Luminiferous ether

“ It appears, from all that precedes, reasonably certain that if there be any relative motion between the earth and the luminiferous ether, it must be small; quite small enough entirely to refute Fresnel's explanation of aberration. ”

“ It is the luminiferous ether, that attenuated medium by which light, and heat, and electricity are transmitted from one part of the universe to another, by undulations of inconceivable velocity. This strange fluid, whose existence and action seems all but demonstrated by the phenomena of light, heat, and electricity, and perhaps, too, by the resistance experienced by Encke’s, Biela’s, and Halley’s comets, must possess the extraordinary characteristic above pointed out. It must exist and act wherever we find light, heat, or electricity ”

“ The luminiferous ether, in which all systems are immersed, kept hereabout in an incessant quiver through its complete and perhaps three-fold gamut of vibrations by the sun, strikes the aërial ocean of the earth about an average of five hundred million millions of blows per second, for each of the seven colors, or luminous notes, not to speak of the achromatic vibrations, whose effects are other than vision or visionary. ”

“ The solar impulse propagated through the luminiferous ether towards any mass encounters in its neighborhood the electrical and calorific ethers, and sets them into motions which may be communicated from one to the other, but which are communicated to ponderable matter, or result in mechanical action, only or chiefly by the impulse of the denser or calorific ether. ”

“ W. Mattieu Williams, must we suppose the existence of a luminiferous ether distinct from other matter, when it is just as easy to account for the phenomena of heat, light, electricity, magnetism, and chemical force as "modes of activity of ordinary matter, analogous to the waves of sound," but differing from them by being molecular vibrations, while sound is molar vibration? Gaseous matter being infinitely expansible in the presence of radiant heat, there is no difficulty in imagining space filled with ordinary gases thus expanded, and performing all the functions ascribed to the ether. ”

“ In the present scientific age every one knows that light is transmitted across space through the medium of the luminiferous ether. This ether fills the whole of the known universe, as far at least as the remotest star visible in the most powerful telescopes, and is often said to be possessed of properties of so paradoxical a character that their unreserved acceptance has always been a matter of considerable difficulty. ”

“ Nothing seems more natural than to suppose that the incident vibrations of the luminiferous ether produce vibratory movements among the ultimate molecules of sensitive substances, and that the molecules in return, swinging on their own account, produce vibrations in the luminous ether, and thus cause the sensation of light. ”

“ No ordinary matter is competent to transmit waves at anything like the speed of light: the rate at which matter conveys waves is the velocity of sound,—a speed comparable to one-millionth of the speed of light. Hence the luminiferous medium must be a special kind of substance; and it is called the ether. ”

“ Cavendish Laboratory, Cambridge, 19th March, 1879 Sir, I have received with much pleasure the table of the satellites of Jupiter which you have been so kind as to send me, and I am encouraged by your interest in the Jovial system to ask you if you have made any special study of the apparent retardation of the eclipses as affected by the geocentric position of Jupiter.
I am told that observations of this kind have been somewhat put out of fashion by other methods of determining quantities related to the velocity of light, but they afford the only method, so far as I know, of getting any estimate of the direction and magnitude of the velocity of the sun with respect to the luminiferous medium. ”

“ First, Fresnel and, more recently, Doppler, Stokes, Challis and several others have published papers on this subject, but it does not seem that any of the theories so far proposed have been able to completely satisfy the physicists. Because of a lack of definite knowledge about the properties of the luminous ether and its relationship to ponderable matter, it has been necessary to introduce hypotheses, among which are those which are more or less probable, but none that can be considered as proven. ”

“ Not less startling is it to be told that a question may yet be raised which will challenge "the conception of a luminiferous aether, which for half a century has dominated physical science. It is possible," so we are informed, "that the field of electro-magnetic energy surrounding an electric charge in motion moves with it, and that the vibrations of light travel through this moving {74} field, instead of through an ocean of stagnant aether." ”

“ According to what precedes, the average ethereal energy can hardly be less than the radiant energy from the stars within a range of a million light-years, and may amount to many times this figure; and as the absorption is a gradual one, the actual duration of luminous propagation may have to be reckoned in thousands of millions of years. Now the radiant energy of the ether represents its temporary mass. ”

“ THE AETHER AS AN ELASTIC SOLID.
When Young and Fresnel put forward the view that the vibrations of light are performed at right angles to its direction of propagation, they at the same time pointed out that this peculiarity might be explained by making a new hypothesis regarding the nature of the luminiferous medium; namely, that it possesses the power of resisting attempts to distort its shape. It is by the possession of such a power that solid bodies are distinguished from fluids, which offer no resistance to distortion ”

“ According to the theory of emission, the transmission of light energy is effected by the actual transference of light-corpuscles from the luminous to the illuminated body. According to the theory of undulation there is a material medium which fills the space between the two bodies, and it is by the action of contiguous parts of this medium that the energy is passed on, from one portion to the next, till it reaches the illuminated body. The luminiferous medium is therefore, during the passage of light through it, a receptacle of energy. ”

“ Huyghens, on the contrary, supposes light to be caused by the waves or vibrations of an infinitely elastic medium—Ether—diffused through all space, which waves are propagated in every direction from the luminous body. In the first theory, a luminous particle is supposed actually to come from the sun to the earth; in the other, the sun only occasions a disturbance of the ether, which extends with great rapidity, in the same manner as a wave spreads itself over the surface of a lake. ”

“ The undulations of ether pass through obstacles that you would believe impenetrable. Clouds are formed of molecules between which rays of light frequently pass. In the contrary case, there are here and there vistas or gaps, across which one can only see obliquely. The case is very rare when nothing can be distinguished. Besides, light is not what it appears to be; it is a vibration of ether, and there are other [107] ways of seeing than by means of the retina and the optic nerve.
The vibrations of ether are perceptible to senses other than those you possess. ”

“ We may, indeed, consider it possible that the escaping ether, when very intense, might be rendered luminous by passing into the surrounding ether, and, as it became more diffused by radiation, at last become invisible. ”

“ Just as in the case of ordinary artificial illuminants, such as lamps of various kinds, we have to manufacture a large amount of ether radiation of long wave length, which is of no use to us for visual purposes; in fact, creating ninety-five per cent, of dark and useless waves for every five per cent, of luminous or useful waves, so in connection with present methods of generating Hertzian waves, we are bound to manufacture by the discharge spark a large amount of light and heat rays which are not wanted, in order to create the Hertzian waves we desire. ”

“ And what is light, indeed, but vibrations of ether from 400 trillions to 800 trillions per second, giving all the colors from violet to red? There is not an atom of ether in all space, so far as science can detect, that has ever ceased to vibrate, or ever will, with the startling rapidity above expressed. ”

“ We have seen that the warmth-ether has the double function of being at once the lowest ether and the highest physical element, thus acting as a sphere of reflexion for the other kinds of ether and the elements respectively. Each stage in the etheric has its reflexion in the physical, as the above table shows. Thus to the physical air the etheric light is related. (The affinity of light and air is best seen in the plant and its leaf-formation.) To bring about real changes in the material composition of the physical world requires the stronger powers of the chemical ether. ”

“ By as much as the intensely-heated gases of the interior are disabled by the dissociation of their molecules from giving off luminiferous undulations, by so much must they be disabled from absorbing the light transmitted through them. And if their great light-transmitting power is exactly complementary to their small light-emitting power, there seems no reason why the interior of the Sun, disclosed to us by openings in the photosphere, should not appear as bright as its exterior. ”

“ The mode of connection between the particles and the ether is not known: it is earnestly being sought: but the fact that therein a connection has been known a long time. We know it, because a particle cannot quiver, or inner, without disturbing the medium in which it is. A boat cannot oscillate on the surface of water without sending off waves; a bell cannot vibrate in air without sending out waves of sound; a particle cannot vibrate in ether without sending out waves of light.
So the second thing to learn about the ether is its property of conveying light. ”

“ On meeting what we call solid matter, ether waves are influenced, not because ether is wanting in the solid matter, but because the presence of something else than ether affects the intervening ether itself. Consequently glass, to take an instance, so affects ether that a very rapid succession of waves (light) are able to continue their way through its interstices, whereas long electric waves are so hampered that they die out altogether. ”

“ Conceive now a medium having similar properties, but incomparably rarer than air, and we have a medium such as we may conceive the æther to be, a fluid as regards the motion of the earth and planets through it, an elastic solid as regards the small vibrations which constitute light. Perhaps we should get nearer to the true nature of the æther by conceiving a medium bearing the same relation to air that thin jelly or glue water bears to pure water. ”

“ It is certainly curious that the astronomical phænomenon of the aberration of light should afford an argument in support of the theory of transversal vibrations.
Undoubtedly it does violence to the ideas that we should have been likely to form à priori of the nature of the æther, to assert that it must be regarded as an elastic solid in treating of the vibrations of light. ”

“ Before considering luciferin and luciferase, however, let us study a few well-known chemiluminescent oxidations with special reference to concentration of reacting substances and temperature. [Pg 145]
The effect of temperature on luminescence is of special interest because it gives us a means of analysis for determining if the luminescence depends on reaction velocity. We know that photochemical reactions are very little affected by temperature because the reaction is dependent on the absorption of light, a physical process, and this increases only a small per cent. ”

“ Other crystals may luminesce in hot water. In all, this luminescence is dependent on a previous illumination or radiation of the crystal. If kept in the dark for a long time no trace of light appears when fluorite is placed at a temperature of 100°, but after a short exposure to the light of an incandescent bulb, although no light can be observed in the fluorite at room temperature, quite a bright glow appears at 100°. ”

“ If the radiant energy is light (visible or ultra-violet) we speak of photoluminescence, if cathode rays we have cathodoluminescence, if anode rays, anodoluminescence, and if X-rays (Röntgen rays) we have radioluminescence. Inasmuch as the α, β, and γ rays of radium correspond to the anode, cathode, and X-rays, respectively, radium radiation also produces luminescence in many kinds of material. If the material gives off the light only during the time it is radiated we speak of fluorescence; if the light persists we speak of phosphorescence. ”

“ The power of the ether in the rapid transmission of undulations seems to attain its limit in the propagation of light and heat and electricity at the rate of nearly 200,000 miles per second. How the ether can act so as to serve as a medium of communication between bodies at all distances, transmitting impressions 10,000,000 times faster, at least, than light travels, nothing at present known to us enables us to say. I have, in a lecture which I gave in America upon the mysteries of the universe, indicated a way in which gravity may be conceived to be generated and transmitted ”

“ Conversely the phenomena of the spectroscope all depend on the fact that the vibrations of atoms and molecules can propagate waves through the ether, as well as absorb ether-waves into their own motions, and thus give spectra distinguished by bright or dark lines peculiar to each substance, by which it can be identified. Whatever ether may be, this much is certain about it: it pervades all space. ”