Explanation of Paradox

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by makis</i>
<br />The whole issue and debate about the speed of gravity has been founded on gross misconception by all parties involved. First, let's understand what gravity is, because nobody knows and then talk about its speed, if it has one.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Trolling is a nasty occupation. You should get up to speed by reading the peer-reviewed, published papers about the speed of gravity at this web site. They contain the latest, unrefuted words on this subject. Especially, learn the distinction between geometric GR and field GR, even though many schools now teach only the former. When you have read this material, understood it, and verified it, you may want to revise half of what you claimed. Some of the opinions you expressed would have sounded right prior to the 1998 paper, but are no longer defensible. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
<br /><blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by makis</i>
<br />The whole issue and debate about the speed of gravity has been founded on gross misconception by all parties involved. First, let's understand what gravity is, because nobody knows and then talk about its speed, if it has one.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Trolling is a nasty occupation. You should get up to speed by reading the peer-reviewed, published papers about the speed of gravity at this web site. They contain the latest, unrefuted words on this subject. Especially, learn the distinction between geometric GR and field GR, even though many schools now teach only the former. When you have read this material, understood it, and verified it, you may want to revise half of what you claimed. Some of the opinions you expressed would have sounded right prior to the 1998 paper, but are no longer defensible. -|Tom|-

<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I agree with you that trolling is a nasty occupation. Since I did not troll, I wonder whose trolling you referred to.

I give you a celebrated example of trolling:

www.metaresearch.org/cosmology/gravity/spacetime.asp

"Because this point is of some importance, we will illustrate it physically as well. Consider the geodesic (orbital) path of the Earth with respect to the Sun in Figure 1. If we choose any two points along that path (call them A and , note that a straight line between A and B (as could be represented by a taut rope) is a shorter path through space than the geodesic path. Precisely the same remarks would be true if the Earth were replaced by a photon whose path is bent with respect to space as it passes the Sun – a taut rope takes a shorter path through space than the photon does. The extra bending is most easily explained as a refraction effect in the space-time or light-carrying medium ii],[iii. This again illustrates that “curved space-time” geodesic paths do not involve any curvature of space."

HaHaHaHaHaHaHaHa. Who is trolling?

Sci.physics.relativity is waiting for you to defend your claims. HaHaHaHaHa

of course Tom is not the one that disputes GR

General Relativity: In his theory of Special Relativity, Einstein attempted to establish space and time as physical objects in their own right, making them scaleable quantities in order to conform with the observed invariance of c in reference frames moving uniformly relative to each other. In his General Relativity, he extended this concept to forces and the related accelerated coordinate systems (in particular with regard to gravitation). With his interpretation, the motion of a mass is determined by the curvature of space-time which in turn is caused by the presence of other masses. This view is inconsistent in several respects: a) it claims that a physical action can result from a 'subject' (i.e. space-time) which has no physical reality but exists only as an idealized, mathematical concept; b) although physical forces are frequently described by gradients of some potential function, this is in principle not acceptable as the fundamental form for the interaction as it implies a non-local nature (a gradient can not be defined through a point); c) there is no reason why a motion due to gravitational forces should be described by a different concept than those for electrostatic interaction for instance; however for the latter the force does not depend on the mass (whereas the resultant acceleration does), therewith invalidating the concept of space-time curvature as an objective and unique quantity for describing the motion of objects in force fields; d) Einstein claims that the alleged space-time curvature around massive objects will affect the path of light rays as well. This is an unallowed generalization as the concept was derived to describe the gravitational interaction, but electromagnetic waves are immaterial and massless physical objects. Effects that apparently confirm this prediction of General Relativity could well be explained by other mechanismsly one that disputes realitivity

this info is from the site

http://www.physicsmyths.org.uk./

Just in case anybody is interested in my topic, here are a couple of papers discussing the application of a time-symmetric approach to electrodynamics to interpretation of quantum theory:



gita.grainger.uiuc.edu/IOPText/0143-0807/3/1/011/ejv3i1p44.pdf

mist.npl.washington.edu/npl/int_rep/tiqm/TI_30.html#3.0


After having read Carlip's paper a bit more carefully, I am suspecting that the situation with general relativity is similar to the case of electrodynamics: that it is apparently possible to interpret radiation-reactive effects as arising from advanced action, but that no experiment known can distinguish between this explanation and the usual explanation where radiation resistance is considered due to the interaction of a particle with its own field.

It seemed plausible to me based on the "Speed of Gravity" paper description that the correction attributable to time-advanced effects in GR would be much more obvious than in the case of classical electromagnetics. However I think now maybe not, if I accept Carlip's contention that GR corrects the aberrational effects up to second order and the remainder (of the angular momentum) is radiated away. I am inclined to accept Carlip's argument provisionally, and I do not comprehend how TVF can take issue with Carlip's 1.6, which is merely the Lienard-Wiechert potential and is thus essentially a restatement of Maxwell's equations. It is interesting and revealing that TVF would take issue with Carlip's position even regarding electrodynamics, seems to me. This seems a very risky position. This case is far more transparent, to me at least, than the GR case and would be very straightforward to calculate directly from the L-W potentials. This even would seem a waste of time though given Carlip's persuasive observation that Lorentz invariance demands that for the linear motion case we may choose a coordinate frame where the field source is stationary. Or am I misrepresenting things? I stand by to be corrected and enlightened.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by DaveL</i>
<br />here are a couple of papers discussing the application of a time-symmetric approach to electrodynamics to interpretation of quantum theory<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">In strong reality physics, nothing real can propagate from the future into the past and have an effect. That would be a form of magic, forbidden because it violates the causality principle and is logically impossible. Don't confuse mathematical explanations for phenomena (which may aid predicting, but not understanding) with physical explanations.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">After having read Carlip's paper a bit more carefully, I am suspecting that the situation with general relativity is similar to the case of electrodynamics<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">In both cases, forces propagate strongly faster than light, as shown for electrodynamic forces by the Sherwin-Rawcliffe experiment.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">no experiment known can distinguish between this explanation and the usual explanation where radiation resistance is considered due to the interaction of a particle with its own field.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">The Sherwin-Rawcliffe experiment for electrodynamics and the binary pulsar experiment for gravity are examples of experiments that contradict your statement unless nature can predict the future position, velocity, <i>and acceleration</i> of source charges or masses. That of course would be an absurd proposition. No one has ever imagined a way for nature to anticipate a future acceleration of a source body.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">if I accept Carlip's contention that GR corrects the aberrational effects up to second order and the remainder (of the angular momentum) is radiated away.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Carlip's argument was demolished in the Foundations of Physics paper I published with Vigier, a preprint of which is the second "speed of gravity" paper at this web site. Neither Carlip nor anyone else has attempted to rehabilitate Carlip's argument.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I do not comprehend how TVF can take issue with Carlip's 1.6, which is merely the Lienard-Wiechert potential and is thus essentially a restatement of Maxwell's equations.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Then you do not clearly understand the physical difference between forces and potential fields. See my paper addressing the L-W potential at:

“Reply to comments on ‘The speed of gravity’”, Phys.Lett.A 262, 261-263 (1999).

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">This case is far more transparent, to me at least, than the GR case and would be very straightforward to calculate directly from the L-W potentials.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It is undisputed that potential field changes (electromagnetic or gravitational waves) propagate at the speed of light. But it is essential to appreciate that tells us nothing about forces or their propagation delays. For a better understanding of these issues, see the preprint of our Foundations of Physics paper at this website:

metaresearch.org/cosmology/gravity/speed_limit.asp -|Tom|-

TVF Quote: <hr noshade size="1">"In strong reality physics, nothing real can propagate from the future into the past and have an effect. That would be a form of magic, forbidden because it violates the causality principle and is logically impossible. Don't confuse mathematical explanations for phenomena (which may aid predicting, but not understanding) with physical explanations."<hr noshade size="1">

I, and many others, view the apparent absense of influence of the future on the past as an observation to be explained rather than a fundamental principle. The problem here is that essentially all of physics outside of thermodynamics and cosmology is time-symmetric. Postulating delayed action only is of course the usual approach to allow work to proceed but there is no understanding in it.

The claim for the time-advanced action as in the Wheeler-Feynman Absorber theory and sequels such as Cramer's transactional interpretation of quantum mechanics however is that causality is not violated in any measurable way in spite of the participation of advanced action. The advanced fields exactly cancel except between two interacting particles. This is undetectable directly in the same way that the exchange of a virtual particle is in quantum field theory, except for the resulting influence on the particles. In the classical theory (per the W-F 1945 paper) the desire was to eliminate the need for interaction of a particle with its own field, which had proven intractable. Cramer (in the paper I linked to) notes that the approach was less than fully successful, but the idea survives today because it allows a quantum mechanical interpretation that is fully local and resolves the EPR paradox and other difficulties with traditional interpretations such as the Born (a.k.a. the "Copenhagen") interpretation.

My view on the correspondence between physics and mathematics is certainly different than yours. My view is that physics is nothing other than mathematics, and that when experiments contradict a mathematical theory it merely means that the particular piece of mathematics under consideration as describing physical phenomena is not the right selection for the task at hand. However, I don't assert that this view is scientific in nature and obvious a priori. I recognize it as a philosophical position but to me it does not seem extreme in the least, but merely naturalism. Your view, on the other hand, if I may paraphrase, that mathematics may not <i>in principle</i> be able to describe nature seems to accede to belief in magic since it accepts that some phenomona may always be beyond explanation. There is no rational basis for such a view as the inability to explain phenomena to date does not imply an impossibility of doing so in the future.

TVF Quote: <hr noshade size="1">The Sherwin-Rawcliffe experiment for electrodynamics and the binary pulsar experiment for gravity are examples of experiments that contradict your statement unless nature can predict the future position, velocity, and acceleration of source charges or masses. That of course would be an absurd proposition. No one has ever imagined a way for nature to anticipate a future acceleration of a source body.<hr noshade size="1">

This experiment you cite is described only in an internal report which I am not inclined to hunt down. Carlip calls it unpublished and unreproduced. In any case, its simply not true that no one has ever imagined a way for nature to "anticipate a future acceleration of a source body". Most of physics, certainly classical electrodynamics, simply has this property, that the future is derivable from the past and present, and vice versa. In special and general relativity, physics is atemporal in the sense that there is no way to consistently define a unique present valid for all observers. So there is no need for nature to anticipate anything. Bodies do not have a free will to accelerate as they see fit under classical physics and whether even human beings do is an open question. However I am perfectly comfortable with the idea that free will and an atemporal world view can coexist, for reasons that would take us too far afield from the present topic.

TVF quote: <hr noshade size="1">Carlip's argument was demolished in the Foundations of Physics paper I published with Vigier, a preprint of which is the second "speed of gravity" paper at this web site. Neither Carlip nor anyone else has attempted to rehabilitate Carlip's argument.<hr noshade size="1">

I don't see that you demolished his argument, or even scathed it in the least. But I will leave that for others to judge, as perhaps you should as well. Carlip's critique of your original position was published in Phys Rev letters, in reply to their publication of your paper, was it not? Seems to me, Carlip is under no obligation to reply to your paper in prepublication. Has it been accepted for publication in Phys Rev Letters? If not, even if it is published elsewhere, I would fail to see any obligation on his part to respond, if he doesn't see fit.


TVF quote:<hr noshade size="1">Then you do not clearly understand the physical difference between forces and potential fields. See my paper addressing the L-W potential ...<hr noshade size="1">

Here I think you are just plain wrong. The L-W potentials are nice in that they are so obviously dependent on only the retarded position and velocity of the source. But out of them one can derive directly all of the forces (except for radiation resistance) and the wave equation as well. So there is really no fundamental distinction between the Coulomb and Faraday/magnetic force components in terms of the former being plausibly instantaneous within conventional Maxwellian electromagnetics. Or do you have some other electrodynamics theory in mind? I can only speak from experience in the case of electromagneitcs, but it seems reasonable to me now to accept Carlip's similar statements for the case of GR, and also it is common knowledge that Maxwell's electrodynamics can be derived (as by Kaluza) from GR, so it hardly seems surprising to me that such would be the case.

Well, its been fun and I did learn a few things through this exercise in spite of all the confusion.

Best Regards,

Dave Lush