Return to Physics of the Ether
1. The influence of the theory of "action at a distance in physical science is well known, and need not be commented on. We shall proceed to examine this theory briefly. If our manner of dealing with the subject be somewhat broad or plain-spoken, this is with the view to clearness, our aim being simply to arrive at truth.
Firstly, this theory assumes that one mass of matter can move or act upon a second mass of matter, placed at a distance, without the intervention of material or physical agency; or the theory assumes that a mass of matter might be surrounded to a considerable distance by absolutely empty space, and yet that the mass might be put in motion without the penetration of matter in any form into this empty space surrounding the mass.
We will take the case termed "gravity." Here it is assumed that a mass of matter can be accelerated or put in motion at different rates by a simple change in its position in empty space, by which its distance from a second mass is varied, without the necessity for the presence of a medium or anything whose physical condition might be affected by the variation of distance between the masses, i.e. without the necessity for the presence of matter or any material means to produce and regulate the different degrees of energy with which the mass is acted upon in different positions; or it is assumed that the mass can be acted upon or moved with different degrees of energy (found to have a somewhat complicated relation to the relative distance of the masses), without the presence of any material means to regulate the varying energy with which the mass is acted upon in the different position: in short, a mass of matter may be wandering about in space some thousands of miles away from anything to control its motions, and yet it is assumed that the mass, by simply passing from one point of empty space to another, can have its velocity adjusted in pro- portion to the square of its distance from another mass. We can imagine nothing more opposed to reason than this, if the question be fairly looked at.
It is important to distinguish between the fact of this exact adjustment taking place, and the cause, for no one doubts the fact; but the theory would assume that there are no varying physical conditions about the mass required to produce the varying effects; or, in other words, that by a mere change of distance the physical effects can vary, without the physical conditions about the mass having undergone any change. Surely the only conceivable way in which the mass could be differently affected at different distances, would be by the presence of something about the mass, whose physical condition might be affected by the distance, for the mass itself cannot possibly be physically affected by the distance.
2. It is sometimes said that this is a "property" of matter or a "law" as if to imply that this in itself constituted a reasonable basis for the assumption or theory, but it is clear that this is merely to assume that it is a fact; for of course a mass of matter may be readily assumed to have the property of doing anything, how- ever incredible; but this would be only assuming the thing to be a fact without a reasonable ground to support the assumption.
Surely, if a thing be stated to be practicable, the least to be required is that some idea should be formed of the means by which the result or mechanical end is to be attained, and this perception of the means constitutes the sole ground to support the assumption as to practicability. If, on the other hand, a thing be assumed to be practicable without any perception of the means, then the assumption falls away of itself from want of ground to support it.
It may be said to be a law or property of light to vary as the square of the distance, but this does not render less essential the existence of regulating physical conditions to produce this special mechanical effect.
Again, in the case of the movement of approach of two masses towards each other, it is sometimes said that the one mass "attracts" the other, or that it is due to "attraction," as if to imply that this constituted in some way an explanation of the effect. To constitute an "explanation," however, something at least must be added to our present knowledge. Before this phrase "attraction" was applied, the remarkable effect was observed that two masses of matter exhibited a tendency to move towards each other, and when free to move, moved towards each other, without anything being known as to the cause of this effect : after the application of this phrase "attraction" the same effect was observed with no further addition to knowledge, so that the application of the mere phrase evidently can teach nothing. It is of course necessary to have some phrase as a convenient means of reference to the case, and the term "attraction" may serve as well as any other; just as the term "repulsion" serves to refer to the opposite movement; as, for example, the repulsion of a pith ball by an electrified body; but to assume that this term gave any insight into the cause of the movement would be very like assuming that the repulsion of the ball was due to repulsion.
A vibrating tuning-fork is known to attract a piece of card, or to cause a piece of card to exhibit a tendency to move towards it; but the term "attract" can evidently give no insight into the physical cause. The same considerations apply as regards the remarkable tendency exhibited by a piece of iron to move towards another piece when in that special physical state termed the magnetic state. The phrase may be varied at will, and can avail nothing, so long as no clear idea is formed of the means by which the mechanical end is attained. Before the atmospheric pressure was recognized, a pump was considered to have some mysterious power of drawing fluids, and the effect was sometimes said to be due to " suction." It is an observed fact that the molecules of a solid hold together in a state of cohesion; or, although these molecules are wholly unconnected and a certain distance apart, they are nevertheless maintained in positions of stable equilibrium, so that a certain resistance is encountered when the attempt is made to move them to a greater distance apart. This resistance of the molecules to separation is sometimes said to be due to "cohesion," which certainly would have the appearance of implying that the cohesion of the molecules was due to cohesion. It is unquestionable that a certain abuse of terms or phrases exists, which appear in some cases to take the place of physical causes. The term "chemical affinity" affords another example, of which others might be given. 3. There is another point in connection with the theory of "action at a distance." It is assumed that time is not required for the effect at a distance to be produced. Thus, if we take the case of an electromagnet and a piece of iron at a distance : then when the electromagnet is suddenly put in the " magnetic " condition by the electric current, it is assumed, in accordance with this theory, that the agency by which the distant piece of iron is put in motion requires no time to pass from the magnet to the iron. Now surely for the piece of iron to be affected, the agency, whatever it be, producing the effect, must cross the intervening interval to get at the iron; and how can it be assumed that no time is required for the transit? It is difficult to see how this would avoid the absurd postulate of an infinite velocity, the speciality of which would be that that which passes would require to have the peculiar property of occupying the beginning, the end, and every inter- mediate point of its path at the same instant. What is it that the theory really means to put forward? Is it an admission of spiritualism ? If it be assumed that intervening matter is here not concerned in producing the movement of the piece of iron, then how is the implied inference as to the intervention of spiritualistic agency to be avoided? There can be no question that this theory is distinguished for a remarkable vagueness, and a complete absence of demand for the exercise of the intellectual powers. Can it be said, and if so in what respect, a clearer idea admits of being formed of the means by which motion is produced, when it is referred to "action at a distance,", and when it is referred to "psychic force." One noteworthy point in connection with theories of a vague nature is, that their very vagueness, in which their real weakness consists, is employed as a defense against argument: hence the long life of such theories.
4. Another important consideration in connection with the theory of "action at a distance," is the practically unlimited application of which such a principle admits. It is a point very generally recognized that all physical phenomena or effects are effects of motion, or that physical phenomena, whatever their diversity, are all correlated in this fundamental respect. I£ there- fore, the principle be once conceded that motion can take place without physical agency, or that the mere presence of a mass of matter suffices to produce motion, then how is it possible to know what might not occur, since all physical effects are effects of motion, or how could there be a rational guide or regulating principle to physical causation left?
In fact, the very movements to which this theory of "action at a distance" is chiefly applied, viz. the movements of approach and recession of masses and molecules of matter, constitute the fundamental and most important movements concerned in the working of physical phenomena. If, moreover, these movements may vary in energy at different points of space, or at different distances, without regulating physical conditions, as this theory supposes, then what result might not be attained by the free application of this theory, which from its very nature may be made to include all physical phenomena?
One of the most palpable facts to any impartial observer will be the extraordinary number of hypotheses that do exist regarding the working of physical phenomena, all built upon this principle or theory; in fact, the principle from its very nature admits of an endless variety of applications, and from the vast number of hypotheses which present themselves by a recognition of this theory, a certain and final solution to a physical problem is rendered impossible. In fact, the very fertility of resource given the fancy by this principle renders the problem insoluble. In short, it must be plain that a principle which would put physical causation under the control of phantom agencies, and which allows physical effects to be brought about much according to the fancy, itself completely precludes the possibility of determining what the facts are.
5. There is another point in connection with this theory. If all physical phenomena or effects be effects of motion, and if, in any case when motion is observed to take place, a rational cause or process capable of being appreciated by the mind is required; then, as a point of principle, why should not such a cause be required in all cases, since all cases are fundamentally of the same kind; or how can it be logically consistent to draw distinctions when the principle involved is the same?
Thus, if it be considered as a point of principle inconsistent or even absurd to assume that the heat (motion) produced in a focus of invisible heat rays has been developed without material or physical agency; then as a point of principle must it not be equally absurd to assume that the motion produced in a distant pith ball by an electrified body has been developed without physical agency?
6. Again, if all physical effects be effects of motion, then, iu principle, the one fundamental cause for investigation must be the cause of motion, or the cause determining the vast variety of motions constituting physical phenomena. To admit, therefore, a theory which would do away with the necessity for investigating the cause of motion, would be to admit a principle which, if carried out universally, would close the field for physical research altogether, or which would assume that physical effects were inexplicable; for if every motion were referred to this theory of "action at a distance," there would be no realizable physical cause left to investigate; and the course taken would be simply to observe physical efferts, and to apply this theory, without making thereby one practical addition to knowledge as regards physical causation. We merely put forward that this would be only carrying out in its entirety a principle which has already been carried out to a very great extent.
Thus, for example, all the varied and remarkable effects of chemical action, or those remarkably diverse movements of molecules which constitute the science of chemistry, are all referred in one great whole to this theory of '* action at a distance." According to this theory, it is supposed that no rational cause capable of being appreciated by the mind exists or is necessary to explain why one molecule should move towards another; should move from a second, or should be indifferent towards a third molecule. Here the effects are most complicated, and yet take place with the utmost precision and regularity in every instance; in short, it would be difficult to conceive of any case where the presence of a regulating physical agent, or a controlling physical cause, unalterable in its nature, is more needed than here.
The direction of the movement may even be reversed at a certain point of space. Thus, to take the case of the component molecules of a solid for example : then these molecules resist an attempt to separate them, or to move them to a greater distance apart. But when these molecules have been separated, such as when a solid has been broken into two parts, then the molecules resist an attempt to make them approach, or the two parts will not readily unite again by pressure. Hence it must follow from this, as a remarkable fact, that the direction in which the molecules tend to move changes at a particular point of space : the molecules being urged towards each other when placed inside this pointy and urge! from each other (separating) when placed outside this point. If there be no explanation required for this, then one might inquire if there be such a thing as an explanation required for anything.
7. There is another aspect in which this theory of " action at a distance " may be viewed, although we cannot out submit that the above arguments constitute in themselves sufficient and reasonable grounds for the rejection of the theory. However, as we would not neglect any material point that might serve to throw a true light upon the subject, we will, in conclusion, briefly examine the theory of "action at a distance" in connection with the principle of the conservation of energy; it being evident that two principles so intimately connected with the working of physical phenomena must have a direct and important bearing upon each other.
It is an admitted fact that energy is indestructible. For the purpose of practical illustration we will suppose a special case. We may imagine the charged metallic conductor of an electric machine and a pith ball, the arrangement being supposed such that the movement of the ball towards or from the conductor can take place with perfect freedom, or entirely without hindrance, the ball being supposed, by any convenient means, prevented from coming into actual contact with the charged conductor. Then, as is well known, when the conductor is charged, or put in the "electric" condition, the pith ball would be impelled towards the charged conductor, or "attracted." If allowed to come into contact with the charged conductor the ball would be impelled from the charged conductor, or " repelled." It is quite indifferent whether we consider the movement from or the movement towards. We will accordingly take the movement towards, and suppose that the ball is prevented from coming into actual contact with the charged conductor, and therefore tends continually to move towards the conductor.
If, then, we suppose that while the ball is in the nearest proximity to the charged conductor a sharp blow or impulse be communicated to the ball, so as to impart to it a certain initial velocity which would carry it away from the charged conductor, then the ball would rapidly lose the motion imparted by the impulse; the ball would at length come to rest, and would then recoil or return, with freshly acquired motion, towards the charged conductor.
8. Now the question at once suggesting itself would be, how was this motion imparted by the first impulse lost by the ball, or what has become of this motion? If the theory of "action at a distance" cannot account satisfactorily for the disappearance of this motion, then, on this one ground alone, this theory would have to be abandoned, and the necessary inference would at once follow, that since in accordance with the principle of conservation this motion lost by the ball cannot have been annihilated, or cannot have gone out of existence spontaneously, that, therefore, this motion must have been transferred to matter; and secondly, therefore, that matter must exist in the vicinity of the ball and electrified conductor.
These two deductions would be absolutely necessary; for, in the first place, in order for the motion given up by the ball to exist, this motion must have been transferred to matter; and secondly, for the motion given up by the ball to be transferred to matter, matter must exist in the vicinity of the ball.
It is unnecessary to add that it is a known fact, that the ether exists in the vicinity of the ball, occupies the intervening space between the ball and charged conductor, and therefore forms a connecting link between the two, the ether even pervading the molecular interstices of both. Moreover, it is a very generally recognized point, that " electricity " must be some form of motion, which motion could not possibly take place without disturbing the ether. However, independently of these considerations, and of the known fact of the existence 01 the ether, the deduction that matter did exist in the vicinity of the ball, to which the motion could be transferred, would be none the less a necessary one, following directly from the principle of the conservation of energy.
It is important, therefore, to note the intimate bearing which the principle of the conservation of energy has upon the theory of " action at a distance," it being observed that the principle of conservation requires absolutely that matter to which the motion can be transferred must be concerned in bringing the ball to rest; while, on the other hand, the theory of "action at a distance " assumes that matter is not concerned in bringing the ball to rest, so that the principle of the conservation of energy being admitted, the theory of " action at a distance " would have to be abandoned.
9. In preference to taking this plain and straightforward course, however, and then proceeding to investigate the special physical conditions concerned in bringing the ball to rest, the vague theory has been advanced that the energy given up by the ball has assumed a different form which is not motion, or the motion lost by the ball has been converted into something else, or the motion is said to have been converted into " potential energy," so termed; and further, it is assumed that, although the motion has been transferred to nothing, yet by some unexplained process, on account of the motion lost, the ball has acquired the power of returning by itself to the electrified conductor at any future time, without the intervention of physical agency.
10. Before considering this further, we may just give an illustrative example, serving to show that in a case where the controlling physical conditions are supposed unknown, precisely the same appearances would present themselves as in the case of the electrified conductor and pith ball. We may imagine the case of a mass of matter suspended freely, and which tends to approach another mass, under the action of invisible matter in motion, in any form (such as, for example, a concealed jet of air) which impinges continually in the rear of the mass. Then one mass of matter, tending to approach another without a visible cause, the appearance here presented would, therefore, be precisely that of a case where the theory of " action at a distance " is applied, and by applying this theory here (the physical conditions being supposed unknown) the assumption would be, that the tendency exhibited by the mass to approach was due to "attraction." If, in an analogous manner, an impulse be supposed given to the mass in a direction opposite to that in which it tends to move, then the mass rapidly loses the motion imparted by the impulse, comes to rest, and finally recoils or returns, with freshly acquired motion, by the same path. The motion lost by the mass of matter during its recession was transferred to the rebounding molecules of the invisible air-jet; the motion acquired by the mass during its return having been (conversely) transferred from the molecules of the air-jet to the mass.
Here, therefore, it may be observed that precisely the same effects present themselves as in the previous illustrative case of tie electrified conductor and pith ball, which exemplifies the general case where the theories of "action at a distance" and " potential energy " are applied. If, therefore, we apply this theory to the case of the mass and air-jet (the physical conditions being supposed unknown), then the assumption would be that the motion lost by the mass during its recession, although not annihilated, and ceasing to exist in the mass itself, was nevertheless not necessarily transferred to anything else; but that this motion took up a different form (" potential energy," so termed), and that thereby the mass of matter acquired the power of recoiling or returning through the same path, without the intervention of physical agency, the something which is not motion being assumed to be converted back into motion at the recoil of the mass.
11. If, now, the above theory appear wholly vague and quite inadequate to replace the controlling physical conditions, after these controlling physical conditions have been recognized (as in the above case), then, as a point of principle, the theory can be none the less open to objection in the case of a similar effect, where the existence of controlling physical conditions is not apparent; or, in other words, if the necessity of controlling physical conditions to produce a given physical effect appear obvious, after their existence has been recognized, then the necessity for the existence of these controlling physical conditions cannot be less imperative in the case of a similar effect, where their existence is not recognized; and surely it must be an important point to recognize the necessity for the existence of a
thing before it makes itself apparent, for this is the sole means whereby the attention can be directed towards its discovery.
12. In fact, this theory of the existence of "potential energy," or an energy without motion, in regard to vagueness, cannot be said to differ from the theory of "action at a distance," which it is intended to support, the same system of procedure being adopted, viz. that of assuming a thing to be practicable, where the sole ground upon which the assumption as to practicability can rest — a conception of the means — is wanting. How can it be possible to guard against error, when such a system of procedure is adopted, if, indeed, it be not very like drifting into error? Nothing can be easier than to put forward assumptions of this character, and at the same time nothing is more certain than that there is no teaching of nature, however plain; no truth but what is subject to be disguised by such a system of procedure. The theory, indeed, conveys no definite idea of the nature of the form which the motion is assumed to have taken up.
The very assumption of the existence of energy in a double form, or the attempt to attach two ideas to the fundamental conception energy, or to assume that two kinds of energy exist, cannot but be regarded by itself as sufficiently questionable.
If in the illustrative case of the electrified conductor and pith ball we disregard, as in accordance with the theory, all influence of the presence of the ether or of anything to which to transfer the motion of the ball; then when the ball comes for an instant to rest previous to its recoil, we have only matter •at rest and empty space, yet the theory puts forward that the assumed form which the motion has taken up exists here; and further, that this form resolves itself back into motion at the recoil or return of the ball, it being assumed in accordance with this theory that the presence of matter or of a physical agent, is not required to* transfer the motion to the ball at its recoil.
It would be surely difficult to imagine anything more vague than this, or any assumption or theory where the absence of a reasonable ground or basis to support it is more apparent than in this case; in fact, the theory may oe well compared in this respect with the connected theory of " action at a distance," it being also well to observe, as a noteworthy and significant fact, the intimate dependence which exists between these two theories, the abandonment of either involving the abandonment of both.
It is moreover impossible to doubt that the question as to whether these two theories are admissible or not, admits of being finally decided as a point of reasoning, for there can exist but one correct method of viewing any subject or question whatever.