A Gravitational and Electromagnetic Analogy
Oliver Heaviside was an outstanding self-taught researcher, one of the most striking personalities in science of the late 19th - early 20th cc. Editorial Border of the Journal ‘ Space and Time ’ represents Oliver Heviside’s paper on the gravitational and electromagnetic analogy translated by Sergey G. Gevorkyan, Ph.D. (Physics and Mathematics), with parallel texts in English and in Russian. Bearing in mind the successful manner in which Maxwell's localisation of electric and magnetic energy in his ether lends itself to theoretical reasoning, the suggestion is very natural that Heaviside attempted to localize gravitational energy in a similar manner, its density to depend upon the square of the intensity of the force, especially because the law of the inverse squares is involved throughout. It is as incredible now as it was in Newton's time that gravitative influence can be exerted without a medium; and, granting a medium, we may as well consider that it propagates in time, although immensely fast. Results showing signs of wave-propagation would require an inordinately large velocity of matter through the ether. It may be worthwhile to point out, Heaviside wrote, that the lines of gravitational force connected with a particle of matter will no longer converge to it uniformly from all directions when the velocity ν is finite, but will show a tendency to lateral concentration, though only to a sensible extent when the velocity of the matter is not an insensible fraction of ν. The gravitational-electromagnetic analogy may be further extended if we allow that the ether which supports and propagates the gravitational influence can have a translational motion of its own, thus carrying about and distorting the lines of force. It must be confessed that the exhaustion of potential energy from a universal medium is a very unintelligible and mysterious matter. When matter is infinitely widely separated, and the forces are least, the potential energy is at its greatest, and when the potential energy is most exhausted, the forces are most energetic! Potential energy, when regarded merely as expressive of the work that can be done by forces depending upon configuration, does not admit of much argument. It is little more than a mathematical idea, for there is scarcely any physics in it. It explains nothing. But in the consideration of physics in general, it is scarcely possible to avoid the idea that potential energy should be capable of localization equally as well as kinetic. That potential energy ultimately kinetic is discrete issue. Heaviside believed that perhaps the best definition of the former is contained in these words: “potential energy is energy that is not known to be kinetic.” But, however this be, there is a practical distinction between them which it is found useful to carry out. Now, when energy can be distinctly localized, its flux can also be traced (subject to circuital indeterminateness, however). Also, this flux of energy forms a useful working idea when action at a distance is denied (even though the speed of transmission be infinitely great, or be assumed to be so). From this point of view, then, we ought to localize gravitational energy as a preliminary to a better understanding of that mysterious agency. Heaviside could not say that the theory of the potential energy of gravitation exhausts the subject. The flux of gravitational energy in the form above given is, perhaps, somewhat more distinct, since it considers the flux only and the changes in the amount localized, without any statement of the gross amount. Perhaps the above analogy may be useful, and suggest something better. Some of the consequences of the modified law arise when we assume that the ether is the working agent in gravitational effects, and that it propagates disturbances at speed v. All we need expect, Heaviside noted, then, so far as he could see from the above considerations, are small perturbations due to the variation of the force of gravity in different directions, and to the auxiliary force. If variations of the force of the size considered above are too small to lead to observable perturbations of motion, then the striking conclusion is that the speed of gravity may even be the same as that of light. If they are observable, then, if existent, they should turn up, but if non-existent then the speed of gravity should be greater. Furthermore, Heaviside noted, that it is to be observed that there may be other ways of expressing the propagation of gravity. Russian translation of this outstanding Heaviside’s work is published for the first time: in his article, Dr. Oleg D. Jefimenko reproduces this work entirely in English, and the amateur translations circulating on the Internet are inaccurate and abound with errors.