Gravity moves at speed of light

[Chris]

Gravity moves at speed of light (http://www.upi.com/view.cfm?StoryID=20030107-080949-3274r)

By Dan Falk
UPI Science News
From the Science & Technology Desk
Published 1/7/2003 9:02 PM
View printer-friendly version


SEATTLE, Jan. 7 (UPI) -- Two U.S. astronomers claimed Tuesday to have measured the speed of gravity for the first time and discovered it travels at the same speed as light.

The finding confirms what most physicists had assumed, but which until now no one had been able to measure directly, the astronomers said.

"Gravity is one of the most important forces in the universe, but it's not understood particularly well," Edward Fomalont of the National Radio Astronomical Observatory in Green Bank, W.Va., told United Press International. "Many people assumed it propagates at the speed of light. We thought, 'we can measure it, so let's measure it.'"

Fomalont, who works with NRAO in Charlottesville, Va., and colleague Sergei Kopeikin, of the University of Missouri in Columbia, presented their research at the 201st meeting of the American Astronomical Society.

They described their experiment as involving technical skill and plain luck as they carefully measured the way light from a distant quasar, or quasi-stellar object -- among the most powerful energy sources in the universe -- was deflected as it passed behind the planet Jupiter during a rare chance alignment of the two objects last September....

[DesertFox]

If Einstein's conjecture (and that of George Riemann before him) was right about geometry (the shape of space) causing what we think of as gravity, gravity doesn't move at all.

[**DONOTDELETE**]

What the hell is gravity anyway? How does it work?

[DoctorDoom]

[ QUOTE ]
What the hell is gravity anyway? How does it work?

[/ QUOTE ]
It's proof that the universe sucks. /ubbthreads/images/graemlins/biggrin.gif

Einstein, working with Reimann's multi-dimensional geometry, conceived of gravity as curved space. As a rather simplistic illustration, imagine a large elastic sheet suspended in a framework. We can call the sheet "space".

Normally, it's flat (ignoring gravitational effects for the sake of illustration).

Into the middle of space, we place a marble. Wherever it sits, it slightly dents the sheet, in effect putting a curve in space. Now, let's replace the marble with a baseball. The dent in the sheet is now deeper. If the marble were placed within the dent, it would "fall" toward the baseball as it followed the contour of the dent.

Let's exchange the baseball with a sphere of lead of the same size. Now the dent is considerably wider and deeper. The marble would "fall" toward it from a greater distance and at a faster rate due to the steeper slope of the dent. If the marble were dropped into the dent with a sideways motion, it would roll around the ball, "orbiting" it. In this imperfect example, friction would slow the marble down until it eventually came to rest against the ball.

If we placed two balls on the sheet, there would be a place between them where the curves of the dents formed a point of equilibrium, such that a marble placed there wouldn't roll toward either one. If the masses are unequal, that point will be closer toward the lighter ball. Etcetera etcetera.

In Reimann/Einstein space, the dents caused by the weights is gravitation. The more massive the weight, the deeper the dent it causes in space and the farther out it extends. The concept explains why small objects move toward much heavier ones, why orbits aound low-density planets require less speed than orbits around heavier ones at the same distance, and so on.

The illustration is imperfect in that the center of a mass' gravitational field is in the center of the mass, not at the point where the surface of the mass contacts the "sheet" of space. The image would be better if a pull on the bottom of the sheet created a dent equivalent to the effect of the mass. But, the principle of Reimann/Einstein space and gravity is demonstrated by the illustration.


Re gravity propogating at light speed, this suggests an actual physical force rather than curved space. If that's the case, there's no reasonable objection to "anti-gravity" equipment that shields or nullifies it, and UFOs become more credible.

[DesertFox]

Newton conceived of gravity as a mechanical force, meaning that for it to work, a particle would have to be exchanged between the affected bodies. The postulated particle that mediates gravity is said to be a 'graviton.'

If the graviton exists, seems to me it argues against Einstein's view of gravity as geometry since geometry wouldn't require a mediating particle to work its effect.

Another problem is that the graviton would be a quantum critter, meaning that it would have a wave aspect and a particle aspect. That would mean that gravity is actually energy and that one should be able, in principle, to "catch" gravitons and make matter of them.

But try as I will, I can't imagine gravity forming matter.

[Triller]

argh darn there goes that potential faster-than-light communication system

[DesertFox]

Not necessarily.

According to Wheeler-Feynman "absorber" theory, an electron can't emit a photon (a signal) unless there is another electron ready to absorb the photon. It finds out where such an electron is instantaneously by sending a wave backwards in time (the "advanced wave") thruout the electromagnetic web that fills the universe. Once an absorber electron is located (usually, but not always, nearby), the original electron emits its photon, the destination of which it already "knows." The photon itself (the "retarded wave") can't travel faster than light, but the advanced wave, going backwards in time, effectively travels instantaneously. Owing to that, the electron effectively emits both waves at the same time.

Seems to me this arrangement could be manipulated for faster-than-light commo.

[Timberwolf]

hoooookay....now my head's SPINNING at roughly the speed of light! LOL

[Wyatt_Junker]

If gravity moves at the speed of light, would:

...the handicapped move at the speed of the retarded?

...fat people move at the speed of the anorexic?

...black jaywalkers move at the speed of Carl Lewis(I wish)?

...poor people move at the speed of DMV workers?

...Dead Heads move at the speed of brain trauma victims?

...Michael Jackson moonwalking at the speed of Special Olympians?

...Rodney King driving at the speed of the limit?

...Ted Kennedy drinking at the speed of a jackrabbit?

...lawyers chasing ambulances at the speed of emotion?

...interns moving at the speed of a political orgasm?

...unions moving at the speed of the employee of the month?

etc. etc.

[DesertFox]

Gravity, that most familiar of the four forces, is perhaps the strangest. It's so much weaker than the other three forces that we ignore it in calculations concerning the inter-particle interactions that we're familiar with in everyday life -- chemical change, physical change, even structural change.

No one's ever had an adequate explanation for why gravity's so weak. Electromagnetism is something like 10³⁹ times as powerful, and the strong nuclear force is even greater than that.

In the theory I've been reading about, gravity is just as powerful as any of the other forces, but the huge majority of gravitons bleed off into another dimension accessible only to gravitons. Gravity seems so weak because only a tiny fraction of gravitons remain in our universe.

Weird.

[Wyatt_Junker]

We experience gravity everyday. I've got the foot calluses to prove it and my own personal bench press record that makes it fairly obvious.

But, there's also sumpin' wierd going on here. Whenever I'm around a hot chick, I can feel the sexual energy just seering in me and I swear, iffin' we were to walk somewhat close side-by-side, together, like parallel lines that sooner or later, I'd run her off the road and knock her over.

Hot chicks got gravity. I trip all over 'em, right into 'em. I always make it look real accidental and all, but now, with gravity, I've got another excuse. /ubbthreads/images/graemlins/icon16.gif