THE GROUNDWORK OF THE UNIVERSE.* MoDERN physical science, whilst it
is becoming so complex in its researches into detail that a subsection of a single depart- ment now furnishes work enough for the lifetime of an able man, is ever approaching nearer and nearer to a magnificent simplicity in its theory of the universe. " Persons who are occupied with other branches of science or philosophy, or with literature "—to use Professor Oliver Lodge's polite periphrasis —" and who have therefore not kept quite abreast of physical science," find it hopeless to attempt to follow contemporary re- search, more especially as it generally involves an amount of mathematical reasoning and language which is quite unfit for publication in any non-technical journal. Instead of plunging into this maze, which seems without a plan to the outsider, they are content to view with admiration the periodi- cal emergence of a student into the open with a new result of practical application. The most recent instances of this kind are the discovery of the Röntgen rays, with their remarkable value to the surgeon, and the practical introduction of wireless telegraphy, of which Mr. Fahie's new book gives
• (1.) Matter, Ether, and Motion. By A. E. Dolbear, Ph.D., Professor of Physics, Tufts College, Maas., U.S.A. London : S.P.C.K. Ds.3-02.1 .4 History of Wireless Telegraphy, 18.15-1899. By J. J. Fable. London : W. Blackwood and Sons. (6s.)
so clear and interesting an account. It is perfectly natural that most of us should be content to judge the progress of physical science by the appearance of its " fruit," as Bacon would have us call these applications of theory to the uses of life. But it would be a pity if all who do not know their way about the physical laboratory, or are not versed in the language of the mathematician, should be condemned to this purely material view of the work now being done by our students of inanimate Nature. They are on the verge of discoveries as to the fundamental constitution of the universe which will revolutionise all our conceptions when they pass from the state of working hypotheses to that of established laws. It may still take generations of ingenious experimenters, happy guessers, and subtle mathematicians to achieve this step ; but we have before us already something more than a glimmering of a dawn of knowledge which can scarcely prove false. Professor Dolbear has done useful service to the general reader by setting forth the outlines of this glimmer- ing in his very interesting and non-technical account of "the factors and relations of physical science," which only lacks the lucidity and pleasant style of such writers as Huxley, Tyndall, or Sir Robert Ball to make it more fasci- nating than any novel. Unfortunately, Professor Dolbear is not a practised writer, and often fails even to attain clearness. To say, as his English editor warns us, that some of his statements are not beyond criticism is only to remind the reader that the whole book moves on the border-line of our present knowledge, and deals with hypotheses as much as with laws of Nature. It is to be read for suggestion rather than for information ; if that is borne in mind it may be heartily commended to such as are curious about the great generalisation which all physicists begin to think they see far off on the lines of their converging inquiries.
A little more than twenty years ago, when Clerk Maxwell wrote his admirable introduction to physical science for the Society for Promoting Christian Knowledge, he called it Matter and Motion,. The more extended title of Dr. Dolbear's book is a fair index of the advance which has occurred in our knowledge,—thanks to Clerk Maxwell him- self more than to any other single man. Twenty years ago it was an axiom of the lecture-rooms that in the physical universe there were but two objective things, matter and energy, or matter and motion (for energy does not exist with- out motion), in terms of which all phenomena—with the possible and much-debated exception of life—would sooner or later be explained. We are now forced to include a third concept, the ether, which is neither matter nor motion, although we are going to show how it is possible that the three factors may again be reduced before long to two. The first serious notion of the existence of this ether, which is now as well established as that of the air, though only the last few years have seen its properties examined, is due to our great Newton, whose gigantic figure—contrary to the ordinary laws of perspective—seems to tower up loftier and more colossal the further we get away from it. He closed the Principia by indicating his belief in the existence of " a most subtle spirit which pervades and lies hid in all gross bodies," filling the whole universe, through whose medium were produced the phenomena of heat, light, physiological sensation and action, electricity, gravita- tion, and all the other natural forces, which for more than a century after Newton's death no one else could imagine to be related. Newton was led to this magnificent guess, har- monising so well with our present knowledge, by his sense of the impossibility of " action at a distance." That one body should influence another without any medium he held to be so great an absurdity that any man who believed it was thereby ruled out of court as a competent thinker. A dozen lines of separate investigation have led us to reaffirm the truth of Newton's statement. The first successful step was taken by Young and Fresnel at the beginning of this century, when they showed that light could only be satisfactorily explained as consisting of waves in a rigid, elastic, friction- less, homogeneous substance, filling the universe, pervading material bodies as well as what we call empty space. The next step was that of Clerk Maxwell, who showed that light and electricity were so closely allied that electricity must also be considered to consist of waves in the same ether, only differing in length from those of light. This theoretical
conclusion, which was left imperfectly understood by the premature death of Clerk Maxwell, perhaps the heaviest loss that physical science has ever known, was experi- mentally verified by Hertz when he showed that electrical waves could be made to exhibit all the phenomena of radiant light. An incidental result of this discovery, as Mr. Fable ably shows, was the practical development of wireless telegraphy which we owe to Signor Marconi and his colleagues. The existence*of such an ether as Young and Clerk Maxwell postulated is now definitely established. That is to say, we are forced to accept, as the only con- ceivable working hypothesis, the existence of a homogeneous elastic substance, different from any known kind of matter but possessing inertia and rigidity, which fills all space and pervades all bodies, and whose waves, varying in length from many miles to tiny fractions of an inch, are already proved capable of producing all the phenomena of light, radiant heat, electricity, and magnetism. Gravitation and cohesion are, in fact, the only great natural forces that this hypo- thesis still leaves inscrutable.
But the hypothesis of the ether has a still wider, and to the philosopher a still more important, range. At first sight it seems that we have rather complicated than simplified our conceptions of the physical universe by adding ether to matter and motion. For the moment that is so, no doubt; but we look ahead to that great discovery which seems to be in sight. " What is matter ?" has always been asked and never answered. Perhaps before long we may know. Many trains of thought have led to the vision of some fundamental kind of matter out of which all things that we know are made, Chemists have for some time suggested that the seventy elements may be modifications or compounds of one or two simpler kinds of matter. Meanwhile, physicists have been working to meet them. Helmholtz and Lord Kelvin between them have shown that the ether may be the one material stuff in the universe, the Urge, of the world, gross matter being simply differentiated portions of it. This is the famous Theory of Vortex Atoms, which may be regarded by posterity as Lord Kelvin's truest claim to immortality, though it is scarcely known to-day by many who justly honour his great contributions to our material welfare. Vortex rings are familiar to all who have watched a smoker projecting what Mr. Ashby-Sterry calls "the azurine curving of cigarette-rings." It has been shown to complete demonstra- tion that a vortex ring formed in a frictionless fluid would persist indefinitely; "none of the motion could be dissipated," as Dr. Dolbear says, "and we should have a permanent structure, possessing several qualities, such as defiuite dimensions, volume, elasticity, attraction, and so on, all due to the shape and motions involved." Lord Kelvin and his followers have shown mathematically that such a ring would have the characteristic property of what we call an atom : it could neither be brought into being nor destroyed by any means that we can conceive. It is still a task for generations of mathematicians to work out the way in which such rings, endowed with different shapes and velocities, could have the properties of the various chemical elements; possibly they may fail to do so, and the hypothesis may be abandoned in favour of a still simpler one, but at present all the work that has been done on the Theory of Vortex Atoms has only established it more firmly. This theory, which is at least the most promising explanation yet known tons of the observed facts of matter, has a fascinating simplicity and beauty in its resolution of the physical universe into ether and motion.
Ordinary matter is thus seen to be a modification of the universal ether, whilst energy is explained as a product of the ether in motion. It is unnecessary, even if we had the space, to do more than indicate one or two of the ideas that such a suggestion arouses in the mind. The omnipresent ether, father and cause of all material things, cannot fail to suggest a physical basis for the dreams of the Greek or Indian pantheist. Again, although this hypothesis throws no more light than any other pronouncement of science on the first beginning of things, it ought to commend itself to the tele- ologist by its simplification of the original creative act, which may have consisted merely in the impressing of motion—in a way, as Helmholtz showed, beyond human conception—upon the universal ether. From that single divine act we may one day be able to show that all the present universe, in. chiding our own intelligences, must with mathematical certainty have followed. The mind is staggered by the grand simplicity of such a thought, which bad already occurred to Newton when he wrote, nearly two hundred years ago: " Perhaps the whole frame of Nature may be nothing but various contextures of some certain ethereal spirits or vapours, condensed, as it were, by precipitation; and after condensa- tion wrought into various forms, at first by the immediate hand of the Creator, and ever after by the power of Nature."
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