First speed of gravity measurement revealed

NewScientist.com ^ | 01/07/2003 | Ed Fomalont and Sergei Kopeikin

[Southack]

I don't know that the geometry *IS* different between electromagnetism and Gravity.

But I haven't been able to find a model as large as our Sun and Earth re: Gravity for the electromagnetism argument one way or the other.

You keep trying to put the burden of proving or disproving the analogy of Electromagnetism and Gravity on me, yet it is your argument, not mine, that they must be the same.

And you may very well be correct, but I see no reason why I should be compelled to show it one way or the other.

[aruanan]

The speed of gravity has been measured for the first time.

NOT! The low end for the speed of gravity had been determined many, many decades ago.

[sandydipper]

Einstien was not from planet Earth.

[Physicist]

But I haven't been able to find a model as large as our Sun and Earth re: Gravity for the electromagnetism argument one way or the other.

Irrelevant. Nowhere in your argument do you make any reference to any sort of length scale.

You keep trying to put the burden of proving or disproving the analogy of Electromagnetism and Gravity on me, yet it is your argument, not mine, that they must be the same.

The theoretical motivation for my saying that they are the same under Newtonian physics goes all the way back to Coulomb. I'm trying to understand your theoretical motivation for saying that they're different, if that's what you're saying.

I see no reason why I should be compelled to show it one way or the other.

Because right now your version of physics isn't hanging together. Rescue it if you can. Either gravity and E&M are analogous in your model or they are not. If not, why not?

[DannyTN]

"This is nothing new, mothers have known this for years. Watch a child the next time they spill a bowl of spaghetti...time and gravity both slow down as the bowl falls to the (usually carpeted) floor. LOL "

Time slows down for the Mother as the bowl falls. The child on the other hand experiences a dramatic speed up in time as the Mother suddenly begins to talk very fast and much louder (obviously a doppler effect).

[MHGinTN]

The gravity field of the Sun (and the entire solar system intermixed) is said to 'propagate at the rate of "c". The background in which the gravity expresses is the spacetime field.

It is believed that were the Sun to instantaneously disappear, the 'curvature' the Sun imparts to the spacetime field would take the same time to effect the Earth's inertial field as it would take to suddenly notice a darkness where the Sun had been radiating. Or would it ... would it take "x" minutes to reach the point in spacetime where light from the Sun no longer exists?

It is believed that gravitons and photons exist at a reality rate of 300,000 meters per second in a vacuum, but the spacetime field is hardly a vacuum if fields propagate using it as the medium of propagation ... is that correct?

[longshadow]

simple geometrical placemarker

[Cboldt]

-- bumpity bump --

FWIW, I'm under the impression that light is a form of electromagnetism, and that much of the discussion on this thread has indeed been in the form of comparing electromagnetic waves with gravity.

[Oberon]

Light does not bend Gravity easily.

Says who? You got any data to back up that assertion?

[Oberon]

Sadly, far too many people have trouble understanding that our whole Solar System is moving en masse in one direction even as our planets revolve around our Sun (which happens to be centered in the middle of the very System that is moving through space), and thus, they erroneously conclude that the Sun isn't really moving because people on Earth can observe that it "seems" to be always in the same place (not comprehending that it only seems that way because the Earth and the Sun are maintaining their relative positions to each other as they hurtle through space).

All motion is relative. So you say our solar system is moving, and I might agree so far as you've gone... but you haven't specified... it's moving relative to what?

[Southack]

"All motion is relative."

No, the appearance of something moving is relative.

Reality, however, cares not a whit for appearances. Either something is moving or it isn't, regardless of how it appears in your relative frame of reference.

[Oberon]

Either something is moving or it isn't, regardless of how it appears in your relative frame of reference.

All right, then. If what you say is true, then there might likely be some motionless object. Is anything in the universe motionless? Can you point to any single object and say with certainty, "This object is motionless in space. This object is stationary within the fixed, absolute frame of reference"?

And if what you say is true, and there are things that are moving and at least one thing that isn't, how can you tell which is which?

[Southack]

Who says that we *can* tell?

I'm simply pointing out that Reality cares not a whit for perception.

[Oberon]

Who says that we *can* tell?

Evidently you can, because you said so. I'm asking for your evidence. You say that there can be an object in the universe that is motionless in the absolute sense. I ask you to give me an example.

Please?

[Southack]

Would you be so kind as to show me the Post # where I said what you claimed I said? Thanks.

[Oberon]

Post 251, in which you write (and I quote):

"No, the appearance of something moving is relative.

Reality, however, cares not a whit for appearances. Either something is moving or it isn't, regardless of how it appears in your relative frame of reference."

Because you make this assertion, you also implicitly assert that you know it to be true, i.e. you can tell. I'm asking how. Please share your insight with me, by pointing out how you know that there's an absolute frame of reference. Where's the motionless object that serves as our absolute reference point?

Is merely asking sufficient, or do you require that I get down on my knees and pray?

[Oberon]

Hey Gary... I could use a little help here. Have you ever taught a pig to sing?

[Southack]

Reality, however, cares not a whit for appearances. Either something is moving or it isn't, regardless of how it appears in your relative frame of reference. - Southack

"Because you make this assertion, you also implicitly assert that you know it to be true, i.e. you can tell [that something isn't moving]." - Oberon

No, by making that assertation, I am pointing out that Reality doesn't care whether we can "tell" or not.

[cinFLA]

Except that if gravity propagated at the speed of light, the earth would long ago have ceased to orbit the sun.

Why?

[mdmathis6]

"Sadly, there are many in this forum who have absolutely no idea of the gravity of this discovery."

Yes...'tis a weighty issue indeed!