Talk:Gravitomagnetism

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Talk page archives:

  • archive1 - include debate over the title of the article (gravitomagnetism is preferred over gravitoelectromagnetism)

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[edit] Clarification?

I know this is a long shot, but I'm going to ask anyway. I read the article and it sounds to me like if you apply a force to a mass that would cause it to accelerate, the GEM analog of self-inductance will cause it to accelerate faster than you would expect classically. That sounds wrong to me. Where does the extra energy come from?

I guess I should explain why I think this. In electromagnetics, self-inductance has the opposite effect (it resists acceleration), but the sign change appears to flip this effect around backwards. Consider a mass current flowing away from a clock face, toward the person looking at the clock. Accelerating this flow would increase J, thus increasing the surrounding B in the clockwise direction (because of the sign-changed 4th equation). By the third equation, this creates an E-field in the direction we just said the particle is accelerating. By the force equation, the particle accelerates even more than it would have originally.

Please help, if you know what I'm doing wrong. Other than being physics-impaired, I mean. X-| Xezlec 23:49, 22 April 2007 (UTC)

[edit] Citations

To ensure uniform appearance and for other reasons, in future please use citation templates. Please bear in mind that this is an encyclopedia article, not a review article in RMP. Don't attempt to list every paper which has ever appeared. Don't list your own papers (very bad form!). Don't list paper A if there is a better paper B, particularly if B cites A. Do list review good papers like Mashhoon 2003. Do think carefully and try to keep the list to a half dozen primary sources. For example, do consider removing A and B if review R cites them. TIA ---CH 01:03, 27 March 2006 (UTC)

[edit] From SI to Planck: Question

The last 2 paragraphs of section 1.1 may be wrong. The fourth Maxwell equation in SI units is:

\nabla \times \mathbf{B} = \mu_0 \mathbf{J} + \mu_0 \epsilon_0 (\partial \mathbf{E}/ \partial t) = c-2(( \mathbf{J} / \epsilon_0) + \partial \mathbf{E}/ \partial t)

In Planck units:

\nabla \times \mathbf{B} = 4\pi \mathbf{J} + \partial \mathbf{E} / \partial t

Planck and CGS units normalize the Coulomb force constant, (4πε0)-1, to 1. The above equation in Planck units makes sense if such units normalize μ0 to 4π, a normalization I cannot confirm. Do CGS units normalize μ0 to 1? How can 4π be eliminated from Maxwell's equations? If you can answer these perplexities, don't reply here; instead, please edit the last 2 paras of section 1.1.202.36.179.65 17:52, 29 March 2006 (UTC)

even though Planck units are a neat topic that i have interest in, i am not sure of the pedgagical advantage in putting all that in this article. we should just point out, in comparison to E&M, that charge is replaced by mass, charge density by mass density and \frac{1}{4 \pi \epsilon_0} \leftarrow -G \ . true, if you use rationalized Planck units (same as Planck units except 4 \pi G \ is normalized to one instead of G \ ), then the GEM equations look just like Maxwell's Eqs. except for a minus sign where there is charge or charge density. Rbj 21:56, 29 March 2006 (UTC)


[edit] Gravitomagnetic explanations for relativistic jets

A paragraph with references was added to present the dramatic ramifications of jet analyses for gravitomagnetism. Tcisco 03:43, 13 April 2007 (UTC)


[edit] Comparison with electromagnetic force

The gravitational attraction between protons is approximately a factor of 1036 weaker than the electromagnetic repulsion. This factor is independent of distance, because both interactions are inversely proportional to the square of the distance. Therefore on an atomic scale mutual gravity is negligible. Even so, the main interaction between everyday objects and the Earth and between celestial bodies is gravity, because at this scale matter is electrically neutral. This means that there is an equal number of positively charged particles in the universe to negatively charged particles. For example, there aren't any positively charged planets that zoom into negatively charged planets. This means that gravity dominates the universe even though it is the weaker force. However, to show the delicate balance of gravity over the electromagnetic force, given two bodies if even there were a surplus or deficit of only one electron for every 1018 protons and neutrons this would already be enough to cancel gravity (or in the case of a surplus in one and a deficit in the other, double the force of attraction).

Though the force of gravity dominates the visible macro universe, the main interactions such as fusion between the charged particles in cosmic plasma, of which the sun is composed and which make up over 99% of the universe by volume, are due to the nuclear forces. In terms of Planck units, the charge of a proton is 0.085, while the mass is only 8×10-20. From that point of view, the gravitational force is not small as such, but because masses are small. The relative weakness of gravity can be demonstrated with a small magnet picking up pieces of iron. The small magnet is able to overwhelm the gravitational effect of the entire Earth. Even though gravity is relatively weak, the small gravitational interaction exerted by bodies of ordinary size can fairly easily be detected through experiments such as the Cavendish torsion bar experiment.

Further reading

J. D. Redding 17:30, 14 April 2007 (UTC)

[edit] Removed phrase

I removed the text:

Frame-dragging is often mentioned as a gravitomagnetic effect, but the Lense-Thirring effect (precession) may be a more appropriate example.

This sounds like a normative opinion, and is unreferenced. It is also somewhat confusing, in that the Lense-Thirring effect is a type of frame-dragging, according to that article. If I'm remembering my E&M correctly, I think both accelerational and rotational frame-dragging have analogies in magnetism, so I don't know why one would be a better example than the other, but if I'm wrong, a reference would be needed to support this claim. -- Beland 00:11, 21 April 2007 (UTC)

[edit] Removed cleanup, expert needed tags

I removed the "expert needed" tag, because we apparently already have one. It might not be a bad idea to explicitly declare that a certain version has been fact-checked by an expert and judged to be without obvious error.

If you feel there are remaining "cleanup" or "expert needed" items, please list them explicitly, because they are not obvious. There were mentions in the talk archive about a "todo" list, but I could not find it, so I assume all the tasks that were listed on it have been completed. -- Beland 00:15, 21 April 2007 (UTC)

[edit] Diagram request

 It is requested that a diagram or diagrams be included in this article to improve its quality.
For more information, refer to discussion on this page and/or the listing at Wikipedia:Requested images.

This article does a pretty good job explaining the concepts involved in words and equations, but many people would be assisted by visual aids. It would be useful to illustrate the "moving X creates a Y field" concept, and perhaps some of the toroidal fields mentioned in the "higher order effects" section. -- Beland 00:18, 21 April 2007 (UTC)

[edit] The Units

The units need to be synchronized so that the magnetic permeabilty and the universal gravitational constant lead to the speed of light for gravitomagnetic radiation. (201.95.155.237 12:32, 8 May 2007 (UTC))

i think they are consistent as such. r b-j 14:42, 8 May 2007 (UTC)

No they are not. These equations involve the universal gravitational constant in Ampère´s law. If we combine the two curl equations to obtain the gravitomagnetic wave equation, the presence of the gravitational constant will destroy the link to the speed of light. You need to use magnetic permeability just as is the case in the electromagnetic equivalents. Permeability lies at the heart of magnetism and it is not catered for in this hypothesis. It needs to be catered for in order to give any credibility to the concept of gravitomagnetism. Dr. Francesco Hidalgo, Buenos Aires, 12th May 2007 (200.43.23.50 20:21, 12 May 2007 (UTC))

Just for my own information, the permeability of free space that you say lies that the heart of magnetism, is, as best as I can tell, a defined scaler that comes about solely because of how the unit of current (and consequentially the unit of charge) was defined. \mu_0 \ is no measured property of free space. Since Maxwell's Equations can be written in such a way to exclude any mention of \mu_0 \ (by using only c and \epsilon_0 \ , the first is the speed of propagation and the second is the inverse of the Coulomb force constant), so also can the GEM equations be written so to exclude any \mu_0 \ symbol, by putting the GEM equations in terms of the speed of propagation, c, and the Newton force constant, G. One might argue that the speed of propagation is different for gravitational interaction than it is for electromagnetic interaction, but there is no need to use the specific "permeability" symbol in GEM, just as there is no such need in ME. 207.190.198.135 17:53, 11 July 2007 (UTC)

[edit] Gravitomagnetic monopoles

Does any theory predicts gravitational analogue of magnetic monopoles? Their existence would make GEM equations more symmetric just as existence of magnetic monopoles would make Maxwell's equations more symmetric. If there is such theory, it should be mentioned in the article. --193.198.16.211 08:15, 11 June 2007 (UTC)

Yes the treatise on gravitomagnetism predicts analogue of magnetic monopoles.
Can you give any reference for gravitomagnetic monopoles? What inertial properties would object with gravitomagnetic charge have? Obviously, gravitomagnetic dipole, would be something with angular momentum, and true one would be elementary particle with spin, but what about monopole? It seems that it would have some rather interesting and unusual inertial properties. --83.131.23.165 10:40, 11 July 2007 (UTC)

[edit] Reed College Senior Thesis Description

I wrote a thesis developing the gravitational analog to the Maxwell's equations, Brown, D.R., "A Gravitational Analog to Electromagnetism" as a Reed College senior thesis in 1968. Since Maxwell's equations can be fully developed from the Coloumb equation and Special Relativity, one can use the same formalism to develop the gravitational equations. Note that since this demonstrates that magnetic fields derive from relavisitically transformed electric fields, the question of magnetic monopoles in either description would appear to be ruled out. This work was never published in the literature, but a copy exisits in the Reed College thesis room, and with me. Please contact me if you have further interest.

Dr. D. R. Brown, drphysic@juno.com —Preceding unsigned comment added by 24.20.192.49 (talk) 17:30, 24 February 2008 (UTC)


[edit] Has anyone succeeded in formally deriving the Lense-Thirring force from the GEM theory described here in detail?

Yes, you can use the Lorentz transformation to directly derive gravitomagnetism laws, search the treatise on gravity and gravitomagnetism in GOOGLE.


I found the following phrases in the suggested article

"Our approach is in accordance with the model published by Maxwell in 1891, in his third edition of Treatise on Electricity and Magnetism. It is by honest analogy to mechanics that Maxwell elaborated the Treatise on Electricity and Magnetism. By analogy to Treatise on Electricity and Magnetism done by Maxwell, it is logical to elaborate the Treatise on Gravity and Gravitomagnetism by using Lorentz Transformation as a mathematical tool without forgetting the specificity of gravity, thus masses of the same sign attract each other. By symmetry, logically masses of opposite signs should repulse each other but this is just a conjecture."

But you can't get gravity from the modified Maxwell's equation. I don't think that is the real answer to the problem. I mean can you get the gravitomagnetism directly from general relativity? —Preceding unsigned comment added by 70.128.182.230 (talk) 16:32, 3 April 2008 (UTC)

Google search for dipole gravity. Dipole gravity is the true gravitomagnetism derived directly from general relativity. It reduces into the Lense-Thirring force near the center of the rotating spherical shell. —Preceding unsigned comment added by 70.128.182.230 (talk) 10:58, 5 April 2008 (UTC)

You don't modify the Maxwell equations, you use the Lorentz transformation de derive gravitomagnetism. You'll find that what you get is in accordance with the astronomical observations. Black Whole bipolar jets can be easy explained by considerating the gravitomagnetic field build in the poles by mass currents. It's a straight forward approach that gives coherent results. It simplifies everything —Preceding unsigned comment added by 195.6.25.114 (talk) 15:27, 7 April 2008 (UTC)

Special relativity itself is not a theory of any kind of a force. It is a well known fact that Wheeler's gravitomagnetism is not based on general relativity, which only means that it is a faulty theory of gravity which has nothing to do with the actual gravity. It's lamentable to see that GP-B experimental result is being analyzed using this nonsensical theory of gravitomagnetism. I don't know what makes them think that they are testing general relativity when they are comparing the data with Wheeler's gravitomagentism. Can you clearly see my point?

The true gravitomagnetism can only be found from general relativity. And dipole gravity proved it is the true gravitomagnetism by successfully deriving the Lense-Thirring force at the center of the rotating sphere. —Preceding unsigned comment added by 70.244.207.137 (talk) 09:13, 11 April 2008 (UTC)

As you can see the Treatise on Gravity and Gravitomagnetism describes linear vector gravity, the results are in accordance with the astronomical observatins, the facts are there, they remain the keystone on which the stability of a theory must be tested —Preceding unsigned comment added by 195.6.25.114 (talk) 13:10, 2 May 2008 (UTC)

Why should we bothered by a theory that has not been tested rigorously? The conventional gravitomagnetism(based on Lorentz invariance) is not "general relativity" period. Please read the paper on dipole gravity. It is the only theory that derives the true Lense-Thirring force. Seeing is believing.

According to the conventional gravitomagnetism, one of the poles of the earth should have less gravity than the other pole, which has never been verified.

Also, the black hole should emit a long jet from one pole but not as long from the other one. This has not been true with the observation. Wheeler's and others gravitomagentism is a false theory which has nothing to do with the reality. Stick to general relativity and all will be fine. —Preceding unsigned comment added by 64.149.161.230 (talk) 07:42, 6 May 2008 (UTC)


In the Treatise on Gravity and Gravitomagnetism, in part one, page 45, you can learn how to to calculate the gravitomagnetic field by using mass currents, in the Earths North Pole and South Pole. The value is exactly Bg = 1x 10 E-14 radians /second. This value is mentioned by WIKIPEDIA (see gravitomagnetism). According to Treatise on Gravity and Gravitomagnetism the two poles have the same gravitomagnetic and gravity field. And as you can also learn in the Treatise on Gravity and Gravitomagnetism, in part two, page 16, how the bipolar jets are produced in the Black Whole North and South Poles. This is in conformity with the scientific observation. Please take time to verify your claims before you publish them because the facts are there, they remain the keystone on which the stability of a theory must be tested. —Preceding unsigned comment added by 195.6.25.114 (talk) 09:16, 20 May 2008 (UTC)


If the ring in rotation creates a gravitomagnetism, which side becomes the north pole and which side the south pole? And what determines the polarity? Does it depend on clockwise or counter clock wise rotation? The designation of the north and the south may be arbitrary but effectively, one side must be an attractive and the other side has to be a repulsive gravity pole, but the geometry of the ring doesn't give any clue on which side will be repulsive and which side will be attractive since they are identical. The rotating hemispherical object makes clear of this question. The domed side and the flat side of the rotating hemisphere has the opposite polarity to each other.

If you can not tell which side of the rotating ring will be attractive and/or repulsive, what's the point of calling it a "gravitomagentism"? —Preceding unsigned comment added by 70.246.92.167 (talk) 07:28, 12 June 2008 (UTC)