar deflection would be wholly insignificant ?

In practical conclusion, as things stand both the 1919 gravitational lensing and the precession of Mercury's perihelion must be deleted from the current list of novel phenomena that caused the general acceptance of GTR.

--Logicus (talk) 15:42, 14 December 2008 (UTC)

Logicus: The following summary conclusion of the outcome of the Eddington eclipse experiments in the highly regarded A History of Mechanics by Rene Dugas is surely worthy of mention in support of their relative inconclusiveness:

"However, several astronomers discussed these experiments and gave contradictory interpretations of them. In the same way the measurements made by Campbell and Trumpler during the eclipse of 21 September 1922 were not considered unanimously conclusive." [p527 Dugas 'A History of Mechanics' 1955/88] --Logicus (talk) 19:19, 17 December 2008 (UTC)

A contribution by David Wilson

I copy below what seems to be an important contribution to discussion of this issue by David Wilson that more properly belongs here rather than in the following discussion topic where it was made. It is relatively self-contained, but does make some references to the previous discussion which can be checked out below in that discussion topic. --Logicus (talk) 16:54, 2 January 2009 (UTC)

---

David Wilson

The problem with Wikipedia's claiming that General Relativity was confirmed by the results reported in the [1920 Dyson et al] paper is not to do with any supposed unreliability of the source, but with the neutrality of that point of view. Unfortunately, the claim has been challenged by other sources which also clearly satisfy Wikipedia's criteria for reliable sources. I say "unfortunately" here, because I happen to agree with you that the analysis of Earman and Glymour's reported by Logicus doesn't appear to stand up to scrutiny. At the risk of polluting this talk page with some original research of my own I will point out that the significance of the differences between the General Relativistic predictions and the experimental results reported in the paper of Dyson et al. are even less than what you have concluded above.

The error bounds given in the paper were not estimated standard deviations as you have surmised, but estimated probable errors—i.e. estimated differences between the limits of a 50% confidence interval about the experimental result and the result itself. If the errors were normally distributed, the probable error would only be 0.674 of a standard deviation. This means that the actual estimate for the standard deviation of the experimental result from the 4-inch Sobral telescope, for instance, is 0.178" rather than 0.12". Thus, a two-tailed significance test of the discrepancy between the prediction and the experimental estimate gives a p-value of 0.196. I'm aware of no circumstances under which any texts on statistics or experimental method have recommend regarding such a high p-value as being "significant". In my opinion, a p-value of 0.196 indicates at least a "fair" agreement between the prediction and the experimental result, and I wouldn't argue with anyone who wanted to describe it as "satisfactory".

—David Wilson (talk · cont) 10:59, 21 December 2008 (UTC)

I can't resist also pointing out that if one ignores the suspicions of Dyson et al. that the results from the Sobral astrographic telescope had been vitiated by systematic errors, then a reasonable statistical analysis of all three results shows that the agreement between those results and Einstein's prediction turns out to be excellent. Contrary to the claim of Earman and Glymour's quoted by Logicus above:

"If one kept the data from all three instruments, the best estimate of the deflection would have to be somewhere between the Newtonian value and the Einstein value."

the maximum likelihood estimate of the deflection, based on all three experimental results, is actually 1.817" with an estimated standard deviation of 0.152". Two-tailed tests of significance of the discrepancies between this estimate and the Einsteinian and Newtonian predictions give p-values of 0.668 and 1.3 x 10^-9 respectively. So if there were in fact no systematic errors in the data, the experimental results would actually be in excellent agreement with Einsteinian prediction and decisively refute the Newtonian. The sum of squares of the appropriately normalised differences between the maximum likelihood estimate and the three experimentally determined estimates is 5.01 5.66. If there are no systematic errors, this should be (at least approximately) distributed as a χ² with three two degrees of freedom, giving a p-value of 0.17 0.06 for a right-tailed test of the significance of the discrepancy. This last (admittedly fairly crude) statistical test therefore gives very little only a slight indication of there being any that there might be systematic errors in the data (not that this provides much grounds for questioning the judgement of the experimenters themselves on the matter).

—David Wilson (talk · cont) 12:17, 21 December 2008 (UTC)

A contribution by BenRG

I copy below a contribution by BenRG that more properly belongs to this discussion topic rather than the following topic where it was made. --Logicus (talk) 16:54, 2 January 2009 (UTC)

---

1919 eclipse experiment references

Here are some references on the 1919 eclipse experiment and the claims of poor data analysis. Apologies if these have already been mentioned somewhere in the discussion above, which I only skimmed.

• Peter Coles, "Einstein, Eddington and the 1919 Eclipse." arXiv:astro-ph/0102462v1
• Daniel Kennefick, "Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse Expedition." arXiv:0709.0685v2
• Philip Ball, "Arthur Eddington was innocent!" Nature, doi:10.1038/news070903-20

-- BenRG (talk) 21:02, 24 December 2008 (UTC)

Logicus to BenRG:Thanks for these references, not mentioned above. It would be most helpful if you could also possibly give a brief summary of what you think their conclusion should be, that is, for example do they suggest a majority of scientists think the 1919 eclipse experiments were indecisive or rather that they conclusively refuted Newton’s law of gravitation and confirmed Einstein’s GTR ? --Logicus (talk) 19:08, 30 December 2008 (UTC)

Not all the GTR novel predictions listed were of previously unpredicted novel phenomena

Since the article presents GTR as a theory of gravity, which maintains gravity is not a force but rather a spacetime curvature, its following current claim is therefore illogical nonsense

"General relativity has enjoyed much success because of how its predictions of phenomena which are not called for by the theory of gravity have been regularly confirmed."

because gravitational lensing was predicted by the Einsteinian theory of gravity, and so presumably it should be and was intended to mean

'General relativity has enjoyed much success because of how its predictions of phenomena which are not predicted by the Newtonian theory of gravity (or any other competing theories of gravity) have been confirmed.'

But then at least the case of gravitational lensing must be deleted from the following stated examples of such, since it is a phenomenon that was also predicted by Newtonian theory with a corpuscular theory of light.

Thus I propose to edit this text as rationalised here, and also to delete the invalid example of gravitational lensing, which could possibly be cited elsewhere as a crucial experiment between Newtonian and Einsteinian gravity theory, if indeed it can be documented that it was i.e. that Einstein was confirmed and Newton refuted. (But it has not yet been documented that it was.)

The example of the perihelion precession of Mercury must also be deleted since that phenomenon was also predicted by Newtonian theory, but just not as completely.

This thus leaves 4 examples of phenomena allegedly not predicted nor explained by Newtonian theory in any way, but at least successfully explained or even predicted by GTR.

But surely the expansion of the universe was no more predicted by GTR, with its cosmological constant, than it was by Newtonian theory, to whose cosmology it also offered a solution to the problem of cosmological gravitational collapse in a 'Big Crunch' ?

I implement these proposed edits for consideration or improvement.

--Logicus (talk) 17:14, 7 December 2008 (UTC)

Black_hole#Newtonian_theories- in Newtonian mechanics light was thought to be massless. But IRC even if you assume that it is massive, then you get the wrong degree of distortion, and so Newton is still denied by the starlight experiment.- (User) Wolfkeeper (Talk) 02:28, 9 December 2008 (UTC)

Logicus to Wolfkeeper: I do not understand your comment and its logical relevance. The issue here is whether the prediction of gravitational lensing was a uniquely historical novel prediction of GTR, but which in fact it was not because it was also predicted by Newtonian theory. The issue as claimed in the article is not that of whether one theory predicted the gravitational deflection more accurately or had its quantiative prediction refuted or not, but rather whether it predicted this kind of phenomenon at all. (Positivist history of science, such as usually indulged in by Wikipedia, has traditionally misrepresented Newtonian theory as not even ever predicting gravitational lensing at all, including nor in the Eddington experiment, and therefore GTR being confirmed merely by virtue of predicting it and the fact that at least one of the three results confirmed the GTR 1.75” deflection prediction, if refuted by the other two.)

The wider issue of scientific method raised here is whether historical theory change in the relevant scientific community is indeed solely due to the new theory making absolutely novel predictions, that is, of a kind of phenomenon never before observed nor even predicted, which are successfully confirmed (i.e. the methodology of theory change apparently adopted by Wikipedia here), OR or may theory change result just from the successful prediction of already known or already predicted phenomena, such as the precession of Mercury’s perihelion already known and predicted (arguably even since the 1713 Principia second edition with its revised prediction of moving aphelia of the inner planets) and indeed already largely explained albeit not completely by Newtonian theory.

Thus should the conversion of the scientific community to GTR have occurred in 1916 with its successful complete explanation of the precession of Mercury’s perihelion, or at least by 1919 in having greater success in explaining gravitational lensing also predicted by Newtonian theory, or should it have occurred much later with the confirmation of some absolutely novel phenomenon not predicted by any other theory ? And as a matter of fact, when was the conversion of at least a majority of the scientific community from Newtonian gravity theory to GTR ? Was it even as late as post 1960 as such as Kuhn seem to imply ?

These issues are of central importance to Wikipedia’s accounts of the scientific method of ‘modern science’ in other articles as being empirical and theory change as being determined by experimental facts. If so, the question then arises of what kind of experimental facts cause theory change e.g. only historically novel experimental facts or also new explanations of old experimental facts ? More later...

--Logicus (talk) 15:53, 13 December 2008 (UTC)

I must refute your claims. You clearly have misunderstood the papers that you read:

1) Newton theory made no prediction whatsoever about bending of electromagnetic radiation. I must stress this words—electromagnetic radiation. And it was known well before GR that light was just an form of electromagnetic radiation. It was also known that Newtonian mechanics was incompatible with classical electrodynamics (this led to creation of special relativity). Therefore Newtonian mechanics strictly speaking was unable to make any predictions about the light deflection. As to the corpuscular theory of light, it had been rejected long before 1920, and nobody seriously considered it as a valid theory.

2) You misunderstands the meaning of the precision in scientific experiment. ±0.11” is just 1σ. If the difference between the experiment and theory exceeds 1σ, it does not mean that the theory is refuted. 1σ is not a rigid barrier. So the difference between 1.74” and 1.98”, which about 2.5σ is not very significant. However the difference between 0.87 and 1.98 (about 11σ) is very large. The probability that the result will fall within the bounds of GR predictions is around 1% (2.5σ). The probability that the NM result is valid is less than e^-100—zero. And you should take into account that ±0.11 is only a lower limit of precision. The real experimental limit was of course larger. For instance if the precision is 0.22”, it will mean that the difference is just 1.25σ—insignificant.

3) It is the first time I read that the Newtonian theory explained precession of orbits. First of all in the coulomb potential particles move along closed trajectories and therefore orbits can not precess. To explain precession the potential must deviate from 1/r law. In the second half of 19-th century several theories were proposed: a new planet (Vulcan) inside the orbit of Mercury, non-zero Solar quadrupole momentum, modification of the gravitational potential of the form 1/r^1+α, where α is a small parameter. All of them were rejected by different reasons. Old books (especially printed in 1711), of course, can contain weird claims, but it only means that they are not reliable sources. Can you provided any citations from the second half of 19-th century that support your claim that NM actually explained precession of orbits? Probably not.

Ruslik (talk) 14:15, 14 December 2008 (UTC)

Logicus to Ruslik: Whether or not I may have misunderstood the papers I have read as you claim, it seems you cannot have read them at all, and also know little of the history of Newtonian celestial mechanics, which you clearly do not understand. I shall comment each of your three points in turn.

I admit that classical mechanics is not my specialization in the theoretical physics. I am more a specialist in optics, classical electrodynamics and condensed matter physics. Still I am curious what I do not understand in it? Ruslik (talk) 20:33, 15 December 2008 (UTC)

1) Provisionally setting aside your views on light and electromagnetism, given your view that Newtonian theory did not make, and indeed could not make, any prediction of any positive gravitational light deflection, how then do you account for the opening statement of the 1920 Dyson, Eddington & Davidson Royal Society paper that the Newtonian law of gravitation predicted a 0.87" gravitational starlight deflection, and that the Eddington eclipse experiments were conducted to decide between the three alternative predictions of (i) no gravitational deflection, (ii) the Newtonian prediction of a 0.87" deflection and (iii) the GTR prediction of a 1.75" deflection ? Do you think Dyson, Eddington & Davidson were simply deluded in thinking Newtonian theory made any prediction of a positive gravitational deflection ? They say in their paper that the 0.87" deflection predicted by the Newtonian law of gravitation was made by Einstein himself in a 1911 paper in the German 'Annals of Physics'. On their opening page they wrote on the hypothesis 2 they were testing:

"The energy or mass of light is subject to gravitation in the same way as ordinary matter. If the law of gravitation is strictly the Newtonian law, this leads to an apparent displacement of a star close to the sun's limb amounting to 0".87 outwards."

The Newtonian result was obtained for massive particles moving much slower that the speed of light. As such it is inapplicable to massless light particles, which move at the speed of light, of course. Ruslik (talk) 20:08, 15 December 2008 (UTC)

2) Thank you for the elementary lecture in experimental error and its standard deviations. So where do you maintain science draws, or should draw, the borderline between the quantitative refutation and confirmation of quantitative predictions ? Nowhere ? Or somewhere ?

In experimental physics the line is usually drawn at 3σ. Ruslik (talk) 20:08, 15 December 2008 (UTC)

You need to evidence this interesting claim. But whatever, it seems your claim now means the Principe result confirms Newton.--Logicus (talk) 19:30, 18 December 2008 (UTC)

Evidence against a normal hypothesis that does not reach 3σ may or may not be considered to have failed to refute it, but would certainly not normally be considered to have confirmed the normal hypothesis below p=0.05.- (User) Wolfkeeper (Talk) 20:44, 21 December 2008 (UTC)

3)I shall offer you some education on the 19th century Newtonian Mercury precession theory of such as Leverrier and Newcomb later. Meanwhile you might like to review whether you mean the inverse-squared law when you write 1/r. --Logicus (talk) 19:29, 15 December 2008 (UTC)

I definitely meant 1/r law. The gravitational potential follows 1/r law, does not it? 1/r² is for the gravitational acceleration. Ruslik (talk) 20:08, 15 December 2008 (UTC)

Logicus to Ruslik: OK, thanks for clarifications. Just on your point 3 here, Will's 1986 'Was Einstein right ?' says precession of Mercury's perihelion was 574" per century, and in the 19th century Leverrier predicted 38" short of 574" = 536" on Newtonian mechanics. I think Newcomb corrected this by little sometime later ? The 1920 Dyson et al paper says motion of Mercury's perihelion exceeded Newtonian predicted value by 43" per century, and this was accounted for by Einstein's GTR. Thus the salient point here seems to be that some 94% or so of the precession of Mercury's perhelion was explained by Newton mechanics. As I said, the precession was very largely explained by Newtonian mechanics.

Well, I concede point 3. Of course, orbits precess under the influence from other planets. I meant only that the anomalous precession had remained unexplained until GTR. However the classical precession was not especially remarkable, while the anomalous part was. Ruslik (talk) 19:49, 16 December 2008 (UTC)

It is most refreshing and welcome to see a Wikipedia editor who apparently regards the 1713 second edition of Newton's Principia as unreliable, as indeed it was, and contrary to the positivist misrepresentation of it in Wikipedia articles as reliable and correct.

My remark about the 1713 Principia arguably predicting a precession of Mercury's perihelion refer to its prediction of moving aphelia for Mars, Earth, Venus and Mercury in its new Scholium to Proposition 14 of Bk 3 that was added to the second edition, and contradicting the 1687 first edition's Proposition 14 claim of static aphelia, also repeated in the second edition. The essential background to this novel prediction is that Roger Cotes had forcefully pointed out to Newton that Leibniz's critique of universal mutual gravitation as unproven in the first edition was correct, and that in particular the proof in Propositions 1 to 8 of Book 3 collapsed into question begging circularity at Corollary 1 of Proposition 5 where Newton invalidly attempted to move from demonstrating unilateral centripetal gravitation to proving mutual bilateral gravitation by appeal to his third law of motion. Given this failure of absolute proof of mutual gravitation from the 6 Phenomena of Book 3 and Leibniz's general point that logically deductive proofs from facts to theorems were impossible in empirical science, Cotes' recommended revised proof strategy seems to have been to adopt the Huygens-Leibniz criterion of empirical proof of a theory by the successful prediction of entirely novel phenomena. And two of these novel phenomena that were supposed to prove mutual gravitation in the second edition of the Principia were the mutual perturbation of Jupiter and Saturn at conjunction and the moving aphelia and nodes of Mercury, Venus, Earth and Mars, all perturbed by Jupiter and Saturn. See Cotes's 1713 Preface, and in particular see Corollary 3 of Proposition 5 and Proposition 13 of Book 3 for the predictions of the unilateral perturbation of Saturn by Jupiter.

But as it happened none of these phenomena could possibly be observed at the time, and morever most farcically in neither case did Newton's predictions imply mutuality, but rather only unilateral perturbations of one planet by another, but not vice versa. But he gave a hypothetical estimate of the motion of Mercury's aphelion as 256" per century conditional upon that of Mars being 33' 20" per century, apparently just to illustrate the proportionalities rather than any absolute values.

Now a moving and precessing perihelion surely follows immediately from a moving aphelion if Mercury were not to crash into the sun eventually. This is the possible argument that in effect the precession of Mercury's perihelion was first (implicitly) predicted in the 1713 Principia by virtue of its prediction of its moving aphelion as a result of Jovial gravitational perturbation. But this was of course only a qualitative prediction inasmuch as the amount of its perihelion precession was not derivable from that of its hypothetical but quantified aphelion advance.

--Logicus (talk) 19:28, 16 December 2008 (UTC)

Logicus to Ruslik:So on point 3 it seems we at least agree that precession was not a novel phenomenon predicted only by GTR. Thus I hope you agree it must be deleted from the current list of such phenomena.

No, it should not. GTR predicted that the precession would remain even if all other planets are absent, which was a remarkable result! It predicted that even in the purely spherically symmetrical gravitational field orbits would precess. This was entirely new phenomenon, which had not been predicted by classical mechanics. This precession becomes huge for relativistic objects. Ruslik (talk) 20:30, 17 December 2008 (UTC)

You are misunderstanding the logic of the issue here. The new novel phenomenon you now cite of precession in the absence of all other planets has never been experimentally confirmed. The relevant point is that orbital precession was not itself a novel prediction of GTR as is claimed, and thus must be deleted from the current list of such. --Logicus (talk) 19:30, 18 December 2008 (UTC)

No, I do not. This novel phenomenon has been confirmed by observations of Mercury and other planets. The relativistic effects have been observed directly in double systems of pulsars. For the review of the Mercury's theory of motions see this, for instance. The paper is a reliable secondary source. Ruslik (talk) 20:07, 18 December 2008 (UTC)

Just for your further information on orbital precession and Newton versus GTR, I understand Newcomb found the motion of Mercury's perihelion per century to be 41.24" more than that predicted by Newtonian perturbation theory, that of Venus to be 10.14" more, and that of Mars 8.03" more.

GTR predicted Mercury's to be 42.09" more than predicted by Newtonian theory, that of Mars to be 1.35" more (one-sixth of Newcomb's estimate), but with no improvement on the Newtonian prediction for that of Venus.

Clearly the success of GTR on orbital precession was not as great as usually depicted, namely just with virtually complete success in the case of Mercury.

Precession of Mercury was known with better precision than precession of both Venus and Mars (and Earth). So it was a clear success. Ruslik (talk) 20:30, 17 December 2008 (UTC)

In fact in the 19th century precession had been a confirmation of Newton's thesis of gravitation between planets, a crucial step in his attempted but failed proof of universal mutual gravitation between all particles of matter, if not of any mutuality between planets. --Logicus (talk) 19:16, 17 December 2008 (UTC)

Logicus to Ruslik: On your point 1, in evidence of the fact that gravitationl lensing was not newly predicted by GTR as claimed, but rather had already been predicted, and in fact by Newton himself, here is Newton's prediction fropm his Opticks

"Might not bodies act at a distance on light ? Does not this action deviate the rays of light and is it not, other things beings equal besides, all the more stronger as the distance is less ?"

The interrogatives are clearly just rhetorical. --Logicus (talk) 19:25, 17 December 2008 (UTC)

I do not see see any predictions, only speculations. Prediction means mathematical calculation. Do you know any paper where Newtonian gravitational potential was somehow inserted into the Maxwell equations, and where it was shown that electromagnetic waves propagate differently in the presence of the gravitation? In the General Relativity it can be easily done. I must repeat the Newtonian mechanics makes no predictions about propagation of the electromagnetic radiation (they are incompatible with each other). Ruslik (talk) 20:07, 18 December 2008 (UTC)

Regardless of any supposed incompatibility between Newtonian Mechanics and Maxwell's theory of electromagnetism, it is a verifiable fact^[1] that in 1784 Cavendish obtained a formula for the amount by which light, according to his interpretation of Newton's theories of optics, mechanics and gravity, would be deflected by a massive body. Expressed in modern notation, his formula was $2\,\arcsin(\epsilon /(1+\epsilon ))$, with $\epsilon =^{def}\ Gm/(c^{2}d)$, $G=^{def}\ {\mbox{gravitational constant}}$, $m=^{def}\ {\mbox{mass of the body}}$, $c=^{def}\ {\mbox{velocity of light at infinity}}$, and $d=^{def}\ {\mbox{distance of the light ray from the centre of the body}}$. To the first order in $\ \epsilon$ (a small quantity) this is half the amount Einstein obtained for the prediction of General Relativity. Cavendish did not publish his result, but essentially the same formula was published in an astronomical journal by Johann von Soldner in 1801.

Cavendish and Soldner's calculations assumed that light was corpuscular, as required by Newton's theory, and seem to have been pretty much ignored throughout the 19th century. However, a non-relativistic (i.e. Newtonian) theory which did'nt make that assumption was proposed by Max Abraham in 1912, between 1911 and 1915 several (incomplete) gravitational theories were proposed which and this predicted a deflection of the same amount (at least, to the first order in small quantities). These theories Abraham's theory assumed that the velocity of light in a gravitational field was an increasing function of the gravitational potential, or, equivalently, that the refractive index of the æther was a decreasing function of it. His theory would therefore appear to me be perfectly compatible with Maxwell's theory for a medium with a non-uniform refractive index. Moreover, as Logicus has already indicated, Dyson, Eddington and Davidson acknowledged in their 1920 paper that if "[t]he energy or mass of light is subject to gravitation in the same way as ordinary matter", and "[i]f the law of gravitation is strictly the Newtonian law, this leads to an apparent displacement of a star close to the sun's limb amounting to 0".87 outwards."

—This is part of a comment by David J Wilson (of 16:40, 19 December 2008 (UTC)), which was interrupted by the following:

I do not understand you, because you made two statements that contradict each other. If the theory is non-relativistic it follows that it is incompatible with Maxwell's theory, which is relativistic. These two statements (that the Abraham's theory is non-relativistic and that is is perfectly compatible with Maxwell's theory) can not be simultaneously true. Ruslik (talk) 16:40, 19 December 2008 (UTC)

If you don't mind, I would prefer not to have a logically united sequence of my remarks interrupted with interpolations from other editors. While the talk page guidelines do say "[i]n some cases, it is OK to interrupt a long contribution" (emphases added by me), I would regard it as impolite in most cases for me to do so without first obtaining the permission of the editor whose comments I was interrupting. In any case, the guideline also requests that any such interruptions be heralded with the template {{subst:interrupted|USER NAME OR IP}}, which I have now prepended to the above comment.

—David Wilson (talk · cont) 02:54, 20 December 2008 (UTC)

In view of all this, it would seem to me to be misleading for the article to say, without any further qualification, that the deflection of starlight by the sun was a "novel prediction" of General Relativity. Such a statement would be apt to leave readers with the erroneous impression that no preceding theory had ever predicted such a deflection.

Nevertheless, since the article doesn't say this at the moment, and as far as I can tell, doesn't now give any misleading impressions about the prior history of such predictions (or of those concerning the change in the apsides of planets' orbits), I'm wondering what the point of all the above discussion is. Do either of you have any proposals for further modifications of the article?

Footnotes

1.^ From Eudoxus to Einstein, by C.M. Linton, p.460.

—David Wilson (talk · cont) 14:35, 19 December 2008 (UTC)

My apology for interrupting your comments. I am too accustomed to this kind of discussions, where comments are frequently interrupted without any permissions and templates. Ruslik (talk) 12:10, 20 December 2008 (UTC)

Thank you for your gracious response. In a discussion where everyone was doing the same thing I probably would have bitten my lip and refrained from complaining. Still, it's a practice I hope never becomes widely established on Wikipedia.

—David Wilson (talk · cont) 07:52, 21 December 2008 (UTC)

Logicus to Ruslik & Wilson: Before reading Wilson's interesting intervention, I had proposed the following.

On Ruslik's Point 1: On point 1, it is clear that even Newton himself predicted gravitational lensing and also that Einstein, Dyson, Eddington and Davidson also regarded it as predicted by Newtonian theory and making a quantitative prediction for it. And it is their view that is relevant here, not your view that it is not so predicted. Thus whether the GTR prediction of gravitaional lensing was successful or not, it clearly cannot be counted as a case of the prediction of a novel phenomenon only predicted by that theory, as required in the Huygens-Leibniz criterion of theory acceptance it seems Wikipedia is employimg here. :So you think that Dyson et.al. is a reliable source that should be relied upon? Well, I will accept this conclusion, but other results of that paper are also valid. For instance, that GTR was confirmed and the Newtonian theory was rejected. You can not cherry pick just one thing from this paper, and neglect another. Ruslik (talk) 20:57, 19 December 2008 (UTC)

Point 2: This point is irrelevant because the issue is whether gravitational lensing was predicted by any other theory, not whether the experiment's quantitative outcome refuted any other theory. And if it did, then this means it was predicted by another theory, and so again gravitaional lensing does not belong in the list in question.

Also note that Dicke & Goldenberg 1960 challenged the validity of GTR Mercury perihelion precession result against Newton, and I understand it may still be unresolved.

In conclusion it seems there are no valid objections to the deletions of orbital precession and gravitaional lensing from the list of novel phenomena otherwise unpredicted. So I conclude that the GTR predictions of Mercury's orbital precession and of gravitational lensing must both be deleted from the current list of novel phenomena only predicted by GTR, and discussed seperately as possibly examples of phenomena just predicted more accurately than by other theories by GTR rather than phenomena uniquely predicted by GTR.

I propose something of the following ilk for such a discussion:

'In its early days GTR also predicted some phenomena already predicted by Newtonian theory more accurately, such as the orbital precession of two planets, Mercury and Mars, and the gravitational lensing of light. But whether the outcomes of these pr'edictions refuted Newtonian gravitation and confirmed GTR is disputed.'

--Logicus (talk) 17:27, 19 December 2008 (UTC)

What are trying to prove here? That GTR is uncofirmed theory and there are alternatives to it? This is wrong. GTR is one of the basic theories of modern physics. GTR is used to calculate trajectories of space probes. If it were wrong Cassini would have been unable to fly by Enceladus at the distance of 25 km. So validity of GTR is out any question.

Dicke et al claimed that quadrupole moment of the Sun is large enough to explain anomalous precession. This is wrong. Currently the value of quadrupole moment of the Sun is not known, because it is too small (on the order of 10⁻⁷)—see ref that I provided above. So the work Dicke was erroneous. Ruslik (talk) 20:46, 19 December 2008 (UTC)

Ruslik wrote:

"I do not understand you, because you made two statements that contradict each other. ..."

Well, I guess that makes us even, since I don't understand (and strongly disagree with) your claim that Maxwell's theory is incompatible with a non-relativisic theory. It may be that we are using the terms "Maxwell's theory" and "incompatible" to mean different things, but in any case, the issue is irrelevant to the point I was making, and further discussion of the matter would be inappropriate for this talk page anyway.

Judging from some of the on-line sources I have been able to find, there would appear to be some disagreement as to whether Abrahams's theory was in fact "relativistic" or not—and even whether it was "consistent" or not—so my description of it may reflect a non-neutral point of view. I have therefore withdrawn it.

Next:

"So you think that Dyson et.al. is a reliable source that should be relied upon? Well, I will accept this conclusion, but other results of that paper are also valid. ... "

The problem with Wikipedia's claiming that General Relativity was confirmed by the results reported in the paper is not to do with any supposed unreliability of the source, but with the neutrality of that point of view. Unfortunately, the claim has been challenged by other sources which also clearly satisfy Wikipedia's criteria for reliable sources. I say "unfortunately" here, because I happen to agree with you that the analysis of Earman and Glymour's reported by Logicus doesn't appear to stand up to scrutiny. At the risk of polluting this talk page with some original research of my own I will point out that the significance of the differences between the General Relativistic predictions and the experimental results reported in the paper of Dyson et al. are even less than what you have concluded above.

The error bounds given in the paper were not estimated standard deviations as you have surmised, but estimated probable errors—i.e. estimated differences between the limits of a 50% confidence interval about the experimental result and the result itself. If the errors were normally distributed, the probable error would only be 0.674 of a standard deviation. This means that the actual estimate for the standard deviation of the experimental result from the 4-inch Sobral telescope, for instance, is 0.178" rather than 0.12". Thus, a two-tailed significance test of the discrepancy between the prediction and the experimental estimate gives a p-value of 0.196. I'm aware of no circumstances under which any texts on statistics or experimental method have recommend regarding such a high p-value as being "significant". In my opinion, a p-value of 0.196 indicates at least a "fair" agreement between the prediction and the experimental result, and I wouldn't argue with anyone who wanted to describe it as "satisfactory".

—David Wilson (talk · cont) 10:59, 21 December 2008 (UTC)

I can't resist also pointing out that if one ignores the suspicions of Dyson et al. that the results from the Sobral astrographic telescope had been vitiated by systematic errors, then a reasonable statistical analysis of all three results shows that the agreement between those results and Einstein's prediction turns out to be excellent. Contrary to the claim of Earman and Glymour's quoted by Logicus above:

"If one kept the data from all three instruments, the best estimate of the deflection would have to be somewhere between the Newtonian value and the Einstein value."

the maximum likelihood estimate of the deflection, based on all three experimental results, is actually 1.817" with an estimated standard deviation of 0.152". Two-tailed tests of significance of the discrepancies between this estimate and the Einsteinian and Newtonian predictions give p-values of 0.668 and 1.3 x 10^-9 respectively. So if there were in fact no systematic errors in the data, the experimental results would actually be in excellent agreement with Einsteinian prediction and decisively refute the Newtonian. The sum of squares of the appropriately normalised differences between the maximum likelihood estimate and the three experimentally determined estimates is 5.01 5.66. If there are no systematic errors, this should be (at least approximately) distributed as a χ² with three two degrees of freedom, giving a p-value of 0.17 0.06 for a right-tailed test of the significance of the discrepancy. This last (admittedly fairly crude) statistical test therefore gives very little only a slight indication of there being any that there might be systematic errors in the data (not that this provides much grounds for questioning the judgement of the experimenters themselves on the matter).

—David Wilson (talk · cont) 12:17, 21 December 2008 (UTC)

I agree with your assessment. I also find the current content of the article satisfactory. I began this discussion only because Logicus wanted to get rid of the light deflection result (and precession result as well) as a confirmation of GTR. In his opinion measurements confirmed both Newtonian and Einstein predictions (or refuted both). I felt that he was trying to insert his personal interpretation (WP:OR) into the article. So I showed him that opinions could differ widely: I, for instance, hold a strong opinion that the classical mechanics made no predictions about light deflection, and therefore there was nothing to test in the first place.

However the article still misses one important fact: the first theory of gravity that was fully relativistic and made testable predictions was Nordstrom theory. It predicted no deflection and was finally refuted by the same measurements of 1919. Ruslik (talk) 13:09, 21 December 2008 (UTC)

Logicus to Ruslik:

You wrote:

": What are trying to prove here? That GTR is uncofirmed theory and there are alternatives to it? This is wrong. GTR is one of the basic theories of modern physics. GTR is used to calculate trajectories of space probes. If it were wrong Cassini would have been unable to fly by Enceladus at the distance of 25 km. So validity of GTR is out any question.

Dicke et al claimed that quadrupole moment of the Sun is large enough to explain anomalous precession. This is wrong. Currently the value of quadrupole moment of the Sun is not known, because it is too small (on the order of 10⁻⁷)—see ref that I provided above. So the work Dicke was erroneous. Ruslik (talk) 20:46, 19 December 2008 (UTC)"

But I fear it seems that, like Silly Rabbit and Wolfkeeper, you misunderstand the main issue I am raising. I am not raising the issue of whether GTR is now generally regarded as empirically confirmed by the (relevant) scientific community or is the best theory of gravitation or not. As I tried to make clear at the outset and again in my above reply to Wolfkeeper of 13 December, the question I am raising is that of whether Wikipedia's original unreferenced claim, at least as claimed when I first raised the issue on 7 December 2008, that the success of GTR is due to its successful prediction of novel phenomena not predicted by any other theory, is true or not. This is a question of scientific method in the history of science, and in particular a question of whether the Huygens-Leibniz criterion for the acceptance of a theory as confirmed by empirical facts is observed by scientists or not, or whether they follow some other criterion.

The subsequent revisions of this claim since I first raised it at least shows some appreciation of the methodological problem here, which is most welcome in Wikipedia. However, in spite of revisions, the problem still remains. For the current formulation of the claim now compounds the problem by raising the issue of whether success is due solely to the successful prediction of novel phenomena not predicted by any other theory, as was originally claimed, or must also be accompanied by some more accurate prediction of already known phenomena or of phenomena also predicted by other theories, as it seems is currently claimed, as follows:

"General relativity has enjoyed much success because it predicted new phenomena that other theories of gravitation could not account for, and was found to be substantially in accord with otherwise anomalous measurements."

To render this claim more intelligible, I presume it means

'General relativity has been widely accepted because it predicted new phenomena that other theories of gravitation did not and also provided more accurate explanations of some phenomena than other theories did.'

So on this account it was the conjunction of better explanations of already known or otherwise predicted phenomena with the unique and successful prediction of entirely novel phenomena that caused the wide acceptance of GTR.

But is this true ? It is certainly false on the conflicting account according to which GTR was accepted just with its 1915 more accurate explanation of Mercury's perihelion precession, or with its 1919 degree of success in explaining gravitational lensing, and hence essentially widely accepted by 1920 at the latest. This view of the GTR 'revolution' is to be found in such as Zahar's 1973 Why did Einstein's programme supersede Lorentz's ? in The British Journal for the Philosophy of Science and in his 1989 book Einstein's Revolution: A study in heuristic

The important fact to be determined here is when did the relevant scientific community convert to GTR from the Newtonian law of gravity. And thus was this after both conjunct conditions of the logically conjunctive cause currently given were satisfied ?

(I refrain from complicating matters further by pointing out that in addition to mercury’s perihelion precession and gravitational lensing, nor was gravitational red shift a novel phenomena unpredicted by any other theory.)

Certainly as the claim stands it needs a justifying reference. --Logicus (talk) 16:00, 21 December 2008 (UTC)

Scientific community converted to GTR from Newtonian theory in 1905, when special theory of relativity was created. Soon after this event it became abundantly clear that the Newtonian theory of gravity needed to be replaced with a relativistic theory. While GTR, of course, did not exist in 1905, it is fair to say that physicists abandoned Newtonian theory in favor of a future theory of gravity in that year. It is because of this abandonment of Newtonian theory, that its "predictions" were of little importance after 1905. Ruslik (talk) 16:25, 21 December 2008 (UTC)

As to criteria used in modern science, they are based on Immanuel Kant's philosophy and, I am afraid, have nothing to do with Huygens-Leibniz. Ruslik (talk) 16:47, 21 December 2008 (UTC)

The scientific community converted to SR from Newtonian theory after 1905; and in many cases well after. It took time for people to take the theory on board and for further experimental results en masse to persuade people. GR took even longer, I'm pretty sure it did not persuade a lot of physicists for many decades, although some would have taken it on board almost immediately, others never. At most the Edison results was the knee on the curve where after that only a highly convincing win for Newton and against Einstein would have turned the tide back the other way- and that has never happened. Could the Edison result be considered compatible with Newton- yes, of course if you modify Newton to add massive light, but that wasn't the theory held at the time, and I am certain that some physicists would have hung on with Newton. Beyond a certain number of modifications to Newton you're up against Ockham's razor, the theory is no longer simple.- (User) Wolfkeeper (Talk) 20:44, 21 December 2008 (UTC)

Logicus to Ruslik and Wolfkeeper: Thanks for your interesting observations. I note that on Ruslik's historical analysis the success of SR from 1905 was not due to any succesful predictions of novel phenomena. But whatever, neither of you state any justifying sources for your views. I shall therefore flag the current claim for citations. However I suspect the claim is so problematic and requires so much research that it would be wiser just to delete this methodological speculation altogether and instead simply list all those experiments/phenomena that are regarded as tests of GTR and what their outcomes were. --Logicus (talk) 18:29, 22 December 2008 (UTC)

Just to clarify the nature of the justifying reference that is required here, it is one that demonstrates GTR was only successful after it had successfully predicted some novel phenomena of a kind not predicted by any other theory. As is clear from the foregoing extensive discussions, Mercury's perihelion precession and gravitational lensing were not such phenomena, and nor was gravitational red shift (1925?), albeit on the basis of these three alleged better explanation by GTR some may wish to argue GTR was widely accepted by the 1950s or even 1930s. For whatever its worth, my own guess without extensive further research is that GTR was not generally accepted until the 1960s or '70s. --Logicus (talk) 18:48, 22 December 2008 (UTC)

I want to repeat my position: Newtonian mechanics made no testable predictions whatsoever about behavior of light in the gravitational field. It also completely failed to explain anomalous precession of Mercury's orbit. Ruslik (talk) 19:44, 22 December 2008 (UTC)

As to sources, you can read the book of Pauli, Theory of Relativity. Ruslik (talk) 19:53, 22 December 2008 (UTC)

Logicus to Ruslik: And I could repeat my position that you are wrong on both counts. But the more immediate priority issue here is whether your kindly provided Pauli reference can justify the proposition at issue for which it is cited. I note you cite the 1958 second edition rather than the 1921 first edition, which raises the possibility Pauli dated general majority acceptance of GTR as post 1921. I would therefore be most especially grateful if you could therefore provide quotation(s) from that book that justifies the proposition asserted that the success of GTR was due to the conjunction of successfuly predicting entirely novel phenomena and also proving better explanations of already known or otherwise predicted phenomena, a summary I note you do not contest. Please note you must provide text that shows Pauli gives a dating of the majority conversion to GTR after both these conditions were satisfied and also specifies when they were satisfied. My request is thus for your compliance with Wikipedia verification policy etiquette stated in footnotes 1 & 2 of Wikipedia:Verifiability. But I anticipate you will be unable to do so. So please do surprise me. Wishing you a good New Year, (in a snow-free Russia ?) --Logicus (talk) 15:57, 28 December 2008 (UTC)

The 1958 edition is the English translation of the original 1921 German edition. Quote: "Translated from the article 'Relativitätstheorie' in Encyklopädie der mathematischen Wissenschaften, Vol. V19, (B.G. Teubner, Leipzig 1921)." I assume we should accept this at face value, that the 1958 edition is a faithful translation of the 1921 text. siℓℓy rabbit (talk) 16:22, 28 December 2008 (UTC)

As for a quote, see pages 168-169 of Pauli's (1958) text (see above regarding the date):

"It has been known to astronomers since Leverrier's time that a remainder is present in the perihelion precession of Mercury, which cannot be caused by perturbations due to other planets... Thus, even if the degree of agreement cannot as yet be determined with certainty, the agreement of Einstein's and Newcomb's values constitutes, at any rate, a great success."

"The theory of relativity has received still more definitive confirmation than for the perihelion of Mercury for the case of deflection of light rays... Quantitatively, too, the agreement is a good one."

--siℓℓy rabbit (talk) 16:35, 28 December 2008 (UTC)

Logicus: Thanks for supplying this logically irrelevant quotation, but which clearly does not justify the proposition at issue. It neither makes any statement about when GTR was first generally accepted, nor mentions any confirmation of entirely novel phenomena not predicted by any other theories. Like to have another go ?

Meanwhile it might interest you to know that contrary to the Wikipedia claim that the success of GTR is due both to successfully predicting entirely novel phenomena and also explaining some known phenomena more accurately, at least in 1962 the distinguished American historian of science Tom Kuhn wrote: "Even today Einstein's general theory attracts men principally on aesthetic grounds, an appeal that few people outside of mathematics have been able to feel." (p157 TSSR 1962 ) --Logicus (talk) 19:29, 29 December 2008 (UTC)

I will admit that the quotations do not satisfy the long list of requirements that you imposed on them. Perhaps it would behoove you to purchase a copy of the Pauli book so that you can debunk it to your own satisfaction (privately, I hope). The quotes do establish that by 1921 GR had at least gained acceptance for explaining the precession of the perihelion of Mercury, and additionally that the 1919 eclipse was seen as a decisive confirmation of the theory. At any rate, I would be interested in seeing you have a go at it (since you obviously fancy yourself an expert). As a cosmological theory, outside of tendentious claims to the contrary, there is no reasonable contention that general relativity is today anything but the dominant theory. Perhaps, out of the many sources that you are undoubtedly intimately familiar with, you could deign to supply an answer to your own question. With eagerness, siℓℓy rabbit (talk) 19:59, 29 December 2008 (UTC)

Update. I have implemented the following (reasonable) suggestion of User:Logicus, which seems to have been lost in all of the above lengthy commentary: "...it would be wiser just to delete this methodological speculation altogether and instead simply list all those experiments/phenomena that are regarded as tests of GTR and what their outcomes were." For future reference, Logicus, keeping suggestions succinct and targetted is generally more effective than attempting to engage other editors in a philosophical or historical debate about the subject. siℓℓy rabbit (talk) 02:18, 30 December 2008 (UTC)

1919 eclipse experiment references

Here are some references on the 1919 eclipse experiment and the claims of poor data analysis. Apologies if these have already been mentioned somewhere in the discussion above, which I only skimmed.

• Peter Coles, "Einstein, Eddington and the 1919 Eclipse." arXiv:astro-ph/0102462v1
• Daniel Kennefick, "Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse Expedition." arXiv:0709.0685v2
• Philip Ball, "Arthur Eddington was innocent!" Nature, doi:10.1038/news070903-20

-- BenRG (talk) 21:02, 24 December 2008 (UTC)

Logicus to BenRG:Thanks for these references, not mentioned above. It would be most helpful if you could also possibly give a brief summary of what you think their conclusion should be, that is, for example do they suggest a majority of scientists think the 1919 eclipse experiments were indecisive or rather that they conclusively refuted Newton’s law of gravitation and confirmed Einstein’s GTR ? --Logicus (talk) 19:08, 30 December 2008 (UTC)

The second paper and the article argue that the 1919 experiment was accurate enough to distinguish the GTR prediction from the obvious alternatives (half as much deflection and no deflection at all), and that the claims of data fudging are unfounded. The first one seems to be ambivalent. I don't know what the majority of scientists believe about this. -- BenRG (talk) 21:10, 5 January 2009 (UTC)

Did GTR predict an expanding universe ?

The article seems to claim GTR predicted the expansion of the universe and its alleged confirmation by Hubble was therefore a successful test of it, as follows:

“The expansion of the universe (predicted by Alexander Friedmann) was confirmed by Edwin Hubble in 1929”

This claim was flagged for a justifying clarification as dubious some time ago, but none has been forthcoming.

Surely on standard accounts, with its cosmological constant GTR did not predict an expanding universe, notably Einstein’s self-proclaimed biggest blunder. More generally the (possibly mistaken) impression from the literature is that the posit of the expansion of the universe is logically independent of GTR, which does not make any such predictions in itself, but rather depends upon positing initial conditions extra to GTR. On this analysis then GTR did not itself predict an expanding universe. And I thought (possibly mistakenly) Friedman calculated various different scenarios depending upon initial conditions.

I therefore propose the deletion of this claim at least until the situation is clarified. --Logicus (talk) 17:13, 2 January 2009 (UTC)

The chain is sketched for example, in ch. 15 (Cosmology: The Standard Model) of Steven Weinberg, Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity ISBN 0-471-92567-5  : Einstein field equation , with solution FLRW metric -> Friedmann equation -> one solution is expanding universe. --Ancheta Wis (talk) 17:44, 2 January 2009 (UTC) Logicus to Ancheta Wis: Thanks for these references, but your phrase “one solution is expanding universe” surely confirms GTR does not in itself predict an expanding universe, as I pointed out. I understand Friedman’s three different models of expansion depended upon independent postulates of both the speed of expansion and of the density of the universe, three different values of which gave the three different models when the cosmological constant is set to zero. Perhaps the easiest way to demonstrate the logical point here is to point out that if GTR entailed expansion then it must also contradict and be refuted by contraction, yet in Friedman’s first model expansion is then followed by contraction. The expanding/contracting/static state of the universe or not is rather a logical consequence of different models of initial conditions rather than of GTR. Hence it seems none of these states can be counted as predictions of GTR and thus of confirmations of it. I conclude the claim must therefore be deleted from any list of tests of GTR itself. --Logicus (talk) 15:56, 4 January 2009 (UTC)

GTR predicted that universe can not be static. It must either contract or expand. Hubble discovered that it does expand. So this prediction of GTR was confirmed. Ruslik (talk) 19:39, 5 January 2009 (UTC)

Of course Logicus is right that GTR doesn't predict an expanding universe as such. I see you've edited the article to reflect this, but I'm still unhappy with the edited version. A nonstatic universe may be a prediction of GTR, but it isn't a new prediction. The problem with a static universe is very simple: a bunch of objects at relative rest are not going to remain at relative rest under the action of a force that's always attractive. Any gravitational theory is going to make this prediction, so the mere observation that the universe isn't static doesn't help you choose between them. Newton was aware of the problem in his theory and tried to solve it by supposing that the universe is infinite in size and filled uniformly with matter—the idea being that this matter would not accelerate in any particular direction because it would be pulled equally in all directions. This doesn't work, though, because the series (or indefinite integral) that gives the force acting on each object is not absolutely convergent and hence can be rearranged to sum to anything at all. You can restore predictivity by factoring out a gauge freedom, and the solutions you get then aren't static, they are expanding/contracting cosmologies that look very much like FLRW cosmologies and even obey the Friedmann equations—see here. Newton lacked the mathematical machinery to understand this, of course. If he had understood it he might well have tried to make the universe static again by introducing a repulsive force that's directly proportional to distance—which is the Newtonian equivalent of the cosmological constant—and it would have failed for the same reason as Einstein's universe, because it's unstable under perturbations. There's nothing in the gross features of general relativistic cosmology that isn't also in Newtonian gravity. Hubble's data strongly suggested an expanding universe but didn't help to select one theory of gravity over another. I don't think it can be counted as a confirmation of general relativity by any stretch of the imagination. -- BenRG (talk) 20:54, 5 January 2009 (UTC)

Thank you for the link. Your explanation was really an interesting reading for me! However I want to note that a hidden gauge freedom is an additional assumption that is normally not a part of Newtonian mechanics. With gravity we can extend this from uniform motion to arbitrary motion Yes, agree with this statement, but this is what the general relativity actually says. So your model is based on some elements borrowed from the general relativity, including cosmological constant, which appears naturally in the general relativity, but needs to be manually (and rather arbitrary) added to the gravitational acceleration in the case of Newtonian mechanics. This model was actually invented after the general relativity was created. So the the first prediction of the non-static universe was still made by the general relativity. Ruslik (talk) 15:30, 6 January 2009 (UTC)

So wot about the red-shift ?

Surely the list of the empirical tests of GTR should include gravitational red shift ? But exactly when it was decisively confirmed seems to be debateable. --Logicus (talk) 17:26, 2 January 2009 (UTC)

An attractive force or not?

The article seems to me to not be able to decide whether gravitation is due to an attractive force or not. Surely the article should be consistent in either it's point of view or in the way that it applies the term (or it's assumption) contextually.

Please note that, to my mind at least, an "attraction" and an "attractive force" are the same thing in the context of gravitation, for what else can cause a genuine attraction than an attractive force? Some other means of making two objects move closer together (eg pushing them) could not accurately be described as an attraction. As such when I use either "attraction" or "attractive force" in this discussion I equally mean the other. (If anyone disagrees with this point of view please let me know, although it's not specifically the subject of this discussion point.)

- The article's opening sentence states that the Gravitation is a natural phenomenon by which objects with mass attract one another. This in my opinion states that there is an attractive force. (Perhaps it could be better expressed as appear to attract one other?)
- The General Relativity section opens with In general relativity, the effects of gravitation are ascribed to spacetime curvature instead of a force, which appears to contradict the article's opening sentence.
- The last paragraph of the Earth's gravity section states that According to Newton's 3rd Law, the Earth itself experiences an equal and opposite force to that acting on the falling object, meaning that the Earth also accelerates towards the object. This clearly assumes an attractive force between the two objects (the Earth and the "falling" object).
That last paragraph in the Earth's gravity section is especially problematic for me. It goes on (in parentheses) to say until the object hits the earth, then the Law of Conservation of Energy states that it will move back with the same acceleration with which it initially moved forward, canceling out the two forces of gravity. It is impossible to be sure what that is trying to say (hence why I'm afraid I cannot suggest any improvements to how it says it) but whatever it is it seems to be incorrect. It also explicitly uses the words "forces of gravity" (two forces of gravity even), albeit without specifying whether these forces are attractive or not. (As it happens I'm not totally sure the final sentence of that paragraph makes sense either.)

There may be other examples. I really think someone should try to tidy up the use (both explicit and implicit), or not, of this force in this article. At the very least it would be nice to sort out the examples I've given.

Slimfast66 (talk) 15:31, 4 January 2009 (UTC)Slimfast66

Logicus: Amen to that ! An underlying problem here is that modern physics is equivocal about whether it believes in forces or not and thus whether or not it still continues the master scientific project of Aristotelian Physics of trying to explain all motion and change in terms of powers or forces (of matter). Thus on the one hand it is claimed dynamical forces such as the force of gravity have been banished in favour of purely kinematical spacetime curvature. But on the other hand we are told modern theoretical physics is primarily concerned with investigating and finding a unified theory of the four fundamental forces of electromagnetism, the strong and weak nuclear forces, and, lo and behold, the force of gravity! Clearly such pedagogically confusing equivocation over the status of forces systematically infects this article. --Logicus (talk) 19:25, 5 January 2009 (UTC)

Let's go easy on this. Physics is a work in process, as Thomas Brody notes in The Philosophy Behind Physics. Although your skeptical POV is valuable, it is not mainstream, so I would advise you not to have reverted Ruslik. One disturbing thing about your POV is that your vision of logic uses monotonic logic, rather than using defeasible reasoning which is very much compatible with the belief revisions which are everyday occurrences in the scientific enterprise. There are some facts which are currently fervently believed, but which upon scrutiny, require revisiting with an open mind. That means, "there is nothing quite so dangerous as the man who believes he is in sole possession of the truth." Thus the scientific enterprise is very much like a 3-ring circus, with well-known facts serving as the foundation for structures currently undergoing revision. That does not call for the wholesale rejection of Newtonian mechanics in favor of post-Newtonian structures. Neiher does it call for defensive bulwarks around Newton and Aristotle. Their work is their work, for good or ill. Neither does it call for blind acceptance of Einstein's work. After all, most of our engineers use Newton, while a few are forced to include Einstein's work in their mechanical systems (such as the Global Positioning System).

There is a mechanism, the functional equation, which is the type of mathematical structure upon which current theory rests, which is beyond the Newtonian POV. It changes shape, as it were, so that it is Newtonian, and Einsteinian, and Aristotelian, etc. It is inappropriate to force Procrustean constraints (read monotonic reasoning) on Ruslik's edit when in fact there is room in the circus tent for all the POVs just displayed here. And Wikipedia expects this, to use a figure of speech about editing and editors.

Having said all this, the positivism and triumphal POV which physical and natural scientists learn at the feet of their teachers could very well be toned down with appropriate edits. There is much for humanity to be proud of in our current science, but there is more science to come, and you are correct to tone down any edits which claim humanity has the last word on anything.

--Ancheta Wis (talk) 20:06, 5 January 2009 (UTC)

Gravity and astronomy section

I assume this section is supposed to describe how theories of gravitation (or specifically the related equations) have been useful in calculating certain astronomical data. I don't believe it achieves this aim especially well because, in two separate ways, it's not neutral.
Firstly it seems to attribute all of this to Newton. Leaving aside the fact that this is probably contentious (hello Kepler, Bullialdus, Einstein, ...) the point is that it's out of place - it should be the equations that are portrayed as calculating/predicting these things, not an individual. Credit for these theories and equations is given elsewhere.
Secondly it presents this "information" not as the results of calculations, but as facts. For example we have calculated masses of planets and stars, but we haven't proven those masses to be correct. In fact there are points in the Anomalies and discrepancies section that indicate that some of these things may not be correct. And Dark Matter was a concept invented to bridge the gap between the theories and the actual results - so while ascribing the existence of the theory of dark matter to gravitation is probably technically correct, it seems rather ill-placed in this section when it's possible that the explanation for the discrepancy is that the theories of gravitation are wrong. (Please note I am not suggesting that they are wrong, although they may be for all I know, merely pointing out the fallacy of using unverified explanations of their apparent failures as a feather in their caps!)

Anyway if someone (who can) would like to edit this section to make it more neutral please do so.

Slimfast66 (talk) 16:25, 4 January 2009 (UTC) Slimfast66

Have you read John Moffat, Reinventing Gravity. It should make you feel better about any suspicion that any one person currently has the last word on this subject. For example, Moffat casts a gimlet eye on Dark Matter. The only difficulty is finding the funding for decisive experiments to rule out one POV over another. It should be very interesting when Stephen Hawking moves to Canada and they get to work together. --Ancheta Wis (talk) 20:20, 5 January 2009 (UTC)

On Ruslik's logic GTR predicts the Moon is made of green cheese !

The article still claims GTR predicted the expansion of the universe in spite of its patent invalidity and deletion given failure to provide any justifying quotation showing such a ludicrous claim has actually been made by anybody. But it was restored by Ruslik, who has failed to find any justifying quotation for this claim in compliance with Wikipedia Verifiablity requirements, just as he failed to do so for the now deleted claim that the success of GTR is due to it successfully predicting entirely novel facts not predicted by any other theory and also proving more accurate explanations of old facts. Ruslik argues as follows:

"Alexander Friedmann in 1922 found that Einstein equations have non-stationary solutions (even in the presence of the cosmological constant). In 1927 Georges Lemaître showed that static solutions (in the presence of the cosmological constant) of the Einstein equations are unstable, and therefore the static universe envisioned by Einstein could not exist. Later, in 1931, Einstein himself agreed with results of Friedmann and Lemaître. Thus general relativity predicted that the Universe had to be non-stationary, it had to either expand or contract. The expansion of the universe discovered by Edwin Hubble in 1929 confirmed this prediction.[14]"

However, for those who cannot immediately see the elementary invalidity of this argument that if a theory predicts the universe either expands or contracts it therefore predicts the universe expands, then perhaps the briefest way of demonstrating this absurdity is to point out that by the same invalid crazy logic GTR also predicts the moon is made of green cheese. For on the standard semantical two-valued logic employed in science, just as for all tautologies, the tautology 'The Moon is made of green cheese or the Moon is not made of green cheese' is a logical consequence of every statement whatever, including the statements of GTR. Thus on Ruslik's logic that we may conclude that GTR predicts the universe is expanding from its logical consequence/prediction that it is either expanding or contracting, then we must also conclude GTR predicts that the moon is made of green cheese i.e predicts the first disjunct of the tautology. Or to make a closer analogy, because, like every theory and statement, GTR entails the tautology that the universe is either expanding or not expanding, on Ruslik's logic GTR therefore predicts it is expanding. And of course so does every theory and statement on this logic. Even the statement 'Ruslik is crazy' predicts the universe is expanding. Thus by reductio the claim is unfounded. QED.

I therefore flag the claim once again for a clarifying quotation that establishes anybody makes such a ludicrously invalid claim, be it Pauli or whoever. However it should be noted that the above quotation from Pauli suggests he may be as unreliable on the history of physics as physicists usually are. For of course it was Leverrier who thought it possible to explain Mercury's anomalous perihelion in terms of a perturbing planet Vulcan, contrary to Pauli's claim. --Logicus (talk) 15:47, 9 January 2009 (UTC)

It is you who seems to have problems with logic. I wrote that GTR predicted a non-static universe. Discovery of the expansion confirmed this prediction (if universe expands it is obviously non-static). Very simple indeed. So GTR predicted evolution of the universe. Though it is possible to say that GTR predicted the expansion to a certain extent too.

Yes, Leverrier thought it is possible to explain Mercury's anomalous perihelion in terms of a perturbing planet Vulcan. However in 1921, when Pauli wrote his book, it was well known that this planet does not exist. So Pauli did not mentioned it. However he mentioned other possible causes of the anomalous precession such as Solar oblateness or some unobserved masses in the Solar System.

So I think you should follow the advise of Silly_rabbit and read the book of Pauli, which is one of the best books about Theory of Relativity ever written. Ruslik (talk) 17:37, 9 January 2009 (UTC)

...and I suggest you should read the Wiki article Tests of General Relativity that you reference and ask yourself why the alleged test and confirmation of an expanding or non static universe by Hubble's galactic red-shift is not listed amongst them. I propose this claim be provisionally deleted at least until such time as you can manage to get it accepted as a test of GTR in that article, at least for consistency between Wiki articles. --Logicus (talk) 15:56, 10 January 2009 (UTC)

That something is not listed in another article is not a reason to delete it from this article. ... I added information about expanding and non-static universe into Tests_of_general_relativity. Ruslik (talk) 16:46, 10 January 2009 (UTC)

...and so I flagged the claim for a justifying quotation and added yet another request for such to its Talk page, as follows --Logicus (talk) 19:23, 13 January 2009 (UTC)

Was Hubble’s discovery of galactic red shift regarded as a test and confirmation of GTR ?

User Ruslik0 has added the following passage to the article:

"Alexander Friedmann in 1922 found that Einstein equations have non-stationary solutions (even in the presence of the cosmological constant). In 1927 Georges Lemaître showed that static solutions of the Einstein equations, which are possible in the presence of the cosmological constant, are unstable, and therefore the static universe envisioned by Einstein could not exist. Later, in 1931, Einstein himself agreed with the results of Friedmann and Lemaître. Thus the general relativity predicted that the Universe had to be non-static, it had to either expand or contract. The expansion of the universe discovered by Edwin Hubble in 1929 confirmed this prediction.[28]"

In compliance with Wikipedia: Verifiability policy stated in its footnotes 1 and 2, and especially footnote 2, as follows. Please comply and provide the requested quotation.

"1 When content in Wikipedia requires direct substantiation, the established convention is to provide an inline citation to the supporting references. The rationale is that this provides the most direct means to verify whether the content is consistent with the references. Alternative conventions exist, and are acceptable if they provide clear and precise attribution for the article's assertions, but inline citations are considered 'best practice' under this rationale. For more details, please consult Wikipedia:Citing sources#How to cite sources.

2 When there is dispute about whether the article text is fully supported by the given source, direct quotes from the source and any other details requested should be provided as a courtesy to substantiate the reference."

will User Ruslik please provide direct quotations from Pauli or indeed anybody else that show galactic red shift was also regarded as a significant test and positive confirmation of GTR by the scientific community, as distinct from a confirmation of Big Bang cosmology, or is now so regarded. This contribution is flagged for the provision of such a clarifying quotation. --Logicus (talk) 19:24, 12 January 2009 (UTC)

Misner, Thorne and Wheeler have an ample discussion of this; I don't have my copy with me right now, but that would provide an appropriate reference. As to whether it is a test of GR, it is a test in the weak, but nontrivial, sense that GR predicts the possibility of (regardless of cosmological constant) and the necessity of (if one sets the constant to zero) a dynamic universe. It doesn't distinguish GR from other dynamic models of the universe, but historically it was very significant, since there were no other dynamic models in existence at the time. So I think a version of the paragraph should stand, with some editing. If I have time and access to MTW soon I'll give it a try. -- Spireguy (talk) 20:50, 12 January 2009 (UTC)

Gravitational table for the planets

75.69.247.75 (talk) 19:22, 11 January 2009 (UTC) Maybe someone could make a table showing the gravitational force of the sun on each of the planets. Thanks75.69.247.75 (talk) 19:22, 11 January 2009 (UTC)

At one time that table was in this article, but it got moved to a child page to keep this article small. See Earth's gravity#Comparative gravities of the Earth, Sun, Moon, planets and Pluto --Ancheta Wis (talk) 19:33, 11 January 2009 (UTC)

Inexperienced in the field of physics - A comment on gravity?

I was studying string theory, and a chain of effects were set into motion leading all the way back to gravity, when a concept dawned on me - Gravity is traditionally thought of as a force that pulls objects together, thus people and objects are pulled towards Earth as Earth is pulled towards the sun. However, if such a pulling force were to exist then wouldn't it cause these objects to pull in towards eachother, causing planets to collide with the sun? I realize this question may sound simplistic to physicists but I am lost. Thanks! 71.54.120.113 (talk) 03:16, 12 January 2009 (UTC)

We really aren't supposed to use this page as a talk forum. Usually you can google your questions, for example "why don't we fall into the sun" and get an answer pretty fast. --Ancheta Wis (talk) 11:57, 12 January 2009 (UTC)

You might also try the Science Reference Desk. - Eldereft (cont.) 12:05, 12 January 2009 (UTC)

(Edit conflict: This response was being prepared at the same time as the above two and therefore repeats their points.) The talk page of a Wikipedia article is an inappropriate place for general discussion or asking general questions about the topic of the article. The purpose of an article's talk page is for discussing suggested changes to the article and ways of improving it. Wikipedia has a science reference desk, which is the appropriate venue for asking general questions about scientific topics. I have already taken the liberty of copying your question there, and provided a brief answer.

—David Wilson (talk · cont) 12:21, 12 January 2009 (UTC)

Archives

1 Opening sentence and title

2 Solar System Photo

3 References

4 Opening statement revisited

5 And the distinction is...?

6 Gravity and Quantum Mechanics

7 Last sentence

8 Who is Mr. Kassner

9 Alternative Gravity Theory

10 Dark Matter

11 The difference between gravity and gravitation

12 Scientific revolution

13 Did Newton predict gravitational lensing, and did Eddington refute Newton and confirm Einstein ?

14 Not all the GTR novel predictions listed were of previously unpredicted novel phenomena

15 1919 eclipse experiment references

16 Did GTR predict an expanding universe ?

17 So what about the red-shift ?

18 An attractive force or not?

19 Gravity and astronomy section

20 On Ruslik's logic GTR predicts thek Moon is made of green cheese !

21 Was Hubble’s discovery of galactic red shift regarded as a test and confirmation of GTR ?

22 Gravitational table for the planets

23 Inexperienced in the field of physics - A comment on gravity?

24 Archives

--Ancheta Wis (talk) 20:54, 17 January 2009 (UTC)

Those discussions all look inactive, so I moved them to Talk:Gravitation/Archive 7. Feel free to pull a section back if I am mistaken. - Eldereft (cont.) 22:00, 17 January 2009 (UTC)

No Original Research

I found this comment in the moved archive group comments.

"The purpose of an article's talk page is for discussing suggested changes to the article and ways of improving it."

Don't you suppose getting the correct science description of gravitation written would be a somewhat MAJOR step in the direction of IMPROVING the article? With other changes being a bit on the ultra-trivial side in comparison. And then discussing that real science description being major, worthwhile talk. Steve Crum (User talk:Steve Crum18:40, 18 January 2009 (UTC) —Preceding unsigned comment added by 4.254.210.92 (talk)

Welcome to Wikipedia. If you start a User Page, such as User:Example, you will typically be welcomed by the Welcoming committee, who will give you a set of links to study. For your convenience these links are shown at the top of this talk page. But currently, you should be aware that the encyclopedia has a distinct set of policies which make life easier when you attempt to contribute to this page. If you try to strike your own path please be aware that you may encounter some policies and reactions which may be counter to your intention.

For example, your current attempts to sign with your account name show that you are attempting to create links to Wikipedia:Article space rather than to Wikipedia:User space. If you want immediate personalized help then create an account, type in {{helpme}} on your talk page, save your edit, and wait for an editor to come to your assistance. To create an account, go to the login page and click create one.

One of the policies which you may find helpful in saving your time and effort on Wikipedia is No Original Research. Follow that link if you want clarification. --Ancheta Wis (talk) 02:07, 19 January 2009 (UTC)

As the editor who made the comment quoted by Steve Crum I have a little more to add to Ancheta Wis's reply. Steve Crum wrote:

"And then discussing that real science description being major, worthwhile talk."

Not all discussions which may be considered worth while by their participants are necessarily appropriate for the talk pages of Wikipedia articles. Whether they are depends on the nature of the discussion. As Ancheta Wis has pointed out, Wikipedia has numerous policy documents that spell out what is and is not appropriate. To the ones he has already listed, I would also add What Wikipedia is not, with particular reference to the sections Wikipedia is not a publisher of original thought (nor a discussion forum) and Wikipedia is not a soapbox.

—David Wilson (talk · cont) 13:45, 19 January 2009 (UTC)

In my above reply I forgot to answer Steve Crum's question:

"Don't you suppose getting the correct science description of gravitation written would be a somewhat MAJOR step in the direction of IMPROVING the article?"

Yes indeed. Wikipedia's policy requires the article to contain a description of gravitation which can be documented by reliable sources. So if the article's current description were unclear, or not properly documented, then obtaining a better one by consulting appropriate sources would certainly be a major step in improving the article, and it would be quite appropriate to discuss that on the talk page.

—David Wilson (talk · cont) 14:49, 19 January 2009 (UTC)

Alternative Theory

If the Universe is governed by the mass-dependent (Newton's law) gravitational force, the Universe shall be spherical in shape as mass-dependent gravitational force has no preference in direction. But the Unvierse is not spherical in shape, in fact flat. An alternative theory is proposed to explain this reason. A more detail description is presented in this link gravitational force Kongkokhaw (talk) 17:21, 20 January 2009 (UTC)

Has this been published in a peer reviewed journal? If not, see WP:FRINGE. Vsmith (talk) 19:04, 20 January 2009 (UTC)

Commonsensible conception of gravity

1. According to the standard model, which describes all the forces in nature except gravity, all elementary particles were born massless. Interactions with the proposed Higgs field would slow down some of the particles and endow them with mass. Finding the Higgs — or proving it does not exist — has therefore become one of the most important quests in particle physics.

However, for a commonsensible primitive mind with a commonsensible universe represented by E=Total[m(1 + D)] , from http://www.physforum.com/index.php?showtopic=22994&st=0&entry373127 this conceptual equation describes gravity. It does not explain gravity. It describes it. It applies to the whole universe and to every and all specific cases, regardless of size.

2. Thus gravity is simply another face of the total cosmic energy. Thus gravity is THE cosmic parent of phenomena such as black holes and life. It is the display of THE all-pervasive-embracive strained space texture, laid down by the expanding galactic clusters, also noticed in the expanding energy backlashes into various constructs of temporary constrained energy packages.

Commonsensible conception of the forces other than gravity

The forces other than gravity are, commonsensibly, forces involved in conjunction with evolution: http://royalsociety.org/downloaddoc.asp?id=4770

The farthest we go in reductionism in Everything, including in Life, we shall still end up with wholism, until we arrive at energy. Energy is the base element of everything and of all in the universe. At the beginning was the energy singularity, at the end will be near zero mass and an infinite dispersion of the beginning energy, and in-between, the universe undergoes continuous evolution consisting of myriad energy-to-energy and energy-to-mass-to-energy transformations.

The universe, and everything in it, are continuously evolving, and all the evolutions are intertwined.

Dov Henis 93.173.169.160 (talk) 06:43, 4 April 2009 (UTC)

Unsatisfactory sentence

The terms gravitation and gravity are mostly interchangeable in everyday use, but a distinction may be made in scientific usage. "Gravitation" is a general term describing the phenomenon by which bodies with mass are attracted to one another, while "gravity" refers specifically to the net force exerted by the Earth on objects in its vicinity as well as by other factors, such as the Earth's rotation.

The last sentence gives a flavour of what's meant, but when you read it closely it is not coherent. Can I suggest we change it to read something like this:

... while "gravity" refers specifically to the net force experienced by objects on or near the surface of the Earth. This net force is dominated by Earth's gravitational force, but also includes other components such as the centrifugual force resulting from the Earth's rotation and the buoyancy force provided by the Earth's atmosphere. —Preceding unsigned comment added by 86.134.115.227 (talk) 03:44, 11 February 2009 (UTC)

Opening sentence

The opening sentence is "Gravitation is a natural phenomenon by which objects with mass attract one another" [emphasis mine]. This sentence is not true since in Einstein's physics of gravitation (confirmed by all observations up to date so most likely the true physics) there is no attraction (though it looks like one to uninformed humans). In Einstein's gravitation there is only something called curvature of spactime and it's easy to show (even at a high school level) that it explains exactly the gravitational force. If there were also some additional attraction (a fundamental force of nature, as those uninformed humans call it) the gravitational force would be bigger than it is, and so Einstein's theory wouldn't work. So maybe it would be good to modify the opening sentence in a way that it wouldn't eliminate Einstein's physics at the onset.

Just a suggestion since I tried for years to modify this line myself to agree with Einstein's physics but it proved only that wikipedia editors don't believe that Einstein's physics is true. Since I'm doing my PhD in Einstein's gravitation I don't have this luxury of not believing in Einstein's physics but if wikipedia chooses to fool high school students (by 9:1 consensus) since grownups don't take wikipedia seriosly anyway, the opening sentence may stay as it is providing an example that the majority is sometimes dead wrong. Jim (talk) 17:40, 15 February 2009 (UTC)

I agree with you. Wikipedia does not care about facts or truth, it is majority rule. That is why I am done with this online "encyclopedia" Trentc (talk) 21:24, 21 November 2010 (UTC)

You have a somewhat blinkered view of gravitation, I think. I suggest you return once you have completed your physics PhD, and then some knowledge of the history and philosophy of science. The concept of "gravitation" clearly predates Einstein by over a century. So for the first sentence to say something like "Gravitation is the field generated by matter creating a change in the curvature of spacetime" would require a fairly specific phenomenological position. Acannas (talk) 02:21, 16 February 2009 (UTC)

It should be rather something that could be understood by high school kids and would motivate them to learn more about it. E.g. "Gravitation is a natural phenomenon by which objects with mass tend to move towards each other despite that they don't attract each other". It eliminates attraction as a reason for the movement and may prompt curious kids to try to find out why those object move if there is no attraction between them. They may also ask their science teachers, which may prompt the science teachers to learn how gravitaton really works and to stop promoting the legend of attraction. Note that even Newton opposed this legend, being strongly against "action at a distance". The science teachers (at least some) may learn why the gravitational force is strictly an inertial force coming from the inside of gravitating object, which is known since 1915, when gravitation stopped being just math and bcame physics. Jim (talk) 15:46, 17 February 2009 (UTC)

I disagree with your proposal, as it implies a specific phenomenological position ("objects do not attract one another"). A more defensible position may be that "Gravitation is a natural phenomenon by which objects with mass tend to move towards each other." Period. Without taking a specific position on the "attraction" issue. Acannas (talk) 03:25, 18 February 2009 (UTC)

The math of gravitation may use "attraction" as a phenomenological model but, as we know, it is only approximate math so the model is false for sure. "Attraction" is not physics (it doesn't deliever true results). Only the inertial force may be true physics (and it is, as far as we know). So why to put garbage into the minds of kids who read wikipedia while we know for sure that it is garbage? Jim (talk) 16:14, 18 February 2009 (UTC)

You haven't addressed my reply, and instead are merely descending further into positivism. Acannas (talk) 05:14, 21 February 2009 (UTC)

People, people, people! I have changed the intro quite a bit, and most of what you say here is already addressed.Kmarinas86 ^(6sin8karma) 14:19, 21 February 2009 (UTC)

I appreciate your effort but the article about gravitation, as a minimum, should explain the simple mechanism of generation of gravitational force without the old "attraction" (spooky action at a distance) that disappeared form physics almost a century ago. Jim (talk) 20:22, 21 February 2009 (UTC)

The lead is not the appropriate place to delve deeply into the history of the subject. However, I am curious to know how you think the current lead compares to the previous one. I am neutral on this matter. The current lead has some major issues that I definitely do not like, but in some ways it is superior to the old version. Perhaps you should consider sandboxing a version of the lead and presenting it here for discussion. Acannas (talk) 00:55, 22 February 2009 (UTC)

I agree that "The lead is not the appropriate place to delve deeply into the history of the subject". Also that "The current lead has some major issues that I definitely do not like". I don't agree that "in some ways it is superior to the old version". The main issue I see here is that everybody can edit wikipedia and the great majority of people, including retired physicists, think that graviation works through "attraction". So all those people feel offended by removing word "attraction" from their texts and fight for it. So anyone who knows how gravitation works has to give up. That's why I never could explain to the high school kids of wikipedia how gravitation really works according to Einstein since it was always reverted by consensus of retired (and even still active but probably in a different branch of physics) physicists who didn't believe that Einstein's physics could be so simple as I described it and thought that I'm presenting my own theory. Jim (talk) 18:41, 22 February 2009 (UTC)

"The current lead has some major issues that I definitely do not like[....]" What are these major issues then?Kmarinas86 ^(6sin8karma) 22:56, 22 February 2009 (UTC)

The major issue is that gravitational force is not "attraction" ("spooky action at a distance" in Einstein's words) but a push from inside of gravitating object. This push is due to inertial force resulting in an interesting and rather simple way from the curvatures of space and from gravitational time dilation. Curvatures of space and gravitational time dilation are called collectively "curvatures of spacetime" and they found to be the only causes of gravitation. So gravitation is caused only by the geometry of spacetime and not by any "attractive forces" seen in the lead all over the place. Since inertial forces can't be "attractive". The mechanism of generation of gravitational force deserves an explanation in further parts of the article but unfortunately it is found nowhere in it. Which is another problem with the article. Jim (talk) 18:00, 23 February 2009 (UTC)

Thanks for making my point for me. Although I don't wish the lead to descend into too specific a phenomenological model (you had proposed stating baldly that gravitation is not attractive), I definitely disagree that the lead should be written from a predominately Newtonian perspective. If anything, the lead should summarize the main points of the article; and the chief among these seems to be how the very idea of gravitation has evolved through history. So I don't really see the current lead as a step forward, just a lateral step which only exacerbates the concerns of the present thread under discussion. Acannas (talk) 03:56, 24 February 2009 (UTC)

Jim, first, you're confusing Einstein's "spooky action at a distance", which was a reference to quantum entanglement, with plain old action at a distance (physics). Second, you're confusing action at a distance with attraction/repulsion. In Maxwell's electrodynamics unlike charges attract, but there's (said to be) no action at a distance because the interaction is mediated by the field. You could say that the particles don't really attract each other, they just respond to their local fields in such a way that they end up getting closer together—but, well, that's what it means to say that they attract each other. If we only used "attract" for direct action-at-a-distance forces then we couldn't use it at all since there don't seem to be any such forces. The other question is whether gravity is different enough from the other forces that it ought not to be called a force. I don't think it is. The Standard Model forces are all gauge forces, meaning that they can be understood very much like gravity as arising from certain "deformations of the background", except that the deformations involve internal degrees of freedom instead of just the four spacetime dimensions. Most (theoretically conceivable) forces can't be written in that way, so presumably it means something that all of the real-world forces can be. Presumably it's going to turn out that all of the "forces" are aspects of the same thing and all motion is equally inertial. That would be your typical particle physicist's guess, anyway. We shouldn't assert in the article that gravity's brand of attraction is special, since we don't know that that's true and it seems pretty likely that it isn't. -- BenRG (talk) 20:52, 24 February 2009 (UTC)

Ben, I didn't. I meant Newton's objections to attractive force based on his disbelief in action at a distance (idea of field acting on his own, also false, was not invented then). I just added to it the famous "spooky" to underline the fact that Einstein was also against action at a distance. Of course Einstein was talking about QM but Newton was talking about gravitation and both were against "action at a distance" in physics. In any case "attraction" doesn't exist neither in Einstein's gravitation, nor in QED, nor anywhere else in physics (it might be OK in math or cosmology which aren't exact sciences in the sense of describing the real world). We just shouldn't feed with false physics the high school kids who look to wikipedia for true information since there are simpler and true (as far as we know) ways of explaining gravitation. Jim (talk) 23:15, 24 February 2009 (UTC)

It looks like a hopeless situation since I have the same problem at my university. The professors want to teach the first year phsics students only the Newtonian math instead of physics of gravitation. Despite that first year students have no problems with understanding relativity since they are already taught special relativity. Yet professors think that physics students are too stupid to understand also the general relativity (or maybe professors are scared that students might be wise enough to understand it and find out that the universe can't be expanding, as the professors tell them, since it would have to violate a few physical principles). The result is that "physicists don't understand gravitation" (as one of professors said). Having no training in general relativity they don't know that the Big Bang is only math that follows the assumption of expansion, not physics, in which there is no visible expansion, just the false interpretation of the Hubble redshift. And this rdshift has also a legitimate physical interpretation contained already in Einstein's theory. "Physical theories are often wiser than their creators" [Heinrich Rudolf Hertz]. Jim (talk) 08:55, 25 February 2009 (UTC)

When we are at it I might reveal my idea of teching physics (and gravitation) that old physics professors are so much against: The last year should be dedicated to teaching the physical principles that students should absorb for their lifetimes. Once they internalize the idea that certain things are already known, as e.g. that speed of light is always $c$, the various principles of conservation, the imposibility of action at a distance (even if theists think otherwise) etc. then they can draw conclusions based on those principles and other things that they know. E.g. that if the time runs more slowly "down there" then necessarily the photons move more slowly "down there", and since the total energy of any particle is (about) its $mc^{2}$ then necessarily on any particle must act a "force" directed "down", equal $-dE/dx$, traditionally called "gravitational force". Smarter of the students may want to calculate this force and be surprised by a result that this force is exactly equal $mg$. Their science teacher should be there to help them to get through the math to get the right result. Which is not only my result but comes straight from Einstein's theory through simple differentiation that many high school students know how to do. Jim (talk) 12:17, 25 February 2009 (UTC)

We may save ourselves some time and consider that many accepted views of gravity can and must be mentioned but to do so effectively requires a certain ordering of the enyclopedic information in the article. Thus the history of gravitational theory can be related to its role in undestanding celestial phenomena. I have given a hint of this in my edits to the lead. One can divide the article according to the effects of gravity (e.g. formation of planets, stars, solarsystem, nebulas, galaxies, black holes, explosions, bending of light, etc.) and in each explaning the extent of validity of various theories of gravity, such as those of Newton and Einstein.Kmarinas86 ^(6sin8karma) 02:29, 26 February 2009 (UTC)

I agree, and I'd add that from the reader's point of view it is imporant to split the theories into physical ones, which postulate a physical mechanism of the phenomenon (like Einstein's), and mathematical (phenomenological) ones, that don't even try to guess the mechanism (like Newton's). This way the readers together with information get education that helps them to organize their knowledge. Calling all theories just "theories" would surely confuse the reader into thinking that all theories are created equal and Newton's theory is as good (or maybe better, being simpler) as Einstein's. The reader may not even notice that Einstein's theory is physical theory with so far unlimited predictive power while Newton's theory is only math (also according to Newton himself) with its predictive power limited to special cases (of "slow velocities" in the frame of observer and "weak fields"). So making a decent article on gravitation without repeating old errors might be quite a job, but then it might become one of the best articles in wikipedia. Jim (talk) 05:30, 26 February 2009 (UTC)

The opening statement is simply not true. Gravitation is a natural phenomenon by which objects with mass attract one another. Try ... Gravitation is an observed effect of curved spacetime whereby masses move toward other masses. The use of the word attraction is at least misleading and as science simply wrong. —Preceding unsigned comment added by 58.170.0.131 (talk) 06:23, 10 May 2009 (UTC)

It occurs to me that objects with mass *do* attract one another. That definition is true, if only because it describes the obvious. Also, masses create a curvature in spacetime that facilitates the shortest path between them. That's an Einsteinian definition. But the real question is, what *is* mass, that it causes curvature? -mjs 173.68.190.122 (talk) 07:16, 4 October 2009 (UTC)

The statement is true on two levels. Firstly, according to James Gleick's biography of Newton, the word 'gravity' wasn't well defined until Newton defined it as meaning the propensity of objects with mass to undergo a mutual attraction. Thus, one could say, by definition gravity is as described in the opening sentence. Secondly Einstein's spacetime is a purely mathematical abstraction of reality. It provides a way of accurately describing the behaviour of systems under the influence of gravity. However, it isn't of itself a tangible reality. Spacetime as an idea is an abstract description of the thing, but has become so conflated with the thing so as to be thought of as the same thing - it isn't it's a description of the thing. Thus the observation that objects with mass undergo a mutual attraction stands as a definition of gravity and is a different thing to that which effectively mimics gravity mathematically.Fizzackerly (talk) 12:08, 16 October 2009 (UTC)

There is something confusing about the statement that gravitation is a force by which masses attract each other. The phenomenon of gravitational lensing suggests that light is affected by gravity. But the article on photons (particles of light) says photos are massless. So gravity doesn't have to be between objects with mass? Xrchz (talk) 20:33, 9 March 2010 (UTC)

Could I suggest as opening sentences the following - "Gravitation is the name given to the observation that objects of mass appear to move towards each other. Several theories have been proposed to explain the observation. These are ......" This gives a neutral explanation of the term "gravitation", with a nicely flowing link to introduce the various theories. The current opening sentence is IMO biased towards certain theories of gravity, which is not what this article should be about. Many people will object to the inference that gravitation "IS" one of the four fundamental interactions and the use of the word "attraction". The observation is quite plainly that objects move towards each other, this does not automatically imply an attraction. These implications belong in the sections that explain specific theories. George4405 (talk) 16:34, 6 June 2010 (UTC)

Gravity & Precessional Motion

It is known in the scientific community that the basic particles that make up matter are the proton,neutron,and electron. Also known is that every indivdual orbiting electron produces its own electromagnetic field while in motion. In an enviroment where matter,(atoms,molecules,mass)experience no or minimal effects from the magnetic fields produced by large bodies,(stars,planets,moons),such as the far reaches of outer space,the electrons orbiting the nucleus of said matter are more evenly distributed around said nucleus and produce no or minimal net electromagnetic output,hence,the physical effects of weightlessness.Matter that falls within or approaches the magnetic fields produced by large bodies,experience torque,causing "precessional motion",simultaneously changing the direction of its axis of rotation,and progressive angular momentum towards the large body,and causing an overall net electromagnetic output from said approraching mass.As the approaching mass feels the effects of a denser magnetic field from the large body,said mass experiences progressive angular momentum,"precessional motion",causing a greater net electromagnetic output and increased acceleration towards the large body.

````Chon Gonzalez 03/04/09```` —Preceding unsigned comment added by Chongonzalez (talk • contribs) 17:22, 4 March 2009 (UTC)

Censoring All Dissent: Does Censorship = Science?

How come there is no criticism of Newton's theory of gravitation on the page? Afraid of criticism and dissent? Is Wikipedia afraid of Neutral Points of View or not?

"Einstein’s theory of gravity is the craziest explanation of the phenomenon imaginable." -- Wallace Thornhill, physicist, 2001

"Leibniz also disagreed with other aspects of Newtonianism, such as the use of gravity, which he held to be a revival of occultism, and Newton's use of space as an absolute. Leibnizian physics defined motion and therefore space as relational." -- William E. Burns, historian, 2001

"Leibniz held that the Newtonian universe was imperfect because it occasionally requires God to intervene to prevent it from running down." -- William E. Burns, historian, 2001

"Leibniz also attacked Newtonian physical ideas, including absolute space and time, [and] the Newtonian theory of gravitation, which he charged introduced an occult force...." -- William E. Burns, historian, 2001

"Like Huygens, Leibniz never accepted Newtonian gravitation." -- Ezio Vailati, philosopher, 1997

"Newton was not the first of the age of reason. He was the last of the magicians." -- John M. Keynes, economist, 1936

"An atom differs from the solar system by the fact that it is not gravitation that makes the electrons go round the nucleus, but electricity." -- Bertrand Russell, physicist/philosopher, 1924

"...what is really wanted for a truly Natural Philosophy is a supplement to Newtonian mechanics, expressed in terms of the medium which he suspected and sought after but could not attain, and introducing the additional facts, chiefly electrical—especially the fact of variable inertia—discovered since his time…" -- Oliver J. Lodge, physicst, February 1921

"Magnetism is possessed by the whole mass of the earth and universe of heavenly bodies, and is an essence of known demonstration and laws. By adopting it we have the advantage over the gravity theory by the use of the polar relation to magnetism. A magnetic north pole presented to a magnetic south pole, or a south pole to a north pole, attracts, while a north pole to another north pole or a south pole to another repels. This gives to us a better reason than gravitation can for the elliptical orbit of the planets instead of the circular. It also gives us some light on the mystery of the tides, the philosophy of which the profoundest study has not solved. Certain facts are apparent; but for the explanation of the true theory such men as Laplace and Newton, and others more recent, have labored in vain." -- C.H. Kilmer, historian, October 1915

"Since Newton announced his universal law of gravitation, scientists have accepted and educators taught it, and rarely has it been questioned. Occasionally one has the temerity to say that gravitation is a myth, an invented word to cover scientific ignorance." -- C.H. Kilmer, historian, October 1915

"What we call mass would seem to be nothing but an appearance, and all inertia to be of electromagnetic origin." -- Henri Poincaré, physicist, 1908

"...the great truth, accidentally revealed and experimentally confirmed, is fully recognized, that this planet, with all its appalling immensity, is to electric currents virtually no more than a small metal ball...." -- Nikola Tesla, physicist, 1904

"If we were to assert that we knew more of moving objects than this their last-mentioned, experimentally-given comportment with respect to the celestial bodies, we should render ourselves culpable of a falsity." -- Ernst Mach, physicist, 1893

"...certain theoretical investigations ... appear to me to throw doubt on the utility of very minute gravitational observations." -- George H. Darwin, physicist, 1882

"The long and constant persuasion that all the forces of nature are mutually dependent, having one common origin, or rather being different manifestations of one fundamental power, has often made me think on the possibility of establishing, by experiment, a connection between gravity and electricity …no terms could exaggerate the value of the relation they would establish." -- Michael Faraday, physicist, 1865

"Thus, thinking as Newton did (i.e., that all celestial bodies are attracted to the sun and move through empty space), it is extremely improbable that the six planets would move as they do." -- Pierre L. Maupertuis, polymath, 1746

"...to establish it [gravitation] as original or primitive in certain parts of matter is to resort either to miracle or an imaginary occult quality." -- Gottfreid W. Leibniz, polymath, July 1710

"Meanwhile remote operation has just been revived in England by the admirable Mr. Newton, who maintains that it is the nature of bodies to be attracted and gravitate one towards another, in proportion to the mass of each one, and the rays of attraction it receives. Accordingly the famous Mr. Locke, in his answer to Bishop Stillingfleet, declares that having seen Mr. Newton's book he retracts what he himself said, following the opinion of the moderns, in his Essay concerning Human Understanding, to wit, that a body cannot operate immediately upon another except by touching it upon its surface and driving it by its motion. He acknowledges that God can put properties into matter which cause it to operate from a distance. Thus the theologians of the Augsburg Confession claim that God may ordain not only that a body operate immediately on divers bodies remote from one another, but that it even exist in their neighbourhood and be received by them in a way with which distances of place and dimensions of space have nothing to do. Although this effect transcends the forces of Nature, they do not think it possible to show that it surpasses the power of the Author of Nature. For him it is easy to annul the laws that he has given or to dispense with them as seems good to him, in the same way as he was able to make iron float upon water and to stay the operation of fire upon the human body." -- Gottfriend W. Leibniz, polymath, 1695

"The present does not seem to be the proper time to investigate the cause of the acceleration of natural motion [i.e., gravity], concering which various opinions have been expressed by various phiolosophers, some explaining it by attraction to the center, others to repulsion between the very small parts of the body, while still others attribute it to a certain stress in the surrounding medium which closes in behind the falling body and drives it from one of its positions to another." -- Galileo Galilei, physicist, 1638

"The example of the magnet I have hit upon is a very pretty one, and entirely suited to the subject; indeed, it is little short of being the very truth." -- Johannes Kepler, astronomer/mathematician, 1609

"It is therefore plausible, since the Earth moves the moon through its species and magnetic body, while the sun moves the planets similarly through an emitted species, that the sun is likewise a magnetic body." -- Johannes Kepler, astronomer/mathematician, 1609

"But come: let us follow more closely the tracks of this similarity of the planetary reciprocation [libration] to the motion of a magnet, and that by a most beautiful geometric demonstration, so that it might appear that a magnet has such a motion as that which we perceive in the planet." -- Johannes Kepler, astronomer/mathematician, 1609

Apparently criticism of creationist religious dogma such as that of Newton, Laplace, and Lemaitre is not tolerated. So much for NPOV Wikkidd (talk) 20:57, 6 March 2009 (UTC)

And to criticise this irrelevant post, I give you:

"Last of all Hurin stood alone. Then he cast aside his shield, and wielded an axe two-handed; and it is sung that the axe smoked in the black blood of the troll-guard of Gothmog until it withered, and each time that he slew Hurin cried 'Aure entuluva!" -- J.R.R. Tolkien, philologist, 1954. Acannas (talk) 02:29, 17 March 2009 (UTC)

I still say "gravity" is God. —Preceding unsigned comment added by 99.246.242.251 (talk) 16:10, 17 March 2009 (UTC)

Gravity + Energy

What happens to the energy used to fight gravity? Standing and sitting for instance... --173.79.127.205 (talk) 12:35, 18 March 2009 (UTC)

Let's say you drop a bowling ball on the pavement. The potential energy of the bowling ball is converted into kinetic energy. When the ball hits the ground, that energy is converted into electrical potential energy between the atoms of the bowling ball and that of the ground. That energy manifests as the vibration we know as sound. Some of that energy travels through the ground, and some of that energy travels back into the air. Compression stores the electrical potential energy, and rarefaction is the action of releasing it. If you stand up, it's similar to that, but the effect is less noticeable since the work is done over a longer time frame and more area is involved, unlike the hard bowling ball drop where a tiny portion contacts the ground.Kmarinas86 ^(6sin8karma) 12:54, 18 March 2009 (UTC)

Lead section

Is it just me, or has the lead section deteriorated recently? (In case it changes under my feet, I'm looking at the version here.) The opening sentence, "Gravitation is a natural phenomenon that gives weight to objects.[1]", strikes me as weak (and, incidentally, the reference given does not seem to even mention the word "weight"). The second sentence is something of a non-sequitur, and the rest of the first paragraph seems, well, kind of rambling.

If we're not happy to say "Gravitation is a natural phenomenon by which objects with mass attract one another", which is how it used to read, then I think we should bite the bullet in the opening paragraph and explain the "force/attraction" and "spacetime" perspectives in as simple and brief a way as is humanly possible. Then, having mentioned these theories about what gravity actually "is", the second paragraph can start explaining the sorts of things that gravity leads to -- weight, tides, planets, convection, stars, etc. -- in some sort of logical order. 86.133.247.13 (talk) 01:43, 19 March 2009 (UTC).

Good point. I at least fixed the first sentence, but there's still more work to be done. Artichoker^[talk] 01:53, 19 March 2009 (UTC)

Actually, I'm slightly partial to going back to the earlier version of the lead, and then merging back in anything that's worth keeping. Of course, the best option is for someone who actually knows what they are talking about, and knows the contents of the article pretty well, to write the lead from scratch. Acannas (talk) 03:09, 19 March 2009 (UTC)

I see you've done this, Acannas. Thanks, this earlier version certainly reads much better to me. Couple of things I'd point out:

• The reference in the first line, to an article called "Does Gravity Travel at the Speed of Light?" does not seem particularly relevant to the sentence to which it's attached.

• The last sentence, "... while "gravity" refers specifically to the net force exerted by the Earth on objects in its vicinity as well as by other factors, such as the Earth's rotation" is IMO grammatically faulty. I think the version here is grammatically better, but it's vague about why the net force on objects "in the Earth's vicinity" should be affected by the Earth's rotation. Is that part really talking about objects on the surface of the Earth? 86.134.90.99 (talk) 03:50, 19 March 2009 (UTC)

No, it refers to objects in orbit. Physicists think differently and apart from other people. They are not writers, and they think laypeople know what they know. Forgive them, they know not what they do.—Preceding unsigned comment added by 134.134.139.70 (talk) 14:37, 1 April 2009 (UTC)

I know what it is, but not why is it.

The beginning of the article explains very clearly what gravity is. But not really what's going on. All particles in the universe attract each other with a force that falls off at the square of the distance, okay, that's simple enough. But why do they attract each other and how? -OOPSIE- (talk) 19:48, 21 March 2009 (UTC)

(I am not an expert.) In Newtonian gravitational theory (the inverse square law that you mention), which is demonstrably not exactly correct, the force just "is" -- the theory does not offer an explanation of how or why. In GR, the curvature of spacetime makes it seem like there's a "force of gravity", as the lead section says. Depending on what you're expecting from the answer, that explains a "how", though very likely not a full and final "how". It seems unlikely to me that we'll ever know "why" if by that you mean "for what purpose". It doesn't seem to be a question for physics, anyway. 86.133.55.86 (talk) 03:51, 22 March 2009 (UTC).

Science ignores the fact that "Gravity" is Jehovah. —Preceding unsigned comment added by 156.34.178.193 (talk) 17:37, 26 August 2009 (UTC) No because science is not some guy who goes around deciding whats true or not. Its a collection of ideas. Science is ignoring nothing. Your just mad that your silly theory (or trolling) is not taken seriously. 98.135.12.214 (talk) 15:57, 1 October 2009 (UTC)

"Centre" vs "center"

A recent edit changed the American spelling of the word "center" to the English "centre" in a quotation of a passage from a memorandum of Isaac Newton's. Since this is a direct quotation, however, the actual spelling used by Newton himself should be preserved. According to the introduction to Subrahmanyan Chandrasekhar's translation of commentary on the Principia, Newton did in fact spell it "center" rather than "centre". I shall therefore change it back.
—David Wilson (talk · cont) 14:49, 2 April 2009 (UTC)

this is all wrong —Preceding unsigned comment added by 69.117.11.148 (talk) 00:33, 17 April 2009 (UTC)

Evidence? Are you saying that Chandrasekhar has misquoted the relevant passage of the memorandum? Have you been to the Library of the University of Cambridge to check the manuscript for yourself? Alternatively, can you cite either a faithful copy which shows that Chandrasekhar's transcription is erroneous, or—at the very least—another reliable secondary source which contradicts it?

—David Wilson (talk · cont) 08:52, 17 April 2009 (UTC)

Template:General relativity

I invite discussion whether Template:General relativity belongs on this article. That is a navigation template, and Gravitation is not one of the articles that it navigates to. It is possible that the template ought to be confined to the set of specialized articles that all concern general relativity in a direct way. We do have one section here, Gravitation#General relativity, and that section points to the main article at Introduction to general relativity, which *does* carry the template. EdJohnston (talk) 16:35, 21 April 2009 (UTC)

It certainly seemed to me that it was misplaced where it was, so I have now moved it to the section on general relativity. It does seem to me to serve a useful purpose there, and I certainly can't see that it does any harm. Nevertheless, I'm not going to complain if anyone wants to remove it. Incidentally, as it was, the template in the article carried an argument, "cTopic= phenomena", but as far as I could tell that doesn't do anything at all, so I took it out. I took a quick look at the template source, and as far as I could tell, it doesn't take any arguments as it is currently written. I apologise if anyone thinks the argument actually does something useful, but if so, please feel free to put it back in.

—David Wilson (talk · cont) 12:29, 22 April 2009 (UTC)

should give mention to Mannheim's theory?

I think Mannheim's theory should at least be mentioned http://arxiv.org/abs/gr-qc/9407010 —Preceding unsigned comment added by 125.237.96.73 (talk) 23:40, 22 April 2009 (UTC)

I don't. An unpublished preprint from 1994 is not notable. See WP:NOTABILITY for details. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:34, 25 April 2009 (UTC)

I agree, although I don't think WP:NOTABILITY is the proper criterion to apply. That seems to me to be a criterion for judging whether a topic merits its own article. Here, I think WP:UNDUE is the applicable policy.

I don't think that even subsequent publication of Mannheim's theory in a reputable scientific journal would be enough by itself to warrant its being mentioned in the article. Unless it has been discussed in something like a review article in a reputable journal, or a text book, or has received a substantial number of citations in the literature by scientists other than the author himself, then I can't see how it can be considered sufficiently significant to be mentioned.

—David Wilson (talk · cont) 08:09, 25 April 2009 (UTC)

Yeah WP:UNDUE is more relevant than WP:NOTABILITY. If the theory itself was the subject of a review (and that the review concludes it's a sound theory, and not a bunch of nonsense), then yes it would be appropriate. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:26, 25 April 2009 (UTC)

gravitational attraction

After the big bang, do dense parts have a strong gravitational pull and pulls materials around it? Does doing that make it gain more gravitational attraction? How can galaxies isolate from one another then if they are pulling on one another? —Preceding unsigned comment added by 89.211.96.253 (talk) 17:18, 4 May 2009 (UTC)

Wrong wording in introduction?

In the introduction:

"... while 'gravity' refers specifically to the net force exerted..."

Shouldn't that say "net acceleration" instead of "net force"?

This apparent error seems to be accurately clarified in the "Scientific revolution", "Newton's theory of gravitation", "General relativity" sections that:

1. Aristotle incorrectly believed gravity is a constant force.
2. Galileo determined gravity is a constant acceleration.
3. Newton refers to the "force of gravity", not gravity as a force
4. Einstein determined, as his proof of general relativity, that acceleration can exist without a force being applied

So, why does that say "net force"? —Preceding unsigned comment added by 98.243.106.85 (talk) 08:55, 27 May 2009 (UTC)

1. A net force does not have to be constant.
2. A net force changes and therefore does not produce constant acceleration.
3. I have to agree with this part. Gravity is a phenomenon involving forces. Yet, it is much easier to say "gravity" instead of "force of gravity".
4. Yet the acceleration due to gravity can be defined in the context of a system, so an effective force may be measured.

• Conclusion: There is no problem stating it that way.Kmarinas86 ^(6sin8karma) 18:13, 26 August 2009 (UTC)

Okay,

1. True
2. If "...", and it "..." So, true.
3. "Gravity is a phenomenon involving forces."... Isn't it clear to you that gravity is an acceleration and not a force? That's the entire reason why I asked about the wording. The rest of the article explicitly indicates that gravity isn't a force. Stating that it is in the intro, but not in the article is confusing.
4. It's true that an "acceleration due to gravity can be defined in the context of a system". But, it's not true that an "effective force may be measured" in all contexts. #4 regarded general relativity where acceleration can exist without forces. It should be possible to define a system which has acceleration due to gravity, but has no force due to gravity in general relativity. Yes? —Preceding unsigned comment added by 98.243.106.85 (talk) 09:11, 15 September 2009 (UTC)

Gravitation vs. gravity vs. effective gravity vs. gravitational acceleration vs. gravitational force

Yes, the introduction is a little sloppy and not accurate. Contrary to what the article suggests, gravity is not considered a "net force" and not necessarily Earth-centric. The term is used for other planets too. Secondly, gravity normally doesn't include other factors such as rotation...I believe that's EFFECTIVE gravity (see article: Earth's Gravity). I think we need an expert to properly delineate the difference between all these confusingly similar, misunderstood terms. —Preceding unsigned comment added by Firth m (talk • contribs) 00:50, 7 October 2009 (UTC)

I'm an active astrophysicist and professor. In all my years of research, I have never heard anyone assert that gravity refers only to the gravitational field of the Earth, not to those of other bodies. I can't be absolutely sure that no dictionary anywhere defines gravity so narrowly (no dictionary I can find in a cursory inspection makes this distinction), but I am certain that the vast majority of astrophysicists use gravity to mean the attractive interaction between any two particles with mass. In my opinion, the distinction currently drawn in the introduction between gravity and gravitation is completely wrong (as is the Australian web page cited), and therefore I am altering it (and removing the cite) immediately. Craigheinke (talk) 01:46, 28 October 2009 (UTC)

Belay that; it's protected. So, let me request that the appropriate Wikipedia higher-ups consider removing the second paragraph of the lede. If you're unsure, just check as many dictionaries as you like. Let me also suggest the Astrophysics Data Service, http://adsabs.harvard.edu/abstract_service.html, where you can check (after removing synonym replacement at the bottom) that there are currently 20937 astrophysics abstracts using "gravity", vs. 7284 abstracts using "gravitation". Virtually none of those papers refer to the gravitational field of the Earth. "Gravity" is the accepted, most common scientific (and popular) term for the gravitational interaction between any two massive bodies.Craigheinke (talk) 01:56, 28 October 2009 (UTC)

It is not protected, just semi-protected. You need to make one more edit somewhere (you already have 9 edits) and you will be able to change this page. Ruslik_Zero 05:26, 28 October 2009 (UTC)

I removed the paragraph. -- BenRG (talk) 11:18, 28 October 2009 (UTC)

Excellent! Craigheinke (talk) 22:50, 1 November 2009 (UTC)

I don't know about anyone else but I find net an ugly word here- surely a better word is 'Sum' because all the forces are additive. Lucien86 (talk) 01:55, 25 December 2009 (UTC)

Include a formula

Could please somebody include the formula for Newton's law of gravitation. I know this is an overview article which should be accessible for anyone, and the formula is in another linked article. But I don't want to read the whole article to find the right link to the formula, which is really the only thing I am interessted in, when I look up gravitation. —Preceding unsigned comment added by 85.127.220.167 (talk) 08:17, 5 June 2009 (UTC)

The "Cavendish experiment" should be mentioned under the history section!

The Cavendish experiment, done in 1797–98 by British scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory.

This should be mentioned in the section: /* History of gravitational theory */ of the Gravitation article! (Perhaps just beneath: "Newton's theory of gravitation" ?). —Preceding unsigned comment added by 84.20.108.34 (talk) 11:16, 26 August 2009 (UTC)

about gravity

was the earth's mass and its radius along with the distance between many heavenly bodies determined before the discovery of universal gravitational law?? if not then how did newton derived the universal gravitational theory?? —Preceding unsigned comment added by 115.187.16.4 (talk) 14:14, 1 September 2009 (UTC)

Embattled article

This vital article should be brought into a better state. I'm sorry to say, but despite the fact that this is a "vandalism target", it does not seem to improve regardless of its state. Someone should endeavor to bring this to GA (which it is currently lightyears away from). I know, it is easier to criticize than to achieve. 74.98.46.129 (talk) 02:48, 10 October 2009 (UTC)

nonsense in Gravitational torsion, weak equivalence principle and gravitational gradient

This section is full of nonsense. In the title, "Gravitational torsion" refers to a specific hypothetical effect that would extend Einstein's theory of general relativity to include more general types of spacetime curvature; see http://www.lightandmatter.com/html_books/genrel/ch05/ch05.html#Section5.8 . The text of the section, however, never talks about gravitational torsion; it talks about torsion balances instead. The two usages are totally unrelated. The material about "Eötvös' law of capillarity" appears to be a joke, or vandalism. Unfortunately I can't edit this article to fix these mistakes, because it's locked. Wow. Wikipedia at its worst. This article should have the tag saying that it's in need of attention from an expert. --75.83.69.196 (talk) 20:36, 3 January 2010 (UTC)

I tagged the section (doesn't seem to be locked now) before I read this comment, with which I totally agree. The same nonsense appears in the article Equivalence principle. The user who inserted it was subsequently blocked.--Keith Edkins ( Talk ) 11:10, 4 January 2010 (UTC)

Is gravity a fictitious force?

General relativity says that objects move in straight lines in curved spacetime. Doesn't this mean that gravity is a fictitious force, just like centrifugal force, Coriolis force, and Euler force?

Like these other fictitious forces, gravity is proportional to mass. So does gravity really act on mass at all? Or is it proportional to mass because it is only an acceleration as perceived from our convenient but erroneous frame of reference?

And if gravity is a fictitious force, how can anyone consider "unifying" it with electromagnetism and so on? You wouldn't "unify" EM with centrifugal force, would you? And why would you expect there to be a graviton to mediate gravity, if there's not one to mediate Coriolis force? Wnt (talk) 19:40, 4 January 2010 (UTC)

Article states that General Relativity and Quantum Mechanics are not compatible theories, so your guess is possibly as good as anyone's since both are widely accepted in the scientific world. Bertcocaine (talk) 13:28, 7 August 2010 (UTC)

Gravitational vector field addition.

• 
  At the center of gravity, the gravitational vector fields add to zero. Equal and opposing forces in all directions. Darker is a vector field that sums towards the center.

That does not imply that the force of gravity at the center of gravity is zero, it implies that the vector field forces, due the masses, are such that they are equivalent in all directions and pull a particle, that is in the center, equivalently in all directions. When a particle enters the gravitational field, the vector sum of the forces due all masses, as that particle passes through that mass, changes direction. For the earth, the force of gravity at the surface is 9.8m/s², which is a vector sum of all the attractive forces due the masses. At the center, inside a uniform sphere, the forces due gravity on that particle are not equal to 9.8m/s², but less (less than half that amount but if somebody would do the exact calculations that would be appreciated), and is a vector field pointing outwards from the center, equivalent in all directions. Any deviation from that central tendency would create a vector field with a higher force in the direction of the center of mass, and less so in every other direction.

If someone could add this explanation it would be appreciated. I am not well versed in the meriat ways to change a project wiki page and definitely not a profesional editor.
Thank you. (Fractalhints (talk) 18:13, 6 January 2010 (UTC))

The sources, the sources, I tend to forget. Any high-school physics book containing forces, technical text on physics, higher educational text on physics, parsed through several minds. This addition is basic physics, not some unholy triple phd parsed through peer review of the extraordinary infighting higher educational system. Ohh, yes, think, that´s the term, uncommon as it may seem. Have brain, will think, at least some times.(190.38.108.80 (talk) 21:24, 6 January 2010 (UTC))(Fractalhints (talk) 21:27, 6 January 2010 (UTC))

I doubt that the center of mass must be the point where an object's internal gravity zeroes out. For example, suppose someone helpfully attaches a 1 solar mass white dwarf to a solar mass worth of space elevator cable to tug it around with. If you're standing on the surface of the white dwarf at the base of that space elevator cable, you'd better have brought your slimming fashions. Yet the center of mass should be halfway between the center of mass of the white dwarf and the center of mass of the cable, i.e. 1/4 of the way up the cable. You'd actually be getting pulled strongly away from the center of mass. Now the center of gravity is a little trickier to define but it still is a term referencing external gravity - e.g. the handled white dwarf would orbit a galactic black hole with its center of mass tracing the ellipse, provided nothing ruptures. Wnt (talk) 21:29, 6 January 2010 (UTC)

Forces due the masses. Center of gravity is the forces due each individual particle or mass, center of mass doesn´t come into play. The sum of the forces at the center of gravity goes to zero. There is a slice of spherical pie that pulls that particle towards it. However, all the other slices of spherical pie also pull with the same force. The vector sum of all the forces on that particular particle are effectively zero. That implies that it has a tendency to stay stationary in that particular position. Any particle with mass has a ´gravitic´ attraction to any other particle with mass, it´s a basic property of matter. A massless particle, not having mass, is not matter. A massless particle is a reference to a form of interaction that has nothing to due with matter, ie:no gravitic attraction, in order to balance an equation.

The implications are that at the center of gravity you only need to exert a very slight force to move that particle but you would need an incremental gradient of force to remove that particular from the sphere of influence of gravity. The cummulative effect of all the vector force fields of all the particles that compose matter. The picture is not completely clear but would need another one to describe the force of gravity outside the mass. This one is only internal to a uniform mass.(Fractalhints (talk) 13:02, 12 January 2010 (UTC))

I'm sorry, but I'm having some trouble understanding what you're getting at. Are you looking to address the idea that a uniform spherical shell exerts no gravitational force on objects inside of it (See Shell theorem#Inside a shell, though alas as written that is not an easy article to understand) Wnt (talk) 20:43, 15 January 2010 (UTC)

Removed probable self promotion

Due to probable wp:COI, I have reverted the edits made by Andwor9 (talk · contribs · deleted contribs · logs · filter log · block user · block log).

See also

• Article Paul Gerber: removed
• Article Quantum gravity: added and removed
• Article Modified Newtonian dynamics: partly removed

DVdm (talk) 15:26, 9 January 2010 (UTC)

What's strange is that I can't find this paper or author in ArXiv, nor any accessible full text. I thought all the physics papers could be found there. Why not this one? I'd likely have reintroduced the paper myself as interesting, if I could read/make sense of it. Wnt (talk) 20:52, 15 January 2010 (UTC)

Here is an abstract. Online subscribers to Physics Essays can apparently download a full copy of the paper, but there seems to be no facility for a non-subscriber to buy one. Physics Essays seems to me to be a reputable scientific journal, but, in my opinion, mere publication of a paper like this in such a journal is not enough by itself to warrant its being mentioned in the article. Unless it has been discussed in something like a review article in a reputable journal, a treatise or a text book by another author, or has received a substantial number of citations in the literature by other authors, then I can't see how it can be considered sufficiently significant to be mentioned.

—David Wilson (talk · cont) 01:36, 16 January 2010 (UTC)

Space between nucleus and electron

What is in the space between the nucleus and the electron cloud? The Ether or spacetime. Most objects are like homogeneous sponges of this ether (like sponges in water), ie there is space between the nuclei and electrons of our atoms, but in black holes this space does not exist because it was forced out by the gravity, so there are nuclei that are in direct contact with their electrons. the ether that was forced out sits on the event horizon waiting to get back in. this is like putting a balloon (black hole) in a tank of water (ether). This also explains gravity on our planet, it is very similar to our atmosphere. This also explains why most calculations give the volume of black holes as infinitely small: because we are using the ether to measure it and all the ether that would normally be inside the black hole (if it was a giant planet) is sitting on the event horizon, therefore the event horizon is the surface of the black hole's mass, and when objects are pulled in they spread out over the entire surface like a balloon creating another layer of matter below the ether conglomeration. And in order to get hte correct volume of the universe we need to include this volume it is not a single infinitely small point, that is like saying the balloon in the water is an infinitely small point because it has no water in it!63.76.208.2 (talk) 18:00, 29 January 2010 (UTC)Kevin Burns63.76.208.2 (talk) 17:59, 29 January 2010 (UTC)—Preceding unsigned comment added by 63.76.208.2 (talk) 17:53, 29 January 2010 (UTC)

The space between the nucleus, consisting of protons and neutrons, and the electron cloud is filled with force lines of whatever you wish to discuss. The four universal forces that they attempt to place together. If you take into consideration beta emission (see alpha, beta, gamma radiation) and consider near-field and far-field radiation, ie far-field being beta decay where an electron is expelled and near-field where an electron is expelled and re-absorbed due proton-nuetron exchange and interaction, then you also have other force fields and particles within that space. In black holes, the radiation that enters a black hole is not emitted in the same spectrum as it entered. If you look at the diagram above (a previous post), you will notice that at the center of a black hole, the gravitic lines are away from the center. This is due the distribution of masses around the center. Particles are extremely compacted but masses none-the-less. At least, that is the common understanding. Now, for the punch-line, somewhere around the event-horizon is a point where the individual parts of an atom are seperated. Each mass particle will have a different velocity vector associated to it due to it´s kinetic energy, ie mass-velocity relationship, and therefore, particles, as we know them, do not exist inside this sphere. There are no atoms, just electrons and whatever the makeup of protons and nuetrons are but in different layers. The heavier particles somewhere in the center, the lighter ones further out.

Using your terminolgy, the event horizon could feasibly the surface of the black hole´s mass and for practical purposes could be considered to be at least the upper atmosphere. Is this in relation to the article in such a manner that a change or an additional link could be placed. I wouldn´t know, I am not the maintainer of this page but I certainly appreciate your viewpoint on this matter as that clarrifies certain other aspects. Cheers.(Fractalhints (talk) 22:13, 27 February 2010 (UTC))

Gravitation (not gravity?)

Why is this article referring to gravity as gravitation? Is this an American vs British English usage thing? --Rebroad (talk) 23:19, 15 April 2010 (UTC)

Try google books. For some authors there is no difference. For some gravity is Earth-related whereas gravitation is more general. According to Misner, Thorne and Wheeler, their bible "Gravitation" is a book about Einstein's theory of gravity. There you go :-) - DVdm (talk) 07:12, 16 April 2010 (UTC)

Edit request from Rockoctagon, 11 June 2010

{{editsemiprotected}} The statement in the opening paragraph: "The simpler Newton's law of universal gravitation provides an accurate approximation for most calculations."

is inaccurate and could be replaced with "The simpler Newton's law of universal gravitation provides an accurate approximation for most calculations of behaviour near the Earth's surface" or similar

and again at the end of the "Newton's theory of gravitation" section I would recommend appending "near the Earth's surface" to the last sentence.

If a specific reference to the Earth is undesirable then perhaps "in very weak gravitational fields" or something. Newton's law is imprecise enough that Einstein's General Relativity is needed for GPS satellite calculations for example.

Rockoctagon (talk) 12:46, 11 June 2010 (UTC)

Newton's law of universal gravitation isn't just for objects near the Earth's surface as seen here. Hope this helps. Set Sail For The Seven Seas 232° 57' 15" NET 15:31, 11 June 2010 (UTC)

100 years from now

100 years from now people will look back on our ideas about gravity and laugh uproariously. Each new generation, including ours, thinks they know "everything", or at least can explain the important issues. It seems to me we probably know very little. I think we're like ants at the edge of a vast ocean. The majority of us are still superstitious and ignorant. Even the smartest of us are incapable of really understanding the scale and duration of the universe. Fundamentally, we don't know what we don't know. It seems obvious there must be basic things about the universe that we currently know nothing about.

Physicists blather on with their mathematics and arcane jargon about things beyond their understanding. The basic idea presented is that when I let go of a ball, it falls because space-time is curved. But what starts the ball moving downward, if there is no force? Einstein's great discoveries came from thought experiments that had intuitive and logical outcomes. This is neither intuitive nor logical.

At least the article doesn't include that silly picture of space-time curving inward like a depressed trampoline, and the ball spinning down toward the middle. That picture is pitiful pseudo-science. We can't draw a picture of the curvature of space-time. And once again, why would the ball go down the "gravity well" if no force?

Every decent scientist acknowledges limits and uncertainties to their work, and I think the article should do the same. The article has an "anomalies and discrepancies" section, but this misses the bigger point that we really know nothing about the actual mechanism of gravity. The emperor has no clothes. I'm sure it pains the physicists to be so ignorant about such a basic phenomenon. At least Newton had the honesty to say he didn't know. 174.31.156.73 (talk) 07:09, 15 June 2010 (UTC)

I would have to agree with the gist of this comment - the article reads as a mass of contradictions, and a number of key comments lack sources. Although finding consistent sources from a field full of differing opinions and a lack of definitive proof might be challenging! On the plus side, the complexity of the language is baffling to the layman; Thus it is unlikely that anyone will go away with misinformation. However, that does raise the question of how suitable is this article for an encyclopaedia? I'm not suggesting that such a major topic should be removed, but it certainly isn't something that can be comprehended by anyone without a prerequisite understanding of complex maths or physics! Bertcocaine (talk) 13:25, 7 August 2010 (UTC)

Support My name is Kmarinas86, and I approve this message.Kmarinas86 (Expert Sectioneer of Wikipedia) ^{19+9+14 + karma = 19+9+14 + talk = 86} 21:57, 21 November 2010 (UTC)

Gravitation is a secondary effect (on masses) generated by Vacuum and Vacuum Energy as the primary source of "gravitational" forces applied on masses (a suggested mechanism)

WP:NOTFORUM - 2/0 (cont.) 22:28, 17 September 2010 (UTC)

Gravity is, in my opinion, originally generated from the medium i.e. the Vacuum and Vacuum energy, on masses. the vacuum energy 10^107 joules per cubic centimeter creates a force (a repulsive in nature, since energy of vacuum is different from energy of mass and mass surface) on the mass surface, similar to surface tension force. The body of the mass provides a surface where vacuum energy fluctuations (waves?)could reflects off. these reflections of the vacuum energy would then become "synchronized" when reflected off the mass surface into high and low energy waves sinusoidal mathematical functions (orbits) mixed with other geometrical representing motion mathematical functions pending on Vacuum and Vacuum energy medium surrounding the mass. The density of the mass would be a deciding factor of the frequency of the vacuum energy synchronized reflection, in such a way that shorter wave reflected will form from a denser body (black hole). When two masses are within the fields of each others synchronized reflected vacuum energy waves(gravitational forces filed), they "shadow" each other from the non reflected vacuum and vacuum energy waves fluctuations; therefore falling into a lesser, a weaker repulsive medium, resulting in the observed attraction of the two masses to each other.--e:Y,?:G 06:37, 15 September 2010 (UTC) —Preceding unsigned comment added by E:Y,?:G (talk • contribs) The Black Hole event horizon support's the above suggested mechanism for Vacuum energy synchronized wave reflection off mass's bodies, in a way that the mass of the black hole is so dense that the vacuum energy waves reflected have wave length that does not support to carry the light waves or the electromagnetic waves as a lesser density mass bodies do. Or the unreflectiveness of light off the Black Hole mass body, is may be because these vacuum energy synchronized wave reflection off the mass's bodies, must reflects off a body not of the dimensions of the Black Hole mass i.e. less than 5 solar masses. The form these vacuum energy waves reflected off the mass must meet a certain geometrical dimensions. gravitational lensing is another example supporting the above suggested mechanism in a way that the reflected vacuum energy waves off dense bodies are not synchronized in the same way the lesser denser mass bodies do. Another conclulsion form the above suggested mechanism for vacuum energy synchronized wave reflection off mass's boies, is it must be in a certien formate for it to "carry" light and electromagnatic waves. The reflection of the vacuum waves off a mass's body could work as "sonar" in way or light reflection in way to evaluate a mass density.--e:Y,?:G 08:44, 15 September 2010 (UTC) —Preceding unsigned comment added by E:Y,?:G (talk • contribs) --e:Y,?:G 21:55, 17 September 2010 (UTC)

What really is Gravitation ?

When people says "Natural Phenomena", that means they dont get what really is the subject. Lets try to find out what really is Gravitation if there is no "graviton" particles as Albert Einstein thought.....

If we take a look at the Universe as a whole we can see matter, energy, antimatter (we can see this only in human experiments) and "gravitation" (i intentionally omit some subatomic interactions as "strong interaction" etc) Dont you see, that something missing in here ?

Well... some people asks " why there is no antimater in the universe....

In my humble opinion there is .... in form of gravitation.

Cause if we imagine that Universe is a spring like thing and if it was created from nothing, and is limited by its borders and gravity interaction is endless in space.... we will find out, that gravitation is nothing less and nothing more than ... ANTIENERGY. Why ?< br>  If the Universe contains matter, antimatter, energy, and gravity, and sum of those must be zero then the only solution is to treat gravity as antienergy.

If E. Einstein is right and E=mc2 then if we try to find similiar equation to antienergy it would be:

AE=-m(-c)2

So if we find out that gravitation is antimatter .... so AE=G we can solve solution of the Universe.

U= m + (am) + E + AE = m -m + mc2 + (-m(-c)2) = 0 + mc2 +(-mc2) = 0

Isnt it showing that gravitation is nothing less than antienergy of the "spring" called Universe ?

Its so obvious that Gravitation is antienergy if we asks ourselfs what we need to put the Newton`s apple back on the tree ... we have to use energy .... to counteract with antienergy caled gravitation. —Preceding unsigned comment added by Cslpl (talk • contribs) 11:35, 25 October 2010 (UTC)

Gravity | G Theory

Has anyone else heard of the new "G Theory" in terms of its fusion with Law of Attraction and Gravity? —Preceding unsigned comment added by TheWikiFriends (talk • contribs) 02:37, 2 December 2010 (UTC)

Opening sentence is poor English

"Gravitation, or gravity, is a natural phenomenon in which objects with mass attract one another."

"in which" is surely not right here. I seem to remember it used to say "by which", which in my opinion is correct English. 86.183.170.249 (talk) 01:12, 3 February 2011 (UTC)

Phenomenon or force in lead

User Kmarinas86 (talk · contribs) changed the lead into an i.m.o. rather awkward expresion going like "... a natural force by which bodies attract with a force...". I think it's better that in the lead we keep referring to the subject as "... a natural phenomenon by which bodies attract with a force...", namely the "gravitational force", or the "force of gravity". A bit further we also say that "Gravitation is one of the four fundamental interactions of nature...". Any further thoughts? DVdm (talk) 18:07, 3 February 2011 (UTC)

Some recent versions of this sentence have been poor English. IMO the current version ("Gravitation, or gravity, is a natural phenomenon by which physical bodies attract with a force proportional to their mass") is better, but still not ideal. "attract" seems to be crying out for an object like "one another". But then the second part would have to be changed to "proportional to the product of their masses" which may be more detail than we want in the opening sentence. Do we have to mention force at all at this point? Could we just say "Gravitation, or gravity, is a natural phenomenon by which obejcts with mass attract one another."? 81.159.110.141 (talk) 03:09, 10 February 2011 (UTC)

Couple more potential problems?

"According to Newton's 3rd Law, the Earth itself experiences an equal [in force] and opposite [in direction] force to that acting on the falling object, meaning that the Earth also accelerates towards the object (until the object hits the earth, then the Law of Conservation of Energy states that it will move back with the same acceleration with which it initially moved forward, canceling out the two forces of gravity.)."

This seems to be saying that the Earth experiences a force that is equal in force. Should "in force" be "in magnitude"?

I have no idea what the part in brackets is trying to say. What happens after the collision (e.g. whether or not the two things bounce off each other) would seem to depend on their material properties. I don't understand the reference to the Law of Conservation of Energy or to "cancelling out" gravity.

"When an object with commensurable mass would "fall" then the acceleration of Earth would really be observable."

English ("when ... then ... would") needs tidying, but I'm not convinced that "commensurable" is actually the correct word. I'm feel there's another, better word, but I can't right now put my finger on it! 81.159.110.141 (talk) 03:34, 10 February 2011 (UTC)

Thanks for the notice. I've had a go at fixing the relevant passages. No doubt the wording could be improved further, but at least the more conspicuous errors and clumsiness have been removed.

David Wilson (talk · cont) 12:12, 10 February 2011 (UTC)

References

Under: -specifics

     -Earth's gravity

-quote: "Every planetary body (including the Earth) is surrounded by its own gravitational field, which exerts an attractive force on all objects. Assuming a spherically symmetrical planet (a reasonable approximation)"

Reference, explain why this is a reasonable approximation. —Preceding unsigned comment added by 81.100.211.117 (talk) 20:54, 12 February 2011 (UTC)

Name Change

Why not change the name to theory of gravitation, as it is after all the very definition of a scientific theory "a collection of concepts, including abstractions of observable phenomena expressed as quantifiable properties, together with rules (called scientific laws) that express relationships between observations of such concepts"

There is more than one theory of gravitation.siNkarma86—Expert Sectioneer of Wikipedia
^{86 = 19+9+14 + karma = 19+9+14 + talk} 12:23, 18 February 2011 (UTC)

Edit request from Turbobeef, 18 March 2011

{{edit semi-protected}}
Done

If the the object doesn't bounce after it has collided with the Earth, each of them then exerts a repulsive contact force on the other which effectively balances the attractive force of gravity and prevents further acceleration.

The is used twice in this sentence. It's under specifics then Earth's gravity 3rd paragraph last sentence. hope I did this right! Turbobeef (talk) 00:48, 18 March 2011 (UTC)

Thanks for picking this up. Now fixed.

David Wilson (talk · cont) 09:15, 18 March 2011 (UTC)

More poor English

The first sentence under the Anomalies and discrepancies section was a bit confusing when I first read it: "There are some observations that are not adequately accounted for, which may point to the need for better theories of gravity or perhaps be explained in other ways." I assume it's meant to indicate they may 1) point to a need to revamp the theory or 2) perhaps have other explanations, but that's not immediately apparent. I think a little rewording would help tighten expression of the idea and get it across more clearly (the long phrase between "perhaps" and "may" almost breaks their connection). —Preceding unsigned comment added by 173.225.203.115 (talk) 01:30, 24 March 2011 (UTC)

Law of Geodesic Motion

This is not a reliable source! http://blog.sauliaus.info/temp/gravity.pdf It's from blog and it's essay! — Preceding unsigned comment added by Alcharkov (talk • contribs) 14:43, 6 April 2011 (UTC)

Even blog's author making fun of it http://blog.sauliaus.info/?p=436 — Preceding unsigned comment added by Alcharkov (talk • contribs) 14:47, 6 April 2011 (UTC)

I have removed the citation. According to my somewhat hazy recollection of my course on General relativity, the claim for which the source was cited is more or less correct. If anyone were to demand a citation to a reliable source for it, it should be easy enough to dig one up .

David Wilson (talk · cont) 15:24, 6 April 2011 (UTC)

Don't know rules here, but maybe it's better to keep this cite (if claim is correct), but remove the reference and put "citation needed"? —Preceding unsigned comment added by 86.100.75.12 (talk) 15:53, 6 April 2011 (UTC)

Comment

I, in my mind invented this theory about if everything was opposite it would all be the same theory about 2-3 years ago and I wasnt sure because if the compilation of two changes wouldnt be effective because there wouldnt be a reason to have two changes in reason you would have one. Could you please explain this to me and also I have another theory. If we ever had the technology in mining equipment and the development of technology to reduce the intense heat and a long enough drill to drill through the entire earth.(Obviously not)but if we were to hypothetically drill through the earth and we jumped in this hole and the velocity and momentum faded away(although there is always momentum and velocity)and it ran out because energy does not last forever, would the gravity, since it pulls toward the centre, make us float in the centre of the earth? I.E. if you lived in north america and someone is in a part of asia (opposite side of the world)they would be relitively standing upside down compared to you but there is gravity so it is focused to the centre. My idea is that the centre of celestial body that has gravity related to the same amount of density to that of earth,would eventually form a bond between you and the forces of the body and make you evidentily weightless?

Sincerely,

--99.236.206.254 (talk) 04:57, 11 June 2011 (UTC) gudspelar@hotmail.com

P.S. please e-mail me back.

Thank you for your interest in Wikipedia's article on gravitation. However, this talk page is devoted solely to suggesting or discussing possible improvements to the article. General questions about the subject of the article or discussion of alternative theories are not appropriate matters for posting here. Wikipedia's Science Reference Desk is the only appropriate venue within Wikipedia where such matters can be dealt with, so please direct any further such queries or comments there.

David Wilson (talk · cont) 06:16, 11 June 2011 (UTC)

does quantum entaglement create all field that exist!!!! as everything were bound together before big bang?? — Preceding unsigned comment added by 117.204.82.47 (talk) 14:19, 15 June 2011 (UTC)

HOW SUN IS FIXED IN IT'S POSITION

As planet are in their position due to sun"s gravitational force so what is the force that keep the sun in its position? — Preceding unsigned comment added by 203.78.174.2 (talk) 12:06, 22 June 2011 (UTC)

the sun is not fixed in its position believe it or not it is spinning wildly around and around the center of the milky way galaxy like a drunk whore on the dance floor!

Redundant disambiguation

I'm trying to delete a redundant disambiguation, and also get rid of a stupid TV disambiguation, but ShelfSkewed has reverted Bhny (talk) 16:06, 22 June 2011 (UTC)

Both of these are legitimate disambiguation hatnotes, and there is nothing redundant or ridiculous about either of them. The terms gravity and law of gravity redirect to this article (as, of course, they should), and the hatnotes are the standard and accepted way of pointing users to other topics that use, or might use, those terms as titles. Gravity (disambiguation) disambiguates topics known as Gravity, which is distinct from (and therefore not redundant with) the disambiguation page Gravitation (disambiguation), which disambiguates topics titled Gravitation. The other hatnote accommodates differences/carelessness in the use of capitalization.--ShelfSkewed Talk 16:18, 22 June 2011 (UTC)

Thanks, it makes sense now that there is a "Law(s) of Gravity" disambiguation and the CSI episode has been renamed, also you are right about gravity/gravitation Bhny (talk) 22:29, 20 October 2011 (UTC)

Force or no force

I have seen sources^[3] online which quote scientists who believe that gravity is not actually a force. Should they be incorporated? AdventureCaverns (talk) 02:00, 3 August 2011 (UTC)

Croatian Wikipedia

http://hr.wikipedia.org/wiki/Gravitacija — Preceding unsigned comment added by 83.131.64.226 (talk) 04:32, 24 December 2011 (UTC)

categories

Shouldn't we add the category "scientific theories" to this article? --Abuk SABUK (talk) 13:55, 6 December 2011 (UTC)

Gravity 1 & Gravity 2

If you drop an object here on earth, it gets draged around with the planets spin(we know this because when we drop something it falls exactly where we expect it to even though the planet is spinning), at what distance does this happen? is this drag relevant to the moon? Enertia is in a line, but the planet is spining. Im honistly starting to believe in two gravities?

If you believe it's Coriolis_effect then what keeps hot air baloons going around with the planet? "Gravity also drags?"! gravity drags works with atomic precision

Paul G Griffiths, Bristol UK 2011
—Preceding unsigned comment added by Gafferuk (talk • contribs) 21:17, 11 May 2011 (UTC)

Thank you for your interest in Wikipedia's article on Gravitation. However, this talk page is not an appropriate place for asking questions about the article's subject, or for proposing or discussing alternative theories about how gravity might work. The purpose of Wikipedia articles' talk pages is to propose and discuss ways in which those articles might be improved. I have therefore taken the liberty of copying your questions across to Science Reference Desk and (partly) answered them there.

David Wilson (talk · cont) 00:01, 12 May 2011 (UTC)

An object dropped from a hight of 1m takes less than half a second to reach the ground (ignoring air resistance and buoyancy). You are right about inertia making the object keep going in a straight line while the earth turns away from it, but in the time it takes for the object to land, the difference will be tiny. This doesn't have anything to do with the moon; instead, it (and any other object in orbit around the earth) is essentially falling down, but moving forward fast enough that it always misses the earth - see Orbit for more details. Wardog (talk) 10:55, 25 February 2012 (UTC)

Edit request on 20 January 2012

Under Specifics / Earths Gravity the following sentence is as follows,

"Thus, an object starting from rest will attain a velocity of 9.81 m/s (32.2 ft/s) after one second, 19.6 m/s (64.4 ft/s) after two seconds, and so on, adding 9.81 m/s (32.2 ft/s) to each resulting velocity."

I think the 19.6 m/s should be changed to 19.62 m/s

It's minor but the the gravity constant of 9.81 m/s is precise to two decimal places and I think the 19.6 m/s value given should also be precise to two decimal places.

209.82.26.132 (talk) 22:48, 20 January 2012 (UTC)

Sounds reasonable to me. Done, thanks. Adrian J. Hunter^{(talk•contribs)} 02:28, 21 January 2012 (UTC)

Morgan Freeman

I saw Morgan Freeman on a show the other night and he said he wasnt sure if gravity works or not in infintesimally small spaces. I want to add that he said that to the lead paragraph but there is a lock on the pagein the upper right hand corner that I cann ot unlock! — Preceding unsigned comment added by 207.238.152.3 (talk) 19:39, 15 July 2011 (UTC)

Morgan Freeman is an actor. As good of an actor he is, it does not make him a very reliable source. A peer-reviewed research papaer would work much better.--137.146.143.108 (talk) 15:34, 8 February 2012 (UTC)

I'm guessing that the op was thinking of Freeman Dyson. 209.252.235.206 (talk) 10:14, 17 February 2012 (UTC)

More likely Morgan Freeman reading from a script on Through the Wormhole on the Science Channel.--Bainst (talk) 06:23, 2 March 2012 (UTC)

Universe-Energy-Mass-Life Compilation

From http://universe-life.com/2012/02/03/universe-energy-mass-life-compilation/ “Since gravitation is the propensity of energy reconversion to mass, and energy is mass in motion, gravity is the force exerted between mass formats.” (and extent depends also on distance-configurations...)

Dov Henis Dov Henis (talk) 03:21, 27 March 2012 (UTC)

This appears to be an unorthodox theory which has yet to be accepted by anyone other than its proposer. As such, it's not appropriate material for coverage in a Wikipedia article.

David Wilson (talk · cont) 04:17, 27 March 2012 (UTC)

a loop hole in newtons theory of gravity..

if i fire a cannon ball right up in the air (neglecting air resistance) it is but obvious that it fall down. sir newton gave inverse square law, according to which gravitational force is inversely proportional to square of distance between the two objects. now as i fire the cannon ball in the air, the distance is going to increase, and so the square, so as per the formula gravitation force should decrease, but it does not happen. ball falls returns to earth. if the force is decreasing as per increase in height according to the formula, then what is making the ball to return back to earth. the answer to this is very simple, its gravity but this force is not exerted by the earth(it according to me) but it is the layer of atmosphere around the earth. --Jokerthedarknight (talk) 13:59, 9 January 2012 (UTC)

The force due to gravity would lessen as the cannon ball went higher, however, it would not completely disappear. The average cannon cannot launch a cannonball high enough that it can escape Earth, however, space shuttles can get to space precisely because they can get "high enough" that Earth's gravity becomes insignificant. 209.252.235.206 (talk) 10:16, 17 February 2012 (UTC)

First, this page is for discussing the article, not the topic itself. Questions about the topic can be asked at the Science Reference Desk. However, the statement above is incorrect. Anything that is in orbit, like the shuttle or the International Space Station, has not 'escaped' the gravity of Earth. The gravitational force is still quite significant there, which is why the object stays in orbit. It is because of its speed that it doesn't return to the ground. Check out the articles on orbital velocity and Kepler's Laws for more explanation. PhySusie (talk) 15:52, 25 February 2012 (UTC)

It does apply and happen. You just need to calculate distance change from the centre of each spherical mass. It doesn't change much and the gravity between the two is inversely proportional to the square of the distance that hasn't changed much. 99.251.114.120 (talk) 03:00, 3 May 2012 (UTC)

Edit request - "their mass"

Lede contains the phrase "their mass". Should this not be "their masses". When the adjective is plural the noun should be also. This refers to the combined **effects** if both masses not combined into one singular mass. 99.251.114.120 (talk) 03:40, 14 April 2012 (UTC)

Done. Ruslik_Zero 16:28, 14 April 2012 (UTC)

History

Gravity was first discovered by a Hindu astronomer who thought of the idea of gravity but did not give it a specific name or meaning. Varahamihira observed the effect of gravity on heavenly bodies as well as things that are coming back to the Earth.

on gravity was Brahmagupta. He was a Hindu astrologer who commented that gravity, as a concept, is a natural affinity or part of the natural order of the world. He even compared it to elements like water and fire.

The 11th century saw the coming of another Hindu astrologer named Bhaskarachaya. He continued the efforts of Brahmagupta. He also wrote a book that mentioned gravity. This book is entitled “Siddhanta Siromani.”

Another worthy contribution of the Hindus on gravity was by giving it a definite term. The term was in Sanskrit and was called “Gurutvakarshan.”

Years, decades, and centuries passed before the Christian world became interested in gravity as much as the Hindus. The Western Christian world became interested in the sciences after the Renaissance, a period of revival of classical knowledge. Although gravity is not particularly mentioned in classical Greek or Roman texts, some scientists began to rediscover ancient beliefs about the world that led to the rediscovery of gravity.

Christian gravity features many people who are famous and familiar with modern people. These people are better known compared to their Hindu counterparts due to the dominant Western history and traditions in the world.

One of the leading figures is Nicholas Copernicus who proved that the Earth is round rather than a flat surface. This contradicts the thought that a vessel traveling the oceans would fall off the “world’s edge” as once believed. All things on Earth are held down by gravity, even in a spherical shaped body like a planet.

Galileo Galilee followed Copernicus in the 17th century. Galileo was known for his famous experiment of dropping two materials with different weights at the top of a tower. He also contradicted a classical teaching by Aristotle, a leading Greek philosopher.

Meanwhile, the most famous scientist focusing on gravity is Sir Isaac Newton. Newton’s discovery was founded from Robert Hooke’s suggestion that gravity is related to distance and its inverse square. Sir Newton also developed the mathematical formula and established the law of gravity.

Another leading and famous figure is Albert Einstein who founded the Theory of Relativity. Like Newton’s, Einstein’s contributions are considered to be the classic or the dominant teaching when it comes to relativity.

Western Europe’s contribution on gravity ideologies are those taught in schools today. In addition, these Western figures are able to express gravity in a formula (specifically a mathematical one) to make gravity more realistic as opposed to an abstract concept. Gravity is a constant element in our reality, but it is still very abstract since we can only feel or experience it even in everyday life.

Both Christian and Hindu gravity concepts have played an enormous contribution to the understanding of gravity.

Read more: Difference Between Christian Gravity and Hindu Gravity | Difference Between | Christian Gravity vs Hindu Gravity http://www.differencebetween.net/miscellaneous/religion-miscellaneous/difference-between-christian-gravity-and-hindu-gravity/#ixzz20rvnxLws — Preceding unsigned comment added by 218.189.138.50 (talk) 09:05, 17 July 2012 (UTC)

Gravitation

Gravitation is nothing else but a black sphere in the center of each star and planet.www.dimension-theory.com[[www.informa-invent-suply.se] Since Wikipedia does not allow any pictures on th is page. I will refer to the above 2 links. NOTICE HOW THE GRAVITATION FACTOR IS MEASURED FROM THE CIRCUMFERENCE OF THE SPHERE PARABOLICLY AS ITS CENTER. Private reasearcher --Bjorn Quarzell (talk) 14:29, 12 June 2012 (UTC)--Bjorn Quarzell (talk) 14:29, 12 June 2012 (UTC)Bjorn Quarzell.

Suggesting Formulas

How about adding pictures of formulas explaining the scenario of a falling object in different scenarios? — Preceding unsigned comment added by 88.65.75.71 (talk) 21:39, 9 August 2012 (UTC)

Missing: The physical expression of Gravition force.

I think it is truly astounding that the most basic formula for gravitation is missing in this article !:

Fg = G m1 m2 / r^2 — Preceding unsigned comment added by 213.93.217.25 (talk) 11:22, 3 March 2012 (UTC)

I also am very confused by this... A more thorough search revealed to me that this equation is located in the pages "Newton's Laws of Universal Gravitation" and "Equations for a falling body" but it's pretty confusing to not have them on the gravitation page. Maybe someone could at least add a sentence along the lines of "for the equation which describes the force due to gravity on an object in a gravitational field see..." — Preceding unsigned comment added by 50.137.182.79 (talk) 20:57, 2 November 2012 (UTC)

Smallest particle where Gravity is measurable

I am just a layperson who is fascinated with the creation of the Universe (the final frontier). I read various theories, such as from nothing came something, but where my lack of knowledge puzzles me, is this; how do these dust particles in space the size of a pinhead (once they collide) start to stick together to eventually form planets? Do these dust particles have gravitational pull? What is the smallest size that has ever been measured to have gravitational pull...........an atom? Again, I am no scientist, but if atoms have gravitational pull, why wouldn't larger objects on my desk be drawing smaller objects to them to 'adhere' to each other?

Thanks to anyone whom will respond to me in a lay person's language.

Beaconmike (talk) 03:54, 24 July 2012 (UTC) The shortest distances on which gravity has been measured is something like tenths (maybe hundreds by now) of a millimeter. But even in those cases the gravitating devices are cm's across.TR 09:29, 6 November 2012 (UTC)

suggestion - 07/11/2012

the article itself lacks information on the differentiation of gravity on other planets and star systems. A section devoetd to neutron stars and black holes might be a nice addition. — Preceding unsigned comment added by Thedarkknight1 (talk • contribs) 19:21, 7 November 2012 (UTC)

Vandalism

Someone added " Lilia is always right about gravity. " to the first paragraph. This is inaccurate and unsourced; it is likely Lilia is only sometimes right about gravity. I suggest removing this change. Ianjk (talk) 23:45, 2 February 2013 (UTC)

• done - thanks! PhySusie (talk) 23:52, 2 February 2013 (UTC)

Sugesting pictures

I think this article needs a picture of a 3D simulation of gravity, something like this:
Gravity in 3D
3D gravity
I don't think these specific pictures are allowed here, but if someone can find a similar picture that is legal to use it would be a nice addition to the article
Sebbes333 (talk) 19:20, 19 July 2012 (UTC)

Yes, I think these pictures demonstrate spacetime curvature a lot better than the usual "ball on a net" kind. It would be nice if there was a CC-friendly image out there.Tofoo (talk) 10:02, 12 April 2013 (UTC)

Edit Request - April 19, 2013

Speed of Gravity section...http://en.wikipedia.org/wiki/Gravity#Speed_of_gravity Is out of date. It states: " In December 2012, a research team in China announced that it had produced findings which seem to prove that the speed of gravity is equal to the speed of light. The team's findings were due to be released in a journal in January 2013.[24] " The article was published. citation information (sorry not in Wiki format) Chinese Science Bulletin February 2013, Volume 58, Issue 4-5, pp 474-477, Observational evidences for the speed of the gravity based on the Earth tide Authors: KeYun Tang, ChangCai Hua, Wu Wen, ShunLiang Chi, QingYu You, Dan Yu -- Note that pub date is Feb 2013, not Jan. (but published online Sept 2012). I suggest replacing the above with the following: "Measuring the speed of the propagation of gravitational effects is very difficult. In February, 2013 a Chinese team reported that they had measured the effect of Solar and Lunar tidal forces on distortions of Earth's shape and mass distribution for over a decade and found that gravity's speed was between 0.93 and 1.05 of the speed of light, consistent with General Relativity's assumption that its speed is the same as the speed of light." -=- I also note that the original claims they "seem to prove...". This is risible. How did the word 'prove' get into a scientific discussion?!! -=- If the < ref > link I inserted in the paragraph doesn't work then try this one: http://link.springer.com/article/10.1007/s11434-012-5603-3 Regards72.172.1.109 (talk) 16:14, 19 April 2013 (UTC)

References

The cause of gravitation is unknown

I think we should mention in the lead that we do not know the cause of gravitation. We can observe gravitation and we can calculate it, but we do not what is the true cause of gravitation. We have noticed that it is assosiated with large bodies such as the Earth or the Sun, but we do not know why these objects create gravitation around themselves. Can the theory of relativity answer this? The cause of gravity is the curvature of spacetime? Unproven. --Hartz (talk) 15:31, 2 November 2012 (UTC)

Yes, the existence of a Wikipedia user named Hartz is also unproven. (These posts could have arisen through random glitches in the Wikimedia software.) We also do not know why charged objects create an electric field. Or why energy is conserved? Or why the laws of nature are time translation invariant? (the last two are equivalent though) Or why the standard model has SU(3)xSU(2)xU(1) gauge symmetry. Science is not in the business of explaining why thing work the way they do, but of explaining how they work the way they do.

What we do know is that general relativity, by describing gravitation as curvature of spacetime rather as a Newtonian force, gives a better description of observed physics than Newtonian gravity. Your GPS proves this everyday (if you have one).TR 09:27, 6 November 2012 (UTC)

Hartz is right. "Action at a distance," otherwise known as gravity, remains one of the four or five unsolved conundrums of the cosmos. (Six if you count "the existence of a Wikipedia user named Hartz.") The article in no way reflects the perplexities still surrounding the phenomenon. Orthotox (talk) 23:01, 5 May 2013 (UTC)

IN SEARCH OF GRAVITY

I have a simple theory covering practicals as well about gravity. Is it possible to be allowed to prove about this. I do not want to say the prove about gravity by other people was wrong but i do feel i have a new theory based on gravity. Thank you. My email:peterfrancis_munguti@yahoo.com41.215.57.170 (talk) 13:58, 26 June 2013 (UTC)

Wikipedia has no original research- wp:original. You should publish it elsewhere. Bhny (talk) 14:09, 26 June 2013 (UTC)

Edit request

"This reproduces general relativity in the classical limit".

The quantum gravity is not reproducing general relativity at any limit, it's only aiming for it. Otherwise please provide references. — Preceding unsigned comment added by Servalun (talk • contribs) 10:27, 22 July 2013 (UTC)

Edit request on 20 May 2013

g = 9.80665 m/s² = 32.1740 ft/s² = 386.088 in/s² Kllwiki (talk) 13:38, 20 May 2013 (UTC)

Not done: please be more specific about what needs to be changed. If you are proposing that we add the in/s² figure, I think that's probably unnecessary. I don't think it's particularly common to use that in calculations related to gravitational acceleration - but I'd be happy to be corrected. Begoon ^talk 14:07, 20 May 2013 (UTC)

Science only uses two forms of linear measurement for velocity:- one is almost obsolete - feet per second, whilst the majority of scientists use the System International Unit of the metre per second. Therefore if someone wishes to express something in inches they are not only using a non-recognised measurement, but also a rather complicated one too. Even NASA uses metres per second in all its calculations - only reverting to feet, miles when it presents information to the general public.The Geologist (talk) 12:25, 23 July 2013 (UTC)

Question

Something bothered me in the article when it came to "...Galileo showed that gravitation accelerates all objects at the same rate." etc. When looking at the formulas for calculating gravity it seems to me that the resulting force is equal to the total mass of BOTH objects. This would mean that a 10kg hammer will fall faster than a 1kg hammer, the reason being the total mass of the 10kg hammer + the earth is greater than the 1kg hammer + the earth. It is probably not easy to measure but logic and the formulas suggest to me that this must be actually be true. So why is it suggested that all things fall at the same rate when that would appear to contradict the newton formulas? Shouldn't somebody make a note on this point?

The same would apply if you use Einsteins theory, the object would have its very own (though very small) effect on space time which must add to the same effect of the earth itself. Strangely in every picture of space time warping I've ever seen only the larger body was assumed to warp space-time and cause a gravity well. Strange. — Preceding unsigned comment added by 62.154.226.26 (talk) 11:51, 13 February 2013 (UTC)

The Galileo example is a simplification that treats the mass of the earth including all the hammers on Earth as well as axes, screwdrivers, and can openers.—GraemeMcRae^talk 21:47, 13 February 2013 (UTC)

Then the comment "Galileo correctly postulated air resistance as the reason that lighter objects may fall slower in an atmosphere." is actually wrong, that is what I'm getting at. The maths from both Newton and Einstein don't allow any two bodies to feel the same force unless they have the exact same mass at the exact same distance, correct? That is what bothers me about the article. — Preceding unsigned comment added by 62.154.226.26 (talk) 07:09, 14 February 2013 (UTC)

Let's say there is a hammer that is 1kg and a car that weighs 1000kg on the international space station. And let's say when we drop the hammer, the gravitational force between the hammer and earth is X. Then when we drop the car, the gravitational force would be 1000 times X, or 1000X. But how is it that they both accelerate downward at the same rate?

Yes, the acceleration is the same because the 1000X force is used to accelerate 1000kg car whereas the 1X force is used to accelerate 1kg hammer. I hope that makes sense.Tofoo (talk) 07:56, 11 April 2013 (UTC)

Acceleration in a vacuum is constant due to there being no air resistance. Galileo's hypothesis was proved during the Apollo missions to the Moon. See the video on the main page. In respect to dropping two objects of different mass on the ISS, they are in weightless conditions - which is actually a continuous free fall on a parabolic plane which means that they accelerate uniformly regardless of mass. However get in the way of a hammer and it will hurt when it collides with you, because its mass is still present.The Geologist (talk) 12:32, 23 July 2013 (UTC)

Acceleration due to gravity

Acceleration due to gravity is not as shown in the article but is correctly expressed in the formula V = Gravity per second SQUARED. I have written it deliberately in that format as many people forget the "per second squared," bit. As written it is a linear acceleration and would not create the "gravity parabola," when plotted on a graph.

Hence at time zero the velocity is equal to 9.8 x 0 squared, after 1 second the object falls 9.8 metres, after 2 seconds it falls a further 39.2 metres making the total fall after 2 seconds 49 metres, after 3 seconds the object will have fallen a further 88.2 metres making the total fall 137.2 metres. This assumes nil resistance due to the viscosity of air, which would reduce the fall and hence the total fall.

Just to prove it further here is a table for 0 to 10 seconds:

G m s2=	9.8	

T secs fall m total fall metres 0 0.0 0.0 1 9.8 9.8 2 39.2 49.0 3 88.2 137.2 4 156.8 294.0 5 245.0 539.0 6 352.8 891.8 7 480.2 1372.0 8 627.2 1999.2 9 793.8 2793.0 10 980.0 3773.0

If you don't believe it then I suggest you go and talk to a physicist, or a parachutist as one lesson that everyone who goes parachuting learns is that once you leave the aircraft you will accelerate to 32 feet per second per second which is 9.8 metres per second squared. Which also limits the amount of time available for free fall.

I use the above formula and table to calculate volcanic bomb fall and distance given the mass of the bomb it becomes simple to calculate the exit velocity from a vent. Which is why as someone claimed "volcanic blocks the size of houses," could not be thrown from an erupting Cumbre Vieja on La Palma to Tenerife some 80 kilometres away. A fact that annoyed the author who told me that people like me made him sick, but then people like him annoy me for presenting science in a way that is impossible for it to do.The Geologist (talk) 12:19, 23 July 2013 (UTC)

Until you introduce legible notation for exponentiation, replace loathsome "x" sign, and make other necessary steps to diminish readers’ aversion to these equations, I’ll simply ignore the thread. And yes, it it me who extinguished your CapsLock. Incnis Mrsi (talk) 13:50, 23 July 2013 (UTC)

MOVE ARTICLE to gravity

"Gravity" is a more common term than "gravitation" WP:COMMONNAME Ticklewickleukulele (talk) 00:11, 28 August 2012 (UTC)

No. In casual discussion, gravity and gravitation are often used interchangeably. However, gravitation is an universal force exercised by two bodies onto each other and gravity is a resultant force: Earth's gravity; gravity on the surface of the Earth. --Hartz (talk) 06:56, 4 November 2012 (UTC)

I agree, I don't see any point in being pedantic when both are covered in the same article. "Gravitation" seems a bit snobbish and reiterates the Wikipedia culture of people wanting to show how smart they are, rather than wanting to actually help... Cypherzero0 (talk) 02:28, 20 July 2013 (UTC)

gravity is the force, gravitation is the action, (the actual movement caused by force) as shown by the suffix of the word. also http://oxforddictionaries.com/definition/english/gravitation plus gravity is in common usage except occasionally gravitation is used to describe something actually moving, not the fundamental force. — Preceding unsigned comment added by 80.229.123.246 (talk) 17:07, 26 July 2013 (UTC)

the speed of gravity

There is no mention of the speed of gravity. For example if we removed the sun how much time would it take to have the heart flung out of the previous solar system. --81.84.152.156 (talk) 19:32, 27 April 2010 (UTC)

Well since gravity doesn't have any spped, it makes sense that there is no mention of it. Gravity-in super amateur (ei, me) terms, accelerates an smaller mass towards a larger mass. this acceleration varies, depending on the mass of the two abjects. —Preceding unsigned comment added by 38.115.132.20 (talk) 20:36, 12 May 2011 (UTC)

Gravity is a force that acts on a distance so if you change the mass distribution at point A the force changes at point B but unless point A is point B the force doesn't change instanly. I understand that if Sun would disapper now, it would take roughly 8 minutes before it would be felt on Earth. That is to say the "speed" of gravity would be c. I might be mistaken but it certainly can't be larger than c because that would violate Einstein causality. 88.148.148.97 (talk) 20:20, 4 December 2011 (UTC)

The above is only true if the force of gravity is "carried" by virtual force-carrying particles in the same way that the electromagnetic force is carried by photons. However, gravitons have not yet been discovered, so the matter is still up for debate. This is in fact hinted at in the article. ~ Lhynard (talk) 22:18, 4 December 2011 (UTC)

Not true. Even in general relativity, gravity, with no gravitons or any quantum stuff, moves at the speed of light. In fact Einstein's motivation for developing general relativity came from realising that, unlike electromagnetism, Newtonian gravity wasn't consistent with special relativity because in Newtonian gravity information travels infinitely fast (ie the strength of a gravitational field in Newtonian gravity is dependent only on the present mass distribution, not any information about where mass may have been in the past). — Preceding unsigned comment added by 92.27.55.215 (talk) 20:57, 18 May 2012 (UTC)

There cannot be such a thing as speed of gravity, if taking general relativity in consideration. It is only information regarding spacetime curvature that is "traveling." For instance, if the sun were to suddenly disappear, the change that occurs to the spacetime manifold between where the sun used to be and where the earth would be updated at the speed of light - which is about eight minutes. But "gravity" isn't really moving at the speed of light. This is a topic which is discussed in [gravitational wave]. Tofoo (talk) 10:05, 12 April 2013 (UTC)

Well, it would be safe to say that gravity is, or gravitational effects are propagated at the speed of light. — Preceding unsigned comment added by Dave509 (talk • contribs) 22:45, 28 July 2013 (UTC)

Perhaps it would be safe, but in general relativity the “speed of light” is not a simpler concept than the “speed of gravity”. Incnis Mrsi (talk) 07:12, 29 July 2013 (UTC)

Grammar

Gravitation is the only of these interactions which affects any matter. Alisdair37 (talk) 04:50, 27 June 2013 (UTC)

I do not see errors in my wikt:grammar. What does your wikt:grammer say about this phrase? Incnis Mrsi (talk) 08:39, 27 June 2013 (UTC)

I guess the problem is 'which' vs 'that'. [[4]]. Because it is a restrictive clause. it should be 'that'. Some British people use 'which' with restrictive clauses. Bhny (talk) 15:07, 27 June 2013 (UTC)

I fixed it Bhny (talk) 15:08, 27 June 2013 (UTC)

The sentence still makes no sense. I could read it as "Gravitation is the only one of these interactions which affects any matter" but that statement itself would appear to be untrue. Harlequin (talk) 01:31, 26 July 2013 (UTC)

I agree that this statement is demonstrably untrue, I was surprised to find such a clearly false statement in the summary intro of an article on such a basic and important subject. Electromagnetism clearly also affects matter, in various ways. For proof, go microwave a hot dog, or walk barefoot on a hot sidewalk. The photoelectric effect would be another example. 66.41.179.140 (talk) 02:36, 11 August 2013 (UTC)

Statement removed. Unsourced and worded in a confusing manner. I assume it was meant to mean "Gravitation is the only one of these interactions which affects any and all matter." — Reatlas (talk) 05:44, 11 August 2013 (UTC)

New alternative theory, please include internal link

Please include in "Recent gravity theories" section:

Extended theory of gravity (GE), (2010), Xavier Hernández Doring and Sergio Mendoza Ramos propose to extend Newton's Universal Law and General Relativity with an empirical approximation.

Please include internal link in other gravity pages. — Preceding unsigned comment added by Mariana Espinosa Aldama (talk • contribs) 11:29, 11 September 2013 (UTC)

What is Chromotivity

Chromotivity is a non Einsteinean Chromodynamic Relativistic theory of spin. Each chromodynamic oscillation perceives a different spin value to each near by chromodynamic oscillation, but as a whole-particle they have an averaged spin. The Big Bang degenerate particle, the black hole degenerate particles and all indivisible particles, are shaped by enveloped chromodynamic oscillations, and are enveloped to form one particle because of the "lightspeed equilibrium law"-read below. — Preceding unsigned comment added by 2.84.214.171 (talk) 05:26, 14 February 2015 (UTC)

Weak Spin Relativistic Degradation

Spin doesn't change directivity if the particle is not crushed on another particle or strong field. Particles though distort the default properties of the void. That tiny perturbation is a field force, therefore causes a small spin degradation over time, towards the area having the lowest energetic potential. That tiny relativistic spin degradation is also known as gravity. Gravity is not caused by reciprocal particle to particle direct exchanging of energy, but via their averaged perturbation to a non default void, because of the particle perturbation. A non default void sucks space and particles to restore it's default levels. The ultimate default levels of the void is the lowest possible quantum noise at almost 0 Kelvin temperature degrees [0 K do not exist in nature, not even before the Big Bang time frame but space can get close to 0K through time and entropy]. That "ultimate" default of the void is accomplished via entropy and requires zillon years. After all black holes would be evaporated in the afar future and all particles would be photons [only photons can exist at these ultra low energy levels of that afar future] spread under the lowest possible quantum noise threshold [therefore mixed with quantum noise and becoming virtual or low energy chromodynamic oscillations],the lightspeed equilibrium [a law that doesn't allow particles gain more kinetorotational energy because the sum of their "spin speed" and "external speed" cannot get higher than the lightspeed kinetic energy] would almost collapse towards an infinite "spin-degrading-speed" but dead-frozen "external speed". That ultimate breakdown mathematically can never occur, therefore many Big Bang hot-spots are perforced to explode.

Matter and particles lower the probability of virtual particle appearance, therefore matter has a lower energetic potential than the void.unsigned comment added by 2.84.214.171 (talk) 03:06, 13 February 2015 (UTC)

Gravity doesn't pull us together, Emptiness compresses us

If we have two spheres, one big and one small that have the same angular momentum, the small sphere has to spin faster in order to maintain the same angular momentum with the big sphere.

Gravity is a relativistic field force of the void that compresses particles in order they shrink, because the void becomes affected by matter and urges to set back to default. That shrinking forces particles spin faster in empty space, therefore you grow older faster, more quantum events occur to you relativistically in comparison with a same room that stands on a planet and not in empty space. Particles cannot shrink in no degenerate pressure is applied, therefore that extra energy is expressed as external relativistic motion, also known as angular distance shrinking.

Empty space has a preferable default [multi Big Bangs themselves, therefore urges to reset all values to that default]. Matter distorts that urge of the void to reset, and when we add more matter to an existing gravitational system, the gravitational field causes the void to exert pressure, to shrink these invasive particles. Particles cannot shrink without huge degenerate pressure, therefore they release that energy as external kinetic energy, that shrinks the angular distance to the area with the lowest energetic potential.

The more matter we have, the closer we are to a low energy potential, because matter and antimatter have lower potential energy than the void, and that's why the absolute void can never exist, only Big Bang is exploded when temperature is very close to 0 Kelvin degrees temperature, and when the quantum noise level is at it's lowest possible. That occurs because of the "lightspeed equilibrium law", a law that forces all particles maintain permenantly the light-speed energy level, and express it in two forms: a.external speed, b.angular momentum[spin speed], at the lowest possible temperature, the void tends to tear apart the lightspeed equilibrium with infinite spin speed, and zero external speed [to an extreme absolute zero void, one gets infinitely old immediately, therefore there is infinite planck potential to express inside that time the entire Universial energy range], but a quantum frame before that occurs, we have a new Big Bang.

Gravity seems to be weak as a force, because most of it cancels out, because it is exerted spherically, omnidirectionally. Gravity forces particles to shrink from all directions, but particles aren't allowed to shrink. All vectors of gravitational forces exerted on a particle cancel out, except a tiny force that pushes the particle towards the lowest energetic potential, thus the centre of gravity.

Gravity doesn't pull us together. Emptiness compresses us. A gravitational field simply reveals paths towards the lowest energetic potential area.

Dark Matter is Dark Energy surrounding matter, but when matter moves fast enough, Dark Matter may lack behind, because it has an affect on the properties of the void, and these affects do not move with external speed close to the light-speed, because on the lightspeed equilibrium theory, Dark Matter spends more of it's lightspeed equilibrium energetic ratio, in the form of rotational [spin] energy. — Preceding unsigned comment added by 2.84.214.171 (talk) 07:35, 12 February 2015 (UTC)

What is it?

All these theories about the effects of gravity but not one theory mention about what gravity actually is and/or the mechanism of how it works. It would appear there may be no theories and the article should state that. If theories exist they should be mentioned in the article. Most of this article apears to be fluff on abstract and unrelated downstream topics based on only the effects of gravity. 99.251.114.120 (talk) 13:40, 1 May 2012 (UTC)

Nobody knows! The best guess we have is that gravity works by atoms exchanging "virtual particles": why this creates a force anyway is very hard to understand. The only reason we think this might be the case is because it's worked for all the other forces we know, but if you do the same maths with gravity, for technical reasons it doesn't work. There are thousands of physicists working to resolve this problem. However, Einstein's equivalence principle suggests that gravity isn't really a force, it is purely an effect of the geometry of spacetime. There are plenty of physicists who believe that there are no virtual particles because (a) the Einstein principle makes gravity different, (b) the maths doesn't work for gravity, and (c) despite dedicated experiments, nobody has seen the elusive gravity particle. — Preceding unsigned comment added by 92.27.55.215 (talk) 21:08, 18 May 2012 (UTC)

I agree that this article is very inaccessible to a layman who comes here to get the answer to the question "What causes gravity?" If we know, the article should say so. If we don't, it should say we don't. --Westwind273 (talk) 04:35, 29 May 2012 (UTC)

In fact the article is quite tendentious insofar as it plumps squarely down in the Einsteinian account of things, as though it was all quite settled: "The phenomenon of gravitation itself, however, is a byproduct of a more fundamental phenomenon described by general relativity, which suggests..." Stating that something is while in the next breath basing that assertion on a "suggestion" is, to say the least, somewhat overreaching. Space time curvature and the finite but open universe that it is premised upon have been in question ever since telescope observations during Einstein's own lifetime strongly "suggested" that the universe was actually non-curved and still expanding and may well be expanding to infinity. All in all, such topics invite a more skeptical, provisional and, dare I say, scientific approach, or so it seems to me. Orthotox (talk) 22:43, 5 May 2013 (UTC)

The simplest answer is that Einstein's suggestion that gravity is the effect of mass on the geometry of spacetime. You stretch out a bed sheet and put a big ball in the middle. Then put a smaller ball somewhere else on the sheet. The smaller ball will roll towards the bigger ball. The question is: why does matter warp the fabric of spacetime in the first place? — Confession0791 ^talk 04:26, 20 July 2013 (UTC)

"The Five Elements/Elders", artwork for a personal graphic novel project. - I first wrote the following Theory of Rendundant Terminology as a question for newton.dep.anl.gov . I'm sure I violated some rules of their format, so they have not as yet replied:

"Is (your weight) not the result of an equation that is based on the pressure (air, water what have you) around you, specially ABOVE you (just like underwater), plus your mass MINUS the weight taken off the total of Pressure + Your Mass from CENTRIFUGAL force of the Earth trying to fling things off of itself? I ask because no one has ever given me a satisfactory answer to what 'gravity' itself is. I've never believed that mass attracts mass (the moon and earth are pretty massive, both with their own supposed 'gravity', yet we live). My question is a call for a true definition of how 'gravity' can seem to inexplicably exist. I believe it has more to do with the pressure of air all around and above us pushing us DOWN at a force all 'round about 1000 pounds per square foot of us. My question calls for an equation solved with factors that I'm unfamiliar with.

(Your/Something's/Anything's mass on Earth + Average Earth air pressure below the clouds) - (the weight that is offset by centrifugal force) = your weight?

Now if the weight offset by the Earth spinning at around 1000 mph IS around the weight of the Air pressure around you, then 'gravity' is a made-up word that says it is an unknown force that somehow magically magnetizes you to the ground when you are more prone to actually being thrown off the Earth if it were not for the Compressed Air between the Atmosphere and the ground.

It doesn't matter how deep into the Earth you go, you won't become 'heavier' because of LAVA MAGNETISM. Go deeper and you think the extra pressure will push you down harder therefore you're heavier? No, you will have MORE centrifugal spin effect the closer you are to Core, therefore equalizing with the air pressure around you and maintaining your weight.

When something is crushed under the weight of earth pressure that is not air (like WATER), we say it was crushed by the pressure all around and above it. We do not say, 'It has more gravity, its own weight crushed it'. Above water, we insist the rules (physics) change somehow right from the quark.

The universe may be labeled 'an empty vacuum', but that doesn't mean to say the whole mass of the Universe does not have PRESSURE. The pressure exerted by the Universe on a Planet PLUS the spinning planets centrifugal release of water, heat, mineral and biological gases EQUALS Atmosphere, with the resulting 'sandwich' of pressurized air created automatically between atmosphere and solid ground. From a universal point of view, this little pocket of air pressure acts as a LOCK for anything that is heavier than what the earth can throw off of itself. Hence, water experiences Evaporation, to be made into Clouds most irrefutably, when the ceiling called Universal pressure is met that pushes it back DOWN (which is why water doesn't just fly off forever, even without 'gravity').

Sorry, I'm not sure this is a question then. It's a request to check the equation to dispel the myth known as gravity. No equation can ever be made that has 'Gravity' in it, it would be flawed in trying to prove its own existence. And a reminder to self that we shouldn't be messing with the clouds above our heads lol, they push us down, it's PUSH, not a non-existent, inexplicable PULL. I have no references for my theory."

Fullchain (talk) 21:36, 13 December 2013 (UTC)

Physicist Michio Kaku says it like this: "The earth doesn't pull you to the ground, space pushes down on you." So, is it plausible that matter is the absence of space, rather than vice-versa? — Confession0791 ^talk 22:44, 13 December 2013 (UTC)

Isn't gravity "a property or quality" of space-time? why don't we just say it that way? 50.181.71.228 (talk) 15:47, 28 March 2014 (UTC)

An incorrect statement: "Even though electromagnetism is far stronger than gravity, electromagnetism is not relevant to astronomical objects, since such bodies have an equal number of protons and electrons that cancel out (i.e., a net electric charge of zero)." Plasma physics is used to describe plasma, not gravitational theories. 99% of the universe is plasma, so gravitational theories apply only to the 1% that is solids, liquids and gasses - i.e. matter composed of equal numbers of protons and electrons. Planetary orbits around a charged object. Plasma is only neutral when it is not in motion. Motion produces electric currents and magnetic fields which affect other particles. At least please get the science correct and make a correct statement. "When the charges move, they generate electrical currents with magnetic fields, and as a result, they are affected by each other’s fields." The only astronomical bodies electromagnetism is not relevant to are planets - made of those atoms that possess equal numbers of protons and electrons. Many air molecules will not create electric currents and magnetic fields. Many ions or electrons will.Steven J White (talk) 00:43, 17 February 2015 (UTC)

As for space being empty - of course it isn't. That is not supported by our own science. "Defining the field as "numbers in space" shouldn't detract from the idea that it has physical reality. "It occupies space. It contains energy. Its presence eliminates a true vacuum."[2] The field creates a "condition in space"[3] such that when we put a particle in it, the particle "feels" a force." And if anyone insists it is empty, then they really need to stop using the permeability and permittivity of space in every single equation. It's empty or it isn't. It's filled with energy or it isn't. But if it isn't, then they need to stop treating it in the math like it is, but tell us it isn't. Steven J White (talk) 00:53, 17 February 2015 (UTC)

With the advent of special relativity...

Does gravity have an infinite range? We all now know that gravitational waves propagate at the speed of light just as electromagnetic waves such as a light itself propagate EM fields at the speed of light, they can still continue forever, right?--195.194.89.201 (talk) 12:11, 13 May 2014 (UTC)