Popular Science Monthly/Volume 72/January 1908/What Is Matter?
|WHAT IS MATTER?|
THE UNIVERSITY OF TEXAS
THIS question is at once the earliest and latest to excite scientific curiosity. It was asked at the dawn of science by Thales and Anaxemander, by Heracleitus, the gloomy, and Democritus, the smiling, philosopher. And to-day, with all the resources of modern science at their command, Thomson, Ramsay, Lodge and Rutherford are still asking, What is matter? What is the stuff of which the world is made? The great difference is that at last the solution seems about ready for acceptance, a solution so simple that we must marvel at the denseness of the human wit that so long failed, and in large measure still fails, to recognize it, though it was proclaimed, in dark words to be sure, by Heracleitus in the early fifth century b. c.
There is, of course, no question as to the reality of matter. That has never been seriously doubted. With the problem properly stated, even Bishop Berkeley would not have done so, though unquestionably he thought he did, and many since his day have been misled by his self-deception. Berkeley merely disagreed, rightly, with the common view of what matter is. Matter, he taught in effect, is very different from what the man in the street thinks it to be. And to Berkeley's real doctrine the doughty Dr. Johnson had no answer. By kicking the stone, he reassured himself that matter is real, which needed no proof, but failed to cast the faintest glow of light on what matter is, which is the real question.
Before reflection, all men think they know matter perfectly. Why, they say, matter is the commonest thing in the world; it is everywhere, which is, of course, true. And they are likely to add at that stage, Everything is matter, which is false as matter is ordinarily conceived. But, if you are still unsatisfied and press to be told definitely what matter is, the man in the street is likely to resort to the "when" definition, so dear to childhood, as did Dr. Johnson, that colossal wayfarer. Matter is "when" you kick a stone, or when you see a tree, or eat its fruit, or hear the thunder roll. Now, it goes without saying that matter is in fact there when you do each of these things. But so is much else besides, including yourself, the ours are there with matter, but matter they simply are not, either singly or all together. Color is with its beauty, in the eye, or rather the mind, of the beholder, and there too is sound with its melody, and all other experiences. They are the effects wrought upon us, through the intermediation of our sense organs, by matter. Given an adequate outer cause, an eye in its organism to be affected, and a mind to perceive, and color is the result. Given cause, ear and mind, and we have sound; or cause, touch organ and mind, and we have the feeling of hardness. But matter, without sense organs or mind, can not have such experiences. And the substance of matter they are not. We know so much about the total situation when matter is present that we easily delude ourselves into thinking that we know the matter too. But, as Dr. Higgins once said, in dealing with experiences we are merely playing with the pebbles on the beach; the sea of reality, matter itself, is still beyond our ken. What matter is not, its effects on our senses, is plain. But what it is, all such talk leaves as dark as before it was uttered.of your toe, if you kick hard enough, the color you see, the savor you taste, and the sound you hear. But matter, of course, is not pain, color, taste or sound, any more than it is yourself or any other self. All these experiences of
And, until recently, science has been as dumb and helpless when confronted by this question, as has common sense. Much is told about the behavior of matter; how fast and far, and when it moves, and what is the result of its impact, etc.; all very interesting and highly useful information. But how anything behaves, what it does, is one thing; what it is is something entirely different. One is reminded of Dr. Johnson's definition of oats, as a grain eaten by men in Scotland and horses in England, except that he does class it as a grain.
Another familiar device of science is to divide and conquer; though in fact dividing does not itself succeed, but merely leads indirectly towards success. "No wonder," says science, "we have not found out what matter is, for matter is very deceptive, and is not at all what it seems. In fact and in truth matter is made up, not of the large bulks we see, but of minute particles, called molecules, in the neighborhood, for the simplest element, hydrogen, of one fifty-millionth of an inch in diameter, and these minute molecules are in turn made up of very much smaller particles, atoms, two to a molecule in some elements, many more than two in others. And observe, we can point out how the atoms are placed in the different molecules, and see how beautifully they shift their places in mystic dance when a chemical reaction occurs. All that happens in the intercourse of matter is at bottom but the interplay of atoms and of molecules. How wonderful is nature, and how searching the discoveries of science!"
All of which is true, indeed profoundly useful truth. For has not science transformed the face of the earth in an incredibly short time, a little over fifty years. And yet how much nearer are we to knowing what matter is when we discover how it is put together? If we ask what wood is, and are told that it is made up of tiny pieces of wood put together thus and so, information, important information, it may well be, is given. But plainly our question is not answered, it is merely pushed a step farther back. In the equations of science, it would seem, matter is represented by an x, whose value is seldom sought. But with everything made out of matter, it is certainly worth the while to search out its intrinsic nature.
Possibly then, since common sense and science appear to be equally unable to say what matter is, the problem is beyond the scope of human powers. May be, as Lord Dundreary says, it is one of those things no fellow can tell. It may be so, but it is well to remember that the discoveries of science have nearly all been things that the faint-hearted said no fellow could tell. Besides, as regards the problem of matter, no philosophic generation has ever been wholly agnostic, and the foremost members of the present and latest scientific generation are not agnostic. And, moreover—a point of especial significance—it is well to remind ourselves that philosophers and scientists, in spite of the difference of their points of view, and of their methods, seem rapidly to be approaching agreement as to the nature of matter. It should then repay us to hear what they have to say.
Insisting, as we have seen, that sensations—colors, sounds, tastes and the rest, are not matter, or any part of matter, philosophers—at least those unconfused by Hume's oversophisticated attack on causes, taken so seriously by Kant—these philosophers, I say, maintain that sensations rightly studied tell us what matter is. Known directly, and indirectly as effects of matter working on our senses, sensations, critically considered, show matter to be a vastly complicated system of active causes, occupying space, that and nothing more. Each material object is thus known to be a group of forces, more or less complicated in their interplay, and varied as to their constituent elements. The forces constituting a living cell are very varied in kind and complicated in interplay, as compared with those composing an equal volume of hydrogen gas; but complicated and varied forces are forces none the less. Moreover, all kinds of matter have one quality in common, the forceful defense of the space they occupy. This is called their solidity or impenetrability. Everything material opposes force to attempted encroachment on its space, and, unless given room elsewhere, absolutely prevents its entire appropriation; though all the forces of the universe pressed upon a single drop of water, it could not be annihilated. Thus impenetrability is the active defense of space. The fundamental constituent of matter is force. And other constituents are the chemical, electrical and remaining physical activities, whose effects are more or less familiar. Nor need philosophers deny that matter is made up of molecules and atoms, or of electrons even, provided always these smaller and smaller particles are admitted to be bundles of forces, occupying less and less extended allotments of space.
Where this view departs from that of common sense, it is simpler, that is all. Common sense says matter is blue, sweet, soft, etc. No, say the philosophers, these are effects, not properties. Again, common sense says, and here with a shrill insistence, Force is not matter, but in it. No, say philosophers, there is no need of complicating with an irrelevant distinction. Force, activity, achievement, that is all there is to matter. As Heracleitus said 2,500 years ago, παντα ῥει, flowing, change, doing is all.
Beyond question the blind force of our nature strongly inclines us to ask for more. But in obeying this prompting we are but worshipping an idol of the tribe, a fallacy patent enough as soon as the nature of the mind is understood. The insistence on something more than force in outer objects registers the triumph of the "imagination," a blind "faculty," as Kant rightly called it, unaware of its own contents and of their significance, over clear-sighted and self-critical reason. Everything we talk of and think about, including matter, is identified, when necessary, and mentally dealt with, by means of its picture stored away in the imagination, which picture appears automatically when its aid is required. Without such counterfeit presentments the mind could not make a beginning of dealing with the objects about it, for their names are not pasted upon them, and besides, the mind is often concerned with them during their absence, and must then have a representative with which to treat. Now, most men picture matter chiefly in visual terms, though partly in terms of touch and muscular feelings, which last are so constantly aroused by the resistance of things. And the fallacy consists in clinging to the picture of matter, naïvely, uncritically, inaccurately constructed before reflection, out of our most familiar sensations, and in insisting that it correctly represents matter, although reason clearly demonstrates that sensations are no parts of matter, but only its effects. And the fallacy continues to impose on us because the picture works in subconsciousness, automatically registering dissatisfaction with force, as failing to fill out its notion of what matter is. As soon as we know that the picture of our imagination is formed during the early unthinking days of our ignorance, we know that it has no proper standing as against the critically tested conclusions of reason. But that does not check the dissatisfaction automatically suggested by the imagination, which philosophers feel in common with other men. The difference is that they disregard the feeling; they refuse to bow down to this idol of the tribe.
The same dynamic view of matter is reached by another avenue of approach, as is pointed out by students of the evolution of mind. Probably the contribution of evolutionary theory to our knowledge of mind that bulks larger than any other is the discovery, growing clearer with each year of study, that the human mind also is fundamentally just a group of activities, greatly complicated, mysteriously unified, wonderfully resourceful, marvelously progressive, self-conscious, moreover, and free, and yet at bottom a system of activities, no more. Activity, doing, will, that is the core of us, the rest, sensation, feeling, idea, they are but the effects of our own or of other activities. A spirit, in etymology, is just the active principle of a liquid: and activity is what distinguishes the quick from the dead. Even superman, in his ascending excellence, we must believe to be but vaster and more skillfully and perfectly ordered activity. And man is distinguished from his humbler brethren, and higher animals from lower, by what they can do. Man hesitates, chooses, plans, contrives and fits things together in fulfilment of his purposes. As we descend the animal scale these activities first diminish, and then disappear, dull routine taking their place. But this implies, not a substitute for activity, merely its simplification. And the same decrease of complexity obtains as the transition is made from animals to plants, and from plants to inorganic matter. This no doubt seems a hard saying to those who have not followed discoveries and discussions in this field; but to those who have it is little more than a commonplace. We do not yet know how inorganic activities become systematized into organic, or what determines their form as vegetable or animal. The cell still keeps its secret. But that inorganic is transformed into organic is plainly shown by every breath taken, every meal eaten, and every development of an embryo to maturity, as the reverse transition is shown by all waste processes, including death itself. As men organize themselves into states, and lesser associations, which have organs and modes of activity which no man has, so, it would seem, molecules organize themselves into cells, and cells into living beings, which differ even more in structure and function from the units composing them.
In substance, then, comparative psychology teaches that a man is a complicated system of activities, sensitive and conscious; an animal a less complicated system, sensitive and conscious; a plant a still less complicated system, sensitive, but only dimly conscious, if at all so; and organic matter, the simplest system of activities we know, whether either sensitive or conscious we are not yet prepared to say. So much is quite plain. But all is not said. It is also plain that inorganic, or so-called dead matter, has, in the way of evolution, developed into organic or living matter, and that matter is being daily transformed into living, yes, into conscious, beings, and living and even conscious beings are being daily transformed back into mere matter. These plain facts of themselves throw not a little light on the nature of matter. For they show that the constitution and the nature of matter must be such as to allow of the development and interchange discovered. Matter can not be very dead, it can not be blankly non-conscious, it would seem, if everywhere and at all times it is, in the ordinary routine of the world, nourishing and stimulating life and consciousness, which in their turn dissolve into mere matter in the same normal way.
Such, too briefly and imperfectly stated, are the contributions of philosophy, and its component and ancillary sciences, to our knowledge of matter. Next we turn to the physical sciences themselves, physics, chemistry and new-born chemico-physics, and find, as will presently appear, a singularly impressive confirmation of the results set forth. This should not surprise us. It merely adds one more to the many instances where philosophy's reasoned conclusions have proved prophetic of the more concretely reached results of experimental science. The former, glancing over the promised land throughout its broad extent, spies out its prominent landmarks, and sets them up as goals to guide the slow and laborious but sure occupation which it falls to the lot of the latter to undertake. Each task yields its own delights, and each performs its peculiar service. Where both are indispensable, only the cramped mind will seek to belittle either.
Nearly two and a half centuries ago, in 1658, to be accurate, Boscovich, the great Italian administrator, diplomat and physicist, set forth and ably defended the view that atoms are but forces, each concentrated in a mathematical point, and held apart by their mutual repulsions. The view did not fail of its adherents, numbering among them names as great as that of Faraday. But even if the prejudices of an imaginative race had allowed it a fair hearing, which they did not, the state of science was not ripe for the general acceptance of the theory. Electricity did not exist for science, and countless hours of research had still to be labored through before a sufficient weight of experimental facts could be accumulated to outbalance our tribal idol. So stiff-necked is an inborn bent of human nature. Besides, Boscovich delayed the triumph of his theory, in its essential principle, in my judgment, by confining his force atoms to mathematical points, and denying them spatial occupancy, the fundamental attribute of matter: a course the more to be regretted, as the denial is unnecessary, indeed contrary to plain experience.
The status of Boscovich's theory, and its more or less modified successors, remained practically unchanged till the end of the nineteenth and the marvelous beginning years of the present century, a few of the best minds of each generation upholding it, but the large majority of physical scientists, including men of unsurpassed eminence, according it a neglect more or less contemptuous. But these recent years have been bringing about a change. A number of physicists of the first rank are aggressively championing the dynamic theory of matter, and as each unexpected discovery, hurrying upon the heels of its predecessor, brings support to the theory, its opponents seem conscious of engaging in a losing fight.
Before passing to the chief evidence, I will just mention some curious experiments of the Hindu physicist, Dr. Bose, a professor in Calcutta University, which indicate the trend of the more advanced research that is now being prosecuted, and indirectly support the dynamic theory, by tending to show that metals, at least, are not dead, but alive, bundles of activities like living animals. Dr. Bose's book, "The Response of Matter," I have not been able to secure; the quotation that follows is from a notice of it in the London Review of Reviews. Dr. Bose's discovery is, that stimulated metals give back, under proper conditions of observation, the electric response that has been thought peculiar to, and characteristic of, organic or living matter, and, with variation of conditions, vary their response just as organic matter does:
But it is not upon such experimental curiosities that the dynamic theory of matter is based, significant as they may be of the future discoveries of science. It is more substantially founded upon the evidence of the spectroscope, the fast-growing knowledge of electricity, and the marvelous results of the experiments on radio-active substances. Recent publications have made these facts familiar, and it will only be necessary to recall them briefly, grouping them in such wise as to suggest their significance as clearly as possible.
There has been a disposition among scientists for the last half century, growing constantly stronger, and finally becoming nearly irresistible, to look upon Dalton's atoms as divisible, therefore misnamed, and not the ultimate constituents of matter. Suspicion was first cast upon their simplicity and ultimateness when the spectroscope disclosed several distinct lines in the spectrum of each element; and was reinforced when it appeared that some elements had two or even three distinct spectra. Nor was the case bettered when it was found that many of the lines in the spectra of hydrogen, calcium, iron and other elements are missing when the light from very hot stars is broken up. For the inference is right at hand, as Professor Bigelow says, "that at extreme, at stellar, temperatures our elements themselves arc dissociated into simpler substances."
Further evidence against the atom resulted from Professor J. J. Thomson's studies of cathode rays, strict reasoning from his careful experiments demonstrating them to be swarms of minute particles, or corpuscles, as he called them, moving with velocities approaching that of light, and each weighing about one eight-hundredth as much as a hydrogen atom. These corpuscles are not merely ordinary atoms of smaller bulk, for they do not obey chemical laws, it having been ascertained, among other things, that the absorption of them by different substances is simply proportional to the latter's specific gravity, and quite independent of their chemical properties.
And recently the case against the atom, together with Thomson's ingenious demonstration of his corpuscles, has secured further experimental foundation, thanks chiefly to the labors of Becquerel, the Curies, and Rutherford and Soddy, on radioactive substances. These wonderful experiments, at once rapid and reliable, have shown that radioactivity consists in the throwing off of two orders of substances: first, atoms; second, rays or corpuscles of various kinds. But the remarkable fact in the situation is that while the atomic weight of the original substances, radium, thorium and uranium, is two hundred or more, the weight of the atoms thrown off is nearer one or two. That is, radium breaks up into, probably, helium, thrown off, and the residuum after the emission, which has a different atomic weight from either and is otherwise shown to be a distinct element. The dream of the alchemist has come true and elements are transmuted before our eyes. Science has achieved an unsurpassed triumph! But, as far as helping us to fortune goes, the dream might as well have remained a dream.
As a result of these discoveries, and many others similar, in general, in significance, it has come to be admitted that Dalton's atoms are very complex bodies, each made up of a large number of corpuscles, which are related to one another very much as are the members of a planetary system, though in size corpuscles are unimaginably minute, and the number of them constituting any atom is very much larger than the number of members in any planetary system with which we are acquainted.
With atoms broken up into corpuscles, the problem of the nature of matter shifts one step farther back, and becomes the problem of the nature of these tiny bodies. Of this problem two rival solutions are now in the field, offered respectively by the conservatives and the liberals. The former, while admitting that a corpuscle is in the main an electric charge, or field of electric force, maintain that the charge has a nucleus or carrier at its core, which alone is entitled to be called matter, in distinction from the electricity of the charge. Lenard, who has given to corpuscles the significant name of dynamides, has calculated the diameter of this center of actual matter, so called, and found it to be smaller than 0.3 of 10-10, i. e., smaller than three hundred thousand millionths of a millimeter. This means that the actual matter, so called, of a cubic meter of so heavy an element as platinum, occupies at most one cubic millimeter of space, the rest of the cubic meter being empty of Lenard's matter, and in fact entirely empty of ponderable matter, but for the electric charges.
With so much of matter acknowledged to be electric force, which to that extent successfully performs all the functions which used to be attributed to matter, it is natural, say the liberals, to inquire whether the whole of matter can not be reduced to force, whether matter is not just force and nothing more. Many facts, they say, make this altogether the more probable, indeed the only comprehensible, hypothesis.
In the first place, as Sir Oliver Lodge, who shares with Professor J. J. Thomson—another hard-headed Englishman—the distinction of leading the liberals, points out, "an electric charge possesses the most fundamental and characteristic property of matter, viz., mass or inertia." If the charges occupying a given space are sufficient, and their potential is sufficiently high, their combined mass will equal, and exhaustively account for, the observed mass of the matter occupying the space. This conclusion was theoretically established long since, and has recently received experimental confirmation from laboratory studies on radio-activity.
On these points, I quote the statement of Professor Bigelow, of the University of Michigan:
This might be looked upon as an interesting mathematical abstraction, but without any practical application, if it were not for the fact that Kauffmann determined the apparent masses of corpuscles shot out from a radium preparation at different velocities, and compared them with the masses calculated on the basis that the whole of the mass was due to the electric charge. The agreement between the observed and calculated values is so close that it leads Thomson to say: "These results support the view that the whole mass of these electrified particles arises from their charge."
Then the corpuscles are to be looked upon as nothing but bits of electric charges. . . . It is this view which has led to the introduction of the term electron. . . . We have but to concede the logical sequence of this reasoning, all based on experimental evidence. . . and we have a universe of energy in which matter has no necessary part.
Facts as many and as significant as these, added to the reasoned conclusions of philosophy and psychology, would seem adequate to settle the controversy in favor of the dynamic theory of matter, were it not that we are dealing with an idol of the tribe, far more difficult to shatter than the golden calf. But more remains to be said. The validity of a hypothesis rests not only upon the facts that support it, but also upon the ability it gives us to explain puzzles in fields adjacent to its own. This makes it worth while to mention, though space will not allow explanations in detail, that a number of knots in physical theory, that before had to be cut or else left alone, can be handily untied by the dynamic hypothesis. Professor Bigelow is again my authority in the statements, that the theory explains the highly puzzling property of valence, and that "An electronic structure of the atom furnishes a basis from which a plausible explanation of the refraction, polarization and rotation of the plane of polarized light may be logically derived." These explanations bulk large in the aggregate, and the exclusive ability of the dynamic theory to make them adds significantly to its credibility.
As an alternative to the dynamic theory, thus substantially supported, the conservatives have little to offer, indeed, in the last analysis, nothing but a word. The "matter" they refuse to identify with force shrinks down to John Locke's "something, I know not what," by which a portion of the mass of bodies is to be accounted for. But, Sir Oliver Lodge remarks, "it would be equally true to say unaccounted for. The mass which is explicable electrically is to a considerable extent understood, but the mass which is merely material (whatever that may mean) is not understood at all." "What is this matter which so many insist we must assume?" Bigelow asks, and answers:
When solidity, and mass or inertia are adequately explained as dynamic facts, and many puzzling physical facts are similarly accounted for, it is surely superfluous to seek further explanation in something more to be called matter, especially when no man can tell or ever has told us what he means by the word.
This is not the place to set forth what we know about electric charges, but some mention should be made of the unification introduced into our knowledge by accepting these minute bodies as the building stones of the grosser structures more immediately experienced.
A word first as to their size:
He proceeds a little later:
On this view all elements would be regarded as different groupings of one fundamental constituent. Of all the groupings possible, doubtless most are so unstable as never to be formed; but some are stable, and these stabler groupings constitute the chemical elements that we know. The fundamental ingredient of which, on this view, the whole of matter is made up, is nothing more or less than electricity, in the form of an equal number of positive and negative electric charges.
This, when established, will be a unification of matter such as has through all the ages been sought: it goes further than had been hoped, for the substratum is not an unknown and hypothetical protyle, but the familiar electric charge.
To an active imagination the dynamic theory opens up fields fascinating to contemplate. Look first at the practical side. Aside from energy of gross position and molar motion, we are accustomed to think of heat and other forms of chemical energy as the only ones available for human use. But Wetham tells us that:
And later that:
Admitting that our coal measures and iron mines may in time give out, it is evident that the present generation need not feel greatly alarmed. For who will deny to ingenious man the ability to harness these literally stupendous new forces as he has their weaker predecessors?And on the theoretical side the gain is no less great. A respectable hypothesis, which experimental, and even laboratory methods can test, correct and enlarge, as growing experience demands, can, even in its initial form, give unity to our thinking. It not only reduces the independent chemical elements to brotherhood in the one mother substance, but it renders matter, as essentially activity, homogeneous with active mind, thus freeing us from the hopelessness of dualism, and giving a monistic view of the whole of things. And nowhere is utter death to be found. The universe, active through and through, comes out from under the heavy hand of rigid mechanism. Spontaneity is at its heart, and in the marrow of its bones. But lawless and chaotic it is not. There is regularity in the operation of its minutest parts, and organization, harmonious coworking is the law of its being, from the cooperative union of electrons into atoms to the organization of men into societies, and possibly farther still. But the order and harmony are not imposed from without by an alien power; as the laws of children's play, they are the natural rules of behavior of spontaneous beings, following, unhampered by others besides themselves, the promptings of their interacting natures.
- Presidential address before the Texas Academy of Science, revised and adapted.
- Nothing more so far as sensations of the special senses can help us to know the intrinsic nature of matter.
- Some would prefer the term "energy," others "activity." I know of no satisfactory term; but the thing denoted is real, many and baffling as are the mysteries it contains.
- Popular Science Monthly, July, 1906.
- In a communication to Nature, July 18, copied in Science, August 2, Sir Wm. Ramsay states that copper, in the sulphate, acted upon by the emanation from radium, was "'degraded' to the first member of its group, namely, lithium." The substance of the quotations that appear later in this paper could be found repeated many times in the writings of Thomson, Ramsay and others of the new school at home and abroad.
- Popular Science Monthly, August, 1903.
- Popular Science Monthly, July, 1906. Instead of conceiving matter as explained away, energy taking its place, I prefer to conceive of it as explained as being energy and nothing else. This difference in terminology is unimportant, but might lead to confusion if not pointed out.
- Loc. cit.
- Loc. cit.
- Loc. cit.
- Popular Science Monthly, August, 1903.