WTF is the speed of gravity

[Ned]

Ethelred and Frogger, Perhaps we are not talking about the same article. The one I read was posted by Slowhand. The article's author is a Tom van Flander, Meta Research, Univ. of Maryland, Army Research Lab.

Here is the link.

The Speed of Gravity - What the Experiments Say

One of the very first topics discussed is that Gravity has no abberation. What the author is talking about is that light travelling from the sun to earth does have abberation due to a time delay, but that gravity does not indicating no or virtual no time delay. The experimental evidence is given in connection with a solar eclipse. There is apparently an observed time delay between the height of eclipse from an light point of view vs. from a gravity point of view.

If gravity is a propagating wave, its speed is much faster than the speed of light.

[KrazyHorse]

I know what article you're talking about. It's full of crap. As to its link with Creationist "science", I make no claims.

I have already debunked the claim that the relative stability of gravitationally-bound two-body systems is inconsistent with a speed of propagation of gravitation of c. See my above post.

[KrazyHorse]

This same argument explains the article's point 2

2. Gravity and light do not act in parallel directions

point 3

3. The solar eclipse test

and "myth" 1

1. Myth: Gravity from an accelerating source experiences light-time delay

Overall, the source displays an astonishing ignorance of GR, Newtonian gravitation, and the difference between the two.

"Myth" 2 is a load of verbose crap. He's basically saying that we haven't proved that the quadrupole moment grav. radiation (which he just spent 3 points and one "myth" in complete ignorance of!!!!!) hasn't been proved to be made of the same stuff as the force carrier for grav. This is absolutely true. So what? We've never even directly observed speed of prop. of grav. yet. Give us a chance.

Point 1 in space-time curvature doesn't mean squat. A load of semantics.

Point 2. in same section is just plain stupid. Just because Newt. grav. with infinite-speed prop.. is better approx. than Newt. grav. with c prop. doesn't mean that GR and Newt grav. with c prop can't both reduce to the same thing.

The rest of the article descends into incoherent rambling.

[KrazyHorse]

Ned, do you ever manage to discuss anything without sounding like a buffoon?

I mean, you failed to sneak security (15 Sept. 11 hijackers came through Canada ) and economics (negative interest rates ) past me.

What makes you think you'll manage to do it in physics, something I've actually received a degree in?

[Ethelred]

Originally posted by Ned
Ethelred and Frogger, Perhaps we are not talking about the same article. The one I read was posted by Slowhand. The article's author is a Tom van Flander, Meta Research, Univ. of Maryland, Army Research Lab.

Its the same thing. Take a look at the URL, its part of Lambert Dolphin's site. He has stuff on it that he didn't write as well as his own. He isn't a stupid person he just bases his thinking on the Bible and not on the physical evidence.

Here is the link.

One of the very first topics discussed is that Gravity has no abberation. What the author is talking about is that light travelling from the sun to earth does have abberation due to a time delay, but that gravity does not indicating no or virtual no time delay.

That is for the simple reason the the gravity field isn't changing to any perciptable degree. The mass of the Sun is warping space we move through the warped space. The warp isn't changing relative to us. The experiment with Jupiter is quite different. Jupiter and the warp in space that moves with it IS moving relative to the light from the quasar.

There may be more to it than that but Frogger has the math and I only have the images of models in my head to work with.

The experimental evidence is given in connection with a solar eclipse. There is apparently an observed time delay between the height of eclipse from an light point of view vs. from a gravity point of view.

If gravity is a propagating wave, its speed is much faster than the speed of light.

So how come HE is the only one claiming this. People have been looking at eclipses and testing General Relativity that way since the end of WWI. So far no one has found any indication that gravity does not propagate at the speed of light. What is likely going on is that he deliberatly avoiding the use of the Relativity equations because he doesn't like them.

I have noticed that Fundamentalists have a definate distaste for relativity. I had one arguement with an engineer that insisted that Einstein's theories HAD to conform to Newton's Laws of motion AND all the rest of Newton's physics. Despite the fact that the no one has found any errors in Einstein and the fact the Einstein's gravity makes successefull predictions that Newton's cannot. He simply refused to accept the facts of the matter. It was a purely belief based thing with him as far as I could tell. He was unable to justify his claims.

[KrazyHorse]

http://www.livingreviews.org/Articles/Volume4/2001-4will/node17.html

For those with 1337 tensor skillz

Demonstrates the beginner aspects of quadrupole formalism...

[Ethelred]

Here are some links to other articles on Lambert's site. The same site Ned was linking to.


Reports of the Death of Speed of Light Decay are Premature

http://www.ldolphin.org/bowden/centj.html

Entropy in the Old Creation

http://www.ldolphin.org/thermod.html

Has the Garden of Eden been located at last?

http://www.ldolphin.org/eden/index.html

IS CREATIONISM IN ITS PRESENT FORM
SCIENTIFICALLY DEFENSIBLE?"

http://www.ldolphin.org/genages.html

How I Approach the Book of Genesis

http://www.ldolphin.org/approach.html

Anything that Lambert can find that could possibly be construed as helping Creationism or hindering anything in science that he doesn't like either goes on the site or is linked to. In this case the article Ned posted a link to is attacking General and Special Relativity both of which help give a strong understanding that the Universe is vastly older than Lambert wishes it to be.

[Ethelred]

Originally posted by Frogger

http://www.livingreviews.org/Articles/Volume4/2001-4will/node17.html

For those with 1337 tensor skillz

Demonstrates the beginner aspects of quadrupole formalism...

Beginner? That stuff is from the Max Planc Institute. Next you will be calling the Princeton Advanced Studies Institute a place for the moderatly inteligent.

I was going to copy part of it and replace all but the most comprehensible parts with BLAH BLAH Einstein BLAH but half of it refused to even show when I pasted it into the reply box. Even Apolyton was to stunned by the equations to allow them.

Do you understand that stuff Frogger? I thought that kind of stuff was post-graduate.

I don't have a clue what tensors are except for being a part of mathematics that Einstein adapted for his use and they have "``effective'' stress-energy pseudotensor" .

PSEUDOTENSORS?

[Switch]

Originally posted by Frogger
I know what article you're talking about. It's full of crap. As to its link with Creationist "science", I make no claims.

First of all, it's science, not "science." There is nothing unscientific about creationist science, it just happens to have a book guidlines, which we believe to be infalliable. However, we both digress. This is about gravity, not religion.

I think gravitons move at the speed of light. Not that I have any degree, or any education beyond gr. 10 science and some free-time reading (Brief hist, Univ. in a nutshell, the birth of time).

Actually, I have my own theory, which I have never tested and doubt could work, and I'm pretty sure has been defeated already: time is constant, c is not. There's just something about the [very slight] time travel availavle with relativity that troubles me.....this conondrum of time is my only real setback, really......perhaps my mind is too weak for physics?

[Rogan Josh]

In all the quantum theories of gravity with which I am familiar (none of which work yet by the way), the graviton is massless, implying gravity propagates at the speed of light.

In Supergravity (the best theory of quantum gravity we have) the graviton is a consequence of local supersymmetry breaking. Whenever one breaks a (local) symmetry of the universe one creates a massless 'Goldstone boson' assiciated with the symmetry breaking.

The photon for example is the Goldstone boson associated with breaking a local U(1) symmetry (just the phase invariance of wavefunctions in Quantum Mechanics). (This is not entirely true: the photon is actually a combination of the U(1) Goldstone boson and one of the SU(2) Goldstone bosons, but I am trying to keep things simple.) Similarly breaking local supersymmetry leads to a massless Graviton.

Now there could be some other effect which gives such particles mass (like the Higgs boson does for the other SU(2) Goldstone bosons), but giving a mass to the graviton would destroy its long range nature. Since gravity is most definitely long range, the graviton had better be massless (or very very very close to massless).

Funnily enough, I have just this moment finished writing a paper which includes the most general graviton couplings to the SU(2) bosons....

[Ethelred]

Originally posted by SwitchMoO


First of all, it's science, not "science."

Its neither, its purest nonsense.

There is nothing unscientific about creationist science, it just happens to have a book guidlines, which we believe to be infalliable.

Except that your premise is false. At least if you take Bible as Creationist do anyway because it is very clear the Earth is vastly older than Creationism allows for. There is no science is Creationism except perhaps for the science of obfuscation. They are exceeding good at that.

I think gravitons move at the speed of light. Not that I have any degree, or any education beyond gr. 10 science and some free-time reading (Brief hist, Univ. in a nutshell, the birth of time).

The catch is that gravitons at the moment are purely hypothetical. If the hypothesis (pretty much any one of dozens) are correct than they really should move at the speed of light. Thats what masseless particles do.

Actually, I have my own theory, which I have never tested and doubt could work, and I'm pretty sure has been defeated already: time is constant, c is not. There's just something about the [very slight] time travel availavle with relativity that troubles me.....this conondrum of time is my only real setback, really......perhaps my mind is too weak for physics?

Time varies with speed and gravity. I know that speed has been very well tested both in accelerators and with atomic clocks in orbit and on planes. I am not sure if we have any tests for gravity effects yet.

As for C that is still open to question. Untill recently it looked completely constant. There are now some things that MAY indicate that it has changed a bit since the early universe. Then again the data could be have other causes. Like not haveing a sufficient understanding of the attributes of super nova that are giving these indications.

[Ethelred]

Originally posted by Rogan Josh

Funnily enough, I have just this moment finished writing a paper which includes the most general graviton couplings to the SU(2) bosons....

Is there any possibility of testing supersymetry in the forseable future Rogan?

[Switch]

Except that your premise is false. At least if you take Bible as Creationist do anyway because it is very clear the Earth is vastly older than Creationism allows for. There is no science is Creationism except perhaps for the science of obfuscation. They are exceeding good at that.

OK, I admit, regarding the actual event of creation, it isn't science. But then again, neither is the big-bacg theory, nor evolution.

[i]Science[/i]
[b]study of the physical world:[/b]  the study of the physical world and its manifestations, especially by using systematic observation and experiment (often used before a noun)

If you can't see it happening, it ain't science, and can actually never be proven. WE can look at the facts and derive a throey based upon them, but there is unfortunately no proof, nor will there ever be

Too bad, I'd so love to prove creation, but all I can really do is give the facts and let you decide.


Well, about the time thing, Ok, you got me there. I forgot about that test.

However, when I mentioned 'c' differing, I meant that the speed of light was as much of a constant as the speed of time (? would that be 1 sec/sec? if time accelerated, it would be 1 sec/sec/sec, or 1 sec cubed )

[Seeker]

Why are there so many links to that nut, Tom van Flandern?

Also: Why are GUTs 'necessary'? What problems do they solve?

Why can't Einsteins 'geometric' description of gravity just stay seperate? Why do we need to connect gravity to the other forces? Maybe it isn't really a 'force' in the same sense and we're really dealing with a problem of definitions?

Of course, it would (possibly) be nice if there was a good theory of 'electro-gravity' for all sci-fi enthusiasts....

[Rogan Josh]

Originally posted by Ethelred
Is there any possibility of testing supersymetry in the forseable future Rogan?

Sort of.

Supersymmetry is a required ingredient of almost all 'theories of everything' anyone has ever tried. (I say 'almost' because I can only think of one theory that doesn't need it - large extra dimensions.) You need it for string theories, supergravity theories, M-theory, etc. So I am fairly (98%) sure that it exists on some level.

One thing is sure. If supersymmetry exists, it must be broken. Exact supersymmetry predicts that all the known particles have 'superpartner' particles of the same mass. We know that this isn't true because we would have seen them. By breaking supersymmetry the masses of these particles are raised proportionaly to how 'badly' supersymmetry is broken. (Incidentaly the breaking of such symmetries is not a problem - indeed in most scenarios it is inevitable.)

If supersymmetry is very broken, then the superpartners could have masses almost at the Planck scale (ie. very very heavy). This would still allow theories like M-theory to work (because they only require the superpartners to be light compared to the Planck scale), but we would not be able to find these superpartner particle in the forseeable future, because they would take far too much energy to produce. Our current colliders would have to boost their energies by a factor of roughly roughly 10^16....

On the other hand, there are arguments of why supersymmetry should be weakly broken (or more technically 'softly' broken) called the 'hierarchy' problem. Basically, without the softly broken supersymmetry, the Higgs boson would naturaly have a mass around the Planck scale, making it so heavy that it would not interact strongly with the particles we know and love, thereby making them massless. Since everyone expects that we will find the Higgs boson, it looks likely that supersymmetry is only softly broken.

In that case, supersymmetry should be just around the corner. The superpartners should have masses which are light enough to produce them at the Large Hadron Collider, which is currently being built at CERN. Its first physics run will be in 2007. If the LHC does not see them then softly broken supersymmetry is dead.

There are also plans (though no funding yet) to build an e+e- collider in Hamburg (called TESLA) which would give precise measurements of the supersymmertic partner particle's propeties when they are found. (I was one of the authors of the Technical Design Report submitted to the German government.)