What if the Sun were charged?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by rodschmidt</i>
<br />suppose we substitute the electric force for the gravitational force. Suppose the Sun were electrically charged, and suppose we had here on Earth an oppositely charged object with which to measure the direction of the force. Which direction would the force be? Toward the Sun's instantaneous position? Or toward the Sun's retarded position?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Toward the near-instantaneous position. Coulomb force also propagates strongly FTL.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">When I took E&M, I learned that it would be toward the instantaneous position. I believe this is part of standard E&M.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, but that means the force carriers for Coulomb force (called "virtual photons") travel FTL. By naming them after photons, many students are misled into thinking it is possible for them to travel at the speed of light also. But that would violate both logic and experiment -- specifically, the Sherwin-Rawcliffe experiment. See papers on this web site and our "Gravity" CD for details.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">If this is the case, then both electrostatic attraction and gravity coincide--they both behave the same and give the same result--so why postulate a difference between their propagation speeds?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Gravitation and electrodynamics do have similar behavior. Their forces propagate at FTL speeds. And when something disturbs the associated potential fields, those waves travel at speed c in both cases.

Now contrast the behavior of the Sun's light field and its gravity field -- same source, same target, same radial path, yet a difference in arrival direction (light retarded, gravity not). How can that be unless the travel speeds are different? -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
Gravitation and electrodynamics do have similar behavior. Their forces propagate at FTL speeds. And when something disturbs the associated potential fields, those waves travel at speed c in both cases.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I'm not sure it's accurate to say that forces propagate.

Force is the derivative of energy with respect to distance. I move a little bit, the energy of my test device changes. If I can find a particular direction to move which gives me the most energy change, I call that the direction of the force.

I took a class about the diffusion equation, in which I learned that the electric field is a voltage as a function of position, and it obeys the same rules as a temperature field: the value at each time is, roughly, equal to an average of the values in the local area at a short time ago.

A wave doesn't have to remember which direction it's traveling. It travels in the way it does as a result of this continual diffusion-equation-obeying behavior of the vacuum.

The shape of the local electric field can be quite complex, depending on the surrounding boundary conditions. The direction of the E force at any point is the gradient of the field. There's no requirement that the force must point "at" whatever "generated" it.

So the force exerted on my test object is the result of an interaction between my test object and the local E field.

Viewing the E field, the vacuum and the diffusion process in this way, I find your statement that electrodynamic forces propagate at FTL speeds to be incomprehensible. It's like saying that the slope of ocean waves travels faster than the waves themselves travel. I see no basis at all for making a distinction between the propagation of the force and the propagation of the wave.

You also have studied the diffusion equation and its application to E&M, right? Do you view force the same way I do--as, essentially, the slope of the wave?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by rodschmidt</i>
<br />I'm not sure it's accurate to say that forces propagate.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">You cannot get work or energy from a motionless cause. Motion is therefore absolutely essential in all cases for forces.

This is one of the reasons Vigier and I cited to show that geometric GR is falsified (in favor of field GR): Geometry alone cannot produce a force because no motion is involved. So a target body at rest in curved space-time cannot begin moving unless a force such as gravity is already acting to push it in some particular direction.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Force is the derivative of energy with respect to distance. I move a little bit, the energy of my test device changes. If I can find a particular direction to move which gives me the most energy change, I call that the direction of the force.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No, this uses terms too loosely. Force is the time rate of change of momentum by definition. Momentum (the vector product of mass and velocity in non-relativistic mechanics) is an energy-like entity, but it is not the same as energy. And time is essential to the definition because of the motion part. Your definition is more like that of work, which again is not the same as force. It can't hurt to grab a basic physics text and refresh on these important but subtle distinctions.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I took a class about the diffusion equation, in which I learned that the electric field is a voltage as a function of position, and it obeys the same rules as a temperature field: the value at each time is, roughly, equal to an average of the values in the local area at a short time ago.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Electricity and gravity are so unalike that it is almost a hinderance to understanding gravitation, dynamics, and mechanics to have studied E&M first. Very few analogies work because of the dipole nature of E&M.

The "velocity" part of the momentum formula is related to both the motion of the force and its direction.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I find your statement that electrodynamic forces propagate at FTL speeds to be incomprehensible. It's like saying that the slope of ocean waves travels faster than the waves themselves travel.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">There is no wave aspect to force unless the cause of the force is oscillatory or modulated. A force may or may not trigger waves if it acts on a medium. But no waves or medium need be present.

In your ocean analogy, you seem to be trying to relate to the property that "force is the gradient of potential". That originally arose as a simplification of the math of gravitation. But when considering the physics, it is less helpful. As a minimum, one needs to think of gravitational force imposing a gradient (slope) on the potential medium, much the way it does on an atmosphere. It would be paradoxical to think of potential gradients causing forces. That would be like velocity causing acceleration!

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I see no basis at all for making a distinction between the propagation of the force and the propagation of the wave.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Take away the potential field and all its effects (such as light-bending, redshift, propagation delay, perihelion advance). One still has gravitational force and all its effects (basic orbital motion). There are no wave properties whatever in such a scenario. But it does emphasize the point that 3-space accelerations of target bodies do require a cause. Then read about "pushing gravity" for the simplest and most intuitive theory of that cause presently in existence. -|Tom|-

P.S. See "News and Information" forum about my travel schedule.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Geometry alone cannot produce a force.... <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No, but it can account for a force if the geometry it correctly described. Tom, I think you're putting too much emphasis on your philosophical aversion to geometry, though you do correctly dispute whether GR has got the geometry right.

By the way, Tom, it would be a big help if you could explain <u>why</u> EM and Gravity waves propagate at a different speed than the associated forces. I get how <i>Pushing Gravity</i> explains the propagation of force at gravity speed, but what is the underlying mechanism for waves at light speed?

[PhilJ] " ... it would be a big help if you could explain why EM and Gravity waves propagate at a different speed than the associated forces."

For the details you will need to read TVF's book "Dark Matter ...". There are also some good papers with additional detail in the Meta Research Bullitin. Here is the really short version.

===

There are two different physical particles responsible for the primary and secondary physical effects of gravity.
Note that neither of these particles has been directly detected yet.

LB

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">But don't try to push the ocean analogy too far. <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I think Tom pushed that analogy too far in his article " The Speed of Gravity - Repeal of the Speed Limit ". He used an anchor and buoy to illustrate the different speeds of gravity force and gravity waves. A tug on the chain instantly moves the buoy, then ripples spread slowly on the surface. Trouble is, the sea of gravitons is more like a rarified gas than a liquid. There is no surface on which ripples may propagate slower than sound waves traveling thru the liquid---unless of course we're talking about unseen dimensions beyond space-time. Do gravity waves propagate like ripples on the boundary between space-time and some fifth dimension?

Waves in a solid seem even less comparable---unless the fabric of space-time has properties comparable to a solid. Take a steel wire in tension, for example: A sudden change of tension, parallel to the wire, travels at the speed of sound in steel; a sideways pluck produces a much slower wave, whose speed depends on the wire's tension. Is the permitivity of space comparable to the tension in a wire?

Earthquakes, emit rapid P (pressure) waves parallel, and slow S (shear) waves perpendicular, to the direction of crustal movement. But a rarified gas, like the sea of CG's, cannot experience a shear force. Come to think of it, electrostatic force and magnetic force are perpendicular to one another. Could it be that magnetism is comparable to shear in the electrostatic medium? Is the elyseum a solid?

If the medium of gravity, and the elyseum, exhibit properties normally associated with solids, that calls the whole "Pushing Gravity" picture into question.

p.s.: Maybe it's a good thing Tom is traveling; that gives him 3 weeks to think up answers to the questions I'm posing, here.