On the Origin of Force
In famous publications, On the Origin of Force (LH:4) is an 1865 article by John Herschel which digresses on force in respect to energy, amid which he ridicules the new term "potential energy" (Rankine, 1853), speculates on mind and matter (§9), and vital force in respect to will, along the way rejecting the "conservation of energy" model (§10), in favor of the "conservation of force"; the gist of the article being an attempt to argue that the "force of the mind" is distinct and an antonymous in the universe, operating on its own accord, albeit without saying so directly.
In 1865, John Herschel, in his “On the Origin of Force”, attempted to digress on “volition” and human “will”, in the context of the physical forces of nature, the underlying aim of which is to defined "vital force" theory, i.e. that mind cannot be explained by the physico-chemical forces; amid which he called William Rankine’s 1853 term “potential energy” (§10) an “unfortunate” coining, insomuch as it “goes to substitute a truism for the announcement of a great dynamical fact”, declared the "conservation of energy" invalid, and advocates "vital force" theory.
In 1867, Rankine, with his "On the Phrase Potential Energy", refuted Herschel, and therein gave a cogent etymology of the term "potential energy", and the difference between "force" and "energy", definitively.
In 1865, Herschel, in his “On the Origin of Force”, opened to the following quote::
- “Mens agitat molem et magno se corpore miscet.”
- “The mind moves mass and mixes itself with a large body.” [English]
- — Virgil (c.25BC), Aeneid (§6: Transmigration of Souls, lines, 724-)
Then gives the following article:
|What is it that we ought to understand by the theory of any natural phenomenon! This is a question not without its importance when we are told, as we so frequently are, that it is useless to inquire into causes: that, in fact, causes are to us as though they were not; seeing that all we can ever attain to is the observation and registry of constant laws of phenomenal sequence in other words, that phenomenon succeeds phenomenon, event event, according to certain rules, which are all we have any business to inquire into.|
|It is unfortunate for this doctrine that within the range of every individual's momentary experience there occurs the phenomenon of volition; and that there are large classes of phenomena, and those most important ones, which, we are quite sure, take place in virtue of such volitions, and without which we are equally sure they would not take place at all. In that peculiar mental sensation, clear to the apprehension of every one who has ever performed a voluntary act, which is present at the instant when the determination to do a thing is carried out into the act of doing it – (a sensation which, in default of a term more specifically appropriated to it, we may call that of effort) – we have a consciousness of immediate and personal causation which cannot be disputed or ignored. And when we see the same kind of act performed by another, we never hesitate in assuming for him that consciousness which we recognize in ourselves: and in this case we can verify our conclusion by oral communication.|
The first step in the way of generalization thus taken, the next is obvious enough. Though a flight rather than a step, it forces itself on our thoughts with ever-increasing cogency, the more it is dwelt upon, and the more utterly abortive all attempt to render any other account of that deep mystery of nature-mechanical force — is found to be. Whenever, in the material world, what we call a phenomenon or an event takes place, we either find it resolvable ultimately into some change of place or of movement in material substance, or we endeavour to trace it up to some such change; and only when successful in such endeavour we consider that we have arrived at its theory.
In every such change we recognize the action of ‘force’. And in the only case in which we are admitted into any personal knowledge of the origin of force, we find it connected (possibly by intermediate links untraceable by our faculties, but yet indisputably connected) with volition, and by inevitable consequence, with motive, with intellect, and with all those attributes of mind in which-and not in the possession of arms, legs, brains, and viscera-personality consists. In limiting thus the domain of physical theory, we keep on the outside of the apparently interminable discussions and difficulties as to the origin of the will itself, which seem to have culminated in some minds in the denial of volition as a matter of fact, and in the dictum of Judge Carleton (1863), that what men term the will, is “simply a passive capacity to receive pleasure from whatever affects us agreeably at the time.”
|It may, however, be said, and indeed there are not wanting those who appear very much disposed to say, if not totidem verbis [so many words], at least by strong implication, that the conception of force itself, as part and parcel of the system of the material universe, is superfluous and therefore illogical. They argue thus. All we know of material phenomena, it is true, resolves itself into the transference of motion from matter to matter. This, however, may be effected by mere collision. Now, when A strikes B, and motion is thereby communicated from A to B, why not at once admit this as a sequence? Why interpose an unknown agent, or intermedium, force, as part of the process? Having come to regard heat, light, electricity, and the “imponderables” generally, some upon more, others on less, cogent evidence, as “modes of motion,” they seem to consider force itself as included in the same category, and think there is reason to believe that it depends on the diffusion of highly-attenuated matter through space.”
This doctrine goes to resolve the entire assemblage of natural phenomena into the mere knocking about of an inconceivable number of inconceivably minute billiard balls (or cubes, or tetrahedrons, if that be preferred), which once set in motion and abandoned to their mutual encounter and impact, work out the totality of natural phenomena. With the amount of forethought and intelligence called for in the initiatory disposal of the place and movement of every individual of this multitude; to work out for countless ages the orderly sequence of observed facts, by their blind conformity to the laws of collision, those disposed to adopt such a view of nature would probably concern themselves little. Their actual disposal at the present moment is a fait accompli; and from this point it would be possible, at least in imagination, if we knew the present position and movement of every particle of matter in the universe, to work backwards, up to any epoch which we might choose to assign as that of creation, by a simple reversal of the velocity and direction of each:-nay, having thus uncreated the world, the molecules would of themselves work out a pre-existent order of things into all past eternity: an image of what might have existed in the past (though it did not) seen, as it were, reflected in the future.
|This simplification (if such it be) of our view of material action is altogether untenable; nor will it be difficult. I think (and certainly not superfluous), to show that such an arrangement must of necessity be rapidly self-destructive, and must result in the gradual but speedy dying away of all relative motion, and the reduction of the universe either to a single block of matter moving uniformly on, for ever, in one direction, without relative motion of its parts; or else in the dispersion into space, and absolute final dissociation of its molecules.|
|For, be it observed, force (except in the sense of bodily extrusion) being non-existent, our billiard-balls must of necessity be supposed inelastic. Elasticity implies force. If this be disallowed, if elasticity be not force, but collision, each billiard ball (each ultimate atom, that is to say) must be itself a universe in miniature composed of other more minute ones, moving and colliding, inter se to give them that resilience which we term elasticity, but which, in this view of the matter, is nothing but “clash.” Now what is to prevent these ultimate atoms of the second order, animated with velocities immense, as compared with their mutual distances, coercea [restrained or coerced] by no mutual attractions, subject to no control but from their mutual collisions; from dispersing themselves out in all directions into space and abdicating their functions as a group? If we waive this objection (which, however, is fatal) nothing is gained. The original objection applies in its full force to these sub-atoms, and so on ad infinitum.|
|Now, in the collision of inelastic bodies, vis vita is necessarily and invariably destroyed. The destruction may be total, or may fall short of totality in any proportion according to the directness of the impact, and the proportion of the moving masses; but whenever contact occurs between such bodies, vis viva disappears, and, once lost, is gone for ever. Taking such a system in its entirety (where force exists not), there is no possibility of its reproduction. There is therefore a necessary and unceasing drain on the vis viva of such a system. Everything which constitutes an event, whatever its nature, exhausts some portion of the original stock. Such a system has no vitality. It feeds upon itself, and has no restorative power. All relative motion in it tends rapidly to decay, or at all events to a final state, when there will occur no more collision, i.e., when phenomena cease altogether; when the minimum of vis viva consistent with the conservation of momentum is attained; and nothing remains but either a single caput mortuum [dead head], journeying through space, or a multitude of such, travelling different ways; having parted company never to meet again.|
|It will of course be urged that this reasoning takes for granted the law just mentioned of the conservation of momentum estimated in any given direction: since we cannot assert à priori that two inelastic bodies, after collision, must move on with a common velocity and unchanged joint momentum. Of course it does so. But the object of the hypothesis we are combating is to exhibit collision as a substitute for force; i.e., to give an account of the acknowledged laws of motion without introducing the conception of force. We are therefore justified, when arguing against it, in assuming all the results of those laws as established truths: they being, in effect, the very things which the hypothesis is framed to account for. The law in question, constituted as the material universe is, is absolute and universal: and no view of matter and motion can be a true one which is incompatible with it.|
|The inward pressure of an etherial medium surrounding the sun upon the earth and planets, suggested by Newton as a mode of escape from the metaphysical difficulty of attraction at a distance, is either only another form of the collision theory above combated, or an evasion of the difficulty by substituting repulsive for attractive force. If the ether press by its elasticity, besides supposing its particles endowed with the necessary amount of repulsion; what, it must be asked, but a repulsion emanating from the sun (and thereby equilibrating and rendering ineffective its inward pressure) is to keep it from rushing in on all sides, and destroying that inequality of density on which its supposed inward pressure depends? If not, its agency must be simply that of an inert resisting medium, rendering the continued revolution of the planets round the sun impossible, and causing them, while it lasts, to rotate on their axes in a direction contrary to that of their orbital motion, as a direct consequence of the more rapid abstraction of motion from their outer than from their inner hemispheres.
The hypothesis of Le Sage [c.1770] which assumes that every point of space is penetrated at every instant of time by material particles, sui generis, moving in right lines in every possible direction, and impinging upon the material atoms of bodies; as a mode of accounting for gravitation, is too grotesque to need serious consideration; and besides, will render no account of the phenomenon of elasticity. Besides this, I am not aware of any other attempt to embody in a tangible form the notion of a substitute for the conception of dynamical force arising out of the elementary conceptions of motion and inertia. There is a tendency indeed, of late apparent, to attribute the elastic pressure of a gas on its containing envelope, as due to the collisive shock of its particles conceived as existing in a continual state of vibration, or of circulation round each other. But the maintenance of such vibrations or revolutions involves the supposition of inter-molecular coercive forces, and is not, therefore, to be classed with such attempts.
|If it be true, then, that the conception of ‘force’ as the originator of motion in matter without bodily contact, or the intervention of any intermedium, is essential to a right interpretation of physical phenomena; and if it be equally so, on the other hand, that its exertion makes itself manifest to our personal consciousness by that peculiar sensation of effort which is not without its analogue in purely intellectual acts of the mind; it comes, not unnaturally, to be regarded as affording a point of contact, a connecting link between these two great departments of being — between mind and matter — the one as its originator, the other as its recipient.
The control we possess over the external world we are sure must arise from a capacity somehow inherent in the intellectual part of our nature, to originate or call into action this one and only agent which matter obeys in its changes of form and situation. We may hesitate about admitting into the system of created things around us so vast an amount of additional or extraneous vis viva, as the totality of animal exertion since the first introduction of life upon earth would seem to imply. But this is not necessary. The actual force necessary to be originated to give rise to the utmost imaginable exertion of animal power in any case, may be no greater than is required to remove a single material molecule from its place through a space inconceivably minute — no more in comparison with the dynamical force disengaged, directly or indirectly, by the act, than the pull of a hair trigger in comparison with the force of the mine which it explodes. But without the power to make some material disposition, to originate some movement, or to change, at least temporarily, the amount of dynamical force appropriate to some one or more material molecules, the mechanical results of human or animal volition are inconceivable. It matters not that we are ignorant of the mode in which this is performed. It suffices to bring the origination of dynamical power, to however small an extent, within the domain of acknowledged personality.
|It will perhaps be objected to this, that the principle so generally cited, and now so universally recognized as a dominant one in physics — that of the "conservation of force" – stands opposed to any, even the smallest amount of arbitrary change in the total of “force” existing in the universe. This principle, so far as it rests upon any scientific basis as a legitimate conclusion from dynamical laws, is no other than the well-known dynamical theorem of the conservation of vis viva (or of “energy" as some prefer to call it) supplemented to save the truth of its verbal enunciation, by the introduction of what is called "potential energy" [Rankine, 1853], a phrase which I cannot help regarding as unfortunate, inasmuch as it goes to substitute a truism for the announcement of a great dynamical fact.
No such conservation, in the sense of an identity of total amount of vis viva at all times, and in all circumstances, in fact, exists. So far as a system is maintained by the mutual actions and reactions of its constituent elements at a distance (i.e., by force), vis viva may temporarily disappear, and be subsequently reproduced between certain limits. Collision, indeed, between its ultimate atoms, regarded as absolutely rigid, and therefore inelastic (for that which cannot change its figure can have no resilience), cannot take place without producing a permanent destruction of it, which there exists no means of repairing. And here we may remark that, this being the case, to ascribe to such atoms any magnitude becomes not only superfluous, but embarrassing. The system of Boscovich has to be accepted in its integrity, if absolute permanence is to be one of the conditions insisted on; and they come to be considered as mere localizations of inertia and such other attributes, including the centralization of force – if any other than this there be – which belong to our notion of material substance. The conservation of energy, then, is in effect no conservation at all in any strict sense of the term, unless so supplemented.
It is a fact dynamically demonstrable that the total amount of vis viva in any moving system abandoned to the mutual reaction of its particles, while depending at every instant of time, solely for its magnitude, on the then relative situation of those particles (or being, in algebraical phrase, a function of their mutual distances), has a maximum value which it cannot exceed, and a minimum below which it cannot descend. Let its state then be what it will, there is sure to be a certain amount of vis viva by which its actual falls short of its extreme possible value; and to say that the amount of this deficiency added to the actual present amount will make up the maximum, is neither more nor less than a truism: whether expressed in so many words, or by saying that the potential together with the actual energy of the system is invariable; or, again, in other words, that when certain changes have taken place in the relative situations of the parts of the system, what it has lost in actual it has gained in potential energy.
When in speaking of a mechanical combination we say that what is lost in time is gained in power, though equally a translation in ordinary language of a dynamical equation, the terms used refer to different modes of viewing the expenditure of force. But in the case before us they stand in their nakedness of similar meaning and convey to the mind no equivalence available for any purpose of reasoning. If, indeed, we could be assured, a priori, that the system is one of simple or compound periodicity in which a certain lapse of time will restore every molecule to identically the same relative situation with respect to all the rest; we should then be sure that in the nature of things there would take place periodically, so to speak, a winding up from a lower to a higher state of potential energy, to be subsequently exchanged for newly-created vis viva. But as we can have no such a priori assurance, can only assume such restoration to be possible, and can see no means of effecting it, if possible, otherwise than by foresight and prearrangement; the one equally with the other is an unknown function, variable within unknown limits, and susceptible of fluctuations to an unknown extent, nor can we have any, the smallest, right to assert that what is expended in the one form is, necessarily, laid up in reserve for further use in the other. It would be very difficult, I apprehend, to show whether in the winding up of a clock, or the building of a pyramid, taking into consideration all the various modes in which vis viva disappears and reappears in the expenditure of muscular power, the evolution of animal heat, the consumption of the materials of our tissues (laying aside all question as to the evolution of force from intellectual effort), the propagation of vibratory motion, and a thousand other modes of transfer; the total vis viva of this our planet is increased or diminished. That it should remain absolutely unchanged during the process is in the last degree inconceivable. The amount of vis viva latent in the form of heat or molecular motion in the sun and planets in our immediate system may bear, and probably does bear, a by no means inappretiable ratio to that more distinctly patent in the form of bodily motion in the periodical circulation of the planets round the sun, and the sun and planets round their axes. The latter amount fluctuates to and fro according to laws easily calculable; but the former we have no means whatever of computing, and to what extent, or within what limits, it may be variable, we are altogether ignorant.
|In what is here said, it is by no means intended to call in question the validity or to underrate the importance of those remarkable physical investigations which have resulted in exhibiting heat as one of the forms in which vis viva reappears in the apparent destruction of motion. That all heat consists in molecular tremor (or circulation), and is therefore accompanied with the alternate development and disappearance of vis viva within a limited space and quantity of matter according to the dynamical laws of such tremulous or rotating movements, may very readily be granted. But that there are no forms of internal molecular movement other than heat, and what we now speak of as its correlated forces in which vis viva may be temporarily stored up, to make its appearance ultimately in a form cognizable to our senses, is what can by no means be so readily admitted. Nor (while accepting with all due admiration as approximate truths these great revelations as to the mutual convertibility of these correlatives according to the measure of vis viva appropriate to each) shall we advance any nearer to a rational theory of any one of them, till it shall be shown with much more distinctness than at present appears, in what these molecular movements themselves consist; by what forces in the dynamical acceptation of the term) they are controlled; in what manner, or by what mechanism, they are propagated from one body to another; and how their mutual interconversion is effected. In referring them to the action of dynamical force upon matter, and in getting rid of the “imponderables” (other than the luminiferous ether) we are at length fairly entered on the construction of a theory of their phænomena, in what, as above remarked, must be considered the true acceptation of that term in physics: and once satisfied that dynamical force itself is a phenomenon sui generis [of its own kind]; that it is not a result of collision an educt [brought out] from the duality inertia and motion; one of those correlatives, in short, to which the epithet “physical forces” has of late been so generally, and, in my opinion, so very improperly applied, we have reached the point where theory ends and speculation begins, where we cease to inquire into the causes of phenomena, and direct our consideration thenceforward to their reasons.|
|The universe presents us with an assemblage of phenomena, physical, vital, and intellectual — the connecting link between the worlds of intellect and matter being that of organized vitality, occupying the whole domain of animal and vegetable life, throughout which, in some way inscrutable to us, movements among the molecules of matter are originated of such a character as apparently to bring them under the control of an agency other than physical (see: Beale ), superseding the ordinary laws which regulate the movements of inanimate matter, or, in other words, giving rise to movements which would not result from the action of those laws uninterfered with; and therefore implying, on the very same principle, the origination of force. The first and greatest question which Philosophy has to resolve in its attempts to make out a cosmos, – to bring the whole of the phenomena. exhibited in these three domains of existence under the contemplation of the mind as a congruous whole, – is, whether we can derive any light from our internal consciousness of thought, reason, power, will, motive, design or not: whether, that is to say, nature is or is not more interpretable by supposing these things (be they what they may) to have had, or to have to do with its arrangements. Constituted as the human mind is, if nature be not interpretable through these conceptions, it is not interpretable at all; and the only reason we can have for troubling ourselves about it is either the utilitarian one of bettering our condition by “subduing nature" to our use through a more complete understanding of its “laws", so as to throw ourselves into its grooves, and thereby reach our ends more readily and effectually; or the satisfaction of that sort of aimless curiosity which can find its gratification in scrutinizing everything and comprehending nothing. But if these attributes of mind are not consentaneous, they are useless in the way of explanation. Will without motive, power without design, thought opposed to reason, would be admirable in explaining a chaos, but would render little aid in accounting for anything else.|
The following are quotes cited in the article:
- “Phenomena occur in the simplest form of living matter, which never have been, and which never can be explained upon any known physical or chemical laws. Living matter is not a machine, nor does it act upon the principles of a machine, nor is force conditioned in it as it is in a machine, nor have the movements occurring in it been explained by physics, or the changes which take place in its composition by chemistry. The phenomena occurring in living matter are peculiar, differing from any other known phenomena; and therefore, until we can ex. plain them, they may well be distinguished by the term vital. Not the slightest step has yet been made towards the production of matter possessing the properties which distinguish living matter from matter in every other known state.”
- — Lionel Beale (1865), “Croonian Lecture”
- Mens agitat molem (2018) – Philaletheians.co.uk.
- Note: the term "material universe", presumably, is code for the fact that Herschel also believes in a parallel "spiritual universe" (or something equivalent), but is want to employ such terminology in scientific discourse?
- Note: Herschel here is arguing, presumably, that "force does not exist".
- Georges Le Sage – Hmolpedia 2020.
- Note: coined "vis viva" was renamed "kinetic energy" in 1871 by William Thomson and Peter Tait.
- Note: Herschel here is denying the "conservation of energy", in favor of that of the "conservation of force", the very same year that Clausius publishes his Mechanical Theory Theory of Heat, in which he defined the "first law of thermodynamics", based on the conservation of energy.
- See: supernatural.
- Beale, Lionel. (1865). “Croonian Lecture”, Proceedings of the Royal Society, 14(72):282.