Talk:Speed of gravity
I read this, and found that Josh Gross had totally removed the content that had been there. I have put back, so information wouldn't be lost. (I hope I haven't stepped on Ben Baker's toes...) Having read the article in the external links section, it was clear Josh was confusing speed of gravity with the speed of gravity waves. (A distinction pointed out in the external link page).
What the heck is the speed of gravity supposed to be, so that we can quantify it at all? Asking because I don't know. --LMS
The speed of gravity is the speed at which changes in the location of an object propagate to all other objects that are affected by the gravity of that object. (essentially the rest of the universe) A gravity wave is a fluctuation in the gravity field around an object, as I understand it.
Why didn't you just put that in the article, if it's correct? :LMS
Okay, I will. but I don't want to get in between a battle between Josh and Ben...
The changes in the location of an object are transmited by the interactions, graviational or electromagnetic. And for most anybody that is the speed of light.
I modified the article not removing the claims, but minimazing its importance (in my years of BS in physics, MS in Astronomy and PhD in Astronomy, never heard of this competing theories, except, I think to remember, as an historic thing). That doesn't by itself mean that it can not be correct, but it is far far away from mainstream science. --AN
Did you read Van Flandern's article ? I'd certainly like to see what flaws you detect in it. He seems to have thought about this a great deal. And yes, he does seem to address your concerns.
I don't think he agrees with you that those changes are transmitted by gravitational waves, nor electromagnetic waves.
I have left in the bit about a supernova, even though he argues they are irrelevant to this issue since the matter distribution from the explosion is symmetric.
Oh, we also need to decide if the link should be to gravitational wave or gravity wave. The article uses both, and they are presumably the same thing.
O.K. I read the article, and I found nothing obviously wrong, what doesn't mean there isn't. I removed the bit about SNe, because the author makes the distinction between gravitational waves (radiation) and the propagation of gravity, and accepts that propagation of radiation has speed c, so that will not prove anything. Still, this seems to be in the fringe of science, the site where the article is hosted has some other weird bits like the one about the "face" on Mars... It is clearly not the most accepted view, and apparently, not one that more that one person accepts. I don't see any of this published in Physics Reviews or any other peer refereed Jornal. This, again, doesn't mean by itself it is wrong, but it can be considered an instance of expert testimony. I will leave the article as it is now, but i'm not sure i want to leave the link in gravity. --AN
Does the electric field even propogate? from what I understand of it, electromagnetic waves broadcast changes in velocity, not position. If acceleration = 0, there are no waves produced, and thus no propogation. The way I found best to think of it was that the electric field does not propogate, it is like a structure, when it changes velocity, however, the relativity induced length expansion/contraction changes the form of the field, and that change needs to propogate out. Sort of like when you stop a car quickly, you get thrown forward because the message of a change in speed needs to reach your body. Not the best analogy, since it isn't exact, but it's what I could come up with. Would gravitational waves work differently? I don't know enough about general relativity to answer, but my gut says they work the same.
They're supposed to work the same. As for the general acceptance of Flandern's work, it didn't take long to find that at one point he was a poster on sci.physics.relativity - many people who disagree with relativity are - and like most of them did not much impress the various people there who actually know what they are talking about. The first thing that came up is this dejanews article and you are welcome to agree or to disagree with it, but all in all I think the evidence establishes the Flandern does not have any credibility with workers in the field, and his material has not been peer-reviewed. Permission to remove discussion of his material, from special relativity at least? --Josh Grosse
I've come into this discussion cold, but I find it very frustrating that y'all are discussing an article that someone keeps removing the link to. I finally found it after looking through ump-teen versions. (And if they had been purged, I would have had NO way to find it... Would people just leave this link here, for the next soul who has some interest in it ?
http://www.ldolphin.org/vanFlandern/gravityspeed.html
Sigh. Van Flandern has been refuted *many* times. Most notably by Steve Carlip (an expert in General Relativity, and one of the editors of Classical and Quantum Gravity, the leading journal in the field). His ``most recent rebuttal of van Flandern's nonsense is at
http://xxx.lanl.gov/abs/gr-qc/9909087.
You can find tonnes more with a bit of searching: for example the Salon.com article
http://www.salon.com/people/feature/2000/07/06/einstein/index.html
or Chris Hillman's excellent rebuttal
http://math.ucr.edu/home/baez/RelWWW/wrong.html#speed.
Frankly the idea of even having an article on the speed of gravity is a bit silly, at best it deserves a minor mention in a full article on general relativity. -M. Nobes
_____
Well, the question comes down to: Is the speed of gravity c (as a limit), or instantaneous? That should be easy enough to determine experimentally, yet nobody has, that I know of.
Carlip expounding on Van Flandern I'll read, he's a genuine practictioner of this stuff.
Hillman, OTOH, is suspected to be a simulacrum constructed for the purpose of opposing and confounding the undergrads. He's purportedly been graduated from U.W. for something like three years now, hasn't announced gainful employment, which is a nasty state of affairs for most PhD's. If he doesn't announce something -- like a Job -- in the next year or two, I'm going to have to conclude that the 'computer construct' thesis is correct, and that Chris Hillman doesn't -- in human terms -- exist.
-- Stranger
- What's with this gratuitous slam of Chris Hillman? He's a perfectly nice guy and has spent an inordinate amount of time arguing against the crazies on sci.relativity. He left academics after he got his Ph.D. which, as you may know, is allowed. I'm tempted to delete this comment. -- Walt Pohl 02:12, 19 Mar 2004 (UTC)
It doesn't matter whether he is or not, though I've been on the physics newsgroups many times and never saw any evidence of him opposing and confounding undergrads. What matter is whether his arguments are reasonable or not, since from what I can tell, he's made every possible appeal for people to learn the material and check the sources for themselves.
I expounded Van Flandern's argument, and why most physicists who look at it think it's wrong. It's really a subtle and interesting counterintuitive brain-twister. Also, I summarized the rebutals and moved them to the end. Also I removed the attributions to the rebutals since it smelled too much like argument from authority (journal editors have been known to be wrong and it's much more important to give a simple synopsis of *why* Van Flandern appears to be wrong).
I also added a reference to MOND since this is an interesting contrast between non-standard and crankish and non-standard and non-crankish.
Removed this statement
- It is well known that the speed of gravity can't be appreciably less than the speed of light, since that could be detected by changes in the angular momentum of the planets.
It's far from well known, and it's not obvious to me that it is even correct. If it's well known, then it should be easy to find a cite.
Moved the statement about gravity moving less than the speed of light to Van Flandern believes. I've thought about it, and that statement seems to be the very issue that Van Flandern seems to disagree with the scientific consensus. If the "speed of gravity" were small, it would
- not* necessarily violate angular momentum. If it *did* violate
angular momentum there would be a problem with gravity moving at the speed of light since even a small difference is in one direction and the angular momentum would build up and cause the planets to fly off.
This is precisely Van Flandern's argument that gravity moves instantaneously, and most scientists think that he is wrong precisely because they don't believe that finite speed of gravity implies non-conservation of angular momentum.
Where do I go to find the name of the author? And why should anyone have to run the maze with their mouse to find it? Sign the article. Although, in the case of "Speed of Gravity," I can see why the reluctance. Terrible writing, unsupported claims, etc., etc. Compare this to Van Flandern's clear, concise, experimentally supported claims. The fact that there is a universe of competent physicists who can reproduce his results does not exonerate the incompetent who cannot. Frederick George Wilson - "Samizdat"
Just want to posit a thought or two here. Gravitons are one of the most elusive objectives in physics. Anyone ever find one? It seems apparent to me that there's something wrong in the way that we're looking for them, and I personally suspect that it's related to the four-dimension space-time continuum, which I think is probably a wrong -- well, actually insufficient -- construct. I'm not talking about the extra dimensions of, say, string theory, but rather, specifically, extra dimensions of time, and that perhaps time is a dimensional continuum other than, but interacting with, the spacial continuum. What this is all leading up to is that the "speed" of gravity could be simply not what we have assumed that it is; it may be involved with more dimensions of time (possibly less of space?). That would not make it necessarily "instantaneous" but could enable an apparent speed faster than that of light/emr. Food for thought, at least. --user:jaknouse
Where do I go to find the name of the author? And why should anyone have to run the maze with their mouse to find it? Sign the article. Although, in the case of "Speed of Gravity," I can see why the reluctance. Terrible writing, unsupported claims, etc., etc. Compare this to Van Flandern's clear, concise, experimentally supported claims. The fact that there is a universe of competent physicists who can reproduce his results does not exonerate the incompetent who cannot. Frederick George Wilson - "Samizdat"
- Mecklen once said that there is always a
answer that is simple, clear, and wrong. Most every physicist I know of thinks that Von Flandern is just wrong. The problem is that it takes some effort to come up with a picture that explains exactly why he is wrong without a huge amount of mathematics. I've tried, but if the explanation doesn't make any sense, let me know. It's much easier if you have a blackboard.
- Basically the answer is that its not the force that is delayed, its the potential.
Imagine a ball on a rubber sheet. Now imagine the ball moving. If the rubber sheet doesn't transmit the depression immediately, the indentation in the sheet will become distorted, and non-circular. Now look at the line of steepest descent of that indentation. It will point to where the ball is *now* not where the ball was earlier. -- User:Roadrunner
- There is a link in each article called "history". Click on that and each edit ever made to the article, when they made and who made it is all there. This is how we "sign" our work. Welcome BTW. Somebody else will have to answer the other part of your statement. --mav
Whoa, geez, what's going on here guys? This is an ENCYLOPEDIA, not a science debating forum. I don't see the majority of the AIDS article taken up by discussions of the various people who claim its a bioweapon or that HIV doesn't cause it. By the same token, this HUGE section on Van Flandern certainly does NOT belong here, and I am moving it to a different article.
As to his theory specifically, I can't answer because I can't get to the article. *&%&^ surf-blocker software. However one way or the other the description of it here is either weong, or his "theory" is sophmoric. No one believes gravity propagates instantly, in fact, the belief that it does not is one of the best pieces of evidence FOR traditional GR! If Van Flandern's problem actually IS based on the claim that he thinks everyone else believes this, it can be dismissed out of hand.
jaknouse, I will write an article on gravitons for you.
I think it doesnt really matter whos right and wrong; More important that most views should at least have a mention, as to have a complete reference (on the term 'speed of gravity')
On reading some of the discussions above, it seems some the people who are dismissing Tom Van Flandern views have not read what he had to say properly.
on the definition of the speed of gravity
Constant, c, in Maxwell's theory has three different facets: (1) the speed of propagation of electromagnetic waves (light), c_l, (2) the constant linking electric and magnetic fields in Farady's law, c_{em}, (3) the coupling constant between electric current and magnetic field, c{m}, ( subscrpt m stands for Maxwell). These constants could be different, but the experiments prove they are equal to certain degree of accuracy. Thus, one uses a connotation c to denote these constants and call it "the speed of light".
Analogously, the constant, c, in Einstein's theory of relativity has three different facets: (1) the speed of propagation of gravitational waves, c_{gw}, (2) the constant linking gravito-electric and gravito-magnetic fields, c_{gem}, (3) the coupling constant between matter (stress-energy tensor) and gravitational field, c{e}, ( subscrpt e stands for Einstein). These constants could be different in arbitrary theory of gravity, but Einstein postulated that they are equal in General Relativity. I have used connotation c_g to denote these constant and call it "the speed of gravity" following the analogy with Maxwell's theory. General relativity has enormous predictive power to propose experiments in which various facets of c_g could be measured. VLBI experiment I have designed and conducted on September 8, 2002 along with Dr. Ed Fomalont from NRAO uncovered that c_g=c with 20%.
If an alternative theory of gravity rather than General Relativity is used the three facets of c_g are not united and each of c_g-s must be called by its own name. If such an alternative theory of gravity is used for interpretation of the experiment, the accuracy of our experiment sets the upper limit on c_{gem} only.
It is clear that "the speed of light" plays no role in the interpretation of the experiment. Critics of C. Will against my interpretation was based on the postulate that c_{gem}=c. From this he concluded that I and Fomalont measured the speed of light. That postulate is invalid from the first principles. It is our experiment that provides a direct test that c_{gem}=c under assumption that test particles move along geodesics which is described by the same equation as in General Relativity.
Experimentally speed of gravity do not have measured but must be not greater than 2.2222×1010×c and not less than 2x1010c
In General Relativity the gravity is a phenomenon of the gravity potential. There is not radiation between the bodies inside a relation of gravity, in the same way as not radiation in the transmission of the electric or magnetic force between electric charges in rest exists or in movement rectilinear uniform. Therefore, the gradient of the potential gravity field, in any point of the field of gravity of the solar system, aims at the real position and no exist speed of gravity.
But in quantum gravity although also the static field of gravity is responsible by the phenomenon of the Universal gravitation however this phenomenon results of the exchange of virtual gravitons between two or more bodies and since aberration is not detected the velocity of the virtual graviton must surpass c, which is physically possible because the virtual graviton does not possess mass in agreement to the fourth moment.
- With base in the ideas about quantum gravity of Andrei Saharov, M Vasiliev, and K Staniukovich, in Bogota, Colombia, in 1969, I formulated and published my theory about that the speed of the gravity is superluminal. The foundations of this theory are:
- 1. All the existing particles in the nature have inertia, that is, according to cuadri- vector -moment as the particles of the matter with mass greater than 0 as the particles of the energy with mass equal than 0.
- 2. The inverse dependency of the speed of particles of the magnitude of its inertia is a law of the nature.
- 3. The inertia of particles of energy of the waves is not just like the inertia of particles of the matter. Inertia in the matter is caused by the action-reaction law between the mass of particles of the matter and the vacuum and the inertia of the energy is caused by the absorption-emission law between the vacuum and the energy of the particles that compose the electromagnetic and gravitational waves. The particles interact with the vacuum because the vacuum is filled with free fields of its sources.
- 4. The inertia of the energy depends of the frequency of the absorption-emission during the propagation of the waves in the vacuum. The process of absorption is of energy of real particles of the waves that cause virtual particles of the vacuum passes to real particles and the back process emission of energy is of real particles passes to virtual particles. The absorption-emission consumes time that contains the passage of the waves. In consequence the contention of the waves by the vacuum is inverse dependent of the frequency of the absorption-emission between the waves and the vacuum. This inertia is increased so much with the greater energy of component particles of the waves that increases its frequency of interaction with vacuum, like with the greater density of the energy of the vacuum that increases its interaction with the waves. Consequently, the interaction of the electromagnetic and gravitational waves with the fields of the vacuum is dependent of the energy of photons and gravitons.
- 5. In the 2001, in the electromagnetic field, this is, for the phenomenon of the electromagnetic energy, the physicists Dimitri Nanopoulos of the Theoretical Physics Division of the Academy of Athens, Nikolaos Mavromatos of King's Collage, in London, and John Ellis of the European for Center Particle Physics (CERN), in Genova, discovered a new expression for the speed of the light, the one that depends on its frequency, that is to say, of their energy in agreement with the relation to greater energy smaller speed. This discovery will be confirmed in project GLAST
- 6. The maximum value of the equivalent energy in mass of the real photon is less that 10(-51) grams, in agreement with its more recent calculation of the 2003, made by Jun Luo and its colleagues in the Huazhong University of science and technology in Wuhan, China and the maximum value of the equivalent energy in mass of the real graviton would be less that 4.5 × 10 (-66) grams, considered by S S Gershtein, A A Logunov and M A Mestvirishvili, in 1997, with base in the observed parameters of the expansion of the Universe.
- 7. The speed of the real graviton is greater than the speed of the real photon because the graviton is less inertial than the photon.
- 8. For the vacuum, with refractive index = 1, the speed of gravity is maximum 2.2222 × 10(10) × c, in agreement with the equation of Cramer-Collins, fit by the author with the considerations of Schaefer for the speed of the photon and the measurement of Tom Van Flandern for the speed of the gravity.
- 9. In 2006, in project GLAST, NASA it will establish if the gamma rays, which had are their high inertia, when interacting with the quantum gravitational field, travel in the vacuum under c. the opposite also will have to be certain, then the NASA indirectly will prove the theory of the author that he exposed in 1969, approaches that the graviton has greater speed than the photon, because the graviton has minor energy, that is, minor inertia and graviton also interacts with the field of gravitation.
- And according to theorical experiments of Tom Van Flandern speed of gravity is not less than 2 x 1010 c.
Einstein considered the existence of gravity waves in analogy with the electromagnetic waves that are produced by the acceleration of an electric charge, although, in the case of the gravity its waves would be generated by the not uniform accelerations mutually induced between the bodies source and objective, that intervenes in a gravity interaction. This would be the case of the elliptic translation of the planets around the Sun. What cause these not uniform accelerations?
Einstein said: "when exists a cuadripolar mass system", by example, binary asymmetric Pulsars.
- General Relativity predicts the existence of radiation of gravitational waves that in the lowest order is proportional to cuadrupole moment of the distribution of the mass-energy of a local region. This radiation is originated in the mechanical lost energy, that is to say, kinetic and/or potential, during the produced no uniform accelerations in the matter within the region.
- In these pulsars with the variation of the time take place within the dipole variations of the common center of masses of the system, this produces cuadrupole, or double dipole that reunites the relation of the energy of four nonsymmetrical angular moments of two masses.
- These not uniform accelerations is believed disturb the continuous 4-Lorentzian structure of a local region but very weakly, so much that according to the calculations of the general relativity not even the gravity waves produced by the asymmetric explosion of a supernova, are capable to accelerate in a level detectable to any another star. In this case, the supernova explodes caused the not uniform acceleration that suffers on its translation movement. That is to say, by a phenomenon strange to the gravity phenomenon.
- The structural disturb of a local region it propagates like a gravity wave that reach remote regions of the Universe.
- The emission of these gravity waves would cause certain loss of the orbital angular moment for the binary Pulsars.
- In effect, the orbit light decays for the P5R1913+16 of according to the prediction of Einstein about such gravity emission. This constitutes the indirect only test about its existence.
- The velocity of propagation of these gravity waves, predicted by Einstein, would be c. In a next future, the projects LIGO, of US, GEO, of Germany, VIRGO, of Italy-France or TAMA of the Japan must will discovery the gravity waves and they will establish the velocity gravity waves.
- Tom Van Flandern and others physicist formulated, that waves radiated by the binary Pulsars are not waves of gravity but if some form of electromagnetism.
- In 2002, Lee Samuel Finn and Patrick J. Sutton of the Center for Gravitational Wave Physics, of the University of the State of the Pennsylvania, USA combined the rates of orbital decay of binary pulsars PSR B1913+16 and PSR B1534+12 and they obtained that mass of the real graviton is maximum less than 1.35342 × 10-52 grams, with a 90% of confidence. This value is much closed to superior limit of the mass of the real photon which is less than 10-51 grams, in agreement with calculation, made by Jun Luo and its colleagues in the Huazhong University of Science and Technology in Wuhan, China, in 2003. And very far from the value superior limit of mass of the real graviton less than 4.5 × 10-66 grams, estimated by S S Gershtein, A A Logunov and M A Mestvirishvili, in 1997, with base in the observed parameters of the expansion of the Universe.
- The rate of orbital decay of binary pulsar Hulse-Taylor, PSR B1913+16, is agrees with predicted by General Relativity with an error of approximately + 0.3%. However, it impresses that this minimum error can lead to reject thesis of which this is gravitational radiation
Nevertheless, according to the intercontinental experiment of radio-interferometer, made by Sergei Kopeikin, the velocity of gravity waves would be of 1.06c, with an error between 10% - 20%.
- ¿Which does gravity field change?. The model of gravity of Kopeikin introduces a force, produced by something that it transmits and in this sense, Kopeikin does transition to the quantum theory. Since, in this model through the gravity field it transmits moment between Jupiter and the radio waves ray. Then, Kopeikin ¡reformulates the general relativity in quantum terms¡. This does none reach still with success.
- The force that speaks Kopeikin is a species of preformation, inside the gravity field nearby, of the wave gravity that occurs far away. Therefore, this force that, does neither move to the heavenly bodies in its translations around other, is the force that in the field of gravity static would be originated with the velocity c. In addition, as preformation of the wave gravity should possess the same velocity of this wave, that if is the gravity wave of Einstein. This was that Kopeikin proposed to measure, with the object he confirms the theory relativist of Einstein. That is to say, the preformation of the wave of gravity remits to Kopeikin to the wave of gravity of Einstein, that does not have anything that to do in front of the model of the heavenly mechanics of the general theory of the relativity.
- Kopeikin said, "The gravitational waves are inherent in the zone of radiation (distant) of a system that is emitting the waves. Nevertheless, the waves of gravity do not spread freely inside the interior of the zone of not radiation (nearby) of the system. But, the process of generation of the gravity waves produces effects retarded in the nearby zone that appears mainly as a force in the equations of movement of the relativity for bodies extended, inside a system of astronomical gravity. The existence of that force is the consequence of the finite velocity of the propagation of the gravity."
- In its mathematician model, Kopeikin includes the Shapiro retards of the Sun, the Land and Jupiter. In addition, the transverse retard of the force that originates the finite velocity of the gravity. The experiment of Kopeikin partially abandons the explanation given by Einstein of the phenomenon of the deflection. This phenomenon would be the simple consequence of the curvature of the space-time. In addition, Kopeikin introduces the dependence of this phenomenon of a class of moment that the gravity static field would transmit, as result of the finite velocity of the preformation of the gravity wave. That is to say, Kopeikin with its explanation of the deflection devises a mixed model of the phenomenon of the gravity that would be then geometric effect of the curvature of the space-time and quantum effect of the wave gravity.
- The experiment of Sergei Kopeikin eludes to confront the debate scientific that in the terms of the velocity of the gravity requires first theoretically to resolves if the gravity is according to the relativity general of Einstein or to the quantum gravity theory. And second, to design a crucial experiment for to establish the velocity of transport of the force of interaction between the source and the objective gravity, that gravity static field transports.
The scientific Paul Marmet and C Couture, of the Department of Physics of the University of Ottawa, by means of E-MAIL of May 15, 2003, 18:05, respond my consultation about if plasma solar affected the experiment of Kopeikin. They are authors of a magnificent study on the deflection of the electromagnetic rays of radio-waves by the plasma of the Sun. They declared, "We read that Sergei Kopeikin compared the velocity of light near Jupiter with the velocity of the light after its retard proper to the plasma near Jupiter. He found that the difference is too much small measuring it (same value of c). You should announce that at present has been measured is the velocity of the light. This is not the velocity of the gravity." Therefore, Kopeikin does not have measured the velocity of the gravity.
- See works of the author:
- The experiments indicate that the speed of the gravity is minimum 20 billion times c by Alfonso León Guillen Gomez.
- The law of the inertia of the energy and the speed of the gravity by Alfonso León Guillen Gomez. October, 2004.
- A speed greater than the speed of the light by Alfonso León Guillen Gomez. December, 1969- February 1970.