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Comixx
2002-Mar-22, 01:28 AM
http://www.alaska.net/~clund/e_djublonskopf/FlatHome.htm

I was actually doing a search for a punk rock band and found this site

*edit I found this disclaimer on their site...it appears it is a joke after all...still rather amusing


The Flat Earth Society is not in any way responsible for the failure of the French to repel the Germans at the Maginot Line during WWII. Nor is the Flat Earth Society responsible for the recent yeti sightings outside the Vatican, or for the unfortunate enslavement of the Nabisco Inc. factory employees by a rogue hamster insurrectionist group. Furthermore, we are not responsible for the loss of one or more of the following, which may possibly occur as the result of exposing one's self to the dogmatic and dangerously subversive statements made within: life, limb, vision, Francois Mitterand, hearing, taste, smell, touch, thumb, Aunt Mildred, citizenship, spleen, bedrock, cloves, I Love Lucy reruns, toaster, pine derby racer, toy duck, antelope, horseradish, prosthetic ankle, double-cheeseburger, tin foil, limestone, watermelon-scented air freshner, sanity, paprika, German to Pig Latin dictionary, dish towel, pet Chihuahua, pogo stick, Golf Digest subscription, floor tile, upper torso or halibut.

<font size=-1>[ This Message was edited by: Comixx on 2002-03-21 20:44 ]</font>

DStahl
2002-Mar-22, 06:46 AM
Flat Earth! Gotta love it. There's a wonderful site created by an artistic fellow, Dave Fischer, creator of the Platygaean Society and FELFAT. Quoting from his FAQ about the Platygaean Society:
----------
1) What is the Earth's shape?

The Earth is flat. It is shaped in the form of a pentagon, and thus has five corners.

2) What is the "middle corner"?

If one was to draw a line from each corner to the centre of the opposing side of the Earth, the line would intersect in the middle of the Flat Earth. This place is known as the Middle Corner.

3) Hey, wait a minute, that is not a real corner...

So? The equator of the spherical earthers is an imaginary line as well. Does this mean that their model does not have a northern and a southern hemisphere? You cannot count in imaginary numbers, but does that mean that they do not exist?
...

5) Does the "middle corner" prove that 5=6?

Yes
-------

Here's a link to the FAQ (http://www.flat-earth.org/platygaea/faq.mhtml).

And for goodness sake don't fail to check out FELFAT (http://www.cca.org/woc/felfat/index.html), which organization holds that the Earth is now spherical but was forced into that unnatural shape by television moguls. FELFAT boldly proposes a remedy:

"The Flat Earth Liberation Front Against Television (FELFAT) is working towards the return of the earth from its current unnatural spherical shape to its original, natural flat unbounded shape. To do this, we propose to dig a trench through the earth's crust, unfold it, and landfill around the edges, infinitely."

Enjoy!

--Don Stahl




<font size=-1>[ This Message was edited by: DStahl on 2002-03-22 01:48 ]</font>

Silas
2002-Mar-22, 02:56 PM
Of course, as a member in bad standing of the International Flat Earth Research Society, I must protest these upstarts and their whimsy. Anyone familiar with the work of the late Charles Johnson, as carried forward by his wife Marjorie, will understand that humor, wit, japery, and bons mot have no place in the rejection of that Greek "Grease Ball" theory.

Marjorie, in the 1970's, took a trip to Australia, and came back with a notarized and witnessed document, in which she stated, under oath, that she had not been upside down while there.

That is how serious this is. There shall be no smirking, giggling, tittering, or wrinkling of the nose. We TRUE Biblical Astronomers know that the cosmos is geostationary and geocentric AND that the world is flat. (Well, kinda lumpy, but that doesn't invalidate the eternal revealed truth...)

Mrmee mrmee mrmee

Silas

DStahl
2002-Mar-22, 07:52 PM
Silas, you have a point--however, I believe that Fischer is deadly earnest in leading FELFAT in its efforts to unfold the Earth. FELFAT proposes to initiate digging along the International Dateline, since this would avoid disrupting major population centers. FELFAT leadership has boldly located the Dateline off Alaska and even done exploratory digging! Here's a photo from the First Expedition, captioned From Here We Head South!

http://www.cca.org/woc/felfat/images/fe9.jpg

PS: I believe Mr. Fischer (arm extended, above) would not mind this link to his work, as it is free publicity.

--Don Stahl

Dunash
2002-Mar-23, 08:05 AM
That the earth is a sphere was known
to scholars since the dawn of history. The ancient Greek sculpture of the Farnese
Atlas shows him holding the globe on his shoulders. Pythagoras, Parmenides, Eudoxus,
Plato, Aristotle, Erastosthenes, Euclid, Aristarchus, Archimedes, Strato, Ptolemy, and the Talmudic sages all held the world to be a globe.

Simon
2002-Mar-23, 08:57 AM
Yaknow, truth can come from unexpected sources.

informant
2002-Mar-23, 11:31 AM
That the earth is a sphere was known
to scholars since the dawn of history. The ancient Greek sculpture of the Farnese
Atlas shows him holding the globe on his shoulders. Pythagoras, Parmenides, Eudoxus,
Plato, Aristotle, Erastosthenes, Euclid, Aristarchus, Archimedes, Strato, Ptolemy, and the Talmudic sages all held the world to be a globe.

It was known in Classical times, by the literate people, but it was almost forgotten in the Middle Ages.
Mind you, it wasn't easy to show that the world was spherical back then. They didn't have pictures from the space shuttle. Some believed in it just because the sphere was considered the most perfect 3-dimensional shape.

Silas
2002-Mar-24, 05:36 PM
On 2002-03-23 03:05, Dunash wrote:
That the earth is a sphere was known
to scholars since the dawn of history. The ancient Greek sculpture of the Farnese
Atlas shows him holding the globe on his shoulders.

Although that was the globe of the sky, not the globe of the earth, you are still correct.

However, that the world was spherical was not known to the Chaldeans, who originated the cosmology that was known to the very ancient Jews. The Bible is explicit: the world was thought to be flat.

And so, of course, it is.

(No, I don't really believe it; I'm just having fun out-Heroding Herod.)

Silas

Prince
2002-Mar-24, 06:09 PM
Bouw's refutation of the idea that the Bible teaches a flat Earth!

http://www.geocentricity.com/flatearth.htm

Silas
2002-Mar-25, 12:10 AM
On 2002-03-24 13:09, Prince wrote:
Bouw's refutation of the idea that the Bible teaches a flat Earth!

http://www.geocentricity.com/flatearth.htm


Staggering. The depths to which intelligent men will sink to defend their prejudices.

The ancients believed the world was flat, and that the heavens were a tent above the earth (a Bible verse that Bouw "forgot" to quote.) The Jews of Genesis and Exodus had no way to measure the curvature of the earth, nor any inclination (is that a pun?) to do so.

The oldest books of the Bible speak of the earth as flat, simply and solely because they had no reason to think otherwise. They didn't know. The oldest books of the Bible fail to speak of Aluminum, or Neptune, or the use of glass to produce a spectrum, or the catenary curve of a hanging cord, or the boardgame of chess, or... Or tens of millions of things that weren't known then, and are known now.

The writers of Genesis and Exodus believed the world was flat. That is not a sin, nor a crime, nor a failure: they simply didn't know.

It isn't necessary to defend them to the degree of perfection. They weren't. Their writings aren't.

(One wonders what Joshua would have answered if asked about whether a feather falls faster than a hammer in a vacuum...)

Silas

DStahl
2002-Mar-25, 03:57 AM
But the point is, Silas, Bouw does believe the Bible is perfect received truth. At least on his personal info page he asserts that science can never correct the Bible. Thus when there is a conflict between scripture and science he has only two ways to respond: he can 'reinterpret' the scripture in question to eliminate the conflict, as he does with the flat-Earth passages; or he can refute the scientific finding, as he attempts to do with his use of Tychonic geocentrism.

The variety of thought patterns among humans amazes me. Some people think in ways I find absolutely unreasonable, and no doubt they feel the same about me. Oh well, let a thousand flowers bloom and a thousand schools of thought contend.

--Don Stahl

Silas
2002-Mar-25, 02:50 PM
On 2002-03-24 22:57, DStahl wrote:
The variety of thought patterns among humans amazes me. Some people think in ways I find absolutely unreasonable, and no doubt they feel the same about me. Oh well, let a thousand flowers bloom and a thousand schools of thought contend.

--Don Stahl


Well, it beats the heck out of "Knowledge proceeds from the barrel of a gun." (Grin!)

Silas

Prince
2002-Mar-26, 12:07 AM
Are we to conclude that anyone who thinks "out of the box" as the saying
goes nowadays and through reason reaches conclusions that run contrary to
current belief is "prejudiced" while the practitioners, promoters, and
defenders of the status quo are not prejudiced? Ask Halton Arp, or the
late Sir Fred Hoyle, or V.C. Reddish who was belittled in his day (mid
'60s) but whose ideas on first-generation stars (stellar evolution) are now
all the rage, though his name is not attached to the ideas. But at least
Silas isn't prejudiced in the least, right?

Come on, now; every last one of us is "prejudiced" one way or another.
Bias is necessary to think and act. Don't believe it? I'll bet you're
biased towards entering a room through a door rather than a window.

DStahl
2002-Mar-26, 01:29 AM
No, thinking outside the box is wonderful. Hoyle, Zwicky, Bethe (I think it was), lots of wonderful scientists have been renowned for it. Sloppy thinking, incorrect facts, refusal to accept disproof--this is bad science. From what I've read Hoyle was exceptional in that he was capable of doing rock-solid research and also pursuing speculative, even outrageous ideas. Bouw's claims are well outside conventional astonomy, but he also admits that he is guided by theology and not science.

Say, for a tour of the loony side of pseudoscience, check out Crank.net (http://www.crank.net/science.html). The people listed are also 'outside the box' but I'm not sure how clearly some of them are thinking...*grin*

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-03-25 20:32 ]</font>

Dunash
2002-Mar-26, 08:21 AM
Stahl says that Bouw suffers from a "Refusal to accept disproof?" - But by definition of Mach & Einstein (and the Bad Astronomer!), there can be no physical, dynamical or observational "disproof" of geocentricity, heliocentricity of acentricity from within this universe. Unless maybe, shock, horror, Stahl is an anti-Relativist perchance? In which case, how does he explain the zero mph MM result?
Check out Bouw's references on the absolute equivalency of the Geocentric model! http://www.geocentricity.com/papers.htm

David Hall
2002-Mar-26, 11:30 AM
Say, for a tour of the loony side of pseudoscience, check out Crank.net (http://www.crank.net/science.html). The people listed are also 'outside the box' but I'm not sure how clearly some of them are thinking...*grin*


Some of them are not just outside of the box, they are in a completely different box entirely. Probably a cardboard one sitting on the side of the road somewhere baking in the sun.

DStahl
2002-Mar-26, 11:59 AM
Dunash: "Stahl says that Bouw suffers from a 'Refusal to accept disproof?'"

I said that refusal to accept disproof is bad science, as part of my point that thinking outside outside the box should not be confused with just plain bad science. I did not say Bouw specifically refuses to accept disproof, I said that even he admits that theology and not science is his first criterion for truth. In that Bouw himself does not claim to be practicing science at all, I think.

I hope that clarified my post for you, Dunash.

Silas
2002-Mar-26, 03:10 PM
On 2002-03-26 03:21, Dunash wrote:
Stahl says that Bouw suffers from a "Refusal to accept disproof?" - But by definition of Mach & Einstein (and the Bad Astronomer!), there can be no physical, dynamical or observational "disproof" of geocentricity, heliocentricity of acentricity from within this universe.

Actually, there's a wonderful proof of geocentricity: we discussed it earlier. When there is an earthquake, the heavens rattle. This is not true when there is a Marsquake, or a Venusquake or a Sunquake (there are such things!) Only when the earth trembles, do the heavens tremble. So, belying our good host, the Bad Astronomer (and myself) we must exclude the possibility of a Mars or Venus or Sun centered cosmos...

All that's required is the surrender of causality...

(Or, of course, we can divorce earthquakes from cosmology, in which case we're back where we began: any object, anywhere, could be the center of the universe, and the earth isn't special in any way whatever.)

Silas

Dunash
2002-Mar-28, 10:38 PM
Naw Silas, you don't have to surrender causality. Maybe you've confused the cause and effect.

Otherwise, if the universe is a standing wave (in Hilbert space), what is its Compton mass? And how will it respond to changes originating at its dynamic center or node?

BTW, I'm still waiting for one of you to explain massive superstrings to me.

Kaptain K
2002-Mar-29, 05:03 AM
Super strings are not mentioned in the Bible. Therefore, they do not exist.

Silas
2002-Mar-29, 02:25 PM
On 2002-03-28 17:38, Dunash wrote:

Naw Silas, you don't have to surrender causality. Maybe you've confused the cause and effect.

Otherwise, if the universe is a standing wave (in Hilbert space), what is its Compton mass? And how will it respond to changes originating at its dynamic center or node?

BTW, I'm still waiting for one of you to explain massive superstrings to me.


Me? What the heck do I know about massive superstrings?

Isn't Hilbert Space a mathematical construct, and not a cosmological one?

I don't know what a Compton Mass is. And I've never heard anyone claim that the universe is a standing wave.

I've been asking you about earthquakes, and whether it is the earth that trembles (common sense and the standard view of the cosmos) or if the stars themselves tremble. Some of your answers imply that you believe the latter, and I'm interested.

If you're just going to be evasive, then please explain to me the Gower Effect, Toroidal Expansion, and Rectofossal Ambiguity.

Silas

GrapesOfWrath
2002-Mar-29, 03:37 PM
On 2002-03-26 10:10, Silas wrote:
Actually, there's a wonderful proof of geocentricity: we discussed it earlier. When there is an earthquake, the heavens rattle. This is not true when there is a Marsquake, or a Venusquake or a Sunquake (there are such things!) Only when the earth trembles, do the heavens tremble.

Hmmm. I think your logic has some holes. If I stand on one side of an earthquake fault, and someone else stands on the other, we will move apart during the earthquake. If the earth doesn't move, that is impossible, by your logic, it seems to me.

Just because one portion of the earth surface moves, with me on it, and I observe a relative motion of the stars, that doesn't mean that the stars are shaking.

Dunash
2002-Mar-30, 06:57 AM
The Bible no where refers to any diurnal or annual motion of the Earth. But that does not rule out lesser motions: Job 9:6, Psalms 99:1, Isaiah 13:13, 24:19: quiver, quake, shake and tremble.

DStahl
2002-Mar-31, 01:57 AM
Grapes, I believe you are missing a bit of ironical sarcasm in Silas' post. Irony is good for you, it strengthens your immune system.

Again, I haven't kept up on the cutting edge of the geocentrism conjecture, but I think Bouw has hypothesized superluminal propagation of effects like earthquakes from the center of the universe to the cosmos at large. The ring-laser interferometer at Canterbury, New Zealand, has measured changes in the Earth's rotation due to earthquakes, so for the geocentric conjecture to be supported it is necessary to explain how the effects of these Earthly quakes spread to the most distant reaches of the universe in very short order.

I think that would be the case, anyway. I find the whole geocentrism thing so silly it's not worth researching--that's a personal opinion and I don't want to debate it, Dunash! *sigh*

--Don Stahl

AstroMike
2002-Mar-31, 03:39 AM
These people are HBs too, of course.


14) What about photographs of the Earth from the moon?
Most of these are fake. It is well known that the "moon landing" was faked. The film of what is claimed to be the moon was taken in the desert in the US state of Arizona.

Silas
2002-Mar-31, 08:32 PM
On 2002-03-30 22:39, AstroMike wrote:
These people are HBs too, of course.


Alas, basically true. The International Flat Earth Research Society holds that there has been no space program at all. None. No Vanguard, no Mercury, no Geminii, nothin'.

For my part, as a modern and enlightened flat earther (yes, this *is* irony!) I can "explain" the photographs of the earth from space as artifacts of the lens effect of the earth's atmosphere...

Now, whoa on before you laugh too hard...

The BA (bless his little retinas!) explained something to me that I hadn't known: the sun appears to set later than the sun has actually set, because of atmospheric refraction. The effect can be as large as two degrees -- or four solar diameters as seen from earth -- in the right circumstances.

I can stand on the beach, and see the sun right on the horizon -- but if the atmosphere were gone, the sun would not be visible at all. It would be below the horizon. The atmosphere, by refraction, has bent the rays of light -- everyone knows about putting a long spoon into a glass of water, right? -- and artificially brought the sun up over the horizon.

So...as a dedicated (make-believe) Flat Earther, I can say -- that from space, the earth's atmosphere acts like a "fish-eye lens" and makes the world appear round, when, really, it is infinite and flat.

NOW -- just because I love the truth more than I love playing games -- the FACT is that atmospheric refraction would make the world appear slightly *larger*, not vastly smaller, than it really is.

So, I must eat my cake, and no longer have it: the Flat Earth fantasy is not supportable. But a guy can "role play," can't he?

Silas

DStahl
2002-Apr-01, 01:18 AM
Silas: **Applause**

Jovianboy
2002-Apr-01, 01:58 AM
On 2002-03-28 17:38, Dunash wrote:

Naw Silas, you don't have to surrender causality. Maybe you've confused the cause and effect.



Now, here's a bit of Dunash's writing from the Bouw/Faulkner thread:

Quote:
--------------------------------------------------------------------------------


On 2002-03-21 12:27, Dunash wrote:
In Geocentricty we basically reverse cause and effect.


--------------------------------------------------------------------------------

To which I replied:

Violating the causality principle must be the surest sign of an illogical argument.

Now that Dunash has done a backflip to avoid critique of his position, perhaps I should modify that to "the surest sign of a DISHONEST argument".

JB

ToSeek
2002-Apr-01, 12:13 PM
On 2002-03-31 20:58, Jovianboy wrote:
Now, here's a bit of Dunash's writing from the Bouw/Faulkner thread:

Quote:
--------------------------------------------------------------------------------


On 2002-03-21 12:27, Dunash wrote:
In Geocentricty we basically reverse cause and effect.


--------------------------------------------------------------------------------

To which I replied:

Violating the causality principle must be the surest sign of an illogical argument.


I am amazed that I am coming to the defense of a geocentrist, but Dunash was basically responding to "A causes B" by saying "No, we believe B causes A." This is not a violation of the causality principle (though the notion that cosmic forces cause earthquakes may violate any number of other things).

David Simmons
2002-Apr-01, 12:22 PM
On 2002-03-24 22:57, DStahl wrote:
Oh well, let a thousand flowers bloom and a thousand schools of thought <u>contend</u>.

--Don Stahl


Unquestionably this has value. However, the contention loses its value when carried on and on in spite of manifold contrary evidence.

For example, one Mr. Pell, a member of congress, was convinced that ESP and other psychic phenomena should be used in operations by the government. He spent some of his time and that of the congress trying to get appropriations for this purpose. All of the evidence from controlled tests regarding psychic phenomena to date has been negative. The time Pell used would have been better spent trying to do something about the real problems that are extant.



<font size=-1>[ This Message was edited by: David Simmons on 2002-04-01 07:24 ]</font>

DStahl
2002-Apr-01, 06:00 PM
David, you are absolutely right. At the moment I wrote that line it was the mental equivalent of throwing up my hands and saying "Sheesh!"

Why does objective evidence and logic seem less important than intuition and personal belief/testimony to so many people? I once tried to explain to a coworker that a particular "charity donation club" was nothing but a pyramid scheme--simple math showed that everyone could not come out with more money than they put in, and that if anyone finished making a profit then others would have to take a loss. But he absolutely believed that this scheme was right and good, and therefore there had to be a way for it to work as advertised. And this was not a dumb or mathematically illiterate guy!

I 'spose nobody really uses only logic and objectivity 100% of the time to make 100% of their decisions. That would be an abomination of another sort, a denial of human values. But yes, the pursuit of bad science in the face of contrary evidence is not productive.

--Don Stahl

Dunash
2002-Apr-01, 08:14 PM
So why don't you make help make the Geos go away by performing a simple controlled experiment on the isotropy or otherwise of space ie Van Der Kamp's 1984 Rayleigh interferometer proposal to be put on on a space shuttle. The Canadian Institute of Science backed his experiment, but NASA backed down at the last minite under pressure from "informed quarters" "because there is no need to re-test the truth of Einsteinian Relativity"!

Dunash
2002-Apr-01, 09:26 PM
WRT Stahl's comments on the Canterbury NZ ring-laser interferometer:

The ring laser measures relative rotation rate of the Earth to the Firmament. The "speed of sound" through the Firmament is the speed of light, but given it acts like a plenum,any linear motion is forbidden. Thus, if the Earth is
at the dynamic center, then any radial change in the shape of the Earth will want to induce a linear (radial) change in the Firmament. That "request" will reach the edge of the Firmament (whatever its radius, say 20 billion light years) in roughly 10E-44 sec. The response is the observed change in relative rotation rate.

Silas
2002-Apr-01, 10:28 PM
On 2002-04-01 15:14, Dunash wrote:
So why don't you make help make the Geos go away by performing a simple controlled experiment on the isotropy or otherwise of space ie Van Der Kamp's 1984 Rayleigh interferometer proposal to be put on on a space shuttle.

Why bother? If the earth is stationary and the stars revolve around us, they should be dragging the ether in a constant westerly etheric wind. If the earth rotates and the ether surrounds us, we would see the exact same wind as the earth rotates beneath it. So the detection of the ether would *by your own standards* prove nothing, since by Einstein/Mach, it would be exactly the same. And, since such a wind is *not* observed, nor ever has been, even with very long baseline interferometry, at this point in time, there seems to be no evidence for the ether anyway.

(Nor need -- nor meaning: for the ether to be the medium that carries light, it would have to be millions of times stiffer than steel -- and yet so evanescent and cloudlike that we can't feel it. Maxwell put paid to the ether; it's like Laplace's magnetic vortices or the classic phlogiston... To quote from Neil Simon's "Murder by Death" "Theory like television set on honeymoon: unnecessary.")

Silas

DStahl
2002-Apr-01, 11:33 PM
Dunash, is this superluminal transfer of info about events on the Earth throughout the universe in 10<sup>-44</sup> seconds the same mechanism Bouw has mentioned? Do you have a reference or link to a technical paper explaining why this does not violate special realitivity?

As to proof or disproof, do you think most geocentrists adhere to Bouw's criteria for truth--ie, that science can never correct the Bible? Certainly it's useless to attempt to convince such believers through experimental evidence, for if the evidence contradicts the Bible it simply will not be accepted.

No evidentiary proof, no logical argument, will convince those who live by belief that they are mistaken. Personally, the only reasons I take up a dispute with a believer anymore is to demonstrate to others that there is a solid alternate view; to oppose an arrogant, obnoxious poster who attacks other members of a forum (not a problem here, thanks to Phil); or, sometimes, just because the topic strikes my fancy. I've come to realize, though, that I will never ever convince a believer that he or she is wrong. Dunash, I dunno if you're a "believer" in the sense I mention above, but at any rate I'm not inclined to argue right now. Maybe later...? *grin* Or maybe not. *shrug*

If there are a few papers on the superluminal hypothesis on the web I'd like to know about them, though.

--Don Stahl

Silas
2002-Apr-02, 01:51 AM
Personally, the only reasons I take up a dispute with a believer anymore is to demonstrate to others that there is a solid alternate view . . .


A truly non-trivial motive. It has been suggested that, in this sort of forum, there are approximately ten times the number of passive readers as there are active participants.

I confess to a more belligerent motive: I'm proud as a peacock that I have forced Dunash to accept that earthquakes are exactly that: quakes of the earth. His original hard-line position that the stars vibrated in such a way as to transmit a gravitational distortion toward the earth was intriguing, but wholly fails the test of mere reason. Okay, yeh, I'm childish enough to "keep score."

But there's an even more selfish motive: I want to LEARN! I want to meet people who have opinions that differ from mine, and match myself against them, and, when they triumph over me by logic, reason, and evidence, I am improved. I'm a better person when I give up my errors.

There will always be those who would rather "know" than "learn." But not me! Someone (Will Rogers?) said, "It ain't the things you don't know, but the things you do know that ain't so."

I can assess my ignorance reasonably well, but I cannot assess my "incorrect knowledge" except by contending with those who darn well know better.

Silas

DStahl
2002-Apr-02, 04:39 AM
Silas: Yes, one does learn a lot from disputation...I hadn't included that in the reasons, but it's a good one. If the person you're arguing against doesn't teach you much, your own research into the subject most likely will.

--Don Stahl

Dunash
2002-Apr-02, 05:55 AM
Re Silas' query as to how motion is still possible inside the ether ("Firmament") despite its 10^93 g/cc Planck Density:

http://www.geocentricity.com/firmamentintro.htm

Dunash
2002-Apr-02, 08:35 PM
Re DStahl's request for a link to a technical paper:

The signal is propagated gravitationally through the firmament (Planck medium, vacuum state, etc.), so the speed of gravity rules this process. For a link to a technical paper: http://www.metaresearch.org/cosmology/gravity/possiblenewpropertiesofgravity.asp

DStahl
2002-Apr-02, 09:01 PM
For those who didn't follow Dunash's link, it references a paper of Tom Van Flandern's.

Yes, I know that Van Flandern has published several papers on superluminal gravity.
Here's a quote from Chris Hillman on their scientific merit:

"In the past year or so, Van Flandern (one must give him a point for self-consistency here) has gone further and now claims that not only do changed in gravitational ``forces'' propagate faster than light, but that changes in electromagnetic 'forces' propagate faster than light! In other words, according to Van Flandern, not only is 'the speed of gravity' infinite, but so is 'the speed of light'! Needless to say, Van Flandern is simply very, very confused."

"Van Flandern has been making incorrect claims about gravitation for a very long time, which have been corrected more or less patiently by experts; see this (very, very long--- currently 85,000 lines and growing fast) collection of posts by Steve Carlip, John Baez, and other leading gravitation physicists. See also this excellent article by John Farrell, which quotes numerous leading physicists who debunk various of Van Flandern's misstatements and misrepresentations."

Ref: This page (http://math.ucr.edu/home/baez/RelWWW/wrong.html#speed) hosted by John Baez.


Here's a link to the rebuttal by Steve Carlip: Abstract (http://xxx.lanl.gov/abs/gr-qc/9909087), downloadable as a PDF or LaTEX document.

The upshot is, Van Flandern didn't get his sums right. Relativity correctly predicts the effects he mentions, using gravitational propagation at the speed of light. No superluminal gravitation is evidenced. If Van Flandern's hypothesis is Bouw's foundation for superluminal signalling, he's building on sand.

--Don Stahl

Silas
2002-Apr-02, 10:50 PM
On 2002-04-02 16:01, DStahl wrote:
For those who didn't follow Dunash's link, it references a paper of Tom Van Flandern's.


Ouch. I've followed Van Flandern and Baez, and it's pretty sad. Van Flandern consistently fails to work the actual mathematics involving GR.

(Tensors are HARD! I sure as heck can't do 'em, and I'm pretty well up on math! But that's no excuse for V.F., who makes claims and then won't or can't back them up.)

Since the universe is "continuous" in practice, it's difficult to conceive of an experiment by which the "speed of gravity" could be measured. e.g., it's "forbidden" to just make the moon disappear, and see if tidal effects are detected before the moon's absence is seen visually. The Cavendish experiment is insufficiently sensitive to make the measurement...

(Or...is it? Could you take two reasonably large masses, a few dozen meters apart, and shift them in such a way as to detect the "speed of gravity?" Hm...)

Silas

Geo3gh
2002-Apr-03, 01:47 AM
On 2002-04-01 20:51, Silas wrote:

There will always be those who would rather "know" than "learn." But not me! Someone (Will Rogers?) said, "It ain't the things you don't know, but the things you do know that ain't so."


It was Artimus Ward (1834-1867)

(How's that for trivia?)

DStahl
2002-Apr-03, 04:58 PM
I apologize--I forgot to thank Dunash for providing a link as I had requested, even though I believe that particular paper doesn't stand. And to be fair, Van Flandern's work is taken seriously on many, many websites. As far as I can tell, though, it's mainly the UFO, free-energy, and other pseudoscience writers that accept his hypotheses, and the professional physicists who reject them.

But thanks again, Dunash, for providing a reference.

--Don Stahl

Dunash
2002-Apr-03, 07:48 PM
"Here's a quote from Chris Hillman on their scientific merit":

Chris Hillman seems to have a mainly math background, and has shown that he knows
little about experimental or practical physics. He blindly slams everything that doesn't conform to his way of thinking. As an example of both statements, when TVF quoted Nobel Laureate Richard Feynman, Hillman slammed Feynman (not recognizing the name) until reigned in by the resident relativists.

> "In other words, according to Van Flandern, not only is 'the speed of gravity' infinite, but so is 'the speed of light'!"

Utter nonsense. What TVF showed was that the speed of propagation of gravitational and
electrodynamic forces is infinite in Einstein's and Maxwell's theories, just as it admittedly is in Newton's theory (which GR supposedly reduces to). In the experimental evidence, the lower limit to the speed is much higher than light-speed, but obviously not infinite.

Because electrodynamic forces are carried by something named "virtual photons", that
seems to provide an excuse to use this "play-on-words" arguments that TVF claim photons go
faster than light. What he claims is that "virtual photons", whatever they may be, cannot be photons, the name notwithstanding.


> "Van Flandern has been making incorrect claims about gravitation for a very long time,which have been corrected more or less patiently by experts; see this (very, very long---currently 85,000 lines and growing fast) collection of posts by Steve Carlip, John Baez, and other leading gravitation physicists."


If the arguments of these physicists had any merit that could withstand scrutiny, then
why did they deem it necessary to delete TVF's rebuttal arguments? It is one thing to have a discussion of the merits or lack thereof of some point, and quite another to show only one side of that discussion.

> "See also this excellent article by John Farrell, which quotes numerous leading physicists who debunk various of Van Flandern's misstatements and misrepresentations."

It is interesting they did not show or even cite the rebuttal to Farrell's article.
Farrell is not a physicist, but a science writer. He is apparently a bad one because he
interviewed only persons on one side of the argument before writing his piece.


So much for any pretense to objectivity on the part of either Farrell or Don Stahl.


John Baez's link:

http://math.ucr.edu/home/baez/RelWWW/wrong.html#speed

and Steve Carlip's:

http://xxx.lanl.gov/abs/gr-qc/9909087.

have been addressed and rebutted (since August 2000) at http://metaresearch.org/cosmology/gravity/speed_limit.asp, which is currently the last word on the subject. Again, why didn’t Don Stahl complete his citations, unless his intent was to deceive?

> "The upshot is, Van Flandern didn't get his sums right. Relativity
> correctly predicts the effects he mentions, using gravitational
> propagation at the speed of light. No superluminal gravitation is evidenced."


Here is a simple question in logic. Relativists claim GR reduces to Newtonian gravity in the weak-field, low-velocity limit. They also admit that Newtonian gravity has infinite propagation speed. Given that the implications of putting a speed-of-light propagation into
Newtonian gravity are catastrophic for the theory, how can GR claim to reduce to Newtonian gravity in the limit, yet retain its slow force propagation speed?

The paper cited above now addresses every argument raised by relativists. I find it
especially telling that no arguments have been raised against the point that ftl propagation is experimentally allowed, whether or not gravitation and/or electrodynamics are examples of it.

Silas
2002-Apr-03, 07:56 PM
Here is a simple question in logic. Relativists claim GR reduces to Newtonian gravity in the weak-field, low-velocity limit. They also admit that Newtonian gravity has infinite propagation speed.

Does it? I've never heard that. Again, since nature is generally "continuous" -- i.e., masses don't just appear and disappear -- and since there is no known gravity shield ("Cavorite," so to speak) -- we can't perform the experiment of "blinking" a mass on and off to see how it affects another mass.

I don't know of any really good natural effects that could be used to measure this either; again, nature is too "smooth" and doesn't provide dramatic examples of masses changing in magnitude.

It seems obvious to me that Newtonian Gravity does not require the force to propogate at any specific speed. Am I missing something?

Silas

Silas
2002-Apr-03, 07:59 PM
http://metaresearch.org/cosmology/gravity/speed_limit.asp


This link doesn't work; can you fix it?

Silas

Dunash
2002-Apr-03, 08:48 PM
The link seems OK here.

Silas
2002-Apr-03, 09:40 PM
Okay: the link works now. Maybe they had an interruption of service...

I was disappointed, frankly; Mr. Van Flandern, in the "rubber sheet" analogy, claimed that there was an assymetry in the abberation of gravitational attraction.

He said, in essence (I am rephrasing this for clarity) that as the earth moves, and gravity takes a few seconds to reach the moon, the moon would always be attracted toward a point slightly behind the earth. But, he says, if the moon moves and the earth is still, there is no such abberation.

This is clearly false, since the point of mutual attraction is the barycenter of the earth-moon system, and any motion of the earth *or* the moon will result in an abberation. His claimed assymetry is bogus.

As for the observation of such abberation, bring it on. Has it been observed? Is it meaningful?

(Besides...ahem...if the earth isn't moving, as you have suggested, then it certainly can't be accelerating...)

Such an effect *might* be observable in a situation where an object is orbiting in a very stable and strongly elliptical orbit; the stability of the orbit would allow us to model the "real" or "instantaneous" position of the satellite, and to determine whether or not the acceleration due to gravity is truly radial or is retarded by the lag of lightspeed.

(e.g., similar to the measurement of the speed of light by timing the Galilean satellites.)

Personally, I think that if the effect were as large as Van Flandern claims, it would be readily detectable within the solar system.

I understand that I'm making the insulting error, common to many creationists, of using "high school level science" to compete with people using more advanced tools. I can't do tensor math, so I'm stuck arguing at a level I comprehend.

I'm *almost* good enough to do the math modeling of orbits using instantaneous and retarded gravity to see how they differ. I'm also almost certain that they would be interchangeable with only a minor change in certain units.

(Lemme get back to that, eh?)

Silas

Dunash
2002-Apr-03, 09:52 PM
Silas asked: > "Does it? I've never heard that".

See for example page 177 of "Gravitation" by Misner, Thorne & Wheeler -- the most comprehensive and respected work on gravitation in existence.

> "Again, since nature is generally "continuous" -- i.e., masses don't
just appear and disappear -- and since there is no known gravity shield
("Cavorite," so to speak) -- we can't perform the experiment of "blinking" a mass on and off to see how it affects another mass."

But we can determine if a target of a gravitational field accelerates toward the true, instantaneous position of a source of
gravity, or towards its light-time-retarded position. TVF's paper is Phys.Lett.A, v. 250, pp. 1-11 (1998), and lists all six major experiments that measure the speed of gravity, including one that vibrates large
masses in the laboratory and looks for the delay in induced vibrations in a target.

> "I don't know of any really good natural effects that could be used to measure this either; again, nature is too "smooth" and doesn't provide dramatic examples of masses changing in magnitude."

This "smoothness" is more than compensated by the incredible precision attainable in astrophysical systems. Binary pulsars, for
example, have very strong fields and very high velocities and accelerations. Cause and effect are easy to observe.

> "It seems obvious to me that Newtonian Gravity does not require the force to propogate at any specific speed. Am I missing something?"

Try writing a simple computer program to numerically integrate a 2-body system using Newtonian gravity alone. Let the force between them propagate at light-speed. The system flies apart in short order. Only
infinite force propagation speeds can preserve angular momentum.

Silas
2002-Apr-03, 10:57 PM
Try writing a simple computer program to numerically integrate a 2-body system using Newtonian gravity alone. Let the force between them propagate at light-speed. The system flies apart in short order. Only
infinite force propagation speeds can preserve angular momentum.


This may be...but my mathematical scribbling in the last hour suggest otherwise... As far as I can tell, a delay in the "speed" of gravity doesn't change a thing. Ordinary momentum automatically compensates for the delay.

(Simplest example: a planet is moving "up," i.e. in the direction its north pole points, while a satellite orbits its equator. The satellite is always pulled toward a point *behind* the actual position of the planet, and so you'd think that, in time, it would get "left behind." But it doesn't; it has an amount of "upward momentum" that compensates for the planet's motion.)

And, really, it all just falls out of the uniformity principle: if what you say is true, and orbits aren't stable with "slow gravity," then distant galaxies with high velocities should have different shapes than nearby ones. It would also violate special relativity, in that it would provide an "absolute" frame of reference.

Remember, the "pull" of gravity, even if it takes a year to travel from the sun to the earth, is still always pulling. The "pull vector field" is continuous and always on.

Silas

DStahl
2002-Apr-04, 01:06 AM
I believe that Silas is correct--from all I've read, the equations of GR using lightspeed gravitational propagation predict exactly the effects Van Flandern purports require superluminal gravity.

I'm curious, though: if Van Flandern's claims have such merit, why is he not publishing in respected scientific journals instead of in his own foundation's house organ? Certainly if he's right and his papers do not contain invalidating errors, physicists who recognize the fact could receive the immense career boost of getting in on the ground floor of a scientific revolution. Are there any research physicists who accept Van Flandern's hypothesis? I'll see what I can find out.

--Don Stahl

DStahl
2002-Apr-04, 06:13 AM
Dunash: In the preface to the newsgroup postings the compiler notes that the intent was not to provide an overview of the debate but rather to archive the posts providing insight into general relativity. That's why Van Flandern's posts--and others--were not included, and why many posts were edited.

Here's a link to a paper by Steve Carlip on the subject of gravitational propogation: Aberration and the Speed of Gravity (http://arxiv.org/PS_cache/gr-qc/pdf/9909/9909087.pdf). Here's a link to the server page (http://arxiv.org/format/gr-qc/9909087) so you can download it in postscript instead if you want.

Tom Van Flandern's online publications are available at his foundation homepage (http://www.metaresearch.org/home.asp)--go to the "Cosmology" section. His refutation of Carlip's paper is also on this site, I believe. I haven't found online papers by other physicists corroborating his claims, although his "The Speed of Gravity: What the Experiments Say" paper is reposted on several sites--Lambert Dolphin's site, etc.

Tom Roberts wrote an article titled "TVF's Clairvoyant Gravity" which purports to show that Van Flandern's description of gravity results in unacceptable results when applied to observations of closely orbiting pulsars. Unfortunately I can't find an online version of the paper, and so have only a few isolated quotations to go on. Can anyone else locate a copy?

About Van Flandern's rebuttal to Steve Carlips paper:

Van Flandern: "We should not be fooled by consideration of retardation in the distance or mass or charge distribution, a common practice in textbooks on electromagnetism and gravitation."

Textbook physics is fundamentally flawed in describing both electromagnetism and gravitation, then? This seems somewhat improbable to me. But what do I know?

Van Flandern: "The evidence from all six experiments that bear on the question of the speed of gravity is unambiguous in excluding answers as slow as lightspeed. A similar remark applies to the propagation speed of electrodynamic forces."

That last sentence seems to imply that Van Flandern does indeed view the propagation of electromagnetic forces as superluminal. Again, this seems improbable--surely such an effect would have been well documented, inasmuch as electromagnetism is one of the most experimentally explored of the four forces?

Personally, I can't follow the math, so I can't say whether Carlip's formulae or Van Flandern's are correct. It's an interesting dilemma for the amateur: how do you arrive at the truth in this kind of debate? I find myself looking to what I consider reputable sources, looking for support and dissent among the physics community at large, and trying to understand the issues as best I can. So far I am seeing more scientists saying that Van Flandern's hypothesis is erroneous than supporting his results.

I found that Van Flandern has indeed had a paper on superluminal gravity published in a journal of astrophysics, so his publication on this topic is not limited to his foundation. I was mistaken. Gerardus has the advantage of me here, since I haven't bothered to read much about Van Flandern's work before now. I'll keep looking around, though.

Incidentally, Dunash, accusing me of posting selective citations with intent to deceive was a bit below the belt, hmmm? I see you posting no links to evidence which contradicts your position.

--Don Stahl

[Later] Say, I've tried not to misrepresent Gerardus' position vis-a-vis the infallibility of the Bible and its relation to science. If I read more into his statements on his website than he meant, I hope he'll correct me.

<font size=-1>[ This Message was edited by: DStahl on 2002-04-04 01:49 ]</font>

Silas
2002-Apr-04, 02:37 PM
I spent some hours last night doing math, and, while my results aren't publishable exactly...

Gravity is a "conservative" field. That just means that you get out of it no more and no less than you put into it. Potential energy (due to gravity) plus kinetic energy is always constant. (If it wasn't, we'd be able to make perpetual motion machines...)

Gravity remains conservative no matter what the "propogation speed" is. Orbits do NOT become unstable; energy IS conserved; and Van Flandern's math APPEARS TO ME to be wrong.

I'm going out of my way, though, to remind folks that I'm not a professional mathematician (well, yes, actually I am, but not in that way) and my results might not stand the scrutiny of a serious referee.

Silas

Prince
2002-Apr-04, 07:30 PM
t looks as if Carlip & Baez are arguing against a physical process using a geometry. Don't they understand the foundation of Mach's principle?" In
other words, they admit that physically the speed of gravity has to be infinite (or indistinguishable from infinite insofar
as the system is concerned), but then they invent non-linear geometries to explain it and then insist that their CONCEPTUAL
geometry is THE ultimate reality, and that the physical realm is merely a virtual reality! In other words, it's the
mathematics behind a bomb that blows you up, not the chemical
and mechanical reactions of the component parts. The problem is there are an infinite number of mathematical explanations
for the bomb, so which is the real one? And that fact is the petard against the geometric "realities," n'est ce pas?

DStahl
2002-Apr-04, 09:18 PM
Hmmm. Prince, there are a number of interpretations of Mach's principle--I think some fellows recently derived it, or at least claimed to have derived it, from the properties of the vacuum. There's a lovely paper somewhere on a preprint server that analyzes various versions of Mach's principle in light of Newtonian and GR gravity. It's not a simple nor clearcut issure, I believe.

As to the math, you might be interested in the thread under General Astronomy Quantum question, sorta (http://www.badastronomy.com/phpBB/viewtopic.php?topic=797&forum=2&start=25). The very last post quotes Kip Thorne, and indicates that (in Thorne's view) professional physicists specializing in relativity and gravitation use the curved-spacetime equations of GR for some problems (like black holes), and a flat-spacetime field set of equations when dealing with other problems (like gravitational waves). But, crucially, Thorne points out that these sets of equations are mathematically equivalent and yield the same predictions about gravity.

I strongly suspect that Baez and Carlip know full well that the Einsteinian tensors can be viewed as geometry, but from Thorne's description I also believe that it makes no difference whether one views them as describing an abstract geometry or whether one views them as describing an actual physical process because the mathematical results are the same.

Incidentally, congratulations, Silas, on working through the GR equations. I am well and truly impressed. And if anyone can formulate Van Flandern's description of superluminal gravity in terms equivalent to Einstein's field equation, I will submit both to some experts in relativity and see if they offer any comments. I'll exclude the eight or so physicists who have already weighed in with criticism of Van Flandern, in order to get fresh opinions.

(I will not try to get Thorne or anyone else to read all of Van Flandern's papers and the rebuttals by Carlip et al. That's really too much to ask of a working physicist, eh?)

--Don Stahl

Silas
2002-Apr-04, 10:01 PM
Incidentally, congratulations, Silas, on working through the GR equations. I am well and truly impressed.


Whoa, no, I didn't do that! All I did was some square-rooting around to compare infinitely fast gravity with "slow" gravity, and all I was able to do was show that either way, gravity is "conservative." (i.e., any closed path will yield no change in energy.) I also *think* that I can show that orbits don't decay or degrade even if gravity is slow...but this contradicts some of the other guys, so I could well be wrong.

Silas

DStahl
2002-Apr-05, 07:16 AM
Here's a quote from Sten Odenwald's Q&A page:

Question: "If gravity travels at the speed of light, why don't the equations used in celestial mechanics include time delays?"

Odenwald's answer: "The standard equations do not worry about this propagation delay effect of gravity because for most ephimerides calculations they are to small to make a difference on the short term. Most sophisticated, relativistic celestial mechanics calculations take this propagation delay into account and the results are in complete accord with the most accurate observations."
...
"General relativity assumes that gravity propagates at the speed of light, and when a PROPER accounting of forces, times, and positions is made, the end result are predictions that match reality based on this finite propagation speed for gravity." [emphasis in the original]

If I am reading that correctly, Van Flandern's claim that GR assumes an infinite speed of propagation is simply wrong, according to Odenwald. Further, Odenwald seems to support the position that GR with a lightspeed limit on propagation does indeed match all observational evidence.

The full text of Dr. Odenwald's answer are at Nasa's Ask a Space Scientist (http://image.gsfc.nasa.gov/poetry/ask/a10662.html).

Interesting. Another piece to the puzzle.

Correction: in an earlier post I was bemused that Van Flandern was able to posit superluminal electromagnetic effects. I misread: he posits superluminal electrodynamic effects, such that the force between charged bodies propagates faster than the speed of light. My bemusement stands, however: the interactions of charged bodies seems a very well-explored field of physics. How could such a result have been missed?

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-05 02:20 ]</font>

Wiley
2002-Apr-05, 04:32 PM
On 2002-04-05 02:16, DStahl wrote:

Correction: in an earlier post I was bemused that Van Flandern was able to posit superluminal electromagnetic effects. I misread: he posits superluminal electrodynamic effects, such that the force between charged bodies propagates faster than the speed of light. My bemusement stands, however: the interactions of charged bodies seems a very well-explored field of physics. How could such a result have been missed?


I have hard time swalling this. Built into Maxwell's equations, the equations the describe electromagnetics, is that light/energy propagates at a finite speed of about 3e8 m/s. All electromagnetic energy propagates at the speed of light (in the material). If you could magically turn a charge on and off, the effect would travel at the speed of light. (Antennas can actually be modelled using this principle.) Maxwell's equations are very well tested. In 1905 they were so well tested, that Einstein chose them over Netwon.

The difference in terms electrodynamics and electromagnetics is not important in this case. Actually I doubt its important in any case. Electromagnetics subsumes electrodynamics, in my opinion. Regardless, the force is transmitted through the electric and magnetic fields and the propagation of the force is an electromagnetic problem.

I do electromagnetics for a living. This is one of those rare occasions (equations?) where I know what I'm talking about.

<font size=-1>[ This Message was edited by: Wiley on 2002-04-05 11:35 ]</font>

DStahl
2002-Apr-05, 08:26 PM
Wiley: Thanks for the analysis. You are a gentleman and a scholar.

I feel quite chuffed, as after poking about for a couple of days I have finally found an online paper which speaks soberly of superluminal physics and mentions Van Flandern as a researcher. The author of the paper is Leonardo F. D. da Motta (Motta is Brazilian, hence the slightly unorthodox phraseology).

Abstract: "In 1972, Smarandache proposed that there is not a limit speed on the nature, based on the EPR-Bell (Einstein, Podolsky, Rosen, Bell) paradox. Although it appears that this paradox was solved recently, there are many other evidences that guide us to believe that Smarandache Hypothesis is right on quantum mechanics and even on the new unification theories. If Smarandache Hypothesis turns to be right under any circumstance, some concepts of modern physics would have to be 'refit' to agree with Smarandache Hypothesis. Moreover, when the meaning of Smarandache Hypothesis become completely understood, a revolution on technology, specially in communication, will arise."

I've just skimmed the paper briefly, but it contains several leads to pursue.
Smarandache Hypothesis: (http://www.gallup.unm.edu/~smarandache/Sm-Hyp.htm) Evidences, Implications and Applications

Enjoy!

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-05 15:33 ]</font>

Dunash
2002-Apr-06, 06:04 AM
As Laplace discovered almost two centuries ago when he set the
first lower limit to the speed of gravity, 10 million times the speed of
light, the effects of propagation delay are drastic because they add
angular momentum to any orbiting system, which works progressively to
cause any orbit to spiral outward.

Relativistic calculations do not contain any propagation delay
because none has ever been detected for gravitational force. Of course,
gravitational waves have propagation delay, but those have no
observational consequences in the solar system, if they exist at all;
and have nothing to do with gravitational forces or changes therein. But
even experts frequently get these two confused. Books by Wald that
promote the "geometric interpretation" of general relativity over the
"field interpretation" favored by Einstein, Eddington, Dirac, and
Feynman among others, have added greatly to this confusion by treating
changes in gravitational forces as if they were a wave phenomenon,
thereby getting many people mixed up about whether "gravitational waves"
are waves of the potential field or the force field. They are the
former, not the latter.

If GR did assume that gravitational forces propagate at the
speed of light (which it does not), then it could not reduce to
Newtonian gravity (which has infinite propagation speed for
gravitational forces) in the weak-field, low-velocity limit.

Odenwald could not be more unninformed about the facts, and is
wrong on every count cited below. Even relativists who dispute my
position, such as Carlip, would not support Odenwald's claims. Odenwald
does a disservice to everyone by making erroneous statements without
justification, citation, or factual basis. (By contrast TVF's,right or wrong, has all three elements in his published papers.)

> [Don Stahl]: the interactions of charged bodies seems a very well-explored
field of physics. How could such a result have been missed?

This wasn't missed. It was a big issue in the early 20th century. It is well-known that electrodynamic forces act without
propagation delay. This was "explained" (sort of) by the theory of retarded potentials. But the only existing experiment that tests that theory (the Sherwin-Rawcliffe experiment) obtained a result in conflict with the theory.

DStahl
2002-Apr-06, 06:41 AM
Dunash: "Odenwald could not be more unninformed about the facts, and is
wrong on every count cited below. Even relativists who dispute my
position, such as Carlip, would not support Odenwald's claims. Odenwald
does a disservice to everyone by making erroneous statements without
justification, citation, or factual basis."

I would note that Dr. Odenwald was not writing a paper for a journal, he was replying to a question on an online Q&A site. To compare the two formats in regards to citations of the literature is a bit disengenuous.

Your accusations against Odenwald should be easily corroborated or dismissed. I'll see what I can find out.

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-06 03:25 ]</font>

GrapesOfWrath
2002-Apr-07, 06:08 AM
On 2002-04-06 01:04, Dunash wrote:
If GR did assume that gravitational forces propagate at the
speed of light (which it does not), then it could not reduce to
Newtonian gravity (which has infinite propagation speed for
gravitational forces) in the weak-field, low-velocity limit.

Odenwald could not be more unninformed about the facts, and is
wrong on every count cited below. Even relativists who dispute my
position, such as Carlip, would not support Odenwald's claims.

Are you saying that Carlip would say that the speed of gravity is infinite, according to general relativity? Is that Steve Carlip (http://hepweb.rl.ac.uk/ppUK/PhysFAQ/grav_speed.html)? He says there that "In general relativity, on the other hand, gravity propagates at the speed of light."

Dunash
2002-Apr-07, 03:37 PM
Grapes of Wrath asks:

> Are you saying that Carlip would say that the speed of gravity is infinite, according to general relativity? Is that Steve Carlip? He says there that "In general relativity, on the other hand, gravity propagates
at the speed of light."

Odenwald was quoted as saying the following things: (1) "The standard equations do not worry about this propagation delay effect of
gravity because for most ephemerides calculations they are too small to make a difference in the short term."

Even Steve Carlip, who disagrees with my interpretation of GR,would certainly agree that adding a simple, uncompensated propagation delay for gravitational force between the Sun and the Earth would have
drastic consequences for Earth's orbit, which would then spiral outward,
doubling its size in about 1000 revolutions. Odenwald is wrong about the
consequences being too small to make an observable difference in the
short term. Of course, his statement is true of gravitational waves, which have never been detected in the solar system. But he makes his claim about "this propagation delay effect of gravity", not about
gravitational waves.

Odenwald says: "Most sophisticated, relativistic celestial mechanics calculations take this propagation delay into account and the results are in complete accord with the most accurate observations."
Carlip would certainly agree that GR uses no propagation delay for gravitational forces. It does, of course, have propagation delay for gravitational waves, a hypothetical phenomenon that propagates at the
speed of light, but is unrelated to changes in gravitational force.

Carlip is really playing with words by saying
"gravity propagates at the speed of light" because there is no observational evidence that gravitational force or changes therein
propagate as slowly as lightspeed, and plenty of evidence that they
propagate much faster. But Carlip argues that what we observe is an illusion created by a hypothetical "velocity-dependent force" that cancels the propagation delay, creating the appearance that gravity propagates without delay. The counterargument is that, while it is easy for a mathematician to invent and force he wishes, Carlip's hypothetical "velocity-dependent force", among other problems, would be
indistinguishable from tidal forces which nature clearly does not cancel.

Silas
2002-Apr-07, 07:08 PM
On 2002-04-07 11:37, Dunash wrote:

Even Steve Carlip, who disagrees with my interpretation of GR,would certainly agree that adding a simple, uncompensated propagation delay for gravitational force between the Sun and the Earth would have
drastic consequences for Earth's orbit, which would then spiral outward,
doubling its size in about 1000 revolutions.


I think I disagree... Even with a time delay, gravity is a "conservative" force field, and would not leak energy in that fashion.

I think you may be making the error of assuming only one change -- the speed of gravity -- but not accepting other changes.

According to Baez, in the famous debate with Van Flandern, the GR equations contain a non-radial component. GR also involves the mass-equivalent of the gravitational field itself (the famous precession-of-Mercury effect.)

If the only thing you do is scotch-tape a delay-of-gravity effect onto Newtonian gravity, well, of course you're going to get weird results.

(Although that is exactly what I have been doing, and I haven't been getting the results you have...)

Van Flandern is not particularly persuasive, and the web site you pointed us to is particularly *un*persuasive.

Silas

DStahl
2002-Apr-08, 05:04 AM
TVF (via Dunash): "Even Steve Carlip, who disagrees with my interpretation of GR,would certainly agree that adding a simple, uncompensated propagation delay for gravitational force between the Sun and the Earth would have drastic consequences for Earth's orbit, which would then spiral outward, doubling its size in about 1000 revolutions."

Sorry, Tom, but in the previous post by Dunash you already claimed to be able to speak for Carlip, and you got it quite wrong: Carlip in fact said exactly what Odenwald did, though you dismiss it as "playing with words." Frankly, I don't trust your interpretation of Carlip's intent.
---------

Earlier I posted a bit on the Smarandache Hypothesis: that there is not a limit speed of c in nature, an idea based on the EPR-Bell paradox involving apparent action-at-a-distance. Florentin Smarandache is an interesting figure. He's a mathematician by education, but he has written poetry, science fiction, constructed theological paradoxes, and founded a school of philosophy based on the idea of 4-fold criteria for truth rather than the more common 2-fold criteria. (2-fold: A proposition is either true or it is false. 4-fold: a proposition can be true, false, both true and false, or neither true nor false. This is an aspect of Hindu and Buddhist philosophy as well, I believe.) But to me some of his excursions into realms other than mathematics seem the work of a dilettante--his "divine paradoxes" seem rather shallow, and his conjecture about superluminal information transfer isn't, as far as I have been able to understand, rooted in physics so much as in a layman's view of quantum entanglement.

(I reserve the right to change my mind if I can find further papers on the Smarandache Hypothesis...)

So, except for a paper or two I have yet to track down, this seems to have led into unpublishably vague fringe science and not a solid corroboration of Van Flandern's hypothesis. Hmmm. At this point no professional physicist that I know of supports Van Flandern, and all that have examined his hypothesis dismiss it as erroneous.

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-08 01:18 ]</font>

Wiley
2002-Apr-08, 10:26 PM
On 2002-04-06 01:04, Dunash wrote:
> [Don Stahl]: the interactions of charged bodies seems a very well-explored
field of physics. How could such a result have been missed?

This wasn't missed. It was a big issue in the early 20th century. It is well-known that electrodynamic forces act without
propagation delay. This was "explained" (sort of) by the theory of retarded potentials. But the only existing experiment that tests that theory (the Sherwin-Rawcliffe experiment) obtained a result in conflict with the theory.


This is just wrong. Out of the five sentences only the first is right: "This wasn't missed."

Electromagnetic force do not act without propagation delay; hence, this could not be well-known. Electromagnetic forces by definition propagate at the speed of light, and this is very well predicted by the Leonid-Weichart potentials. Not "sort of", but as accurate as we can measure. To sum up: There is no known experiment or observation that even suggests Maxwell's equations are wrong in flat spacetime and on a macroscopic scale. If the theory of retarded potentials is wrong, so is Maxwell equations.

So what does this say about the Sherwin-Rawcliffe experiment? That you are misinterpreting it. Often the potentials are split into its contribution from velocity and contribution from acceleration. Since a charge moving at a constant velocity does not radiate, it's usually convenient to seperate the acceleration term and only work with this term. Now if you look at the field due a charge moving at a constant velocity, it appears to know instantly the charge is moving. But this is really more predictive since we know the charge is moving at a constant velocity, we can accurately predict where it will be. If you include the acceleration terms, this artifact disappears. The Sherwin-Rawcliffe does not invalidate Maxwell's eqs. nor the Leonid-Weichart potentials.

Wiley
2002-Apr-08, 10:57 PM
On 2002-04-07 11:37, Dunash wrote:

Carlip is really playing with words by saying
"gravity propagates at the speed of light" because there is no observational evidence that gravitational force or changes therein
propagate as slowly as lightspeed, and plenty of evidence that they
propagate much faster. But Carlip argues that what we observe is an illusion created by a hypothetical "velocity-dependent force" that cancels the propagation delay, creating the appearance that gravity propagates without delay.


No, this is not an accurate representation. We write the total gravitational force in position dependent terms plus velocity dependent terms plus acceleration dependent terms plus even higher order terms. Mathematically, this is known as a Taylor expansion. To say that we willy-nilly add terms is incorrect. They are there because it's a general expansion and we can't make assumptions on their existence or non-existence. (We assume they do exist and if we are wrong, they coefficients of those terms will be zero.)

Steve Carlip starts with a physical principle, i.e., conservation of momentum and energy, and shows for this to hold there must be velocity dependent terms. He gives also gives an analytic example which shows these terms. (Finding any analytic solution in the GR framework is, as the mathematician would say, non-trivial; so we should not be surprised if very few, if any, analytic examples exist.)



The counterargument is that, while it is easy for a mathematician to invent and force he wishes, Carlip's hypothetical "velocity-dependent force", among other problems, would be
indistinguishable from tidal forces which nature clearly does not cancel.


The cat sips rasberries on whiskey Thursday. This is my sarcastic way of saying, your sentence does make any sense. E.g. the Yahoo Serious Film Festival.

Wiley
2002-Apr-08, 11:28 PM
On 2002-04-05 15:26, DStahl wrote:
Wiley: Thanks for the analysis. You are a gentleman and a scholar.

Thank you.



Abstract: "In 1972, Smarandache proposed that there is not a limit speed on the nature, based on the EPR-Bell (Einstein, Podolsky, Rosen, Bell) paradox. Although it appears that this paradox was solved recently, there are many other evidences that guide us to believe that Smarandache Hypothesis is right on quantum mechanics and even on the new unification theories. If Smarandache Hypothesis turns to be right under any circumstance, some concepts of modern physics would have to be 'refit' to agree with Smarandache Hypothesis. Moreover, when the meaning of Smarandache Hypothesis become completely understood, a revolution on technology, specially in communication, will arise."

I've just skimmed the paper briefly, but it contains several leads to pursue.
Smarandache Hypothesis: (http://www.gallup.unm.edu/~smarandache/Sm-Hyp.htm) Evidences, Implications and Applications



I read the article and what I found interesting is the idea of superluminal information transfer using evanescent modes. Evanescent modes decay exponentially; they do not propagate. For example, radio waves incident on copper will decay in less than a millimeter. Typically these modes travel slower than propagating modes, but if you can couple to an evanescent mode wierd solutions can result. I would like to see the math behind these claims.

However, practical applications of superluminal communications over distances on the order of a millimeter are probably nonexistent. /phpBB/images/smiles/icon_smile.gif



<font size=-1>[ This Message was edited by: Wiley on 2002-04-08 19:30 ]</font>

Jovianboy
2002-Apr-09, 12:22 AM
On 2002-04-01 07:13, ToSeek wrote:


On 2002-03-31 20:58, Jovianboy wrote:
Now, here's a bit of Dunash's writing from the Bouw/Faulkner thread:

Quote:
--------------------------------------------------------------------------------


On 2002-03-21 12:27, Dunash wrote:
In Geocentricty we basically reverse cause and effect.


--------------------------------------------------------------------------------

To which I replied:

Violating the causality principle must be the surest sign of an illogical argument.


I am amazed that I am coming to the defense of a geocentrist, but Dunash was basically responding to "A causes B" by saying "No, we believe B causes A." This is not a violation of the causality principle (though the notion that cosmic forces cause earthquakes may violate any number of other things).



Alright, ToSeek, I have to concede your point in relation to Dunash's overall explanation, in that a violation of the causality principle is not implied. I guess I should have been clearer by emphasising that Dunash's wording appeared (to me) to create a self-contradiction, ie: "In Geocentricity we basically reverse cause and effect", followed by "Naw, Silas, you don't have to surrender causality". A two-way misinterpretation, perhaps.

BTW, don't be too surprised that you defended a geocentrist. As I'm sure you're fully aware, if a mistake is made, it needs to be corrected - even if it means supporting your opponent on a given issue. That to me is the essence of a fair, unbiased approach to science.

Just my thoughts.

Cheers,

JB

DStahl
2002-Apr-09, 07:08 AM
Wiley: You have hit the ten-penny right on the head. I emailed Dr. Pieter Visscher, professor of physics at Cal-Berkeley, with the question:

"Is Van Flandern correct in writing that Maxwell's equations assume instantaneous propagation, or is lightspeed propagation included implicitly (in retarded potentials, perhaps) or even explicitly in the equations?"

He replied,

"Maxwell's equations do not assume instantaneous propagation, and it can be proved that any fields at time t that result from the currents you put into them at time zero are confined to a distance ct, i.e. they travel at the speed of light. Electrodynamic forces do not 'act without propagation delay'. Any instantaneous propagation that is 'derived' from Maxwell's equations must result from an approximation."

So Visscher agrees with you that Van Flandern is incorrect, and perhaps his erroneous results arise from using an approximation to the full equations. Dr. Visscher also notes that "...lots of experiments have been done in which it would have been noticed if some signal moved faster than light." So Van Flandern is fudging on this too.

Note: In my email to Dr. Visscher I asked to quote his reply on the forum, so this is a legitimate use of an otherwise private communication.

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-09 03:12 ]</font>

Dunash
2002-Apr-09, 06:35 PM
"Electromagnetic forces" are a synonym for radiation pressure forces, a common
example of which is the pressure of sunlight. TVF uses that example repeatedly in his papers as an example of forces propagating at the speed of light, to show how differently they behave than *electrodynamic* forces such as Coulomb fields. For example, radiation pressure
has a "Poynting-Robertson effect", which is one manifestation of propagation delay; whereas Coulomb forces conspicuously do not have such a feature, suggesting to many physicists of the last century that they have no propagation delay. But Wiley has obviously not bothered to read TVF's papers before commenting, so he did not see these examples. Hence his excursion to left field to beat up a few strawmen.

[Wiley]: "Electromagnetic forces by definition propagate at the speed of light, and this is very well predicted by the Leonid-Weichart potentials. Not "sort of", but as accurate as we can measure. To sum up: There is no known experiment or observation that even suggests
Maxwell's equations are wrong in flat spacetime and on a macroscopic scale. If the theory of retarded potentials is wrong, so is Maxwell equations."

This betrays unfamiliarity with what things are assumptions and what are
experimentally verified. The Lienard-Wiechert (note spelling) potentials (again, fully discussed in TVF's papers) describe the potential field, not the force field. No one disputes that electromagnetic or gravitational waves (disturbances of the potential fields) propagate at the speed of light. But every experiment in existence with the needed sensitivity (there
are now eight) shows that electrodynamic and gravitational *forces* propagate much, much
faster than light speed.

Forces are gradients of potentials. Forces and potentials are related in certain
specific ways to accelerations and velocities, respectively. Clearly, constraints on velocities do not apply to accelerations; nor do constraints on potentials apply to forces.
Specifically, forces are gradients, which have directions; and those directions are
unambiguously either instantaneous or retarded. In the cases of gravitational and
electrodynamic forces, the directions are always instantaneous to the full accuracy of all experimental data.

[Wiley]: "So what does this say about the Sherwin-Rawcliffe experiment? That you are
misinterpreting it. Often the potentials are split into its contribution from velocity and contribution from acceleration. Since a charge moving at a constant velocity does not radiate, it is usually convenient to separate the acceleration term and only work with this term. Now if you look at the field due a charge moving at a constant velocity, it appears to know instantly the charge is moving. But this is really more predictive since we know the charge is moving at a constant velocity, we can accurately predict where it will be. If you
include the acceleration terms, this artifact disappears. The Sherwin-Rawcliffe does not invalidate Maxwell's eqs. nor the Leonid-Weichart potentials."

The experiment starts from rest, so there can be no experimental confusion of
velocity and acceleration effects. The confusion in the above paragraph comes from mixing the concepts of forces and potentials.

[DSTahl]: Dr. Visscher also notes that "...lots of experiments have been done in which it would have been noticed if some signal moved faster than light." So Van Flandern is fudging on this too.

Yet, when pressed, this professor will be unable to name a single such experiment. By
contrast, TVF's papers list *all* eight experiments that bear on this question. And all indicate ftl propagation of forces.

DStahl
2002-Apr-10, 07:35 AM
Dunash: "Yet, when pressed, this professor will be unable to name a single such experiment. By contrast, TVF's papers list *all* eight experiments that bear on this question. And all indicate ftl propagation of forces.

First, you are not empowered to speak for Dr. Visscher. I believe that Visscher could, as he indicated, provide references to experimental evidence. You presume too much.

Second, Van Flandern's interpretation of observations are mistaken, in particular where he compares incident light to gravitation. The two phenomena are described by quite different equations. His analogy fails.

Here, as I see them, are the fundamental issues.

1. General relativity fits all observations of gravitational interaction, to the limits of measurement.

I believe this is undisputed. If Van Flandern knows of cases in which physicists have been unable to use the equations of GR to explain observations, he should post references to the observations, and the relevant failure of the field equations.

2. All physicists I have consulted agree that GR uses lightspeed propagation, not instantaneous propagation, of the time-varying component of gravity.

Sten Odenwald, quoted above, stated the case correctly. Steve Carlip agrees. Kip Thorne agrees ("In general relativity as in electromagnetic theory the time changing part of the field propagates at the speed of light..." [private communication, quoted with permission]. John Baez agrees.

Tom Van Flandern disagrees. As far as I know, no professional physicist supports Tom Van Flandern in his claim that GR uses instantaneous propagation of gravity.

3. Maxwell's equations provide for propagation at c and not at superluminal speeds. Dr. Visscher has pointed out that this is inherent in the equations: "...it can be proved that any fields at time t that result from the currents you put into them at time zero are confined to a distance ct, i.e. they travel at the speed of light." The BABB's Wiley arrives at the same conclusion.

Tom Van Flandern disagrees. Again, no professional physicist who has weighed in on the subject supports Van Flandern. I asked Dr. Gabriel Barton, of the University of Sussex, to evaluate the following paragraph from one of Van Flandern's self-published documents:

"If the field around a charge propagated with lightspeed delays, then Maxwell's equations would be wrong because they neglect transverse aberration, the main manifestation of field propagation delay. The fact that the equations are correct to first order in v/c tells us that the field propagation speed must be very fast compared to lightspeed, because the neglect of transverse aberration is the logical equivalent of adopting infinite field propagation speed. If Maxwell's equations did work for fields propagating at lightspeed, then they would work for radiation pressure from light fields too, which they do not. If the field has a measurable delay in reshaping itself to register the motion or acceleration of its source, then one would need to add propagation delay into Maxwell's equations (for example, by taking partials with respect to retarded coordinates instead of instantaneous coordinates). The absence of such propagation delay in the equations means that instantaneous propagation of fields is already built in."

Dr. Barton wrote,

"The paragraph you quote from Dr Van Flandern is simply gibberish: its assertions (both about facts and about Maxwell's equations) to which a definite meaning can be attached are simply false, and some of the words convey no meaning to me at all. I think that, to-day, rational discussion is possible only using (correctly) the language of Maxwell's equations, and against the experimental evidence on which they rest, all of which can be learnt from standard textbooks. Thus, in empty space all electromagnetic effects do propagate with the speed of light, and the vast body of evidence underlying special relativity does not allow any signals
to be transmitted instantaneously. These are facts."

"Even for revolutionary theories, and even pending experimental verification, there is at least one universal test, namely that they must not, in its proper domain, contradict knowledge already well-established. The quote fails this test (insofar as it makes sense at all), and the only responsible advice regarding it and all its ilk is to stop wasting time."

[Personal communication, quoted by permission.]

Again, a professional physicist specializing in electrodynamics states quite clearly that Van Flandern is wrong--"These are facts", Dr. Barton writes, and Van Flandern has simply ignored them. His assertions fail conformity with well-established knowledge. I'm reminded of Fleischmann and Pons, faced by refutation of cold fusion from every lab which attempted to duplicate their results, retreating into denial and obfuscation. Like Fleischmann and Pons, Van Flandern is working outside his field of expertise (he is not a physicist, still less an expert in either relativity or electrodynamics). Like Fleischmann and Pons' cold fusion, Van Flandern's assertions contradict well-tested experimental observations and well-established theory. And like Fleischmann and Pons, I suspect that Van Flandern will never admit he has errored.

Just as Dr. Barton has said, I am convinced that debating Van Flandern's claims is a bloody waste of time. I have yet to contact several of the physicists I wished to consult on this, and I will post their evaluations of Van Flandern's claims if they bring new material to light, but to me the case against Van Flandern seems clear.

--Don Stahl

Wiley
2002-Apr-10, 07:23 PM
Excellent reply, Don. It's so good, I almost feel like I don't have to reply. Almost. /phpBB/images/smiles/icon_smile.gif



On 2002-04-09 14:35, Dunash wrote:
This betrays unfamiliarity with what things are assumptions and what are
experimentally verified. The Lienard-Wiechert (note spelling) potentials (again, fully discussed in TVF's papers) describe the potential field, not the force field. No one disputes that electromagnetic or gravitational waves (disturbances of the potential fields) propagate at the speed of light. But every experiment in existence with the needed sensitivity (there
are now eight) shows that electrodynamic and gravitational *forces* propagate much, much
faster than light speed.

Forces are gradients of potentials. Forces and potentials are related in certain
specific ways to accelerations and velocities, respectively. Clearly, constraints on velocities do not apply to accelerations; nor do constraints on potentials apply to forces.
Specifically, forces are gradients, which have directions; and those directions are
unambiguously either instantaneous or retarded. In the cases of gravitational and
electrodynamic forces, the directions are always instantaneous to the full accuracy of all experimental data.


Yep, I mispelled Lienard-Wiechart, but the does not change the validity of my criticisms. Your response shows a fundamental lack of understanding about forces and electromagnetics. There is a unique one-to-one mapping between the potentials and the fields/forces. This means that a constraint on a force is a constraint on the potentials and vice-versa.

In electodynamics, forces are not the gradient of the potentials. Electrodynamics require vector potentials, usually the magnetic vector potential, and you can not take the gradient of a vector. Depending on the gauge you chose, you may not need any scalar potentials. The force calculation may not involve any gradients at all.

In electrodynamics, forces and potentials are dependent on both velocity and acceleration of the particle. If you try to determine a force or a potential without velocity and acceleration, you'll get the wrong answer. Your suggestion that potential/velocity and force/acceleration are independent quantities is silly.



The experiment starts from rest, so there can be no experimental confusion of
velocity and acceleration effects. The confusion in the above paragraph comes from mixing the concepts of forces and potentials.


You're making my point for me. If it starts from rest, there must be acceleration. As I said before, both forces and potentials are dependent on both velocity and acceleration. You need to account for both their effects.



Yet, when pressed, this professor will be unable to name a single such experiment. By
contrast, TVF's papers list *all* eight experiments that bear on this question. And all indicate ftl propagation of forces.


All these high-tech gadjets like computers and cell phones would not work if electrodynamic forces propagated faster than light. This delay is built into their designs. So with every reply you make, you're disproving TVF's theory.

<font size=-1>[ This Message was edited by: Wiley on 2002-04-10 15:25 ]</font>

Steve Carlip
2002-Apr-10, 08:10 PM
I don't usually follow these discussions, but this one was
pointed out to me recently. I'll make a few brief points
and then disappear. (Sorry for the ``hit and run,'' but
apart from my own work, I have a new baby, and limited
time.)

1. In general relativity, it is unambiguously true that all
nonstatic gravitational effects propagate at the speed of
light. For weak fields, this is very easy to show, since small
disturbances in the geometry of spacetime obey a standard
wave equation. For strong fields it's a little bit trickier---the
gravitational field affects the path of light, so there's some
disentangling to do to compare the ``speed of gravity'' to
the speed of light. But this can be done. A nice reference is
Robert Low, ``Speed Limits in General Relativity,'' Class.
Quantum Grav. 16 (1999) 543, available electronically at
http://arXiv.org/abs/gr-qc/9812067 .

Let me stress that there is no ``interpretation'' involved here.
The question can be posed unambiguously, as Low does:
essentially, ``Given two separated regions R_1 and R_2 at
an initial time, suppose that conditions in R_2 are changed
in some arbitrary manner; how long does it take for anything
starting in R_1 to be affected by the changes?'' The answer
requires calculation, not assertion or hand-waving, and it is
unambiguous. One is, of course, free to try to invent a theory
different from general relativity in which the answer is different,
but for general relativity there's no question.

(I restrict myself to ``nonstatic gravitational effects'' because
it's operationally meaningless to speak of propagation speed
for something that is exactly static: how do you measure the
speed of no change?)

2. In ordinary Newtonian gravity, if you add a speed-of-light
propagation delays you get a result that disagrees drastically
with observation. The forces in a two-body system no longer
point toward the center of mass, and orbits become unstable.
If you want to check this, start with problem 12.4 in Lightman
et al., _Problem Book in Relativity and Gravitation_, where it is
shown that Newtonian gravity with speed-of-light propagation
would make the Earth's orbit unstable on a time scale on the
order of a hundred years.

3. This instability does not appear in general relativity, despite
speed-of-light propagation of gravity. This is not a contradiction,
since general relativity is very different from Newtonian gravity
with speed-of-light propagation stuck in. In particular, general
relativity includes additional velocity-dependent interactions,
which partially (not completely!) cancel the effects of propagation
delay. (The possibility of such cancellation was noted by Poincare
as early as 1905.)

Let me emphasize that these velocity-dependent interactions
were not add-ons put in to deal with propagation delay. They
come out of the Einstein field equations, which are determined
uniquely, with no adjustable parameters, from considerations
that have nothing to do with propagation delay. In fact, it would
be impossible to change general relativity in a way that eliminated
these velocity-dependent terms without completely discarding
both the geometrical picture and the basic symmetries of the
theory.

A very similar cancellation happens in Maxwell's electrodynamics,
where it is somewhat easier to analyze (since the equations are
much simpler). You can find a careful discussion in Volume II,
chapter 21 of the _Feynman Lectures in Physics_. For the case
of gravity, see my paper ``Aberration and the speed of gravity,''
Phys. Lett. A267 (2000) 81, available electronically at
http://arXiv.org/abs/gr-qc/9909087 .
The computation is a bit harder, but you can see the cancellation
taking place before your eyes, term by term.

4. If this cancellation between the effects of propagation delay and
velocity-dependent terms were exact, one might well argue that it
was just math, and that the propagation speed was really infinite.
But the cancellation is not exact, and this has major implications.

Consider first the simpler case of electromagnetism. Suppose a
charged particle is moving in a straight line at constant speed, and
that you are sitting one light second away. According to Maxwell's
equations, the electric field you observe will point toward the
``instantaneous'' position of the charge, not the position it was at
a second earlier. But now suppose the charge suddenly stops.
According to Maxwell's equations, for one more second the electric
field you observe will continue to point toward the ``extrapolated''
position of the charge, the place it would have been if it hadn't
stopped. Then after one second---the light propagation time from
the charge to you--- the field will suddenly swing back to the actual
position where the charge stopped.

This prediction is confirmed every day. The abrupt change in the
direction of the field in response to a charge's stopping or starting
is what we call electromagnetic radiation. Let me stress that this is
not just hand-waving or guesswork or analogy. Using the picture
I've just described, you can get exact, quantitative predictions about,
for example, the rate of radiated power and the shape of the electric
and magnetic fields of an accelerated charge. To see how to do this,
using no more than Gauss's law and speed-of-light propagation,
see Appendix B of Purcell's _Electricity and Magnetism_. For a set of
beautiful simulations of solutions of Maxwell's equations, that clearly
show the connection between propagation delay and radiation, see
R. Tsien, Amer. J. Phys. 40 (1972) 46.

Because of the weakness of the gravitational interaction, similar
observational tests are much more difficult for general relativity,
though Kopeikin has recently proposed a possible Solar System test
(Astrophys. J. 556 (2001) L1-L6, http://arXiv.org/abs/gr-qc/0105060 ).
But the relation between propagation speed and gravitational radiation
is essentially the same as in electromagnetism, and will be tested with
the next generation of gravitational radiation detectors.

There is, in fact, one test already in existence: the orbital decay of binary
pulsar systems. This is often presented as evidence for gravitational
radiation, and it certainly is. But it is also evidence for propagation
effects that are not canceled exactly by velocity-dependent terms: it
is this inexact cancellation that's responsible for the ``radiation reaction''
that leads to the decay of orbits. You can find a nice description of this
in Damour's article in the book _300 Years of Gravitation_, edited by
Hawking and Israel.

Note that the observation of radiation reaction and orbital decay is
a severe problem for theories with ``instantaneous'' propagation of
gravity. In such theories, orbits are absolutely stable, and don't decay,
period. This requires that people like Van Flandern introduce some
ad hoc description of ``gravitational radiation'' that's unrelated to
gravity, and is just stuck in to get agreement with observation. Imagine
the same thing in electromagnetism: it would require throwing out
Maxwell's deepest result, that light is just propagating electric and
magnetic fields, and ``ununifying'' electromagnetism and light.

5. Finally, a few quick comments.

[list]
The quote from Sten Odenwald's Q&A page is correct, though a
bit incomplete. It's important that he's talking about general
relativity, and not just about Newtonian gravity with propagation
delay stuck in.

Dunash wrote:

``Relativistic calculations do not contain any propagation delay
because none has ever been detected for gravitational force.''

As someone who's done these calculations, let me say that this is wrong.
Relativistic calculations certainly do include propagation delay, but
they also include (partial) cancellations from extra velocity-dependent
interactions. In some cases, the cancellations are made early in the
calculation, and someone who just looks at the final equations might
not see that this has happened. But anyone who goes back to the actual
derivations will not make this mistake.

Dunash wrote:

``The Lienard-Wiechert (note spelling) potentials (again, fully discussed
in TVF's papers) describe the potential field, not the force field. [...]
Forces are gradients of potentials. Forces and potentials are related in
certain specific ways to accelerations and velocities, respectively. Clearly,
constraints on velocities do not apply to accelerations; nor do constraints
on potentials apply to forces.''

This is a complete red herring. Potentials are convenient for solving Maxwell's
equations, but the equations can be solved directly without ever using a
potential. The result is exactly the same: the electric and magnetic fields
at a point are determined completely by the propagation-delayed positions
and velocities of charges, and not at all by their ``instantaneous'' positions
and velocities. You can find the exact solution for E and B in, for example,
section 14.1 of Jackson's [i]Classical Electrodynamics[i].

Dunash wrote:

``In the cases of gravitational and electrodynamic forces, the directions are
always instantaneous to the full accuracy of all experimental data.''

This is not at all right. I suspect that the statement comes from not thinking
carefully about what propagation-delayed forces would look like. I suggest
the appendix of Purcell's book, cited above.

[list]


<font size=-1>[ This Message was edited by: Steve Carlip on 2002-04-10 16:15 ]</font>

Dunash
2002-Apr-11, 06:45 PM
Steve Carlip [sc] writes:

> [sc]: In general relativity, it is unambiguously true that all nonstatic gravitational effects propagate at the speed of light. For weak fields, this is very easy to show, since small disturbances in the geometry of spacetime obey a standard wave equation. For strong fields it's a little bit trickier---the gravitational field affects the path of light, so
there's some disentangling to do to compare the ``speed of gravity'' to the speed of light. But this can be done.

Carlip's specialty is general relativity (GR), and as is popular these days, he tends to think of the field equations as
synonymous with GR. However, TVF's specialty, celestial mechanics, also deals with GR, yet rarely gets involved with the field equations because it is interested in physics, practical applications, and comparisons with observations. None of those can be easily reached from the field equations. Instead, one must develop equations of motion from the field equations. Equations of motion, which are expressions for the 3-space acceleration of bodies with respect to coordinate time, then allow orbit computation via gravitational forces, and comparison with data. For an example of these equations of motion in GR, see page 1095 of the classic textbook “Gravitation” by Misner, Thorne and Wheeler.

To simplify this distinction between field equations and equations of motion by an analogy, note that the word "field" is used with two distinct meanings in relativity. People with Carlip's training use it most commonly for potential fields, which is what solutions to the field equations describe. Celestial mechanicians use "field" for "force field", which is what the equations of motion describe.
Now it is true that the two concepts are related: Force is the gradient of potential. But still they are independent concepts, and
constraints (such as propagation speed limits) that apply to one do not necessarily apply to the other.


For example, potential fields relate to force fields in many of the same ways that velocity relates to acceleration. In each case, the latter is a derivative (in the calculus sense) of the former. Indeed, potential for a free body (with zero point suitable defined) is proportional to velocity squared; and force is proportional to acceleration. So the difference between the relativists’ “field” and the astronomers’ “field” is like the difference between velocity and acceleration.

As this point relates back to this discussion, we know that special relativity (SR) attributes a limit to velocity, the speed of light.
But it has no limit for acceleration, which can in principle approach infinity. The most important point to understand is that claims made about “gravitational fields”, or “gravity” for short, might be about either potential fields or force fields. So one must be clear what one is talking about, because claims applicable to one type of field will not in general apply to the other.

Carlip is speaking exclusively about potential fields. It is disingenuous of him not to state clearly that his statements do not necessarily apply (and in general do not apply) to gravitational forces. In particular, his first two sentences are dead wrong if applied to gravitational force fields. There is no “wave equation” for gravitational force fields.

[sc]: Let me stress that there is no ``interpretation'' involved here. ... One is, of course,
free to try to invent a theory different from general relativity in which the answer is
different, but for general relativity there's no question.

Carlip knows there is no issue here over the mathematics of relativity. Yet there are several issues over the physical meaning of
the equations. Why does he insist on calling different interpretations of the same equations “new theories”, except perhaps to
make interpretations that he does not favor seem less plausible by implication. However, in that sense, Einstein’s own views,
which much favored the force field interpretation of GR over the presently popular geometric interpretation, must be classed as a
different theory than the one Carlip espouses.

[sc]: it's operationally meaningless to speak of propagation speed for something that is
exactly static: how do you measure the speed of no change?)

Here again playing with words. “Static” can mean unchanging in the sense of “no moving parts”, much like a frozen waterfall. Or it
can mean unchanging in the sense of “looks the same from moment to moment”, as for a flowing waterfall. Yet in the latter, the
falls are continually regenerated; while in the former, they are not.

Gravitational force fields must be static in the latter sense because, if they were frozen into space and time in the former sense,
old gravitational fields would remain behind even as the source of gravity accelerated away. Black holes would lose all contact with
the mass that generated them behind an event horizon. And gravitational fields that had no moving parts could not transfer
momentum to a target body, as real force fields do.

However, fields that are unchanging but continually regenerated will immediately betray their propagation speeds by the direction
they appear to act from. So propagation speed for “static” fields is a well-defined concept. If one goes back to potential fields, as
Carlip does, none of this applies. But properties of potential fields are almost irrelevant for gravitational forces.


> [sc]: In ordinary Newtonian gravity, if you add a speed-of-light propagation delays you get
a result that disagrees drastically with observation.



Here we can agree. That is because Newtonian gravity is about force fields, not potential fields.

This instability does not appear in general relativity, despite speed-of-light propagation of
gravity. This is not a contradiction, since general relativity is very different from
Newtonian gravity with speed-of-light propagation stuck in.

In that GR as Steve defines it describes potential fields and Newton described force fields, yes, these are very
different. In particular, general relativity includes additional velocity-dependent interactions, which partially (not completely!)
cancel the effects of propagation delay. This is where his viewpoint starts to get very fuzzy on the physics. Van Flanderen 's
second paper contains an argument due to Dennis McCarthy that proves on physical grounds that no such “velocity-dependent
interactions” can cancel propagation delay in physical reality. Of course, it is trivial for a mathematician, oblivious to the physics,
to simply invent such terms and stick them in where needed.

[sc]: Let me emphasize that these velocity-dependent interactions were not add-ons put in to
deal with propagation delay. They come out of the Einstein field equations, which are
determined uniquely, with no adjustable parameters, from considerations that have nothing to
do with propagation delay. In fact, it would be impossible to change general relativity in a
way that eliminated these velocity-dependent terms without completely discarding both the
geometrical picture and the basic symmetries of the theory.

Carlip argues that he did not invent the “velocity-dependent terms”. But in a meaningful sense, he and other relativists did. His
precedent is an argument by Feynman applied to electrodynamics, and the assumed necessity of keeping propagation speeds at
light speed or slower. However, that is not the only way to interpret the same equations, or even the simplest way to interpret
them, despite his protests that any alternate interpretation is a “new theory”. But now that we know that Lorentzian relativity is an
experimentally viable, mathematically identical alternative to special relativity, yet lacks any physical speed limit in nature, we see
there never was a necessity to complicate the interpretation of the GR equations by arguing (as Steve does) that propagation
speeds are really as slow as light speed, but that something else (mostly) canceled the propagation delay effects so that we
cannot observe them.

The geometrical interpretation of GR and the referenced symmetries are almost certainly invalid physics, and are even in conflict
with one experimental result (the Greenberger-Overhauser experiment, Scientific American, v. 242, p. 66, May 1980). More details
are at http://metaresearch.org, “Cosmology” tab, “Gravity” sub-tab.

[sc]: The abrupt change in the direction of the field in response to a charge's stopping or
starting is what we call electromagnetic radiation.

No one denies that disturbances of electromagnetic fields are photons, and disturbances of gravitational potential fields are
“gravitational radiation”; or that these propagate at the speed of light. But these are both extremely different from changes in
electrodynamic (e.g., Coulomb) fields and in gravitational force fields, both of which are limited by all existing experiments to
propagate strongly faster-than-light. Despite the bravado of his words, Steve does not claim that the experiments say otherwise. (If
he did, he need only mention an experiment, any experiment, showing these forces to propagate as slowly as lightspeed. But no
such experiment exists.) Instead, he interprets the experiments as evidence for light-speed propagation combined with an
otherwise undetectable “velocity-dependent” force that cancels almost all evidence of propagation delay. I suggest we simply take
the evidence at face value and interpret it in the simplest consistent way.

[sc]: Note that the observation of radiation reaction and orbital decay is a severe problem for theories with ``instantaneous'' propagation of gravity. In such theories, orbits are absolutely stable, and don't decay, period. This requires that people like Van Flandern introduce some ad hoc description of ``gravitational radiation'' that's unrelated to gravity, and is just stuck in to get agreement with observation.

Nonsense. The force field viewpoint doesn’t deny the existence of potential fields. To do that would be to throw out much larger
effects than gravitational radiation – light bending, gravitational redshift, and perihelion advance among them. However, the force
field viewpoint does deny that potential fields are the cause of gravitational forces. The geometric interpretation of GR does
maintain exactly that. This is a bit like arguing that velocity is the cause of acceleration.

[sc]: Imagine the same thing in electromagnetism: it would require throwing out Maxwell's
deepest result, that light is just propagating electric and magnetic fields, and
``ununifying'' electromagnetism and light.

Although this claim is also too extreme to be valid, it is true that the nature of this “unification” has been widely misunderstood.
Many people in this discussion, for example, thought that forces in Coulomb fields were carried by real photons. However, that is a completely wrong concept. The force carriers are “virtual photons” (just a name), whose properties, as best we can describe an as-yet-undiscovered entity using experimental constraints, have nothing in common with real photons – most especially
propagation speed.

GrapesOfWrath
2002-Apr-12, 07:50 AM
On 2002-04-11 14:45, Dunash wrote:
Carlip's specialty is general relativity (GR), and as is popular these days, he tends to think of the field equations as
synonymous with GR. However, TVF's specialty, celestial mechanics, also deals with GR

Good.


Carlip knows there is no issue here over the mathematics of relativity. Yet there are several issues over the physical meaning of the equations. Why does he insist on calling different interpretations of the same equations “new theories”, except perhaps to make interpretations that he does not favor seem less plausible by implication.

I'm glad you pointed this out. I'd been under the impression that the TVF stuff was being touted as a new or different theory. I'll have to go back and read that a little more carefully.

DStahl
2002-Apr-14, 03:15 AM
I think Van Flandern's proposal can be stated pretty succinctly at this point. I'll give it a shot, anyway, although I have to include some background info that non-physicists like myself normally don't have.

[Added later: I'm not trying to speak for Van Flandern nor to put words in his mouth. I'm stating his proposal as best I understand it, and if I get it wrong I hope he speaks up! *grin*]

1. Physicists calculate the direction of the force felt by a body based on both the relative position and the movement of the attractor. In both electrodynamics and gravitation, this calculation has the effect of 'tweaking' the direction of the force felt by the test body to point at the instantaneous position of the attractor, and not its position minus the 'propagation time' for a force field assumed to be propagating at c.

In more depth: this calculation arises from the coupling of scalar fields like electromagnetism and gravity to matter. In situations where this phase-lag cancellation, as it's called, is not complete, for example when an electric charge is accelerated rather than moving inertially, then the conservation laws mandate that energy be emitted. In this case, dipolar electromagnetic radiation is released from a charge accelerating in a field. Because the equations describing gravity are of a higher order (contain more degrees of freedom) than those of electromagnetism, phase-lag cancellation works for bound systems undergoing regular, cyclic acceleration, like bodies in the Solar System. In this case the direction of gravitational attraction of the Earth by the Sun always points directly toward the instantaneous position of the Sun and not toward it's position 8 minutes in the past, as would be the case if one subtracted the transit time for a force propagating at the speed of light. However, if the Sun's motion were somehow interrupted in an irregular manner then this change in the force vector would propagate at the speed of light. And the conservation laws require that when the phase-lag cancellation is not complete the bound system must emit energy--in this case, quadrupolar gravitational radiation, or gravity waves.

2. I think Van Flandern proposes to eliminate the phase-lag cancellation calculation and simplify the coupling of the scalar fields to matter. By assuming that the forces propagate at some speed greater than 2 X 10<sup>10</sup> times c, causing the force vector to point directly at the attractor's position with virtually no delay for propagation time, this theory produces the same results as phase-lag cancellation in the Solar System. In this sense it is a return to Newtonian gravity, which assumed no propagation delay in the effect of gravitation.

Why does Van Flandern assert that in GR one assumes gravity propagates instantaneously? Because for most purposes astrophysicists can rest assured that the phase-lag cancellation will give the same results as instantaneous (ie Newtonian) propagation, and the calculation is much simpler that way. However, the full 'toolbox' of GR mandates lightspeed propagation of gravity and phase-lag cancellation--and that's why every professional physicist I've asked has said Van Flandern is wrong.

What about Van Flandern's experimental evidence, for instance his claim that during an eclipse of the Sun, the Moon is aligned with the direction of the Sun's gravitational pull on the Earth (what he terms a 'gravitational eclipse') 8 minutes before the optical eclipse, when calculations using GR and lightspeed propagation of gravity show that the 'gravitational' and optical eclipses should occur simultaneously? This is true in GR only if one adds the propagation delay and omits the phase-lag cancellation calculation. To the best of my knowledge, this is not how the calculations are done--you get your sums wrong this way. If you put in the propagation delay, you have to put in the phase-lag calculation. If you leave out the propagation delay, then you are assuming that the phase-lag cancellation will be complete enough that it will make no difference for your purposes.

When used correctly, general relativity with lightspeed gravity propagation agrees with observation to the limits of our observational accuracy.

Does Van Flandern's theory modify or contradict relativity? Well, superluminal transfer of information obviously violates special relativity, so SR would be right out the window. As to the general theory, Van Flandern writes that his proposal is a reinterpretation of the theory, not a modification of it. Frankly, I dunno: the phase-lag cancellation calculations predate general relativity and in some sense are built into its foundation. From what I understand, Poincare, writing in 1906, showed that any theory of gravitation in which the laws of physics are invariant to changes in coordinate systems must use some form of velocity-dependent correction, such as the phase-lag cancellation formulae. This, to me, seems in direct opposition to Van Flandern's proposal, since general relativity is indeed a Lorentz-invariant theory.

And finally, elimination of the phase-lag cancellation aspect of the coupling of these scalar fields with matter 'unanswers' some questions physicists had thought they had explained: why does a charge only radiate under acceleration and not when in unaccelerated motion? With phase-lag cancellation, it was clear that this had to occur to prevent violations of the conservation laws. And what about Poincare and his assertion that the velocity-dependent correction is necessary? Without phase-lag cancellation, would gravity waves still be predicted? Why? In the current physics, of course, they arise naturally as a consequence of the conservation laws plus phase-lag cancellation.

-----

Much of this material can be found in more precise and technically correct form in Steve Carlip's paper, already linked to twice in this thread. I also relied heavily on mathpages.com, from which I glean the following quote (note that what I've been calling phase cancellation they refer to in this instance as numerator dynamics):

"In view of this, we expect that a two-body system such as the Sun and the Earth, which essentially produces no gravitational radiation (according to general relativity) should have numerator dynamic effects in the gravitational field that give nearly perfect phase-lag cancellation, and therefore the Earth's gravitational acceleration should always point directly toward the Sun's position at the present instant, rather than (say) the Sun's position eight minutes ago. Of course, if something outside this two-body system (such as a passing star) were to upset the Sun's pattern of motion, the effect of such a disturbance would propagate at the speed of light. The important point to realize is that the fact that the Earth's gravitational acceleration always points directly at the Sun's present position does not imply that the "force of gravity" is transmitted instantaneously. It merely implies that there are velocity and acceleration terms in the transfer function (i.e., numerator dynamics) that effectively cancel out the phase lag in a simple periodic pattern of motion."

Reference: Lead-Lag Frequency Response (http://www.mathpages.com/home/kmath249/kmath249.htm)

I could have all this arsey-versey, and I encourage all and sundry to read through Carlip's paper and the mathpages site linked above. Also, there ought to be references to this in any sufficiently advanced physics textbook. I'm going to send a copy of this screed off to a physicist at WSU who I hope will correct anything and everything that's wrong, but I figured I'd post it here too and let you guys have at it as well.

Cheers--it's a warm and rainy April night in Oregon.

Don Stahl

[Edited for terminology and clarity. Sheesh.]

<font size=-1>[ This Message was edited by: DStahl on 2002-04-14 03:28 ]</font>

Wiley
2002-Apr-15, 09:34 PM
Again, thanks for the post, Don.

I never thought of this in terms lead and lag responses. I've always separated the velocity and acceleration terms:

A<sub>0</sub> v<sub>s</sub> + A<sub>1</sub> (d v<sub>s</sub>/dt) = B<sub>0</sub> v<sub>o</sub> + B<sub>1</sub> (d v<sub>o</sub>/dt)

which, I now know, leads to the lead-lag framework. I like how this form shows the symmetry of Maxwell's eqs. As an added pedagogical bonus, this relates well to control systems which most electrical engineers are more familar with. Thanks again.

<font size=-1>[ This Message was edited by: Wiley on 2002-04-15 17:35 ]</font>

Dunash
2002-Apr-20, 05:43 AM
> [dstahl, summarizing tvf's position]: However, if the Sun's motion were somehow
interrupted in an irregular manner then this change in the force vector would
propagate at the speed of light. And the conservation laws require that when the
phase-lag cancellation is not complete the bound system must emit energy--in this
case, quadrupolar gravitational radiation, or gravity waves.

Stahl's summary was on track up to here. TVF's position is that the
propagation speed of the forces is unconditionally much faster than light, no
exceptions and no imitations. As a thought experiment, if the Sun
disappeared, the Earth would cease accelerating toward it instantly, not after
an 8.3-minute delay. Such rapid response automatically conserves momentum
without having to manipulate the equations.

The release of gravitational radiation, if it happens, has nothing to do with gravitational force or incomplete phase-lag cancellation. In this alternative
explanation, it is due to energy loss through friction or drag through the
potential field (the "light-carrying medium", also called the "space-time
medium" in the geometric interpretation of GR).

> [ds]: this theory produces the same results as phase-lag cancellation in the Solar System. In this sense it is a return to Newtonian gravity, which assumed no
propagation delay in the effect of gravitation.

This interpretation is not a separate "theory" because nothing changes in
the math. It is just a different interpretation of GR as it already exists. In this sense, this interpretation is no more like Newtonian gravity than is GR. Both
predict all the post-Newtonian effects caused by the existence of the potential
field, such as light-bending, perihelion advance, gravitational redshift, and
gravitational radiation. TVF's position is that GR in all interpretations has
propagation delay only in the potential field (which is irrelevant for force), and
no propagation delay in the force field (the equivalent of infinite force
propagation speed).

The basis for this is simple.
(1) All experiments show zero propagation delay for forces. (His
interpretation: there is no detectable delay; their interpretation: the
propagation delay is the same as that for light, but something
unspecified cancels that delay and makes it invisible to experiments.)
(2) For all the places where the speed of light, c, shows up in the
equations, c plays a role equivalent to that of an index of refraction in
a “light-carrying medium” (or “space-time curvature” if you prefer).
This always appears in the second or higher orders of (v/c), and has
nothing to do with propagation delay, which is a simple first-order
effect in (v/c).
(3) If force propagation delay at light speed is added to the equations,
they depart rapidly and drastically from reality.

> [ds]: Why does Van Flandern assert that in GR one assumes gravity propagates
instantaneously? Because for most purposes astrophysicists can rest assured that
the phase-lag cancellation will give the same results as instantaneous (ie
Newtonian) propagation, and the calculation is much simpler that way. However,
the full 'toolbox' of GR mandates lightspeed propagation of gravity and phase-lag
cancellation--and that's why every professional physicist I've asked has said Van Flandern is wrong.

True, TVF's way is the simplest interpretation of the experiments, and there
are no observational consequences (to the accuracy of existing data) to choosing either interpretation. Reality might be that the propagation delay for gravitational force is somehow magically canceled (at least 99.999999% canceled), or that there never was a measurable delay in the first place. The physicists you have asked are either unfamiliar with the issue or don’t care to change their interpretation, but that doesn’t make the issue go away. In fact, there is no question that, if physicists had not believed for the
better part of a century that faster-than-light (ftl) propagation in forward time
was impossible, they would have adopted the ftl interpretation of gravitational
force right from the outset.

The downside of the geometric interpretation of GR (with
mathematically-canceled light-speed delays that lack any physical mechanism
for the cancellation) is that it has boxed in cosmology and quantum physics in
ways that lead to paradoxes and logical contradictions, and prevented
progress in unification of the forces. The upside of the ftl interpretation is,
with no universal speed limit, many things thought forbidden become possible.
Therefore, quite a bit is at stake in choosing which path physics should follow
into the future.

> [dt]: What about Van Flandern's experimental evidence, for instance his claim
that during an eclipse of the Sun, the Moon is aligned with the direction of the
Sun's gravitational pull on the Earth (what he terms a 'gravitational eclipse') 8
minutes before the optical eclipse, when calculations using GR and lightspeed
propagation of gravity show that the 'gravitational' and optical eclipses should
occur simultaneously?

TVF claims both interpretations of GR predict the same result: optical eclipses
occur about 40 seconds before gravitational eclipses. But that is only because,
even in the conventional interpretation, Earth somehow manages to accelerate
toward the true, instantaneous position of the Sun, a direction that Earth
observers will be unable to *see* until 8.3 minutes later. He simply tries to show
how implausible it is to invoke magical cancellations of propagation delays in a
three-body problem, as the conventional interpretation must do.

This is an example of an experiment where lightspeed propagation of
gravitational force would give a null result, and something approaching infinite
propagation speed of gravity gives a non-null (40 seconds difference) result.
For most experiments, it is the other way around, and null results can sometimes be interpreted in various ways. Not so here.

If a photon and a “graviton”
leave the Sun at the same instant, traveling the same linear path to Earth, and
if they do so at the same speed, then why does one appear to arrive from one
direction and the other from a different direction? If the speeds of travel are
different, the explanation for different directions (retarded vs. instantaneous
positions of the source) is obvious.

> [ds]: When used correctly, general relativity with lightspeed gravity propagation
agrees with observation to the limits of our observational accuracy.

GR uses the speed of light, c, only for phenomena in the potential field
(the “light-carrying medium” or “space-time curvature”), which produces small
effects such as light-bending. (This is not a propagation delay effect, but does
depend on (v/c)^2.) GR has no propagation delays for its force fields.
Whether that is because they were never there, or because something
canceled them, does not alter the fact that GR has no propagation delays in
its equations of motion. We have two proposals on the table to explain that
remarkable, undisputed fact.

> [dt]: Does Van Flandern's theory modify or contradict relativity? Well,
superluminal transfer of information obviously violates special relativity, so SR would
be right out the window.

It is true that SR would be right out the window, but the mathematically
identical Lorentzian relativity (LR) would fly right back in the same window,
leaving almost the status quo. Most physicists would never miss special
relativity because the only part of it never confirmed by experiments, frame
reciprocity, has done nothing for physics except create such pastimes as the
“twins paradox”, the “EPR paradox”, and other headaches. When LR replaces
SR, the predicted phenomena are the same, but understanding of phenomena
gets simple and in accord with “common sense” again.

> [ds]: From what I understand, Poincare, writing in 1906, showed that any theory
of gravitation in which the laws of physics are invariant to changes in coordinate
systems must use some form of velocity-dependent correction, such as the
phase-lag cancellation formulae. This seems to me to be in direct opposition to Van
Flandern's proposal, since general relativity is indeed a Lorentz-invariant theory.

However, that Lorentz-invariance ends with solutions to the field equations
(which describe potential fields). The GR equations of motion (which describe
force fields), a necessary step before GR can be compared with observations,
are equations for a 3-space acceleration with respect to a coordinate time.
Both the space and time coordinates for these equations of motion are
defined exclusively for the frame in which the center of mass is at rest. As
such, these equations are no longer Lorentz invariant. They lost that
invariance when the lightspeed delays for force field propagation were
canceled. (This happens when one chooses instantaneous rather than
retarded gradients of the potential field.) So GR’s greatest elegance, Lorentz
invariance, ultimately must be given up to secure agreement with
observations.

But that should come as no surprise. Everyone studying GR has been
taught that GR reduces to Newtonian gravity in the weak-field, low-velocity
limit. And Newtonian gravity is definitely not Lorentz invariant. How can a
theory (GR) that is Lorentz-invariant reduce to one that is not under certain
fairly typical conditions, such as exist for almost our entire solar system?

> [ds, quoting Carlip]: “The important point to realize is that the fact that the
Earth's gravitational acceleration always points directly at the Sun's present
position does not imply that the "force of gravity" is transmitted instantaneously. It
merely implies that there are velocity and acceleration terms in the transfer
function (i.e., numerator dynamics) that effectively cancel out the phase lag in a
simple periodic pattern of motion."

One can be satisfied that the right mathematical terms have been stuck
into the equations so that they conserve angular momentum and work well; or
one can ask what the physical justification for these terms might be, other
than “magic”.

[ds]: I encourage all and sundry to read through Carlip's paper and the mathpages
site linked above.

To be fully informed, they should also read Physics Letters A, v. 250, pp.
1-11 (1998) and the follow-on paper to be published this fall. For those
without a technical library handy, preprint versions of these two papers appear
at http://metaresearch.org, “Cosmology” tab, “Gravity” sub-tab.

If only Stahl can just get past the
relative safety of siding with the authority figures and let his own judgment
and common sense guide him a bit, he may come to appreciate that all
scientific controversies (both the ones that pan out and the more numerous
ones that don’t) start out this way. So taking polls of authorities is no useful
guide at all to the ultimate outcome. Only the merits of the arguments matter
in science. Have the courage to insist on answers with comparable clarity from
both sides.

When you cut through all the verbiage and smoke, this issue comes
down to this: All experiments are in agreement. TVF insists on taking the
experimental results literally. Most relativists insist that can’t be right because
that would mean ftl propagation, so they insist that nature is deceiving us in
these experiments. Demand to know what is wrong with the literal
interpretation of the experiments. Ask how a reasonable person can be
expected to decide between the two interpretations.

If that decision is to be made on the basis of a poll, then look no
further. The status quo in science will always prevail.

DStahl
2002-Apr-20, 09:20 AM
--Deleted--Sorry! Don.

<font size=-1>[ This Message was edited by: DStahl on 2002-04-21 00:01 ]</font>

DStahl
2002-Apr-20, 08:02 PM
Dunash writes: "[dstahl, summarizing tvf's position]: 'However, if the Sun's motion were somehow
interrupted in an irregular manner then this change in the force vector would
propagate at the speed of light. And the conservation laws require that when the
phase-lag cancellation is not complete the bound system must emit energy--in this
case, quadrupolar gravitational radiation, or gravity waves.'"

"Stahl's summary was on track up to here..."

Please reread the post. You will find that section 1 summarizes conventional physics, not Van Flandern's position. Section 2 summarizes Van Flandern.
-------

Dunash: " The release of gravitational radiation, if it happens, has nothing to do with gravitational force or incomplete phase-lag cancellation. In this alternative explanation, it is due to energy loss through friction or drag through the potential field (the 'light-carrying medium', also called the 'space-time medium' in the geometric interpretation of GR)."

In eliminating phase-lag cancellation Van Flandern must posit an alternative mechanism to explain the gravitational waves predicted by GR and tentatively confirmed in the decay of pulsar orbits. As far as I know Van Flandern has not provided any mathematical structure to support this mechanism. Such mathematics must duplicate the math of the phase-lag cancellation mechanism in order to salvage Van Flandern's claim that his theory is an [I]interpretation of GR. This is quite crucial: if the math is not explicitly equivalent to the mathematics of GR which predict gravity waves then his theory is not interpretational at all--it is a structural modification of GR. This brings us to:

Dunash: "This interpretation is not a separate 'theory' because nothing changes in
the math. It is just a different interpretation of GR as it already exists."

As I explained, Van Flandern is altering the equations used by physicists: he proposes eliminating the phase-lag cancellation, or retarded potential, calculations and substituting an unspecified calculation to describe the genesis of gravity waves...and, as a matter of fact, to describe the emission of electromagnetic waves by a moving charge, since the phase-lag cancellation equations lead to both phenomena. This is not trivial, nor it is interpretational. I absolutely disagree with his statement.
-------

Dunash: "TVF's position is that GR in all interpretations has propagation delay only in the potential field (which is irrelevant for force), and no propagation delay in the force field (the equivalent of infinite force propagation speed)."

As far as I can tell this is meaningless verbiage. First, it is the potential field which gives rise to the force, eh? Hence the common term, "retarded potential" (reference (http://www.astro.warwick.ac.uk/warwick/chapter4/node8.html#SECTION00170000000000000000)) which gives rise to the force vector. As to the second part, Van Flandern may assert, over and over, that GR uses no propagation delay. He's still wrong, and he remains wrong every time he asserts it. As I explained, as Carlip has explained, as is explained on Mathpages.com, and as physicists assert, GR uses lightspeed propagation and phase-lag cancellation. Van Flandern can interpret GR to include little green bunnyrabbits if he wishes, but he's still wrong.
--------

Dunash: "All experiments show zero propagation delay for forces. (His interpretation: there is no detectable delay; their interpretation: the propagation delay is the same as that for light, but something unspecified cancels that delay and makes it invisible to experiments."

That is a bit sneaky, Tom: I have not read anything indicating that phase-lag cancellation is "something unspecified" as far as physics is concerned. If I wished to resort to similarly loaded language I might say that "...the propagation delay is the same as that for light, but something that Tom Van Flandern is too dense to grasp cancels the delay." I think, from what I have read, that physicists grasp the reasons pretty darned well, and have done since the late 19<sup>th</sup> century. Don't toss out calumnies so readily.
--------

(The points concerning the order of phase-lag cancellation and the assertion that GR using lightspeed propagation plus phase-lag cancellation gives incorrect results have been refuted by Carlip. Refer to his paper. Van Flandern's counter-refutation is mathematically lacking.)
--------

Dunash: "The physicists you have asked are either unfamiliar with the issue or don’t care to change their interpretation, but that doesn’t make the issue go away."

Here's a fine kettle of fish: when the experts say you're wrong, attack their competence and honesty. Sorry, Tom, I don't believe you.

Dunash: "In fact, there is no question that, if physicists had not believed for the better part of a century that faster-than-light (ftl) propagation in forward time was impossible, they would have adopted the ftl interpretation of gravitational force right from the outset."

More utterly unfounded rhetoric: "there is no question that" pseudoscientific hacks are prone to blow the hard math, and "there is no question" that Tom Van Flandern is out to make a buck or two by making sensationalistic claims on his website. See how easy it is? Anyone can do it! "There is no question that" "my confidential sources" have uncovered a "secret conspiracy of disinformation" to hide the development of super-ftl gravity spacecraft! Come on, Tom, talk sense.
--------

Dunash: "[ds, quoting Carlip]: 'The important point to realize...'"

Read the post again. That's not from Carlip's paper.
--------

Dunash: "If only Stahl can just get past the relative safety of siding with the authority figures and let his own judgment and common sense guide him a bit..."

I resent that. First: If one wishes to understand some particularly thorny aspect of physics then one would be very well advised to seek out the opinions of experts...in other words, ask a physicist. I relied heavily on the work of the pros in trying to understand exactly what Van Flandern is proposing and why physicists ignore him. I don't view this as siding with authority. I view this as an intelligent approach to gathering information and arriving at an understanding about an issue. I think I now understand the issue well enough to have an opinion: Van Flandern's proposal is not consistent with fundamental physics theory and there is no scientific evidence which favors his theory over the conventional one.

I go to a professional dentist to have my teeth fixed. I send my son to a professional pianist to learn music. Why in the world would I not go to a professional physicist when I have a question about physics? That doesn't make sense.

Second: "...all scientific controversies (both the ones that pan out and the more numerous ones that don’t) start out this way." Van Flandern flatters himself: there is no scientific controversy surrounding his theory. Rather, as far as I have been able to tell, there is no disagreement at all in the scientific community: Van Flandern is wrong. To view his ftl gravitation as the seed of a scientific revolution seems rather optimistic...it appears that after a cursory look revealed serious errors everyone has pretty much ignored Van Flandern. I could be wrong about that, but I certainly could not find any reputable papers that were taking him seriously. Science is not a popularity contest but good science--especially solid but controversial results--draws attention very fast, for obvious reasons.

Third: "Have the courage to insist on answers with comparable clarity from both sides."

I find this immensely ironic. Van Flandern has misrepresented basic physics, slyly denigrated physicists, retreated into verbal smokescreens instead of resorting to straightforward explanation and explicit mathematics, and glossed over important points. Very well, I will insist on clear answers:

Tom! If you're out there, please respond with clarity and detail:

1. Show how the math describing gravity waves in your theory is identical to the conventional GR phase-lag cancellation equations predicting gravitational waves. If the calculations are not mathematically equivalent then admit your theory does not merely interpret GR but modifies it.

2. You assert that Steve Carlip got the math wrong in his paper. You do not, however, show the corrected formulae nor do you show mathematically how the corrected formulae would change his conclusions. Please provide this math. As it stands, I find his paper is much more coherent and persuasive than your material.

3. Show how you propose to add the velocity-dependent factors to Lorentzian relativity such that the conservation laws are not violated yet your superluminal propagation (both electrodynamic and gravitational) gives the correct results (note that this is a very deep issue, for it's through the velocity-dependent retarded-potential calculations that some fundamental symmetries and conservation laws are expressed.) Please use math and be concise.

Anyone else got questions for Tom Van Flandern? Post 'em here! I may come up with more myself.

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-04-21 01:36 ]</font>

Wiley
2002-Apr-20, 08:42 PM
I just wanted to correct some misinfo that Dunash and/or TVF is propagating.

Dunash claims that the force travels faster than the potential. This is hogwash. Earlier Dunash said the force is the gradient of the potential, and this is true for scalar potentials. With the help of elementary calculus, it's easy to show the the force and the potential propagate at the same speed.

Consider a potential propagating at the speed of light. We can write the potential as

u(R - c*t)

This is known as d'Alembert solution, and solution for a propagating wave must take this form. (Usually people use retarded time t<sub>r</sub> = t - R/c, but since they only differ by a constant, it does not matter.)

Now take the gradient of u. One obtains

grad u = r (d/dR)u(R - c*t)

where r is unit vector in radial direction. (I used the identity grad f(R) = r (df/dR).)

The derivative in the above expression can be evaluated using the chain rule.

(d/dR) u(R - c*t) = u'(R - c*t) (d/dR)(R - c*t)

which simply becomes

(d/dR) u(R - c*t) = u'(R - c*t)

Thus the force is

F = grad u = r u'(R - c*t).

We note that the force and the potential both explicitly depend on R - c*t. This means the both propagate at the value c.


<font size=-1>[ This Message was edited by: Wiley on 2002-04-20 16:47 ]</font>

Andrew
2002-Apr-20, 10:45 PM
Hey Don, don't you mean Dunash? You kept calling him Dapted, but I haven't seen Dapted post in this thread.

DStahl
2002-Apr-21, 02:29 AM
Darn! You're right, Andrew, in my fuzzy early-morning haze I misread the name. I'll go back and change the names...Thanks for the heads-up.

--Don

[Later] I deleted one of my previous posts and completely rewrote the other. Geez. I went off at a real tangent thinking I was responding to dapted rather than Dunash/TVF. What a mess. Sorry, all.

<font size=-1>[ This Message was edited by: Dstahl on 2002-04-22 04:22 ]</font>

DStahl
2002-Apr-21, 02:44 AM
I don't believe Van Flandern's claim that his theory is interpretational. It revises the basic calculations used in figuring retarded potentials in electromagnetics as well in gravitational systems. This is not trivial, as Wiley points out: in fact, it contradicts established theory at a very fundamental level indeed.

I also do not believe Van Flandern's claims to have found errors in Carlip's mathematics. Van Flandern omits crucial information that would give his claim substance: he never posts what he believes is the correct version of the equations. And he never shows, mathematically, why his version of the equations would yield conclusions opposite to Carlip's. I wish he would post some physics instead of vague accusations and tangential commentary.

--Don Stahl

DStahl
2002-Apr-22, 08:48 AM
Dunash: "Most physicists would never miss special relativity because the only part of it never confirmed by experiments, frame reciprocity, has done nothing for physics except create such pastimes as the “twins paradox”, the “EPR paradox”, and other headaches."

John Baez: "I will stick to discussing gravitation theories on this page simply because the various experimentalf verifications of special relativity are far too many for me to even attempt to explain n a single web page! The reason is very simple: all of high energy physics is predicated upon the accuracy of special relativistic kinematics, and in particular, the Standard Model of particle physics, the most successful scientific theory of all time, would utterly worthless if str were not I will stick to discussing gravitation theories on this page simply because the various experimental verifications of special relativity are far too many for me to even attempt to explain on a single web page! The reason is very simple: all of high energy physics is predicated upon the accuracy of special relativistic kinematics, and in particular, the Standard Model of particle physics, the most successful scientific theory of all time, would utterly worthless if str were not about as close to truth as science is likely to get. In a very real sense, str is confirmed tens of thousands of times every day by independent high energy physics experiments carried out in thousands of labs all over the world, so explaining the reasons why str is a good theory would be a truly Sisyphean task.. In a very real sense, str is confirmed tens of thousands of times every day by independent high energy physics experiments carried out in thousands of labs all over the world, so explaining the reasons why str is a good theory would be a truly Sisyphean task."

So, according to Baez, physicists rely on SR daily. Van Flandern is wrong. SR is a valuable tool, and is is used by physicists. Further: SR is "as close to truth as science is likely to get." Since Van Flandern's theory contradicts special relativity, and SR has never been disproven and in fact according to Baez "...is confirmed tens of thousands of times every day by independent high energy physics experiments carried out in thousands of labs all over the world..." it appears that Tom Van Flandern has taken on an exceptionally difficult task: he must disprove SR or else his superluminal gravity fails. At the moment I remain deeply skeptical that he can disprove special relativity.

--Don Stahl

Wiley
2002-Apr-23, 01:20 AM
DStahl,

I posted a link (http://www.badastronomy.com/phpBB/viewtopic.php?topic=1131&forum=2&0) to review article on the experimental foundations of GR including the speed of gravity waves. Warning: some of it's quite technical; however the introduction and conclusions are fairly accessible. Have fun.

Dunash
2002-Apr-24, 08:50 PM
DStahl (ds): In eliminating phase-lag cancellation Van Flandern must posit an alternative
mechanism to explain the gravitational waves predicted by GR and tentatively confirmed in the
decay of pulsar orbits. As far as I know Van Flandern has not provided any mathematical
structure to support this mechanism. Such mathematics must duplicate the math of the
phase-lag cancellation mechanism in order to salvage Van Flandern's claim that his theory is
an interpretation of GR. This is quite crucial: if the math is not explicitly equivalent to
the mathematics of GR which predict gravity waves then his theory is not interpretational at
all--it is a structural modification of GR.



There is no need of an alternative mechanism to explain gravitational waves. They are
disturbances of the potential field and propagate at speed c. TVF interprets the potential
field as identical to the so-called "spacetime medium", also formerly called the
"light-carrying medium". As such, he considers gravitational waves as simply
very-long-wavelength electromagnetic waves. That is, of course, an interpretation. He does
not accept that a different interpretation requires him to adopt a different mechanism and
different equations. That makes no sense. The existing framework used in GR will serve just
fine.



You suggest that the phase-lag cancellation mechanism is needed to show where
gravitational waves come from in GR. However, that is not the case. Gravitational waves are
waves of the potential field, not the force field; and can therefore be modeled as a form of
“drag”. The same is true for electromagnetic waves. This “drag” model yields the same
mathematical formulation as the “waves” model. So once again, it is simply a matter of
physical interpretation of the equations.



Indeed, isn't it conceptually easy to see that a body must experience drag as it
propagates through a medium ("potential field") around a source mass, thereby losing orbital
angular momentum? And isn't that description easier to visualize and understand than the
usual "quadrupole moment" description? And isn't it then more obvious why "gravitational
radiation" is an after-effect of gravitation rather than a component of gravitational force?
Relativity has become littered with such confusions because of the geometric interpretation
of GR.



[ds]: Van Flandern is altering the equations used by physicists: he proposes eliminating
the phase-lag cancellation, or retarded potential, calculations and substituting an
unspecified calculation to describe the genesis of gravity waves...and, as a matter of fact,
to describe the emission of electromagnetic waves by a moving charge, since the phase-lag
cancellation equations lead to both phenomena. This is not trivial, nor it is
interpretational. I absolutely disagree with his statement.



The periodicity of, e.g., an electron in a hydrogen atom is whatever it is, and that
periodicity necessarily determines the wavelength of the disturbance the electron makes in
the “potential field” medium it propagates through. Because an electromagnetic wave is just
such a disturbance by definition, it necessarily has the same frequency as the electron. This
is true whether the physical mechanism of the “disturbance” is drag through the medium, or
“preserving a Lorentz-invariant theory”. You and Carlip propose the latter, which is
unphysical. But without doubt, this choice comes down to a question of interpretation, your
“absolute disagreement” notwithstanding.



[Dunash]: "TVF's position is that GR in all interpretations has propagation delay only in
the potential field (which is irrelevant for force), and no propagation delay in the force
field (the equivalent of infinite force propagation speed)."



[ds]: As far as I can tell this is meaningless verbiage. First, it is the potential field
which gives rise to the force, eh? Hence the common term, "retarded potential" (reference)
which gives rise to the force vector. As to the second part, Van Flandern may assert, over
and over, that GR uses no propagation delay. He's still wrong, and he remains wrong every
time he asserts it. As I explained, as Carlip has explained, as is explained on
Mathpages.com, and as physicists assert, GR uses lightspeed propagation and phase-lag
cancellation. Van Flandern can interpret GR to include little green bunnyrabbits if he
wishes, but he's still wrong.



This is "meaningless verbiage" only to someone determined to cling to the existing
interpretation of GR at all costs. However, reality is that potential fields are closely
related to potential and kinetic energy, and orbital velocity squared is related to potential
through the virial theorem. Force fields, by contrast, are proportional to acceleration. And
just as velocity and acceleration are related (one is the time derivative of the other),
potential fields and force fields are related in an equivalent way. (A gradient is a type of
derivative.) No physicist would claim that limits on velocity imply limits on acceleration.
And analogously, limits on potential fields (such as propagation at the speed of light) do
not logically imply limits (e.g., a speed limit) on force fields.



"Retarded potentials" have nothing to say about gravitational forces until one takes
a gradient. A gradient has both magnitude *and direction*. The direction of the gradient can
be toward the retarded or instantaneous source mass. If forces propagate at lightspeed, the
gradient will be retarded. If forces propagate very much faster than lightspeed, the gradient
will be the near-instantaneous one. GR uses this latter choice, not the former one.



Relativists such as Carlip can say over and over that GR uses retarded gradients and
something magical then cancels the phase-lag, and that the seemingly instantaneous nature of
the resulting gradient is just an illusion of nature. But repeatedly and authoritatively
asserting that it must be so and creating the math to make it so are both a far cry from
demonstrating some physics for the magical phase-lag cancellation. Not only is there no
proposal on the table for physics behind this cancellation, but any such physics would have
to resemble a tidal force. And (using an argument suggested by D. McCarthy) nature does not
cancel tidal forces. So how can nature be smart enough to cancel one kind of phase-lag and
not the other?



Although no physics presently exists to support Carlip's belief in a "phase-canceling
force", it is important to note that, even if some physics were found, it is still
*unnecessary*. All anyone needs to understand the existing equations of GR, which work very
well, is near-instantaneous propagation of gravitational fields. That is the simplest and
most literal interpretation. The fact that this interpretation clears up many mysteries in
quantum physics and cosmology is a bonus. The only reason to cling to the traditional
interpretation is to preserve Lorentz invariance. But where is it written that nature
guarantees us a Lorentz-invariant reality? In point of fact, when Carlip’s “phase-lag
cancellation” is included, the equations are no longer Lorentz invariant. If they were, they
couldn’t reduce to Newtonian gravitation – a non-Lorentz-invariant theory – in the
weak-field, low-velocity limit.



[Dunash]: "All experiments show zero propagation delay for forces. (His interpretation:
there is no detectable delay; their interpretation: the propagation delay is the same as that
for light, but something unspecified cancels that delay and makes it invisible to
experiments."



[ds]: That is a bit sneaky: I have not read anything indicating that phase-lag cancellation
is "something unspecified" as far as physics is concerned. If I wished to resort to similarly
loaded language I might say that "...the propagation delay is the same as that for light, but
something that Tom Van Flandern is too dense to grasp cancels the delay." I think, from what
I have read, that physicists grasp the reasons pretty darned well, and have done since the
late 19th century. Don't toss out calumnies so readily.



Demand to know the physics behind the "phase-lag cancellation". While you are at it,
ask why a phase lag is needed at all. Preserving Lorentz-invariant equations is not a
physical mechanism, but a mathematical one. Tidal forces are an example of a non-conservative
force that nature does not cancel. If Carlip’s phase-lag mechanism were physical, why
wouldn't nature cancel tidal forces too?



[ds]: (The points concerning the order of phase-lag cancellation and the assertion that GR
using lightspeed propagation plus phase-lag cancellation gives incorrect results have been
refuted by Carlip. Refer to his paper. Van Flandern's counter-refutation is mathematically
lacking.)



This is an assertion without explanation. The referees who recently passed the paper
containing my comments on Carlip's paper did not agree with this assertion. I have no idea
what "mathematically lacking" means in this context because there is no mathematical point
involved in the debate. It's all in the physics.



[Dunash]: "If only Stahl can just get past the relative safety of siding with the authority
figures and let his own judgment and common sense guide him a bit..."



[ds]: I resent that. First: If one wishes to understand some particularly thorny aspect of
physics then one would be very well advised to seek out the opinions of experts...in other
words, ask a physicist.



You used the argument that, because the overwhelming majority of physicists would
vote for the traditional interpretation, that somehow makes it more likely to be correct. But
"argument from authority" is against the principles of scientific method because it is known
to be fallacious. Only the merits of the respective arguments count. So your resentment is
unwarranted. You did in fact use "argument from authority", and that is improper to do in
science.



Of course, everyone concerned will want to hear the arguments on both sides, and
*that* is a reason to consult physicists. One can never be sure of a position until one has
heard every possible rebuttal argument. But over the past eight years, I think every such
potential rebuttal argument has now been expressed and then refuted to the satisfaction of
neutral parties such as referees and editors. The result is that, since 1998, peer-reviewed
journals have been accepting papers on this subject, and that is continuing to happen. It is
still only the merits of the arguments that matter, and not how rapidly the new idea gets
around, or how many physicists support or reject it at any given moment.



[ds]: it appears that after a cursory look revealed serious errors everyone has pretty much
ignored Van Flandern.



You might benefit from more study of the history of science. When ideas are
“rebutted”, nothing has really happened until one sees the response of the proponents, who
may or may not have a good counter. Rarely can any idea ever be truly refuted because any
creative person can usually keep it alive with ad hoc patches. If the proponents of the idea
must use ad hoc patches to keep their idea viable, the idea is usually doomed. But whether
they do or not, the mainstream usually falls silent after an initial round of refutation
because it has learned that bad ideas can be polished and reincarnated forever; and that good
ideas will make the mainstream look bad if they are openly debated. So the best defense of
mainstream science is to put out "sound byte" rebuttals, then fall silent and ignore the idea
without waiting for any counter from the proponents. That saves everybody a lot of time
repeatedly putting down bad ideas, but causes the occasional worthy idea to be missed too.



Those who know this history (that good and bad ideas are treated pretty much the
same) will want to know how to tell which is which. The answer in most cases is to examine
which side had to introduce the ad hoc patches to keep his position viable. In the present
case, the replacement interpretation (ftl propagation of gravity) has needed no change or
modification since its inception. It is now the simplest interpretation of the equations of
motion of GR (the form of the equations that matches observations). By contrast, when pressed
on why the equations operate with no propagation delay for the force of gravity, Carlip
(following mainstream traditions) has had to postulate an unphysical, almost magical, ad hoc
"phase-lag cancellation" for which no observational or experimental evidence exists. It is
just a patch needed to keep the mainstream interpretation viable. So there is your clue.



[ds]: good science--especially solid but controversial results--draws attention very fast,
for obvious reasons.



Even good science that threatens to replace something already widely accepted is
resisted more-or-less in proportion to how many people have already accepted the potentially
displaced idea. Again, the history of science is filled with examples.



[ds]: 1. Show how the math describing gravity waves in your theory is identical to the
conventional GR phase-lag cancellation equations predicting gravitational waves. If the
calculations are not mathematically equivalent then admit your theory does not merely
interpret GR but modifies it.



The math is identical because gravitational waves involve the potential field (not
the force field) and propagate at the speed of light. (They are really just a form of
very-long-wavelength electromagnetic waves.) The sameness of the math was never a point in
dispute because the generating frequencies are the same, and only the postulated physical
mechanism (drag vs. preserving Lorentz invariance) is different. But these waves have nothing
to do with gravitational forces or force fields. However, people accustomed to confusing
changes in gravitational force fields with changes in gravitational potential fields
("gravitational waves") are often confused by this distinction.



[ds]: 2. You assert that Steve Carlip got the math wrong in his paper. You do not, however,
show the corrected formulae nor do you show mathematically how the corrected formulae would
change his conclusions. Please provide this math. As it stands, I find his paper is much more
coherent and persuasive than your material.



TVF never asserted that there is anything wrong with Carlip's math. What aspect of
his paper refuting Carlip's interpretation do you find unclear or unconvincing?



If you wish to see what the GR equations of motion look like with light-speed propagation
of gravity and no artificially forced phase-lag cancellation, see section 5 of “The speed of
gravity – Repeal of the speed limit”, preprint at <http://metaresearch.org>, “cosmology” tab,
“gravity” sub-tab.



[ds]: 3. Show how you propose to add the velocity-dependent factors to Lorentzian
relativity such that the conservation laws are not violated yet your superluminal propagation
(both electrodynamic and gravitational) gives the correct results (note that this is a very
deep issue, for it's through the velocity-dependent retarded-potential calculations that some
fundamental symmetries and conservation laws are expressed.) Please use math and be concise.




This betrays that you have not given equal time to studying the merits of both sides.
The Newtonian universal law of gravitation is not Lorentz-invariant. So neither are the
equations of motion of GR, which of course reduce to the Newtonian law in the weak-field,
low-velocity limit (as applies to most of the solar system beyond Mercury). Those
"fundamental symmetries and conservation laws" are still present in this "ftl propagation of
gravity" interpretation, but have a different physical interpretation. If there is any
particular one of these that you would like more details on, you need only ask. No change to
the math of GR is involved, just as SR and LR have the same math but different physical
interpretations.





[Wiley]: Dunash claims that the force travels faster than the potential. This is hogwash.
Earlier Dunash said the force is the gradient of the potential, and this is true for scalar
potentials. With the help of elementary calculus, it's easy to show the the force [F] and the
potential [u] propagate at the same speed. ... Thus the force is F = grad u = r u'(R - c*t).
We note that the force and the potential both explicitly depend on R - c*t. This means the
both propagate at the value c.



This betrays that Wiley has not read the papers supporting the position he is
criticizing. He would not have bothered with an elementary demonstration of the obvious if he
had read my discussion of "gradients". Not reading before criticizing is never a good idea.
Here is one paragraph quoted from the most recent paper (cited above):



Consider the gradient of gravitational potential, where potential is a scalar quantity. In mathematics, the gradient of
a scalar field is a unique, unambiguous thing [see sample expression at web site]. Note that the gradient of a scalar field is a
vector, not another scalar. But if the field source begins to move, does the field gradient point toward the instantaneous or
retarded position of the source? That depends on whether the field updates and regenerates instantly or with delay. So when
we say that the gravitational acceleration of a test body follows the field gradient, we must ask which gradient it will follow --
instantaneous or retarded. Physics has an issue that math does not. Retarded potentials in math allow for delays only in the
mass distribution and in changes of distance between masses in a scalar field. Retarded potentials in physics must allow also
for delays in the vector direction of the field (normally the dominant effect of retardation) which is different for the target
frame of reference than for the source frame.



Hence, Wiley’s derivation completely ignores the crucial issue – the direction of the
gradient (retarded or instantaneous). Choosing that the gradient will be instantaneous is
identical to choosing zero force propagation delay. Carlip (for example) argues for retarded
gradients (lightspeed propagation delay) combined with an add-on force (lacking physical
justification) that cancels all the propagation delay effects almost exactly. That is *not
* the solution developed by Wiley, which simply adopts the instantaneous gradient as if
there were no issue about its direction.





[ds]: I don't believe Van Flandern's claim that his theory is interpretational. It revises
the basic calculations used in figuring retarded potentials in electromagnetics as well in
gravitational systems. This is not trivial, as Wiley points out: in fact, it contradicts
established theory at a very fundamental level indeed.



Nice strawman. Can I kick it too? J



[ds]: I also do not believe Van Flandern's claims to have found errors in Carlip's
mathematics. Van Flandern omits crucial information that would give his claim substance: he
never posts what he believes is the correct version of the equations. And he never shows,
mathematically, why his version of the equations would yield conclusions opposite to
Carlip's. I wish he would post some physics instead of vague accusations and tangential
commentary.



You are developing a great collection of strawmen. Are you planning a
showcase? J





[John Baez (quoted by DS)]: "I will stick to discussing gravitation theories on this page
simply because the various experimental verifications of special relativity are far too many
for me to even attempt to explain on a single web page! The reason is very simple: all of
high energy physics is predicated upon the accuracy of special relativistic kinematics, and
in particular, the Standard Model of particle physics, the most successful scientific theory
of all time, would utterly worthless if str were not about as close to truth as science is
likely to get. In a very real sense, str is confirmed tens of thousands of times every day by
independent high energy physics experiments carried out in thousands of labs all over the
world, so explaining the reasons why str is a good theory would be a truly Sisyphean task..
In a very real sense, str is confirmed tens of thousands of times every day by independent
high energy physics experiments carried out in thousands of labs all over the world, so
explaining the reasons why str is a good theory would be a truly Sisyphean task."



Aha. An authoritative strawman. TVF has already kicked this one in his paper: “What
the Global Positioning System tells us about relativity”, in “Open Questions in Relativistic
Physics”, F. Selleri, ed., Apeiron, Montreal, pp. 81-90 (1998). Also available at
http://metaresearch.org, “cosmology” tab, “gravity” sub-tab. But he was more specific than JB. He listed all eleven
independent experiments supporting SR, pointed out that they all support LR also, and mentioned what kind of experiment
would distinguish between the two theories.



But the above sure sounds good if you don’t read anything of the opposing viewpoint, which
is what many relativists hope will happen.



[ds]: So, according to Baez, physicists rely on SR daily. Van Flandern is

wrong. SR is a valuable tool, and is is used by physicists. Further: SR

is "as close to truth as science is likely to get." Since Van Flandern's

theory contradicts special relativity, and SR has never been disproven

and in fact according to Baez "...is confirmed tens of thousands of

times every day by independent high energy physics experiments carried

out in thousands of labs all over the world..." it appears that Tom Van

Flandern has taken on an exceptionally difficult task: he must disprove

SR or else his superluminal gravity fails. At the moment I remain deeply

skeptical that he can disprove special relativity.



Here we have the reward for kicking the stuffing out of strawmen: We make illogical
but very satisfying conclusions that we don’t need to strain our brains thinking, as if there
were a real issue on the table. We can all just dismiss the dispute as more ignorant nonsense
and go back to sleep.



Fortunately for those not dozing, our falsification argument against SR and much of
the other material discussed here still stands and may be found in: “The speed of gravity –
Repeal of the speed limit”, preprint at http://metaresearch.org, “cosmology” tab, “gravity”
sub-tab.





"You can never solve a problem with the same kind of thinking that created the problem in the first place." -- Albert
Einstein

Wiley
2002-Apr-24, 09:29 PM
This betrays that Wiley has not read the papers supporting the position he is
criticizing.


No, actually it betrays you really don't know what a gradient or a retarded position is. The quanitity is R - c*t is retarded position. The derivation shows that if potential is a function retarded position then so its gradient.

I presented the simple case which happens to be directly usable for such cases as Sun-Earth system.

And for your information, I've read TVF's papers. I just think he needs to take some remedial math classes. For instance, he regularly confuses radiation and waves.

DStahl
2002-Apr-29, 07:15 AM
A few of Dunash's last points are worth answering.

Dunash: "TVF never asserted that there is anything wrong with Carlip's math."

Tom Van Flandern: "Our problems with Carlip’s equations begin with his (1.6). This is missing transverse aberration, the largest manifestation of propagation delay. That is obviously a critical error for such an early step. If one never considers genuine retardation of propagation between source mass and target body, then infinite propagation speed for gravity is being assumed, whether one says so or not."

So: Van Flandern does indeed say, quite explicitly, that Carlip's math is faulty. And just as I said, Van Flandern never, anywhere in the paper, gives what he considers to be the corrected equations; nor does he work them through to show how his versions force an opposite conclusion to Carlip's.

I don't understand why you deny that he faulted Carlip's math, when it so obvious to anyone reading the paper that he did just that. How odd that seems. I truly don't understand your motivation.

I also notice that, once again, Van Flandern has neglected to answer anything in the language of physics--ie mathematics. Unlike Carlip and Wiley, he presents no mathematical argument, though I have specifically asked him to. I'm especially interested in the equations describing the generation of gravitational waves, but so far he has not been forthcoming.

Someone signing as "J" opines that I have set up strawman arguments in asserting that Van Flandern's omission of the retarded potential equations modifies the physics of GR, and also that Van Flandern criticizes Carlip's math without showing corrected equations (see above). Please, "J", explain how my comments are false or misleading interpretations of Van Flandern. Clearly, he has argued loudly that his theory is only a "reinterpretation" of GR and does not change the math, yet he proposes to omit the retarded potential which has been used in GR (when circumstances demand it) since the inception of the theory. And, as shown above, to claim that he did not fault Carlip's math is simply a lie.

There are more strawman accusations from "J". Fine--just mudslinging as far as I'm concerned.

I would love to see some links to mathematicians or physicists who have confirmed Van Flandern's physics. So far all the links lead back to Van Flandern's own pages, which is not independent confirmation. Has there been any independent confirmation of any of Van Flandern's conjectures?

Well, I took a week off from this debate in order to spend some time in my son's middle-school math class and some other things, so I'm out of touch--I have to go back and work through your math, for instance, Wiley. It's absolutely criminal that Oregon's education budget has been cut to the point where one teacher has 35 kids and no help (except, last week, for me). In his situation the guy must choose either to teach the material to those willing to listen or else spend all his time trying to enforce a reasonable standard of behavior on those unwilling to listen--he cannot do both. Ye cats, what a dilemma. I expect I'll be working with him the rest of the year, and off-and-on in the science class as well. (Though the woman that teaches science is an absolutely brilliant, phenomonal teacher.)

--Don



<font size=-1>[ This Message was edited by: DStahl on 2002-04-29 03:21 ]</font>

2002-Apr-29, 02:04 PM
<a name="20020429.5:46"> page 20020429.5:46 aka 5:46 A.M. PST
On 2002-04-13 23:15, DStahl wrote: To: 2 CHUEN 5 UO
1: well i forget what i was going to say
2:thanks for all the lines.. {oh now i remember}
3:uploading a file I called 29am
4:-------------------------------
5:page [17]1, [18 , [19 3 0 4)
6:page [17]1, [18]2, [19]3, [20]4)
7:From: Boulder, CO
8:[INLINE] Posted: 2002-04-15 17:34
9:
10
1:OK the cruxt of that tail was
2:a while ago I was looking at this THREAD
3:and it said to me {probably no one else
4:{maybe:MAYBE} that there maybe are
5:17 posts on page one 18 posts on page two
6:and 19 posts on page 3 etc.
7:when I go to click page 4 {latest one}
8:
9:
20
1:it looked to me like there were 0 posts
2:and this made no sence whatever {at all}
3:I went back to the ???/???
4:and started over
5:by that time however there was already
6:a new post
http://www.mathpages.com/home/kmath249/kmath249.htm
8:and so the number had changed while
9:I was
30
1:actuallly trying to see what was happening
2:with the numbers changing as I looked on
3:it was clear i could not discover
4:exactly how many posts / per page
5:I thought there should be {eventually}
6:but was very happy to end up here on
7:the current Galtic Orbital #38
_38 lines set aside to do math { note this is the orbital number for sun about galixy at this time ?