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E-MAILS TO JEFIMENKO, CHIEFLY ON CLOCKS
It filled me with deep sadness to learn of the death last year of Dr. Oleg D. Jefimenko. His name will be familiar to some of you as it has come up more than a few times in these columns. I briefly reviewed a couple of his books in “Recent and Worthy” from the April 2003 Analog. I also discussed his work on the theory of electromagnetic retardation in my January 2006 column, “Length Contraction.”
We had a valuable period of e-mail exchanges about five years ago, a portion of which I am publishing here. It relates to one of the most interesting findings of his work and other admirers and “students” of his should know what he had to say.
While doing consulting work in late 2000, I stumbled upon an abstract for a lecture in an old physics journal that I knew he would find of interest. I regret that I didn’t tell him immediately, but better late than never.
I sent the first e-mail on July 14, 2005, with the subject line, “The rate of moving clocks.”
Dear Dr. Jefimenko,
I was going through once again Electromagnetic Retardation and Theory of Relativity and (once again) came upon this statement on pg. 236-237: “For some inexplicable reason, apparently nobody has attempted to calculate and compare the rates of any types of stationary and moving clocks . . .”This reminded me that I have long intended to send you the ref. in the attached photo.(I finally have a scanner, so now I can just e-mail it to you.)
The ref. is from pg. 770 of Phys. Rev. Vol. 85 (1952).I have never been able to find an article by Ruark in which he followed up on his analysis of simple clocks, and I don’tknow if he ever compared the rates of clocks like you did—but this is the closest hit to that I’ve been able to find.
If you know about this already, please pardon the intrusion.
Best,
Jeff
This is what the abstract said:
P1. Electrodynamics as a Basis for Special Relativity. Arthur E. Ruark, Institute for Cooperative Research, The Johns Hopkins University.—The Lorentz transformation is usually derived from the symmetry of the physical experiences of two observers on inertial frames, and the assumption that both observers obtain the same value of c, no matter how the source is moving. Suppose we replace the second postulate by the statement that the Maxwell equations and the Lorentz force are valid for the “resting” observer. We can discuss a simple clock—a negative charge, rotating (sic) around a heavy positive charge in a plane perpendicular to the X-axis. Setting this system into uniform motion, it becomes the clock of the moving observer. The resting observer can use the retarded potentials to discuss its behavior. A few lines suffice, to derive the mass increase and the decrease of angular velocity that occur when the clock is set into motion. The expansion of times associated with a moving body, the constancy of light velocity for the moving observer, the Lorentz contraction of a moving body, and the Lorentz transformation follow in order, with ease. This attack makes these matters so readily understandable, on the basis of retardation of electrical forces, that it appears to possess didactic value.
Dr. Jefimenko said, in his reply on July 19:
Thank you very much for the very interesting abstract of Ruark’s paper on relativity. I did not know of its existence. It is interesting for me for two reasons. First, because Ruark speaks of a moving electromagnetic clock, but mostly because he associates relativity with electromagnetic retardation.
As far as his clock is concerned, it is physically and mathematically much more complex than any of my clocks in Electromagnetic Retardation and the Theory of Relativity (the electric field of a charge in a circular motion is far from simple—see Example 4-4.1 on pp. 89-92 in R&R). It would be interesting to see Ruark’s calculations, but it is entirely possible that he had never published them. I suspect that he simply had an idea—an intuition—and submitted the abstract of the paper that he intended to present at the Physical Society meeting before actually completing the calculations. It is also entirely possible that he never presented the paper at the meeting because, as I suspect, the calculations had not supported his initial announcement. Specifically, I do not think that it is possible to deduce mass increase, time dilation, constancy of light velocity, Lorentz contraction, and Lorentz transformation—all this by simply analyzing the behavior of a moving clock. It may be noted that Larmor, as early as in 1897, concluded that the period of an orbiting electron in a moving reference frame is longer than its period in a system at rest. But Larmor based his calculation on what we now call Lorentz (incomplete) transformations, not the other way around. And as far as the constancy of light velocity, length contraction, and mass increase are concerned, I do not see at all how they can be deduced just from an analysis of a moving clock. I may be wrong of course.
What is especially interesting for me in Ruark’s abstract is that he associates relativity with retardation of electrical forces. Until now I believed that the idea of an association of relativity with electromagnetic retardation was original with me. I now see that Ruark anticipated the idea already in 1952. If there shall be a third edition of my R&R, I will mention in it Ruark’s abstract and will express my gratitude to you for letting me know of its existence.
So let history show that before his death, Jefimenko did find out that he wasn’t the first to notice the connection between relativity and retardation. He did send the book as promised, and we discussed a number of other things in subsequent emails. But I wasn’t quite finished with the matter of the rates of moving clocks.
Paraphrasing from the earlier columns, let “us” again define electromagnetic retardation. Since electric and magnetic fields propagate at a finite velocity (the speed of light), there is always a time delay before a change in electromagnetic conditions initiated at a point in space can produce an effect at any other point in space. This time delay is called electromagnetic retardation. But, for the most part, the equations of classical electromagnetism are not usually expressed in a form that explicitly takes this fact into account. When you do cast the equations in their retarded forms, some interesting results appear.
What Jefimenko found is that relativity is the result of retardation.
In “Length Contraction” I described how retardation predicted length contraction. In “Recent and Worthy” I described how it was done with clocks and said that “Jefimenko’s approach is to ‘construct’ an electromechanical system that could function as a simple clock, and then show how the retarded equations predict that the clock slows down when put in motion.” I then described one of those simple clocks, but I need to describe a different one this time.
Picture a coordinate system near the origin, x-axis left to right, y-axis up and down, z-axis positive out of the page and negative into it. Imagine two like charges q fixed at positions +a and –a on the z-axis. Picture another charge –q near the origin and constrained to oscillate up and down on the y-axis. This oscillating charge is a form of simple clock. If we put this clock system in uniform motion along the x-axis, and apply the retardation equations to see how the motion affects the clock rate, lo and behold we find that the clock slows down at the rate predicted by relativity. Now let’s alter the clock by fixing the two like charges at +a and –a on the x-axis (we rotate the clock 90 degrees in the x-z plane) and again put it in uniform motion down the x-axis. This time the clock will also slow down, but at a different rate from the relativistic prediction. (These are clocks #3 and #7 in chapter 10 of Jefimenko’s book.)1
Although Jefimenko had described this matter in depth in his book, he had not described the “non-Einsteinian” clocks in a paper he had published in the American Journal of Physics. So I asked him why.
Ever since I first read R&R, and also your AJP paper “Direct Calculation of Time Dilation,” and now also “On the Experimental Proofs of Relativistic Length Contraction and Time Dilation,” I’ve wondered why you didn’t mention in these papers what you showed in the book (what I consider one of the most interesting results of retardation), that being that some simple clocks are “non-Einsteinian”?
Did you think that added wrinkle would detract from the point of your papers? Did the referees balk at it?
To which Jefimenko replied with the following explanation:
As to AJP and non-Einsteinian clocks, there was a non-Einsteinian clock in the original manuscript for AJP. However, the editor, R. H. Romer, declared that he would not publish the manuscript unless I “either REPAIR THE WRONG CLOCK or delete it.” Since I could not “repair” the clock (it functioned perfectly, and Romer did not suggest how it could be “repaired”), I decided to delete it, so that at least the basic idea of the dependence of clock rate on clock mechanism would be published.
And I did not even try to include non-Einsteinian clocks in “On the experimental proofs . . .”
He had also sent me a paper of his I had not requested (because I didn’t know of it) and in a subsequent e-mail added this additional point:
There is a very good reason why I sent to you the third reprint—the reprint of the article “On the Relativistic Invariance of Maxwell’s Equations.” Perhaps you already know that at least some of my “non-Einsteinian” clocks can be converted into “Einsteinian” clocks by simply assuming that they are Lorentz-contracted. Of course, I do not believe that relativistic (kinematic) length contraction is a true physical effect as is explained in Chapter 9 of “Electromagnetic Retardation . . .”
But is the dynamic (causal) length contraction suggested by Fitzgerald and Lorentz a true physical effect? About that I have no definite opinion.
However, as is shown in the article “On the Relativistic Invariance of Maxwell’s Equations,” if one accepts the existence of length contraction of any kind, then one must modify Maxwell’s equations and, hence, modify the entire electromagnetic theory and, consequently, the theory of relativity as well.
I finished up my side of the conversation this way, speaking specifically on the reason why the non-Einsteinian clocks were left out:
I find this both tragic and amusing—and it’s also pretty much what I thought must have happened. (I hope you let me relate this story in a future article sometime.) Sometimes my readers ask me why, if certain “heretical” ideas are true, they haven’t heard about them. Well, guys like Romer wouldn’t publish it for one thing.
Jefimenko sent me a copy of his last book,2 in which he rigorously applies retardation to gravity. One thing he discovered is that some mass distributions will result in repulsive gravity fields.
How do you like them apples?
Copyright © 2010 Jeffery D. Kooistra
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