That pervading all Space in the Universe—not only between planets, stars and suns, but also "filling in the cracks" between molecules, and atoms as well—there is a subtle Substance in and through which the waves of Light, Heat, Electricity and Magnetism travel at the rate of 184,000 miles per second. This Substance is said to be "Matter that is not Matter"—in fact, Science does not venture to say just what it is, although it freely states just what some of its properties must be, and, alas! these properties are most contradictory and opposite to each other, as we shall see as we proceed.
This Universal Ether is purely hypothetical. It has been called a "necessity of Science"—something assumed for the purpose of explaining or accounting for certain phenomena. It is undemonstrated and unproved—in fact, may truthfully be said to be undemonstrable and unprovable. Some have gone so far as to say that its claimed properties and qualities render it "unthinkable" as well. And yet, Science finds itself compelled to assume that the Ether, or "something like it" exists, or else cease speculating about it. It belongs to the realm of pure theory, and yet, many writers treat it as if it were a positively demonstrated and proven fact. Let us examine into the nature of Science's problem, and her attempted solution, and the trouble arising therefrom.
Light travels at the rate of 184,000 miles a second. Remember, that Light and Heat are that which we call by those names only when considered in connection with Substance. According to the theory, Light in the Sun's atmosphere is transformed into a Light-wave of the Ether on its travels to the earth, and only when the "wave" comes in contact with the Substance on the earth's body or atmosphere does it become again transformed into Light as we know it. In its travels through space it meets with no Substance, and has nothing to "turn into light"—consequently Space (between worlds) is in a state of absolute darkness. The same is true of Heat, and inter-world Space is absolutely cold, although passing through it are countless heat-waves of great intensity, which, later on, will be transformed into Heat when they reach the Substance, the earth. The same is true of Electricity and Magnetism.
Although the Ether, as we have seen, is a purely theoretical substance, yet Science has found it reasonable to conclude that it must be possessed of certain attributes in order to account for certain known facts. Thus, it is said to be frictionless, else the worlds, suns and planets could not pass freely through it, nor could the light and heat waves travel at such a tremendous rate. It also is thought to have something like Inertia, because Motion once started in it persists until stopped; because it is at a state of rest until Motion is imparted to it; and because it takes a fraction of time to impart motion to it. It is thought to be different from Substance in any of its known forms, for many reasons, among such being the fact that no known form of Substance could carry vibrations through space at the rate of 184,000 miles a second. And Light and Heat waves travel at that rate, and have forms and shapes, and lengths of their own. Light for instance, vibrates on two planes, and a light-wave is something like a Greek cross, thus (-|-), having a horizontal and a vertical line, or plane of vibration. And the Ether cannot be a fluid of any degree, because a fluid cannot transmit cross vibrations at all. And it cannot be a Solid, because a Solid could not stand vibrations at such a terrific speed, and still remain a Solid. And yet, to transmit the two-plane light waves, the Ether must have a certain degree of Rigidity, else the waves could not travel. Lord Kelvin estimated this degree of Rigidity as about 19,000,000,000th of the rigidity of the hardest steel. So, you see, Science is compelled to assume that the Ether is "a continuous, Frictionless medium, possessing both Inertia and Rigidity." Some scientists have thought it to be a kind of "elastic jelly."
Of the Ether, Prof. Oliver Lodge has said, "We have to try and realize the idea of a perfectly continuous, subtle, incompressible substance, pervading all Space, and penetrating between the molecules of ordinary Matter, which are imbedded in it, and connected to one another by its means. And we must regard it as the one universal medium by which all actions between bodies are carried on. This, then, is its function—to act as the transmitter of motion and energy."
To give you an idea of the wonderful thing that Science is compelled to think of the Ether as being, by reason of the qualities it is compelled to ascribe to it—although it confesses itself unable to "imagine" the nature of the "Thing" which it has created in bits by the adding and bestowing of qualities which were made necessary by the logical requirements of the case—let us take a hurried view of the Thing as the several departments of Science say it must be thought of.
To meet the requirements of the case, Science says that The Universal Ether must be Substance infinitely more rare and evanescent than the finest gas or vapor known to Science, even in its rarest condition. It must convey Heat in the manner of an infinitely Solid body—and yet it must not be a Solid. It must be transparent and invisible. It must be Frictionless, and yet Incompressible. It cannot be a Fluid. It cannot have Attraction for Substance, such as all Substance has. Nor can it have Weight—that is, it is not subject to Gravitation. It is beyond the reach of any known scientific instrument, even of the greatest power, and it refuses to register itself in any way, either to senses or instruments.
It cannot be known "of itself," but may only be recognized as existent by the "things" for which it acts as a medium or transmitting agent. It must convey Energy and Motion, yet it must not take up any part of either from the Matter in its midst. It must not absorb any of the Heat, Light or Electricity. It must fill up the spaces between the worlds, as well as the most minute space between the Molecules, Atoms and Corpuscles, or any other minute particle of Substance, either known by name to Science now or which may be discovered or imagined later as a necessity of some conception regarding the nature of Substance. In short, The Universal Ether, in order to do the things attributed to it, must be more solid than Solids; more Vapor-like and Gas-like than Vapor or Gas; more fluid than Fluids; infinitely less rigid than steel, and yet infinitely stronger than the strongest steel. It must be a substance having the qualities of a vacuum. It must be continuous and not composed of Particles, Atoms or Molecules. It must be an "everything" in some respects, and yet a "nothing" in others. It must not be Substance, and yet it must carry Substance within its ocean of dimensions, and, besides, interpenetrate the most minute space between the particles of Substance. It must not be Energy or Force, and yet Science has been considering Energy and Force as but "interruptions of rest" or "agitations" within, and of, itself.
So you see that this mysterious, wonderful Universal Ether—in order to "be" at all—must be a "Something" possessing certain qualities or properties of Substance—many of the properties of qualities being exactly contradictory and opposed to each other—and yet it cannot be Substance as we know it. It is a Paradoxical thing. It could only belong to another and an entirely different order of existence from that of Substance as we know it. It must possess characteristics and properties of an order as yet unknown to us by name—for which the material world contains no analogy—for which Substance has no analogues. It must be a far more complex thing than is even the most complex thing we call Matter, or that which we call Force or Energy. And yet, it has been claimed that it would explain both—yes, contain within itself the possibility of both.
And yet, in face of what has just been said, the writer must confess, humbly and with a full realization of the enormity of the offence, that he supposes advancing a theory, a little further on in this book that will attempt to identify this Something—this Universal Ether—with a Something else that we know, although not through the senses or by means of instruments. Bear with him kindly, he begs of you, while he proceeds gradually along the path that leads to the theory.