gravity does not propagate but is instantaneous

Saiph · Dec 26, 2005

It is true there is no confirmation of the actual speed of gravity. However, the arguements you bring up don't require or support an instantaneous gravitational force. First, it is a warpage in spacetime. However, the propagation of gravity people are concerned about is the propagation of a change in gravity (so if something moves, how long until other objects notice the change in the gravitational location). This change is considered a "wave" in spacetime (like the ripples in a pond) and because of this, GR can easily support and tends to indicate a finite speed for gravity. Your conservation of momentum arguement is also unfounded, as the gravity wave can change the momentum of object it encounters, and the "radiating" object's momentum also changes. There is no net difference caused by gravitational radiation. So yes, the actual speed is in contention, but you've failed to provide adequate support for your arguements of instantaneous gravitational forces (you've provided plenty of speculation though). For example, you say that without instantaneous gravity things would appear different. Okay, show me. When asked how you know that, you said you could use a probably off the shelf orbital mechanics program...but you haven't and I'm not going to make the effort if you don't. One thing you could do is ask what observations would be different if gravity was finite vs instantaneous...and find the answers. So something like: Mercury's orbit would be ___ for finite gravity but ____ for instantaneous...then do a comparison with observation. These are things Van Flandern has tried to do...but others tend to give it a grain of salt, as he's been shown to make mistakes in the mathematics and various assumptions he makes are invalid (IIRC some of the counter-papers I scanned years ago). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

savster · Dec 27, 2005

The whole subject of the "velocity" of gravity is still very much up in the air, folks. While tantalizing evidence that the propagation velcity of a CHANGE in a gravitational field might be measured, the actual propagation velocity of static gravity itself isn't measurable. And the change in the gravitational field, when "measured" exceeds the velocity of light by many magnitudes (at least according to van Flandern). But for all practical purposes, the propagation of gravity is instantaneous. All new experiments to the contrary rely on very subtle measurements that are very hard to pin down due to the resolution of the measuring instruments themselves. Btw, I'm not a proponent of the "nothing can move faster than light" school. While I respect Eintstein's achievements, I don't worship him as some kind of God of physics.

raghara2 · Dec 27, 2005

"what computer models? What mechanics is used in the models you refer to?. " Have you wrote any such simulation, if not you'd need to try it before your questions might be answered.

kmarinas86 · Dec 27, 2005

Both gravity and electromagnetism can arc light.

paintwoik · Dec 27, 2005

My take on this is that gravitational waves travel at C. However if you could somehow remove the sun instantaneously, the Earth would immediately change course from the circular orbit it was maintaining around the sun that used to be there. This might imply faster than light speed of gravitational waves but not really. What can be known here is location on an almost instantaneous fashion, but knowledge of distance requires light speed propagation. One other thing to consider is that if you could remove the sun, the gravitational waves would have to go with it in that they are every bit as much the sun as the matter. Hence we would remove any possible interaction. Obviosly I don't agree with the curved spacetime possibility.

yevaud · Dec 27, 2005

Why not? Experimentation and observation have conformed to theory, so far. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

Saiph · Dec 28, 2005

I don't believe electromagnetic fields can deflect light. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

kmarinas86 · Dec 28, 2005

I don't believe electromagnetic fields can deflect light. Yes they can. All you need is a beam of white light and a prism and you will see the effect. That is high school physics knowledge. Add the fact that prisms are made of charged protons and electrons, and you know that electromagnetism can deflect light. http://en.wikipedia.org/wiki/Refractive_index http://en.wikipedia.org/wiki/List_of_indices_of_refraction At the microscale, an electromagnetic wave's phase velocity is slowed in a material because the electric field creates a disturbance in the charges of each atom (primarily the electrons) proportional to the permittivity. The charges will, in general, oscillate slightly out of phase with respect to the driving electric field. The charges thus radiate their own electromagnetic wave that is at the same frequency but with a phase delay. The macroscopic sum of all such contributions in the material is a wave with the same frequency but shorter wavelength than the original, leading to a slowing of the wave's phase velocity. Most of the radiation from oscillating material charges will modify the incoming wave, changing its velocity. However, some net energy will be radiated in other directions (see scattering)./safety_wrapper>

bonzelite · Dec 28, 2005

we were all taught that light speed is "it." it does not mean that it is true. gravity may not be what it has been made out to be. it may be a spatial dimension and not a force. maybe this thread should be relocated to phenomena, then. of course, as a scientist, one must conduct life as if gravity and gravitons, light speed of propagation of gravity, were true. and one can get along nicely in their career and life without ever having to breach c. one can remain insulated from attacks on c, and realize that anyone who claims c is not limited is simply an uneducated fool. you can realisitcally be disaffected by any claims, even possible proof to the contrary of c, and everything will still be in harmony. in other words, the industry of science will not shut down if a few fringe people, some of them scientists, banter on and on about how c can be breached. i can guarantee you that.

paintwoik · Dec 29, 2005

Obviosly I don't agree with the curved spacetime possibility. <blockquote>In reply to:<hr />Why not? Experimentation and observation have conformed to theory, so far. <hr /></blockquote> Well it just don't make any sense. What I don't see is an interaction being bandied about. In the bowling ball on a mattress analogy, what makes something roll down an incline toward the bowling ball? Please don't say gravity. What I want to see is direct interaction, and what I'd like to get across is that the Moon and the Earth for example are in direct interaction with one another. What I'm saying is that there is no third party intermediary like that of space. There is no real distance between them. I.E. They are in direct contact and although a gravitational wave travels at C, the positions of the Earth and Moon are known instantaneously through this constant interaction. In other words Gravitational waves move at C, but act in an almost instantaneous fashion.

Saiph · Dec 29, 2005

actually, that's light interacting with charged particles, and then the observation of the "re-emitted" wave. And that'd even in your quote. <blockquote>In reply to:<hr />the electric field creates a disturbance in the charges<hr /></blockquote><blockquote>In reply to:<hr />charges thus radiate their own electromagnetic wave that is at the same frequency<hr /></blockquote> No mention of an electric or magnetic field affecting the light. Only that the Electric/magnetic field of the electron affects it's surroundings. An EM field, by itself, does not deflect light. Otherwise, photons would scatter eachother (as my gf points out a good example: this would preclude the existence of lasers and other collimated light sources..thank you masked_squiggy). <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Saiph · Dec 29, 2005

well, many scientists don't argue with the speed of light limit. They do indeed learn about, and understand, the origins of this premis, and use it without worrying about it's validity (after, btw, we have to examine it during our graduate school education). But, some still look at it, and verifying this aspect, and others, of relativity is still a major field of research today. So I don't get your point. Should every researcher be bent towards the analysis of this one aspect of modern physics? Or can the majority look at the years of confirmation (direct experimentation, and correct prediction of other phenomena using this information...i.e. indirect use) and continue on with other work? <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

darknrg · Dec 29, 2005

all entropy = C an experiment a couple of years back involving the sun and some alignment was set up proving this

bonzelite · Dec 29, 2005

i think what this does is address yet again just what the hell gravity really is. it may not be a force in the traditional sense. if gravity is really a structural dimension, it may be free from conventional wave behavior. is this true? it seems like it is despite other evidence that it propagates at c. perhaps gravity has a wave and a geometric component, with the wave aspect of it being given the spotlight. i tend to believe that gravity is not yet fully understood. and i'm willing to give the premise of instantaneous reaction of gravity the benefit of the doubt, even if it is seen as a whacko fringe notion. the only peer review i face is here on SDC. but i don't believe there are petrified tree trunks on mars <img src="/images/icons/wink.gif" />

bonzelite · Dec 29, 2005

+1 steve, i agree with you. the biggest point of contention is the BB theory. it is purely religiously based in faith.

chew_on_this · Dec 29, 2005

For a good example of steves scientific accuracy and sound thinking, see: http://uplink.space.com/postlist.php?Cat=&Board=seti in seti question.

paintwoik · Dec 30, 2005

I happen to like what Ranur has to say. He has an open mind with a thirst for speculation. I could care less if some of his ideas are wacked. As for you stevehw33 - I'm not even remotely interested in what you have to say, because it's already been said by carbon copies of you many times before. This is not a college class and nobody is keeping tabs, with the exeption of you of course.

paintwoik · Dec 30, 2005

I know.... he's a walking dictionary. If he is willing to use some imagination and be less worried about saying something stupid or others saying something stupid. He might actually think up something that isn't in the dictionary. What are you going to do stevehw33? Are you going to curl up in the fetal position if you get caught saying something stupid? Do you have any ideas that are your own? Spit it out (show some balz). This isn't physics forums ...... you are allowed to speculate here. Smoke a duubee if that'll help. Stop being a cop.

smartie · Dec 31, 2005

http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html I prefer Einsteins view myself. bonzelite, <blockquote>In reply to:<hr />General relativity (GR) explains these features by suggesting that gravitation (unlike electromagnetic forces) is a pure geometric effect of curved space-time, not a force of nature that propagates. <hr /></blockquote> Recent ideas from Professor Evans suggests that electromagnetism can also be shown to be a geometric effect of twisted space-time. http://www.americanantigravity.com/documents/Myron-Evans-Interview.pdf

aorton27 · Jan 29, 2006

"In the bowling ball on a mattress analogy, what makes something roll down an incline toward the bowling ball? Please don't say gravity." Why not say gravity? What if time and space is like the mattress? When the mattress is flat with no disturbances there is zero gravity because everything is equal but when there is a mass placed on this fabric of time it acts just like a bowling ball on a mattress and gravity is the result and draws thing to the center of it. It is insanly hard to describe it because it is the 4th dimension. Maybe try drawing a 3d picture on paper and then add another dimension which is only triggered by 3d glasses(red/blue glasses)

unlearningthemistakes · Jan 29, 2006

I conceptualized/imagined before, should it be clarified/proven that gravity is a particle, --->then we could /somewhat/ safely deduce propagation is limited by C. if proven otherwise, i.e. gravity is a bend/curvature/distortion in space-time fiber and not a particle, I speculate it's propagation speed would be nearinstanteneous but not instant---since cause and effect requires time. no time ( as in instanteneous time=0) would yeild no effect. and in physics, I believe there is no such thing as instant effect. <div class="Discussion_UserSignature"> pain is inevitablesuffering is optional </div>

harmonicaman · Jan 29, 2006

Here is a simple philosophical argument for gravity propagation occurring at "c", the speed of light. Point sources of gravitational force, light, and radiation all obey the inverse square law: S/sub>4 x pi x rsup>2 = I S = Source I = Intensity Since the propagation of gravity follows the same basic rules as the propagation of light; I think it logically follows that they propagate at the same velocity. There is likely no such thing as a "Graviton Particle". Gravity is merely the effect of "m" (mass) on the propagation of time and space.

raghara2 · Jan 29, 2006

A lots of events obey an inverse square law. For example shockwaves of explosions, sound intensity, energy transfers with unrestricted propagation, nonlocal force transfers. However some of the above events are different (different aberation, different requirements for propagation). Basically forces in 3D space could be aproximated by inverse square law. Events that could propagate in 4D space would be highly likely using inverse cubic law.

raghara2 · Jan 29, 2006

"unusual effects like Inverse Faraday, Ahronson-Bohm, Sagnac, and violation of complementarity interpretation from the Asfhar experiments " Could you post some links for this?

rogers_buck · Jan 29, 2006

Interesting. Seems like a bimetric could explain some of this, or possibly massive field effects? Both of these mechanisms have been proposed as reasons for variations in vg/c. http://www.arxiv.org/PS_cache/gr-qc/pdf/0103/0103036.pdf http://arxiv.org/PS_cache/gr-qc/pdf/9705/9705051.pdf I don't see how either of these cases could explain the lunar eclipse, however.

gravity does not propagate but is instantaneous

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