Starship Asterisk*

Speed Of Gravity

Have a Look at this link

http://metaresearch.org/cosmology/speed_of_gravity.asp

Quote "Conclusion: The speed of gravity is 2x10^10 c"

That is fast


Merry Xmas

In September 2002, Sergei Kopeikin made an indirect experimental measurement of the speed of gravity, using Ed Fomalont's data from a transit of Jupiter across the line-of-sight of a bright radio source. The speed of gravity, presented in January 2003, was found to be somewhere in the range between 0.8 and 1.2 times the speed of light, which is consistent with the theoretical prediction of general relativity that the speed of gravity is exactly the same as the speed of light.

Some physicists have criticised the conclusions drawn from this experiment on the grounds that, as it was structured, the experiment was incapable of finding any results other than agreement with the speed of light. This criticism originates from the belief in the electromagetic field origin of the fundamental speed c so that, according to those physicists, the Einstein equations must depend on the physical speed of light, which explains why gravity will always propagate in that theory with the speed of light. An alternative point of view is that the Einstein equations describe the origin and evolution of the space-time curvature and gravitational waves which are conceptually independent of the electromagnetic field and, hence, the fundamental speed c in the Einstein equations cannot be interpreted as the physical speed of light despite that it must have the same numerical value as the speed of light in a vacuum if general relativity is correct. The Kopeikin-Fomalont experiment observed the bending of a quasar's light caused by the time-dependent gravitational field of Jupiter and measured the ratio c / cg. This observation shows that this ratio is unity with precision 20%.

http://en.wikipedia.org/wiki/Speed_of_gravity

Speed of gravity gets cancelled out at L4. Oh yeah, gravity is massless and can only be detected by the influence on objects that have mass, governened by Newton's laws. Are you trying to bridge Newtonian physics to quantum physics ????
Pass the ice cold one !!
Can you take a picture of the Southern Cross? My all time favorite since I grew up in the southern hemisphere and could see it often.

ta152h0 wrote:Speed of gravity gets cancelled out at L4. Oh yeah, gravity is massless and can only be detected by the influence on objects that have mass, governened by Newton's laws. Are you trying to bridge Newtonian physics to quantum physics ????
Pass the ice cold one !!
Can you take a picture of the Southern Cross? My all time favorite since I grew up in the southern hemisphere and could see it often.

Can you define "L4"?

Remember this?




Now sit back and enjoy that cold one.

The Earth-Sun L2 Point

Earth is in a stable orbit around the sun because our planet's forward motion exactly counterbalances the gravitational pull of the sun at this distance (about 93 million miles). All orbiting bodies have achieved this balance between gravitational pull and forward speed.

Since gravitational pull decreases with distance, objects farther from the sun move forward more slowly as they orbit. If the sun, earth, and a more distant spaceship all happened to be in alignment at some moment, the spaceship would soon drift behind (assuming it didn't fire its rockets), unable to keep up with the earth as they both orbited the sun.

But there is one spot - on a straight line from the sun to the earth and nearly a million miles beyond - where the sun's gravitational pull combined with that of the earth are just enough so that, to balance it and remain in orbit around the sun, a spaceship must move forward faster than it otherwise would at that distance from the sun. And with this increased speed, the spaceship just exactly keeps up with the earth as they both orbit the sun. Sun, earth, and spaceship remain aligned.


Lagrange Points L1 through L5.


This spot is called the earth-sun L2 point, the second of five "Lagrangian Points" named for Joseph-Louis Lagrange (1736-1813) who calculated their existence.

In practice, a spaceship is actually more stable orbiting around the L2 point than trying to remain at the precise point. But the effect remains the same.

Wherever earth happens to be in its annual path around the sun, an L2 spacecraft would be positioned a million miles above the night side of the planet. And with the sun and the earth at its back, a telescope aboard the spacecraft would always have a clear, uninterrupted view outward into the Universe.

More on Lagrange Points can be found at the Wilkinson Microwave Anisotropy Probe (WMAP) website.

Here is the link

http://herschel.jpl.nasa.gov/lagrange.shtml

That jogged the old memory, thanks.

From the link

http://metaresearch.org/cosmology/speed_of_gravity.asp

quote

"The same dilemma comes up in many guises: Why do photons from the Sun travel in directions that are not parallel to the direction of Earth's gravitational acceleration toward the Sun?

Why do total eclipses of the Sun by the Moon reach maximum eclipse about 40 seconds before the Sun and Moon's gravitational forces align? How do binary pulsars anticipate each other's future position, velocity, and acceleration faster than the light time between them would allow? How can black holes have gravity when nothing can get out because escape speed is greater than the speed of light?"


Has anybody got answers?

Happy New Year

Nope, no answers that are politicaly correct any way.

Norval

Don't you hate it when someone agrees with you.

One sec I was trying to be unpolitical.

Smile

Merry Xmas,,,,ooops

gone

Happy New Year

Great link Harry !!! 'The Speed of Gravity'

Here is a good kernal of the situation, and way beyond my arrival of thinking so far.

" To retain causality, we must distinguish two distinct meanings of the term "static". One meaning is unchanging in the sense of no moving parts. The other meaning is sameness from moment to moment by continual replacement of all moving parts. We can visualize this difference by thinking of a waterfall. A frozen waterfall is static In the first sense, and a flowing waterfall is static in the second sense. Both are essentially the same at every moment, yet the latter has moving parts capable of transferring momentum, and is made of entities that propagate.

As this applies to gravitational fields for a fixed source, if the field were static in the first sense, there would be no need of aberration, but also no apparent causality link between source and target. If the field were static in the second sense, then the propagation speed of the entities carrying momentum would give rise to aberration; and the observed absence of aberration demands a propagation speed far greater than lightspeed.

So are gravitational fields for a rigid, stationary source frozen, or continually regenerated? Causality seems to require the latter. If such fields are frozen, then what is the mechanism for updating them as the source moves, even linearly? Even a "rigid" bar pushed at one end would not move at the other end until a pressure wave had propagated its entire length. Moreover, we seem to need two mechanisms - one to curve space-time when a mass approaches, and another to unbend it when the mass recedes. This is because, once a curve is "frozen" into space-time, it will not necessarily "melt" back to its original condition when the cause is removed. Yet, there is no available cause for either process to result from a field with no moving parts.

We can also deduce the consequences for a source in continual acceleration, such as the Sun in our solar system. The Sun's path around the solar system barycenter induced by planetary perturbations causes excursions of over a million kilometers, and the barycenter is sometimes outside the physical body of the Sun. So the Sun's field must be continually updated at all distances to infinity. Surely, this updating requires the propagation of causal agents from the source. And since the source is continually accelerating, the regeneration of the distant field must likewise be a continuous process, requiring propagation. However, propagation involves delays, and even in the solar system, we have observationally ruled out delays as great as lightspeed propagation would produce. For example, the solar eclipse experiment is sensitive to delays in the continual updating of the Earth's field by the Sun as they both affect the Moon, and update speeds of at least 20 c are required."

20 times the speed of light to account for how the moon moves around the earth as perturbed by the sun.

A brilliant and simple method for gravity investigation.
(they did remember to subtract the speed of light in their results)

How most humbling to read this brilliant paper.

Hello All

Previuosly I posted a link showing gravity to be much faster than the speed of light.
I may have been wrong or should I say the link maybe wrong.

Have a look at this link
http://www.newscientist.com/article.ns?id=dn3232
quote:

"The speed of gravity has been measured for the first time. The landmark experiment shows that it travels at the speed of light, meaning that Einstein's general theory of relativity has passed another test with flying colours"


All these updates make me feel like.
Sometimes I wish I did not leave home.

Maybe next year a new link, who knows.

Harry,

Nice links on gravity, the first one and the second one. I was recently reading a book on Quantum Particle behavior and relativity. It discussed a thought experiment and some other goofy stuff. The basic conclusion of quantum particle behavior is that they behave the way they do because there is a mind to study their behaviour. I do not remember the exact phrase but, I have found a nearer link for you...

http://website.lineone.net/~kwelos/Quantumphenomena.htm

Hello Astroton

Thank you for the link

Hello All

Yet again update.
http://metaresearch.org/media%20and%20l ... peikin.asp

Quote:
"Contrary to Kopeikin's announced result, reference [10] shows that the speed of light is no longer a universal speed limit. Travel and communication at unlimited speeds are now possible. These take place in forward time, creating no paradoxes. (E.g., you can't go back in time and kill your own grandfather when he was still a child.) Nothing at all about the mathematical theory of relativity is altered. However, the experimental interpretation of special relativity now favors Lorentz's version over Einstein's. And the experimental interpretation of general relativity now favors the force interpretation (as preferred by Einstein, Dirac, and Feynman, among others) over the geometric interpretation ("curved space-time")."

Can someone read this link and compare it with

http://www.newscientist.com/article.ns?id=dn3232
http://metaresearch.org/cosmology/speed_of_gravity.asp

I'm up in the air,,,,,,,,,,,,can someone give me a bit of light on this.

Harry,
do the work yourself and present us with the results, like a real scientist would.

Smile,,,,,,,,,,,,,

Have you ever had a flu in the head,,,,,,,,,,,

My brain will not click over,,,,,,,,,,,,,cold start,,,,,,,,,,,,

It is unable to do any lateral thinking,,,,,,,,,,,,must be a public holiday

Until than if you wish to comment,,,,,,,,,,,,,

The question is,,,,,,,,

Is the speed of gravity equal to that of light.?

The question is:

Does this tell us anything about the speed of propagation of gravity?
The consensus among relativists is NO!

If we could measure the effects on the Shapiro delay to order (v/c)^2, then we could test the speed of gravity. But these effects would be at the thousandths of a picosecond level, hopelessly small.

The science press was surprisingly uncritical of this story. Few writers seem to have consulted with leading relativists to see if the idea made sense. Others merely reported or rehashed earlier reports. No story has appeared to date to indicate that the overwhelming opinion of the community of relativity experts is that this experiment does NOT test the speed of gravity.

Hello Martin

What is your opinion on the speed of gravity?

Is greater or equal to that of light.

------------------------------------------------------
Can gravity be slowed down?

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If gravity is greater than the speed of light can this be a means of travelling faster than the speed of light.

Argh...
I wonder if anyone on this thread can even define what (s)he means by "speed of gravity", or "speed of light", or just "speed". I doubht it, because if you guys could, there wouldn't even be such a question

here's in interesting link that may shed some light on the subject.

http://www.answers.com/topic/gravity-1

Orin

Is that a rhetorical question Makc?

makc wrote:Argh...
I wonder if anyone on this thread can even define what (s)he means by "speed of gravity", or "speed of light", or just "speed". I doubht it, because if you guys could, there wouldn't even be such a question

Well, 'speed of gravity' basically implies the rate of propagation of changes in the gravitational field.

For example, if you have two massive, gravitating bodies, and one of them changes position suddenly, how long does it take before the second body 'notices' that the first has moved to a new position, and begins feeling the gravitational force pulling it in that direction rather than the original direction? This would be the 'speed of gravity'.

Does it propagate at the same fundamental speed limit that light does? Is it faster? Does this violate causality? I'm terribly curious about this question, but unfortunately I've never gotten an explanation of how light-speed-limited gravity can work, that I was able to understand.

Hello ALL

I'm just here in spirit,,,,,,,,,,I have a head cold and flu

With all the science info someone must know the speed of gravity.

Qev wrote:Does it propagate at the same fundamental speed limit that light does? Is it faster? Does this violate causality? I'm terribly curious about this question, but unfortunately I've never gotten an explanation of how light-speed-limited gravity can work, that I was able to understand.

Yeah well one has to work to understand something, it doesn't come itself. The whole "speed of light" thing is one example. As Einstein said, the theory (SRT) was often criticized for using light motion as its basis, as if things could turn out different, would we use some other physical process. A theory predicts that any particle with no rest mass will behave just like light does, it's just an unhappy co-incidence that we have learned about light first, and so "light" part now sticks with this notion. The truth is, however, that this constant merely reflects the property of Time, unknown before 1905.

For ground-level reasoning, think how nuclear bombs proove SRT. I don't think anyone in Japan has any doubts in SRT. Then, GRT = SRT + 1 more postulate, namely that inert mass IS gravitational mass. I'm sure you would win Nobel prize, if only you could proove it otherwise And that's all to it, everything else is logical consequence, including "speed of gravity propagation". Now, what reasons, in the name of ***, you have to doubt it?? I just don't get it.