| T O P I C R E V I E W |
| DaveL |
Posted - 02 Apr 2005 : 15:16:17
The paradox being, if the speed of gravity is the speed of light, how does the earth stay in orbit?
Here is my proposed solution:
Gravity travels at the speed of light, but both time advanced and time retarded forces are in action.
Its easy to draw the same diagram that shows the paradox and see that a linear combination of equal-size time-retarded and time-advanced forces exactly cancels any non-radial component of the force.
Also, the idea of time-advanced forces is considered plausible. Many people will know, Feynman and Wheeler wrote a famous paper about it, and Huw Price's book, "Time's Arrow and Archimedes' Point" is all about it and how it might account for the apparent non-locality of quantum theory.
I did a search on "time advanced" and couldn't find a match on this. I am interested if anybody else has considered this.
It seems possible to me, that the fact that the earth stays in orbit may be a first demonstration that time-advanced effects exist. Thew Wheeler-Feynman paper explained something with it too but that is not the only explanation for what they explained, of course.
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| 20 L A T E S T R E P L I E S (Newest First) |
| nonneta |
Posted - 09 Mar 2007 : 11:26:59
Your argument against Carlip is invalid, because “tidal forces” are due to the spatial variation in a gravitational field, not to temporal variations. Even a perfectly static gravitational field exerts “tidal forces”. The dynamic velocity-dependent aspect of relativistic fields (first clearly pointed out by Poincare in 1905, when he explained why Laplace’s aberration-speed argument doesn’t apply to any force consistent with Lorentzian Relativity) do not in any way contradict the existence of tidal effects.
I know of no reputable scientist, whether relativist or not, who believes that the ideas about theoretical physics you espouse are valid. I know of many who believe your ideas are invalid and irrational. |
| tvanflandern |
Posted - 09 Mar 2007 : 03:19:51
quote:
Originally posted by nonneta
TVF's appraisal is a bit skewed. I think it's fair to say that, within the scientific community, Carlip's explanation is considered to be correct, and Tom's is considered to be... well... let's just say, incorrect.
If you had said "within the relativity community", I wouldn't dispute that. The physics community at large has reacted very positively, and the rest of the scientific community even more so. The doors this opens for breakthrough progress in ohysics cannot be ignored.
And I would add that, even within the relativity community, most people just ignore the arguments and stick with the status quo. You probably cannot find a single person who has read both arguments and understands them, yet still favors Carlip's. And that apparently includes yourself. If you understand anything Vigier and I wrote, you would see that Carlip made an elementary error of logic, and that his proposed solution, a "velocity-dependent" cancellation force, is physically impossible because nature cannot distinguish an aberrational displacement of a source mass from a tidal displacement of the same source mass, and therefore cannot possibly cancel one but react to the other. -|Tom|-
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| nonneta |
Posted - 08 Mar 2007 : 22:11:58
TVF's appraisal is a bit skewed. I think it's fair to say that, within the scientific community, Carlip's explanation is considered to be correct, and Tom's is considered to be... well... let's just say, incorrect. |
| tvanflandern |
Posted - 08 Mar 2007 : 14:40:53
quote:
Originally posted by DaveL
After thinking about Carlip's response to your paper I got to thinking that even assuming everything he said about EM theory is true ...
However, it was not true. The Foundations of Physics paper Vigier and I wrote is pretty clear about why Carlip's argument is wrong, and Carlip himself has never challenged our rebuttal argument.
quote:
Tom, we do disagree on what is the significance and interpretation of these kind of seemingly paradoxical phenomena...
There is no cancellation of aberration, which tends to invalidate conclusions based on the assumption that there is such cancellation. That is the main point where we diverge. -|Tom|- |
| DaveL |
Posted - 03 Mar 2007 : 23:55:01
Tom, the paper I wrote and linked to is directly related to the discussion in this thread, and answers the questions I raised in it. I'll explain further but first I would like to respond directly to this statement by you:
tvf wrote: "The abstract makes some assertions of a possibly mathematical character with no hint of any plausible physics behind them."
The abstract is merely that and so there is only so much it can explain, but as it says that electromagnetic forces are being analyzed, I was hoping the reader would take it to mean that I am using standard tools of electromagnetism, which is indeed the case. The mathematics behind this is not terribly complicated, but it certainly is too complicated to post directly here. In any case, the point I want to get to is that I use entirely only completely standard electromagnetic theory, and arrive at what might seem quite paradoxical results. I expected you would be interested in this sort of thing.
After thinking about Carlip's response to your paper I got to thinking that even assuming everything he said about EM theory is true there were some interesting issues remaining. Supposing the propagation delay effects are canceled to first order, that could easily leave a residual effect that would be significant. Carlip in one of your online discussions I think hinted that the leftover energy might account for what is radiated. Well, I thought, if that were the case that would be pretty important because the radiation resistance force is quite mysterious as I think I cover in the thread above. A new way to understand it would be quite valuable. On the other hand, if aberrational forces could cancel radiation resistance that should be interesting as well as it might for the first time provide a non-ad hoc explanation for the stability of atomic systems.
So I analyzed the magnitude of the aberrational Coulomb force classically for the point charge hydrogen model. It turned out that the residual aberrational component after the correction as pointed out by Carlip is quite small, too small to cancel radiation resistance at typical atomic radii, although it has the proper sign to cancel. Also, adding in the time advanced action part (as proposed by Wheeler and Feynman and discussed above) does exactly cancel any non-conservatve force for a circular orbit, identically. For an elliptical orbit it is not zero everywhere but it appears to integrate to zero around the course of the orbit.
That was some substantial effort that didn't amount to anything of great import, but I found the answer to the questions I proposed here and so do feel at least duty-bound to report about it. No need for somebody else to repeat the exercise at this point. Then I went on thinking about the classical atomic model, and it occurred to me that there is another interesting force, simply another direct consequence of Maxwell's equations, due to the intrinsic magnetic moments of the electron and proton. As I show in the paper, the motion of the magnetic moments naturally leads to electric forces due to the time variation of the intrinsic magnetc fields. These forces are rather asymetrical though because the electron has a much larger intrinsic magnetic moment, and also because it is moving a lot faster. So, this force that is merely a consequence of Maxwell's theory would seem to break that old adage about for every action there is an equal and opposite reaction. I think that is worth knowing. I also think it's weird enough it could provide a basis for quantum behavior. It has Planck's constant attached to it via the spin. I have gotten the Bohr formula for the hydrogen ground state radius from it a couple of different ways. One of them is in the currently posted paper, and the other I hope to post pretty soon. I won't bother you with it though if you're uninterested.
The final wrinkle I will trouble you with is how when one takes into account propagation delay for this force due to motion of intrinsic moments, the aberrational component of it is quite large, larger than in the case of the Coulomb force. It's interesting because the Coulomb force is about a million times stronger to begin with, but the correction term Carlip points out integrates out in the case of the other, so that the aberrational force is enough to cancel radiation resistance. It has a different range dependency, though, so it doesn't happen at just any distance. Rather, as I show in the paper, it happens in the classical hydrogen atom at 9/16 times the Bohr ground-state radius. So, the radiative decay of the classical atom that is mentioned in so many physics textbooks simply doesn't happen according to Maxwell's elecftrodynamics. It stops at about the typical atomic dimension. Also, this newly-recognized (so far as I know, and I have now done quite a bit of searching through the APS online archives back to the 1800s) aberrational force does not cancel out when the time-advanced action is included.
Tom, we do disagree on what is the significance and interpretation of these kind of seemingly paradoxical phenomena, but in any case I believe you deserve great credit for raising the issues. |
| tvanflandern |
Posted - 07 Jan 2007 : 16:54:34
An anonymous message pointed out that I did not provide links to the subjects in Meta Science I mentioned in the last message. These discussions will be found in this "Gravity & Relativity" forum and in the "Meta Science" forum. By default, subscribers see only topics active in the last 30 days in each forum. The older topics and messages are still there -- you just need to open your message "horizon" to see them:
Click on the forum name (e.g., "Gravity & Relativity"). On the right side of the page just above the topic headers is the drop-down option box for your topic horizon for that forum. Choose an older horizon to see more older topics and older history of discussions.
The published articles are in the book "Pushing Gravity", in our Meta Research Bulletin, and on our "Gravity" CD. More of these will become available on the web site in the future. But for most MRB articles, there is a 2-year horizon before they can appear on the web site. -|Tom|- |
| tvanflandern |
Posted - 01 Jan 2007 : 03:44:35
quote:
Originally posted by DaveL
I have written up some of my work related to this topic, and posted it for public viewing. Please check it out and sign the guestbook.
We discourage the use of this web site for advertising of any sort, including advertising other web sites. I do understand why you did it in this instance. But this is a discussion board, not a place to publish papers or even abstracts. To generate discussion here, what you should do is post a self-contained summary of the physics with comparison of the pros and cons versus the Meta Science way of explaining the same phenomena. Then just provide the link as a reference for anyone who might want to see equations or technical depth.
As it stands, your abstract does not provide a good basis for a discussion. And people are unlikely to be lured to your site without some reason to get interested in it. The abstract makes some assertions of a possibly mathematical character with no hint of any plausible physics behind them. In particular, since this is the Meta Research Message Board, what physics do you propose to go up against the FTL propagation of gravitons producing density changes in elysium that is the model for both gravitation and electrodynamics put forward by Meta Science and discussed often here in other topics? What advantages does your physics offer? What defect in Meta Science does it overcome? -|Tom|-
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| DaveL |
Posted - 30 Dec 2006 : 21:16:57
I have written up some of my work related to this topic, and posted it for public viewing. Please check it out and sign the guestbook.
http://home.comcast.net/~d.lush/dave_30DecY6.htm
Title: Aberration and the Stability of the Classical Atom
Abstract:
An analysis of electromagnetic forces present in a bound
Hydrogen atom is presented, including forces due to the orbital motion
of intrinsic magnetic moments, and accounting for propagation delay
between the atomic constituents. Orbital motion of the
electron intrinsic magnetic moment is shown to result in a radial force
on the proton that is not directly balanced by a similar force on the
electron. It is argued that this unbalanced force may give
rise to oscillatory motions that plausibly may account
for the apparent wave nature of the electron.
Propagation delay of this force results in an aberrational force capable of negating
the radiation resistance force expected from energy
and momentum conservation principles. |
| Larry Burford |
Posted - 01 Jun 2005 : 13:28:34
Dave,
While I agree with TVF that the gravitational force case has fewer complications than the electrical force case, it is not without its own complications. In this particular discussion one of those complications is that you have stated that you are more familiar with electricity than with gravity.
Another complication is that most schools today teach that gravitational force is not a real force, and does not propagate. If nothing propagates there can be no aberration.
===
Assuming that you agree that electrical force is a real force, and that it does propagate with some finite speed, I'd like to see if we can work out the aberration issue using electrical force. Are you interested in trying?
LB
|
| tvanflandern |
Posted - 30 May 2005 : 19:04:05
quote:
Originally posted by DaveL
quote:
[TVF]: The case I commented on was the fixed-source, static-field, moving-target case. That is where a non-zero aberration inevitably occurs; i.e., the force cannot be central.
If the source is fixed then there is clearly no problem with aberration of the force. The sun would be in the same place now as it was 8 minutes ago, so there is no non-central force component. (That's not to say there isn't still aberration of the light.)
There is indeed aberration because of Earth's transverse motion (v) combined with the propagation speed of sunlight (c). Specifically, the angle of aberration in radians is v/c. By exact analogy, any force propagating from the Sun at speed V suffers the same kind of aberration for the same physical reason, by the angle v/V. The only possible way that such a force can remain central is if V = infinity.
To see this in action, see animation 4) at http://metaresearch.org/media%20and%20links/animations/animations.asp along with its caption. It is physically impossible to have zero aberration when the target body has a transverse motion relative to the source. The zero aberration case would be the logical equivalent of firing a bullet at the spot where a flying target is now instead of where it will be when the bullet gets there. One can expect no bull’s eyes that way.
quote:
What is in question here is the origin of the force which is q*(E + v X B)
Why complicate matters that way? Let's get the basics down first with the much simpler gravitational case, where forces are monopole and unidirectional. Then with aberration firmly established and understood, we can apply it to bidirectional forces such as electricity and/or orthogonal forces such as magnetism. We have to understand the one-mass (monopole) case before we can understand the two-charge (dipole) case.
quote:
If you want to separate out the coloumb part of the E-field and call that the force component, that's not unreasonable, but it is also obviously a function only of the past position of the source.
I agree that the force applied to a target is a function of the distance and direction of the source relative to the target at the moment the force propagation commences, and of the propagation speed of that force.
quote:
If you want to give this force a different speed than the Faraday part of the E-field, that is, the part that comes from the time derivative of the vector potential, you would have to modify the L-W formulas so that the scalar potential part is delayed not by c but by some number much greater than c.
Your meaning here was lost on me. First, did you mean a lesser delay caused by a greater speed than c? Your words seemed to say the opposite. Second, could you unlink the propagation speeds of forces from the propagation speeds of changes in potentials, which are physically unrelated quantities, and make your statement again? For example, the propagation speeds of gravitational and electrodynamic forces are experimentally constrained to be >> c, whereas the propagation speeds of changes in gravitational potential (gravitational waves) and electromagnetic potential (light) are all undisputedly c. The L-W potentials are all about retarded *potentials*, and say nothing (directly) about forces or their propagation speeds.quote:
So seems to me your position is inconsistent with Maxwell's electrodynamics. … An alternative theory might be possible …
There is a big difference between having an alternative theory, and having a different physical interpretation of the same equations. I have been discussing the latter. -|Tom|-
[I'm on travel most of June, but will follow up as needed when I can.] |
| Thomas |
Posted - 23 May 2005 : 09:48:48
Apart from the excerpt from my site that north posted above, I have shown on my page http://www.physicsmyths.org.uk/retard.htm that the assumption of a retarded static interaction force is generally inconsistent as the force would be different in reference frames moving uniformly relatively to each other, i.e. the 'speed' of gravity as well as of the electrostatic force must be infinite. This does of course not speak against the speed of light being the propagation speed of electromagnetic waves as the latter are not associated with the static interaction between two particles.
---------
http://www.physicsmyths.org.uk
http://www.plasmaphysics.org.uk |
| DaveL |
Posted - 22 May 2005 : 23:51:35
TVF wrote:
The case I commented on was the fixed-source, static-field, moving-target case. That is where a non-zero aberration inevitably occurs; i.e., the force cannot be central. ...
If the source is fixed then there is clearly no problem with aberration of the force. The sun would be in the same place now as it was 8 minutes ago, so there is no non-central force component. (That's not to say there isn't still aberration of the light.)
So, we don't have an issue unless both the sun and earth are orbiting around their common center of mass.
Yes, I am aware that F = d/dt(3-momentum) but that is not particularly pertinent as its the effect of the force. What is in question here is the origin of the force which is q*(E + v X B), where E and B may be obtained from the L-w (retarded) potential, if you believe Maxwell's electrodynamics. If you want to separate out the coloumb part of the E-field and call that the force component that's not unreasonable but it is also obviously a function only of the past position of the source. If you want to give this force a different speed than the Faraday part of the E-field, that is, the part that comes from the time derivative of the vector potential, you would have to modify the L-W formulas so that the scalar potential part is delayed not by c but by some number much greater than c. Now, I haven't tried this but I am pretty confident it won't lead to a consistent set of equations. If it was that easy I would have done it long ago, if I were you.
So seems to me your position is inconsistent with Maxwell's electrodynamics. I don't think that's a tenable position, given the degree to which this theory has been confirmed. An alternative theory might be possible, but this theory would be very strongly constrained to correspond to Maxwell's theory under so many circumstances, it too could not have a different propagation speed for the different components of its electric field, I would be willing to bet.
|
| tvanflandern |
Posted - 16 May 2005 : 02:00:32
quote:
Originally posted by DaveL
The L-W potentials are certainly not static, for a moving source...
The case I commented on was the fixed-source, static-field, moving-target case. That is where a non-zero aberration inevitably occurs; i.e., the force cannot be central. The best we can do is to reduce aberration below the threshold of detection by a fast force propagation speed. (Remember, force is defined as the time rate of change of 3-space momentum.)
quote:
It seems to me that you are arguing that Maxwell's electrodynamics is incorrect on its face.
Let's not go there because it sheds no new light on the situation. For both GR and electrodynamics, the situation is similar: Potential fields are either static, or change in waves propagating at speed c. But potential waves have no impact on forces because the potential field does not cause force. (Curvature or gradients cannot initiate motion in the absence of a force.)
Meanwhile, gravitational (and electrodynamic) force propagates at strongly FTL speeds, as is experimentally demonstrated in half-a-dozen experiments. And those forces induce gradients on the potential fields near masses, e.g., as described in Pushing Gravity.
quote:
If you can make everything drop into place, then you must a have a quantitative theory or a modified form for Maxwell's equation where there are different propagation rates for these different force components? Please direct me to where this is published so that I might examine it.
There is no modification to the math, but there is a major difference in the physical interpretation, especially in what is cause and what is effect. These ideas are developed in several papers, some of which are in the gravity section on this web site, some in the PG book, and all are on our new "Gravity" CD.
But these are not replacements for GR or Maxwell (although differences do exist beyond the first order in potential). They are mainly an improved physical understanding of the original math.
quote:
I don't see how there is any other way to evaluate the force on a particle with the L-W potential than by determining the field quantities at the location of the particle at the time the particle is at that location.
This presumes that potential gradients are the cause of force. That cannot be true without producing causality violations. Rather, force is the cause of potential gradients. -|Tom|-
|
| DaveL |
Posted - 15 May 2005 : 21:04:00
TVF wrote
And right there is a statement of the crux of the matter. It has been wrongly assumed that forces can be derived from static potential gradients for most of the last century. But that is true only for the case of fixed field points. For a charge or mass moving through a field, there is an aberration that can be reduced to zero (as experiments demand) if and only if the force propagates strongly FTL. Once that point is understood, everything else drops into place. -|Tom|-
I'm not sure how literally you mean that first sentence. The L-W potentials are certainly not static, for a moving source, and there is more than just a gradient involved in their application, as a "curl" operation is also required.
It seems to me that you are arguing that Maxwell's electrodynamics is incorrect on its face. Would you agree with this? I don't see how you can have it both ways, that the Coulomb force propagates much FTL while the Faraday and Magnetic forces propagate with c. There is no such freedom to separate these within Maxwell's theory, even I can see in this case. This is not different either if one adopts a "Lorentzian Relativity" point of view, either, I don't believe.
If you can make everything drop into place, then you must a have a quantitative theory or a modified form for Maxwell's equation where there are different propagation rates for these different force components? Please direct me to where this is published so that I might examine it.
Also, I don't see how there is any other way to evaluate the force on a particle with the L-W potential than by determining the field quantities at the location of the particle at the time the particle is at that location. The Lorentz force then accounts for the speed of the particle itself in traversing the field. Or have you an alternative approach here?
|
| tvanflandern |
Posted - 09 May 2005 : 11:57:56
quote:
Originally posted by DaveL
quote:
[tvf]: Don't confuse mathematical explanations for phenomena (which may aid predicting, but not understanding) with physical explanations."
I, and many others, view the apparent absence 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.
We must have different definitions of “understanding”. Here’s the one I used: “the ability to perceive and explain the meaning or the nature of something”. In ordinary parlance, “nature” means its physical nature, not its mathematical nature. So signals from the future may aid predicting, but cannot possibly assist in understanding, as I said above with my definitions in mind.
And in my experience, that time-symmetry you reference is illusory. Both the entropy of electrodynamic systems and the stability of gravitational systems are unidirectional in time.
quote:
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.
Now that we know that nothing in physics constrains phenomena to lightspeed, there is no longer any need to jump through these estranged logical hoops. Non-locality is simply FTL action in forward time.
quote:
Your view … that mathematics may not in principle be able to describe nature seems to accede to belief in magic since it accepts that some phenomena 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.
My view was not understood. It is true that some phenomena may always be beyond explanation. That is necessarily true in an infinite universe, especially one infinite in scale. However, while continuing to maintain that position, I also agree with your statement that purports to argue against it: “The inability to explain phenomena to date does not imply an impossibility of doing so in the future.” In an infinite universe, there will be an unlimited supply of examples of both things that will be explained in the future and things that never will.
quote:
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.
It was published as a university work product, as was the habit for university funded work in those days. It is not independently replicated, not because of any failure to replicate, but only because no agency has been willing to put up the funds to make the attempt. In case you had not noticed, virtually nothing that contradicts a mainstream paradigm can get funded through official channels these days.
But the experiment was simple in concept and sound in execution. In brief, charges accelerated jointly in the same direction respond to each other’s instantaneous positions, and not to the “left-behind potential hill” following acceleration from zero speed. The paper describing the experiment is: [“Electromagnetic mass and the inertial properties of nuclei”, C.W. Sherwin and R.D. Rawcliffe, Report I-92 of March 14, 1960 of the Consolidated Science Laboratory, Univ. of Illinois, Urbana; obtainable from U.S. Department of Commerce’s Clearinghouse for Scientific and Technical Information, document AD 625706. See description in Heretical Verities, T.E. Phipps, Jr., Classic Non-fiction Library, Urbana, pp. 273-282 (1986).]
quote:
Carlip's critique of your original position was published in Phys Rev letters, in reply to their publication of your paper, was it not?
No, it was in Physics Letters A, a different journal than Phys. Rev. Letters, but the same journal in which I published two of my papers.
quote:
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?
It was joined by J.P. Vigier as co-author and published in 2002. It was too long for any of the Letters journals, so we instead published it as: [“Experimental Repeal of the Speed Limit for Gravitational, Electrodynamic, and Quantum Field Interactions”, T. Van Flandern and J.P. Vigier, Found.Phys. 32(#7), 1031-1068 (2002).]
quote:
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.
Of course there is no obligation. If he has no answer, the proper response is to say nothing. If he has an answer but is disinterested in publishing it, we and others are free to continue to assume, logically enough, that he has no answer. Even Carlip could not be sure that any answer he might think up could stand up under peer review unless he tries to publish it.
quote:
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.
And right there is a statement of the crux of the matter. It has been wrongly assumed that forces can be derived from static potential gradients for most of the last century. But that is true only for the case of fixed field points. For a charge or mass moving through a field, there is an aberration that can be reduced to zero (as experiments demand) if and only if the force propagates strongly FTL. Once that point is understood, everything else drops into place. -|Tom|-
|
| DaveL |
Posted - 08 May 2005 : 13:47:33
TVF 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."
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 in principle 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:
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.
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:
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.
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:
Then you do not clearly understand the physical difference between forces and potential fields. See my paper addressing the L-W potential ...
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
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| tvanflandern |
Posted - 04 May 2005 : 18:10:42
quote:
Originally posted by DaveL
here are a couple of papers discussing the application of a time-symmetric approach to electrodynamics to interpretation of quantum theory
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.
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
In both cases, forces propagate strongly faster than light, as shown for electrodynamic forces by the Sherwin-Rawcliffe experiment.
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.
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.
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.
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.
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.
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).
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.
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:
http://metaresearch.org/cosmology/gravity/speed_limit.asp -|Tom|-
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| DaveL |
Posted - 04 May 2005 : 03:04:26
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:
http://gita.grainger.uiuc.edu/IOPText/0143-0807/3/1/011/ejv3i1p44.pdf
http://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.
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| north |
Posted - 26 Apr 2005 : 14:45:04
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./ |
| makis |
Posted - 26 Apr 2005 : 09:41:53
quote:
Originally posted by tvanflandern
quote:
Originally posted by makis
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.
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|-
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:
http://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 B), 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
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