Talk:Gravity

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)

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)

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 ?

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)