In the first place, we may get a general, relative conception of the interval referred to, by comparing it with the interplanetary spaces. If, for example, we suppose the Earth, which is, in reality, ninety-five millions of miles from the Sun, to be only one foot from that luminary; then Neptune would be forty feet distant; and the star, Alpha Lyrae, at the very least, one hundred and fifty-nine.
Now, I presume that, in the termination of my last sentence, few of my readers have noticed anything especially objectionable — particularly wrong. I said that the distance of the Earth from the Sun being taken at one foot, the distance of Neptune would be forty feet, and that of Alpha Lyrae one hundred and fifty-nine. The proportion between one foot and one hundred and fifty-nine has appeared, perhaps, to convey a sufficiently definite impression of the proportion between the two intervals — that of the Earth from the Sun, and that of Alpha Lyrae from the same luminary. But my account of the matter should, in reality, have run thus: — The distance of the Earth from the Sun being taken at one foot, the distance of Neptune would be forty feet, and that of Alpha Lyrae one hundred and fifty-nine — miles; that is to say, I had assigned to Alpha Lyrae, in my first statement of the case, only the 5280th part of that distance which is the least distance possible at which it can actually lie.
To proceed: — However distant a mere planet is, yet when we look at it through a telescope we see it under a certain form — of a certain appreciable size. Now I have already hinted at the probable bulk of many of the stars; nevertheless, when we view any one of them, even through the most powerful telescope, it is found to present us with no form, and consequently with no magnitude whatever. We see it as a point and nothing more.
Again; — Let us suppose ourselves walking, at night, on a highway. In a field on one side of the road, is a line of tall objects, say trees, the figures of which are distinctly defined against the background of the sky. This line of objects extends at right angles to the road, and from the road to the horizon. Now, as we proceed along the road, we see these objects changing their positions, respectively, in relation to a certain fixed point in that portion of the firmament which forms the background of the view. Let us suppose this fixed point — sufficiently fixed for our purpose — to be the rising moon. We become aware, at once, that while the tree nearest us so far alters its position, in respect to the moon, as to seem flying behind us, the tree in the extreme distance has scarcely changed at all its relative position with the satellite. We then go on to perceive that the farther the objects are from us, the less they alter their positions; and the converse. Then we begin, unwittingly, to estimate the distances of individual trees by the degrees in which they evince the relative alteration. Finally, we come to understand how it might be possible to ascertain the actual distance of any given tree in the line by using the amount of relative alteration as a basis in a simple geometrical problem. Now, this relative alteration is what we call “parallax;” and by parallax we calculate the distances of the heavenly bodies. Applying the principle to the trees in question, we should, of course, be very much at a loss to comprehend the distance of that tree, which, however far we proceeded along the road, should evince no parallax at all. This, in the case described, is a thing impossible; but impossible only because all distances on our Earth are trivial indeed; in comparison with the vast cosmical quantities, we may speak of them as absolutely nothing.
Now, let us suppose the star Alpha Lyrae directly overhead; and let us imagine that, instead of standing on the Earth, we stand at one end of a straight road stretching through Space to a distance equalling the diameter of the Earth’s orbit — that is to say, to a distance of one hundred and ninety millions of miles. Having observed, by means of the most delicate micrometrical instruments, the exact position of the star, let us now pass along this inconceivable road, until we reach its other extremity. Now, once again, let us look at the star. It is precisely where we left it. Our instruments, however delicate, assure us that its relative position is absolutely — is identically the same, as at the commencement of our unutterable journey. No parallax — none whatever — has been found.
The fact is, that, in regard to the distance of the fixed stars — of any one of the myriads of suns glistening on the farther side of that awful chasm which separates our system from its brothers in the cluster to which it belongs — astronomical science, until very lately, could speak only with a negative certainty. Assuming the brightest as the nearest, we could say, even of them, only that there is a certain incomprehensible distance on the hither side of which they cannot be; how far they are beyond it we had in no case been able to ascertain. We perceived, for example, that Alpha Lyrae cannot be nearer to us than nineteen trillions, two hundred billions of miles; but, for all we knew, and indeed for all we now know, it may be distant from us the square, or the cube, or any other power of the number mentioned. By dint, however, of wonderfully minute and cautious observations, continued, with novel instruments, for many laborious years, Bessel, not long ago deceased, has lately succeeded in determining the distance of six or seven stars; among others, that of the star numbered 61 in the constellation of the Swan. The distance in this latter instance ascertained, is six hundred and seventy thousand times that of the Sun; which last, it will be remembered, is ninety-five millions of miles. The star 61 Cygni, then, is nearly sixty-four trillions of miles from us — or more than three times the distance assigned, as the least possible, for Alpha Lyrae.
In attempting to appreciate this interval by the aid of any considerations of velocity, as we did in endeavoring to estimate the distance of the Moon, we must leave out of sight, altogether, such nothings as the speed of a cannon ball, or of sound. Light, however, according to the latest calculations of Struve, proceeds at the rate of one hundred and sixty-seven thousand miles in a second. Thought itself cannot pass through this interval more speedily — if, indeed, thought can traverse it at all. Yet, in coming from 61 Cygni to us, even at this inconceivable rate, light occupies more than ten years; and, consequently, were the star this moment blotted out from the Universe, still, for ten years, would it continue to sparkle on, undimmed in its paradoxical glory.
Keeping now in mind whatever feeble conception we may have attained of the interval between our Sun and 61 Cygni, let us remember that this interval, however unutterably vast, we are permitted to consider as but the average interval among the countless host of stars composing that cluster, or “nebula,” to which our system, as well as that of 61 Cygni, belongs. I have, in fact, stated the case with great moderation; — we have excellent reason for believing 61 Cygni to be one of the nearest stars, and thus for concluding, at least for the present, that its distance from us is less than the average distance between star and star in the magnificent cluster of the Milky Way.
And here, once again and finally, it seems proper to suggest that even as yet we have been speaking of trifles. Ceasing to wonder at the space between star and star in our own or in any particular cluster, let us rather turn our thoughts to the intervals between cluster and cluster, in the all comprehensive cluster of the Universe.
I have already said that light proceeds at the rate of one hundred and sixty-seven thousand miles in a second — that is, about ten millions of miles in a minute, or about six hundred millions of miles in an hour; yet so far removed from us are some of the “nebulae” that even light, speeding with this velocity, could not and does not reach us, from those mysterious regions, in less than three millions of years. This calculation, moreover, is made by the elder Herschel, and in reference merely to those comparatively proximate clusters within the scope of his own telescope. There are “nebulae,” however, which, through the magical tube of Lord Rosse, are this instant whispering in our ears the secrets of a million of ages bygone. In a word, the events which we behold now — at this moment — in those worlds — are the identical events which interested their inhabitants ten hundred thousand centuries ago. In intervals, in distances, such as this suggestion forces upon the soul rather than upon the mind, we find, at length, a fitting climax to all hitherto frivolous considerations of quantity.
Our fancies thus occupied with the cosmical distances, let us take the opportunity of referring to the difficulty which we have so often experienced, while pursuing the beaten path of astronomical reflection, in accounting for the immeasurable voids alluded to; in comprehending why chasms so totally unoccupied and therefore apparently so needless, have been made to intervene between star and star, between cluster and cluster; in understanding, to be brief, a sufficient reason for the Titanic scale, in respect of mere Space, on which the Universe of Stars is seen to be constructed. A rational cause for the phenomenon, I maintain that Astronomy has palpably failed to assign; but the considerations through which, in this essay, we have proceeded step by step, enable us clearly and immediately to perceive that Space and Duration are one. That the Universe might endure throughout an aera at all commensurate with the grandeur of its component material portions and with the high majesty of its spiritual purposes, it was necessary that the original atomic diffusion be made to so inconceivable an extent as to be only not infinite. It was required, in a word, that the stars should be gathered into visibility from invisible nebulosity — proceed from visibility to consolidation — and so grow gray in giving birth and death to unspeakably numerous and complex variations of vitalic development; it was required that the stars should do all this — should have time thoroughly to accomplish all these Divine purposes — during the period in which all things were effecting their return into Unity with a velocity accumulating in the inverse proportion of the squares of the distances at which lay the inevitable End.
Throughout all this we have no difficulty in understanding the absolute accuracy of the Divine adaptation. The density of the stars, respectively, proceeds, of course, as their condensation diminishes; condensation and heterogeneity keep pace with each other; through the latter, which is the index of the former, we estimate the vitallic and spiritual development. Thus, in the density of the globes, we have the measure in which their purposes are fulfilled. As density proceeds — as the divine intentions are accomplished — as less and still less remains to be accomplished — so, in the same ratio, should we expect to find an acceleration of the End; and thus the philosophical mind will easily comprehend that the Divine designs in constituting the stars, advance mathematically to their fulfilment; — and more, it will readily give the advance a mathematical expression; it will decide that this advance is inversely proportional with the squares of the distances of all created things from the starting-point and goal of their creation.
Not only is this Divine adaptation, however, mathematically accurate, but there is that about it which stamps it as Divine, in distinction from that which is merely the work of human constructiveness. I allude to the complete mutuality of adaptation. For example, in human constructions a particular cause has a particular effect; a particular intention brings to pass a particular object, but this is all; we see no reciprocity. The effect does not react upon the cause; the intention does not change relations with the object. In Divine constructions the object is either design or object as we choose to regard it — and we may take at any time a cause for an effect, or the converse — so that we can never absolutely decide which is which.
To give an instance: — In polar climates the human frame, to maintain its animal heat, requires, for combustion in the capillary system, an abundant supply of highly azotized food, such as train-oil. But again: — in polar climates nearly the sole food afforded man is the oil of abundant seals and whales. Now, whether is oil at hand because imperatively demanded, or the only thing demanded because the only thing to be obtained? It is impossible to decide. There is an absolute reciprocity of adaptation.
The pleasure which we derive from any display of human ingenuity is in the ratio of the approach to this species of reciprocity. In the construction of plot, for example, in fictitious literature, we should aim at so arranging the incidents that we shall not be able to determine, of any one of them, whether it depends from any one other or upholds it. In this sense, of course, perfection of plot, is really, or practically, unattainable — but only because it is a finite intelligence that constructs. The plots of God are perfect. The Universe is a plot of God.
And now we have reached a point at which the intellect
is forced, again, to struggle against its propensity for analogical inference
— against its monomaniac grasping at the infinite. Moons have been seen
revolving
about planets; planets about stars; and the poetical instinct of humanity
— its instinct of the symmetrical, even if the symmetry be but a symmetry
of surface — this instinct, which the Soul, not only of Man but
of all created beings, took up, in the beginning, from the geometrical
basis of the Universal radiation — impels us to the fancy of an endless
extension of this system of cycles. Closing our eyes equally to
deduction
and induction, we insist upon imagining a revolution of all
the orbs of the Galaxy about some gigantic globe which we take to be the
central pivot of the whole. Each cluster in the great cluster of clusters
is imagined, of course, to be similarly supplied and constructed; while,
that the “analogy” may be wanting at no point, we go on to conceive these
clusters themselves, again, as revolving about some still more august
sphere; — this latter, still again, with its encircling clusters,
as but one of a yet more magnificent series of agglomerations,
gyrating
about yet another orb central to them — some orb still more unspeakably
sublime — some orb, let us rather say, of infinite sublimity endlessly
multiplied by the infinitely sublime. Such are the conditions,
continued in perpetuity, which the voice of what some people term “analogy”
calls upon the Fancy to depict and the Reason to contemplate, if possible,
without becoming dissatisfied with the picture. Such, in general,
are the interminable gyrations beyond gyration which we have been instructed
by Philosophy to comprehend and to account for — at least in the best manner
we can. Now and then, however, a philosopher proper — one whose frenzy
takes a very determinate turn — whose genius, to speak more reverentially,
has a strongly-pronounced washer-womanish bias, doing everything up by
the dozen — enables us to see precisely that point out of sight,
at which the revolutionary processes in question do, and of right ought
to, come to an end.
It is hardly worth while, perhaps, even to sneer at the reveries of Fourrier; but much has been said, latterly, of the hypothesis of Madler — that there exists, in the centre of the Galaxy, a stupendous globe about which all the systems of the cluster revolve. The period of our own, indeed, has been stated — one hundred and seventeen millions of years.
That our Sun has a motion in space, independently of its rotation, and revolution about the system’s centre of gravity, has long been suspected. This motion, granting it to exist, would be manifested perspectively. The stars in that firmamental region which we were leaving behind us, would, in a very long series of years, become crowded; those in the opposite quarter, scattered. Now, by means of astronomical History, we ascertain, cloudily, that some such phenomena have occurred. On this ground it has been declared that our system is moving to a point in the heavens diametrically opposite the star Zeta Herculis; but this inference is, perhaps, the maximum to which we have any logical right. Madler, however, has gone so far as to designate a particular star, Alcyone in the Pleiades, as being at or about the very spot around which a general revolution is performed.
Now, since by “analogy” we are led, in the first instance, to these dreams, it is no more than proper that we should abide by analogy, at least in some measure, during their development; and that analogy, which suggests the revolution, suggests at the same time a central orb about which it should be performed; so far the astronomer was consistent. This central orb, however, should, dynamically, be greater than all the orbs, taken together, which surround it. Of these there are about one hundred millions. “Why, then,” it was of course demanded, “do we not see this vast central sun — at least equal in mass to one hundred millions of such suns as ours; why do we not see it — we, especially, who occupy the mid region of the cluster, the very locality near which, at all events, must be situated this incomparable star?” The reply was ready — “It must be non-luminous, as are our planets.” Here, then, to suit a purpose, analogy is suddenly let fall. “Not so,” it may be said, “we know that non-luminous suns actually exist.” It is true that we have reason at least for supposing so; but we have certainly no reason whatever for supposing that the non-luminous suns in question are encircled by luminous suns, while these again are surrounded by non-luminous planets; and it is precisely all this with which Madler is called upon to find anything analogous in the heavens — for it is precisely all this which he imagines in the case of the Galaxy. Admitting the thing to be so, we cannot help here picturing to ourselves how sad a puzzle the why is it so must prove to all a priori philosophers.
But granting, in the very teeth of analogy and of everything else, the non-luminosity of the vast central orb, we may still inquire how this orb, so enormous, could fail of being rendered visible by the flood of light thrown upon it from the one hundred millions of glorious suns glaring in all directions about it. On the urging of this question, the idea of an actually solid central sun appears, in some measure, to have been abandoned; and speculation proceeded to assert that the systems of the cluster perform their revolutions merely about an immaterial centre of gravity common to all. Here again, then, to suit a purpose, analogy is let fall. The planets of our system revolve, it is true, about a common centre of gravity; but they do this in connection with, and in consequence of, a material sun whose mass more than counterbalances the rest of the system.
The mathematical circle is a curve composed of an infinity of straight lines. But this idea ofthe circle — an idea which in view of all ordinary geometry, is merely the mathematical, as contra- distinguished from the practical, idea — is, in sober fact, the practical conception which alone we have any right to entertain in regard to the majestic circle with which we have to deal, at least in fancy, when we suppose our system revolving about a point in the centre of the Galaxy. Let the most vigorous of human imaginations attempt but to take a single step towards the comprehension of a sweep so ineffable! It would scarcely be paradoxical to say that a flash of lightning itself, travelling forever upon the circumference of this unutterable circle, would still, forever, be travelling in a straight line. That the path of our Sun in such an orbit would, to any human perception, deviate in the slightest degree from a straight line, even in a million of years, is a proposition not to be entertained; yet we are required to believe that a curvature has become apparent during the brief period of our astronomical history — during a mere point — during the utter nothingness of two or three thousand years.
It may be said that Madler has really ascertained a curvature in the direction of our system’s now well-established progress through Space. Admitting, if necessary, this fact to be in reality such, I maintain that nothing is thereby shown except the reality of this fact — the fact of a curvature. For its thorough determination, ages will be required; and, when determined, it will be found indicative of some binary or other multiple relation between our Sun and some one or more of the proximate stars. I hazard nothing, however, in predicting that, after the lapse of many centuries, all efforts at determining the path of our sun through Space will be abandoned as fruitless. This is easily conceivable when we look at the infinity of perturbation it must experience from its perpetually- shifting relations with other orbs, in the common approach of all to the nucleus of the Galaxy.
But in examining other “nebulae” than that of the Milky Way — in surveying, generally, the clusters which overspread the heavens — do we or do we not find confirmation of Madler’s hypothesis? We do not. The forms of the clusters are exceedingly diverse when casually viewed; but on close inspection, through powerful telescopes, we recognize the sphere, very distinctly, as at least the proximate form of all; their constitution, in general, being at variance with the idea of revolution about a common centre.
“It is difficult,” says Sir John Herschel, “to form any conception of the dynamical state of such systems. On one hand, without a rotary motion and a centrifugal force, it is hardly possible not to regard them as in a state of progressive collapse. On the other, granting such a motion and such a force, we find it no less difficult to reconcile their forms with the rotation of the whole system [meaning cluster] around any single axis, without which internal collision would appear to be inevitable.”
Some remarks lately made about the “nebulae” by Dr. Nichol, in taking quite a different view of the cosmical conditions from any taken in this Discourse, have a very peculiar applicability to the point now at issue. He says: —
“When our greatest telescopes are brought to bear upon them, we find that those which were thought to be irregular are not so; they approach nearer to a globe. Here is one that looked oval; but Lord Rosse’s telescope brought it into a circle.... Now there occurs a very remarkable circumstance in reference to these comparatively sweeping circular masses of nebulae. We find they are not entirely circular, but the reverse; and that all around them, on every side, there are volumes of stars, stretching out apparently as if they were rushing towards a great central mass in consequence of the action of some great power.” <I must be understood as denying, especially, only the revolutionary portion of Madler’s hypothesis. Of course, if no great central orb exists now in our cluster, such will exist hereafter. Whenever existing, it will be merely the nucleus of the consolidation.>
Were I to describe, in my own words, what must necessarily be the existing condition of each nebula, on the hypothesis that all matter is, as I suggest, now returning to its original Unity, I should simply be going over, nearly verbatim, the language here employed by Dr. Nichol, without the faintest suspicion of that stupendous truth which is the key to these nebular phenomena.
And here let me fortify my position still farther, by the voice of a greater than Madler; of one, moreover, to whom all the data of Madler have long been familiar things, carefully and thoroughly considered. Referring to the elaborate calculations of Argelander — the very researches which form Madler’s basis — Humboldt, whose generalizing powers have never, perhaps been equalled, has the following observation: —
“When we regard the real, proper, or non-perspective motions of the stars, we find many groups of them moving in opposite directions; and the data as yet in hand render it not necessary, at least, to conceive that the systems composing the Milky Way, or the clusters, generally, composing the Universe, are revolving about any particular centre unknown, whether luminous or non-luminous. It is but Man’s longing for a fundamental First Cause, that impels both his intellect and fancy to the adoption of such an hypothesis.” <Betrachtet man die nicht perspectivischen eigenen Bewegungen der Sterne, so scheinen viele gruppenweise in ihrer Richtung entgegengesetzt; und die bisher gesammelten Thatsachen machen es auf’s wenigste nicht nothwendig anzunehmen, dass alle Theile unserer Sternenschicht oder gar der gesammten Sterneninseln, welche den Weltraum füllen, sich um einen grossen, unbekannten, leuchtenden oder dunkeln Centralkörper bewegen. Das Streben nach den letzten und höchsten Grundursachen macht freilich die reflectirende Thätigkeit des Menschen, wie seine Phantasie, zu einer solchen Annahme geneigt.>
The phenomenon here alluded to — that of “many groups moving in opposite directions” — is quite inexplicable by Madler’s idea; but arises, as a necessary consequence, from that which forms the basis of this Discourse. While the merely general direction of each atom — of each moon, planet, star, or cluster — would, on my hypothesis, be, of course, absolutely rectilinear, while the general path of all bodies would be a right line leading to the centre of all; it is clear, nevertheless, that this general rectilinearity would be compounded of what, with scarcely any exaggeration, we may term an infinity of particular curves — an infinity of local deviations from rectilinearity — the result of continuous differences of relative position among the multitudinous masses, as each proceeds on its own proper journey to the End.
I quoted, just now, from Sir John Herschel, the following words, used in reference to the clusters: — “On one hand, without a rotary motion and a centrifugal force, it is hardly possible not to regard them as in a state of progressive collapse.” The fact is, that, in surveying the “nebulae” with a telescope of high power, we shall find it quite impossible, having once conceived this idea of “collapse,” not to gather, at all points, corroboration of the idea. A nucleus is always apparent, in the direction of which the stars seem to be precipitating themselves; nor can these nuclei be mistaken for merely perspective phenomena; the clusters are really denser near the centre — sparser in the regions more remote from it. In a word, we see everything as we should see it were a collapse taking place; but, in general, it may be said of these clusters that we can fairly entertain, while looking at them, the idea of orbitual movement about a centre, only by admitting the possible existence, in the distant domains of space, of dynamical laws with which we are unacquainted.
On the part of Herschel, however, there is evidently a reluctance to regard the nebulae as in “a state of progressive collapse.” But if facts — if even appearances justify the supposition of their being in this state, why, it may well be demanded, is he disinclined to admit it? Simply on account of a prejudice; merely because the supposition is at war with a preconceived and utterly baseless notion — that of the endlessness, that of the eternal stability of the Universe.
~~End of Text (Section 8)~~