XXV How the Idea of a Universal Ether Developed
The evening for the meeting of the Science Club had arrived. Its membership had increased tenfold within a year. At its monthly meetings, which were open to the public, an audience of two hundred, old and young, was usually present—a number about three times that of the regular membership. General science was now the study of this club. At its weekly meetings, which only members attended, the studies of specific topics by individuals, oftentimes illustrated by experiments, were reported. These meetings were held in one of my laboratories, while the open monthly meeting was always held in my lecture room, with some rather famous speakers to instruct the audience. An enthusiastic friend of science had given a fund with the stipulation that we should engage the services of those who both knew their subjects and had acquired the art of presentation. The fund was $10,000 and it yielded $500 a year. I think beyond question it was doing more for science than any other fund of ten times that amount which can be mentioned.
On the particular evening of which I am about to speak, the lecturer told the members of the Science Club frankly how, beginning at the age of thirteen, he had spent forty years of enjoyment in study, that he had always found great satisfaction in the study of ancient civilizations and literatures. He had been fortunate, he said, in having teachers early in life who could make these subjects full of meaning to him. His greatest satisfaction, however, during the last twenty-five years had been found in tracing the development of modern science, both in the evolution of its theories and in its applications to modern industries. He said he was sure that young people of high-school age would find it profitable to learn, for instance, how the modern theory of combustion had developed slowly through the centuries, even if to do so they must curtail somewhat their study of how Greece and Rome developed and declined. He said that science furnished a tremendously rich field of study for young people, which as yet had been untouched by our schools, first, because educational conservatism had made it impossible to determine the relative importance of subjects of study, and, second, because education in science had, for a brief period, found its worst enemies within its own camp. He would like especially to commend on this evening some historical studies in science, and had chosen for his subject, “How the Idea of a Universal Ether Developed.”
Men seem to talk freely now about the transmission of light, heat, and electricity by means of the ether. How did this idea arise? Is it a product of wild imagination? or did the idea develop out of experiences which, if given to any person of fair intelligence, would yield the same result?
A little over thirty years ago, at the Royal Institution of Great Britain, James Clerk Maxwell (1831–1879) delivered a lecture on “Action at a Distance.” It was no new subject, but rather one of the oldest and most often discussed subjects from the days of the ancient Greeks down to the present. We talk of gravitation as an attraction or pull between the various bodies of the universe, but how can they pull one another without some material bond between? This was Sir Isaac Newton’s great puzzle which he never solved, though he expended upon it the greatest efforts of his great intellect.
The sun appears to repel the tail of the comet, yet how can there be a push without intervening material with which to push? When we speak of light pouring or streaming in, do we think of it as a substance? When we speak of warm bodies losing heat, or when we cover them to keep the heat in, are we thinking of heat as a substance? What are heat, light, electricity, magnetism, and gravitation?
These are no new questions. They are certainly older than history. Various ideas have prevailed at different times. It is much easier to change our ideas than to change our language. You occasionally see and hear the words calorie and caloric used in connection with heat. They stand for an idea, abandoned for three generations, that heat is a substance called caloric, which saturates warm bodies and drains out of them when they cool off. I hardly think these ideas either arise or fall without good and sufficient reason. Each theory has been the natural conclusion from our observations of nature as far as we have gone with them. To be sure, it is difficult for us to see how men acquired, from any observations of nature, the idea of light which seems to have prevailed previous to the time of Aristotle, three and a half centuries B.C. This idea was that objects were made visible by something projected from the eye itself. Still, the questions which I have indicated regarding heat, light, and electricity have impelled men for many centuries to observe nature for hints as to the answers. The doctrine of the universal ether as a medium for transmitting wave motions, and of light, heat, and electricity as being motions of different wave length, is the natural conclusion of the present time. It may give place to another theory when we have further facts to reason upon. Imagine your never having seen a harp or other musical instrument. Would it require a long time, do you think, for you to find out its use, at least to this extent, that it will produce tones whenever the strings are made to vibrate? That the short strings vibrate more rapidly than the long ones, and at the same time produce tones of a higher pitch? Imagine that having become familiar with the harp you should successively come upon scores of other musical instruments of very differing types. You would soon become adept at divining their uses. Now, a study of the microscopic structure of the eye, for one thing, would suggest that light may be in the nature of a vibration. Scores of other lines of study in a similar manner have at length brought all who pursue them to the conclusion that light is a form of vibration.
Robert Hooke in England (1631–1703) and Christian Huygens in Holland (1629–1695), back in the seventeenth century seem to have been the first to give expression to this idea, which was nothing more than an inkling in Hooke’s mind, but which was the necessary result of observations on the part of Huygens. For nearly a century the idea lay dormant, largely because Sir Isaac Newton (1642–1727), the cleverest thinker of his time, opposed it. It was perhaps unfortunate for the success of the theory that Huygens, its founder, adopted the word ether, for that was an old term, and had been very badly overworked. The word ether, or æther as it was often written, had been invented in the days of ignorance, for such foolish reasons as: (a) because “nature abhors a vacuum,” or (b) “for planets to swim in,” or (c) “to constitute electric atmospheres and magnetic effluvia,” or (d) “to convey sensations from one part of our bodies to another.”
“When we remember,” says Maxwell, “the mischievous influence on science which hypotheses about æthers used formerly to exercise, we can appreciate the horror of æthers which sober-minded men had during the eighteenth century.”
Newton in England (1642–1727) and Laplace in France (1749–1827) stoutly opposed the undulatory theory of Huygens and championed a corpuscular or emission theory, that light-giving and heat-giving bodies emit a subtile fluid.
There is no other instance in the whole history of modern physics in which truth was so long kept down by authority. Fresnel (1788–1827) and Arago (1786–1853) in France appear to be the only persons during the eighteenth century who caught a clear vision of the truth of the undulatory theory.
But it remained for Mr. Thomas Young (1773–1829), a colleague of Sir Humphrey Davy at the Royal Institution, in his Bakerian lecture (1801) on “Theory of Light and Colour” to bring together such good evidence for the ether wave theory that it has hardly been questioned since.
Young, like Davy, was a most remarkable man in literature and in science. It was he who first deciphered the Rosetta Stone, now in the British Museum, and gave us a key to the Egyptian hieroglyphics. Probably he was the only man who was able to overthrow the influence of Newton’s authority even a century after Newton did his work.
Faraday’s (1791–1867) chief work as director of the laboratory of the Royal Institution, London, was a study of ether phenomena, particularly electric and magnetic. About seventy-five years ago he became impressed with the fact that although wires may give direction to an electric current the electric influence is not confined to the wires, but may permeate more or less widely the region about them.
Nearly fifty years ago Maxwell (1831–1878) professor of physics at Cambridge University, England, conceived the idea that light is electricity of a very short wave length.
Nearly twenty-five years ago Heinrich Hertz (1857–1894), in Germany, proved by experiments the existence of electric waves, and measured their length and velocity, determining their various characteristics as compared with light.
About fifteen years ago Marconi developed a wireless telegraph apparatus, which made it possible to use electric waves for purposes of communication.
Thirteen years ago (1897) the first wireless telegraph company was formed. Eleven years ago (1899) the international yacht races in New York Harbour were reported by wireless telegraph, and bulletin boards in New York City announced to waiting crowds the details of the race while it was in progress. Nearly ten years ago (1901) wireless despatches were first sent across the Atlantic Ocean. Wireless telegraphy was opened for public use in 1905, and very soon the company began to coöperate with the regular telegraph companies. Nearly all coastwise and trans-Atlantic steamers are now equipped with wireless telegraph outfits, and a law has passed both houses of Congress making it obligatory on the part of steamers which carry fifty or more passengers to have such equipment. On several disabled steamers, notably the Republic, loss of life has been averted by the wireless emergency call for help, to which the captains of all steamers feel obliged to respond. If you desire to communicate with a friend who left for Europe several days ago, you simply write him a telegram, addressing it to his ship, and deliver it at your nearest telegraph office. Each telegraph office has a record of the location of every ship having a wireless telegraph outfit. It despatches your message to the wireless station along the coast which is nearest to your friend’s steamer, and from this station it is sent on the ether to the ship. Or in some cases it may be repeated from one ship to another along the Atlantic highway until it reaches the desired one. Thus also news of important events on either continent is distributed daily on board ships which are crossing the ocean. There are said to be more than 50,000 amateur wireless stations in the United States, and already Congress is taking steps to regulate the use of the wireless telegraph in order to prevent interference with Government and other important messages.
More than three dozen books and countless magazine articles have already been written upon wireless or ether wave telegraphy. Hundreds have and thousands are contributing to our knowledge of ether wave phenomena. If the names of all who have said or done something to render stable the foundations of this idea of a universal ether, whose undulations account for the phenomena of heat, light, and electricity, were to be mentioned, the list would contain nearly all the important workers in the field of physics for the last century.