"...There are new scientific studies which show there is in fact a speed faster than light. New evidence which is currently meeting the trials of intense scientific peer reviews, show the "speed of gravity" is at least one hundred times faster than light..."---M.Battros on interviewing Van Flandren.
http://www.sierratimes.com/03/06/09/carlworden.htm
Haven't heard anything about this 4-month old story.

I coulda sworn I already replied to this post??

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"Most editorials are written by people that love to argue but got kicked off debate team for not making any sense." -Seanbaby

The board went down, and was restored from backup, so many posts are missing. Either that, or it's a conspiracy to keep us from discussing this.

For what it's worth, I don't know of any mainstream physicist who thinks that the speed of gravity is anything other than the speed of light, or any serious experiments that suggest it.

If it were, that would cause some serious problems with relativity, since we could send information faster than light by shaking really heavy things in a modulated pattern, and having a really sensitive detector at the far end. Any transfer of information faster than the speed of light would be a major violation of relativity theory, requiring serious changes to our entire understanding of physics.

Proponents of Van Flandern's work would say that he's done just that, but that the mainstream scientific community is suppressing his reasearch. I think if he could really support his views with experimental evidence, there would be a lot more physicists who believed him and he'd be a likely candidate for an upcoming Nobel prize.

Van Flandern has some theories out there too - one of them was that Mars was once a moon of a larger planet nearby. For some reason this planet smashes (or parts of it) into Mars, and becomes a meteor stream (Taurids or Leonids I can't remember)...

Hoagland took this theory further and claimed that some 'hyperdimensional' force caused the planet to explode, and this is why Mars has an equitorial bulge, and once had tides... I forget what other brilliant science Hoagland did based on it - that stupid tides pdf was one of the first things that rotted my brain on the 'net.

So when ever I hear the name Van Flandern (even though he's somewhat unfortunate to have been bundled into Hoaxie's group), I break out the salt shaker.

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bunk: Empty talk; nonsense.
de·bunk: To expose or ridicule the falseness, sham, or exaggerated claims of.
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I may be out of my league here, but.....

I had an idea years ago that gravity varied according to mass and speed (speed, not velocity).
Some subatomic particles seemed to travel faster than c. These calculations depended on the particles' estimated mass.
Massive objects, .001 gram or more, seem to fit accepted physics; but when objects/particles were lighter they did not conform.

Since then, gravity has been accepted as a wavicle. My supposition is that gravity is many times slower than c, and the more massive the object the greater/lesser the effect of gravity.

I would like to 'spin a disk' at incredible speed and monitor time and weight (not mass), inside it. If the quartz timepiece or the load cell readings vary; then c/time or gravity are affected inside the 'disk'.
I have some ideas about creating the 'spin', but the power input may be beyond our technology at this time.

Wingnut or what?

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'Sir........, I don't like these numbers.'
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("`-/")_.-'"``-.,,
\. . `; -._( );, `)
(v_,)' _ )`-. \ ``'`
_.- _..-/ /((.'
((,.-' ((,/

Nevertheless, it is an intriguing idea, and apparently he's been working on it for awhile:
http://www.metaresearch.org/cosmolog...of_gravity.asp
And, plugging "speed of gravity" into google definitely shows Tom has his work cut out for him.

This is just my small understanding of the effect so correct me if I'm wrong but...

if gravity is really the warping of space-time by matter, then it doesn't need to have a speed, since it its influence is already at your current position.

The example with a bed sheet pulled taught is a good one I figure. When you roll a large ball into the middle of the sheet, it will push down into the sheet. Then, if you place another smaller ball at the edge of the sheet, it will begin to roll towards the original ball. If you imagine that the sheet is invisible, then it would appear as if the smaller ball was dragged toward the larger one as soon as you released it, but thats only because the bend in the sheet was already present in the location that you dropped the smaller ball.

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"Most editorials are written by people that love to argue but got kicked off debate team for not making any sense." -Seanbaby

Sure is intriguing - I want to go FTL...

And yes, you don't always need to salt alternative theories - they can already have the right flavour - and I'll never accuse Van Flandern of not doing his homework.
It just remains to be seen what comes out of the peer-review process.

__________________
bunk: Empty talk; nonsense.
de·bunk: To expose or ridicule the falseness, sham, or exaggerated claims of.
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You're correct in the case of a static gravitational influence. However, imagine that your small test ball is already sitting on the sheet. Then you roll the large ball into the middle of the sheet. Will the deformity in the sheet appear instantaneously at arbitrary distances from the large mass? The answer turns out to be no, the deformation will move with a definite speed (in this case, it will be determined by the density of the sheet, the tension, and things like that). It's probably fast enough that you'd have a hard time seeing the effect well, though, unless it was a pretty big sheet.

So there's the same consideration with gravity. If there's a static distribution of mass, it doesn't matter what the speed of gravity is, you'll get the same response regardless. But if there's a moving distribution of mass, you'd see effects propogating with a certain speed. The question is whether this speed is different from the speed of light.

How about FTS, just until your vehicle is ready?
"Pratt & Whitney's 6.5-Mach, 150-Pound Scramjet Success...the hypersonic scramjet that recently completed a series of successful ground tests at 6.5 Mach...
http://www.avweb.com/newswire/9_29b/...5339-1.html#2a

I see. But if that is the case, then shouldn't it be obvious that gravity moves faster than light? After all, we don't see light from the sun until 8 minutes after it left the sun, but we feel the gravitational influence of the sun immediatly.

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"Most editorials are written by people that love to argue but got kicked off debate team for not making any sense." -Seanbaby

Do we? How can we prove that - short of eliminating the Sun and timing how long it takes for gravity to change?

Hey that's much faster than sound... But thanks sarongsong - that is the first thread derail that I actually appreciate! Seriously! 8)

__________________
bunk: Empty talk; nonsense.
de·bunk: To expose or ridicule the falseness, sham, or exaggerated claims of.
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You wrong there grey. The sun wobbles do to varying gravitional pull from the large mass planets.

This wobble effects its grav feild which is updated to us on the earth in REAL time.

Changes to gravity are instantanious.

Sorry, but it's not that simple. Gravitational interactions do appear to propogate with a definite speed, but in general relativity the relative velocity of the objects has an effect on the direction of the force. Here's a pretty good but non-technical discussion of the issue. To summarize, if you work out the equations of motion using GR, you still get stable orbits even with gravity propogating at the speed of light. The cancellation of the retarded potentials arises naturally from the equations governing the periodic motion of the planets. The deviations from a Newtonian picture with instantaneous transmission need very large masses with high accelerations to be seen, and the predictions of general relativity in this matter agree very nicely with observations of binary pulsars. If you somehow magically whisked the sun away, though, we wouldn't notice for 8 minutes.

A direct measurement is reported here, though it's disputed. It's worth noting, though, that most of the physicists disputing the measurement don't think that there's a problem with gravity propogating at the speed of light:
They just don't think that this particular measurement was sufficiently rigorous to demonstrate this experimentally.

Yes. Precisely. We had a discussion on this a while back, with Van Flandern himself responding (through the medium of Prince). Steve Carlip wrote a paper demonstrating Van Flandern's mathematical errors in working with general relativity, and as I recall Van Flandern was not able to refute Carlip's rebuttal. As far as I am concerned, GR properly accounts for the observed effects of gravitation and Van Flandern is peddling baloney.

I emailed the relativist Kip Thorne on the subject and he noted that--just as Grey wrote--the gravitational field of the Sun already exists as the Earth orbits it, and the Earth simply follows the shape of the existing field. As I understand it, the gravity well of the Sun is "tweaked" by the regular orbital velocity of the Sun in such a way that the vector of action points to the instantaneous position of the Sun and not it's position 8 minutes ago, as Van Flandern says it should. This particular aspect of field theory predates relativity, and is tied to Noether's Theorem so that if Van Flandern is correct then the conservation laws as we understand them would be incorrect.

Chris Hillman (via GR guru John Baez's site) makes this issue perfectly clear by stating, Hillman also refers to the "many rebuttals and corrections which reputable physicists have offered over the past five years of Van Flandern's many flagrantly erroneous statements" and notes that "Van Flandern has published several other erroneous papers repeating the same errors..."

Hillman closes by stating that As I recall, Van Flandern also believes that the "face on Mars" could have been constructed by an advanced civilization. Need I say more?

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Everyone is entitled to his own opinion, but not his own facts.

Well, I went to the Sierra Times website and found this as part of the same article:
Anti-Cavorite.

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What's this Stahl's on about? I don't recall ever having had any communication with TVF or posting on his behalf!

Prince, at what point will you understand that you are not welcome on this board?

Go away. Stay off this board. I cannot make this any clearer.

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Phil Plait
The Bad Astronomer
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That was quick, Phil. I was just about to email you aboot him...