Uranie. English by Iain Pears
IV.
THE FIXED POINT IN THE UNIVERSE.
The memory of Urania and the celestial journey on which she had borne meaway, the truths she had made me realize, Spero's history, his trials inhis pursuit of the absolute, his apparition, his story of another world,still haunted me, and kept the same problems (partly solved, partlyveiled in the uncertainty of our knowledge) incessantly before my mind.I felt that I had gradually risen to a perception of the truth, and thatthe visible universe was really but an appearance, which we must passthrough in order to reach reality.
The testimony of our senses is but an illusion. The Earth is not what itseems to be. Nature is not what we think. In the physical universeitself, where is the fixed point upon which material creation is inequilibrium?
The natural and direct impression given by the observation of Nature isthat we inhabit a solid, stable Earth, fixed in the centre of theuniverse. It took long centuries of study and a great deal of boldnessto free ourselves from that natural conviction, and to realize that theworld we are on is isolated in space, without any support whatever, inrapid motion on itself and around the Sun. But to the ages beforescientific analysis, to primitive peoples, and even to-day to threequarters of the human race, our feet are resting on a solid Earth whichis fixed at the base of the universe, and whose foundations are supposedto extend into the depths of the infinite.
And yet from the time when it was first realized that it is the same Sunwhich rises and sets every day; that it is the same Moon, the samestars, the same constellations which revolve about us, those very factsforced one to admit with absolute certainty that there must be emptyspace underneath the Earth, to let the stars of the firmament pass fromtheir setting to their rising. This first recognition was aturning-point. The admission of the Earth's isolation in space wasastronomy's first triumph. It was the first step, and indeed the mostdifficult one. Think of it! To give up the foundations of the Earth!Such an idea would never have sprung from any brain without the study ofthe stars, or indeed without the transparency of the atmosphere. Under aperpetually cloudy sky, human thoughts would have remained fixed onterrestrial ground like the oyster to the rock.
The Earth once isolated in space, the first step was taken. Before thisrevolution, whose philosophical bearing equals its scientific value, allmanner of shapes had been imagined for our sublunary dwelling-place. Inthe first place, the Earth was thought to be an island emerging from aboundless ocean, the island having infinite roots. Then the Earth, withits seas, was supposed to be a flat, circular disk, all around whichrested the vault of the firmament. Later, cubic, cylindrical, polyhedricforms, etc., were imagined. But still the progress of navigation tendedto reveal its spherical nature, and when its isolation, with itsincontestable proofs, was recognized, this sphericity was admitted as anatural corollary of that isolation and of the circular motion of thecelestial spheres around the supposed central globe.
The terrestrial globe being from that time recognized as isolated, tomove it was no longer difficult. Formerly, when the sky was looked uponas a dome crowning the massive and unlimited Earth, the very idea ofsupposing it to be in motion would have been not only absurd butuntenable. But from the time that we could see it in our minds, placedlike a globe in the centre of celestial motion, the idea of imaginingthat perhaps this globe could revolve on itself, so as to avoid obligingthe whole sky and the immense universe to perform this daily task, mightcome naturally into a thinker's mind; and indeed we see the hypothesisof the daily rotation of the terrestrial sphere coming to light inancient civilizations, among the Greeks, the Egyptians, the Indians,etc. It is sufficient to read a few chapters of Ptolemy, Plutarch, orSurya-Siddhanta for an account of these conjectures. But this newhypothesis, although it had been prepared for by the first one, was nonethe less bold, and contrary to the feelings inspired by the directcontemplation of Nature. Thoughtful mankind was obliged to wait untilthe sixteenth century, or, to speak more correctly, until theseventeenth century, to learn our planet's true position in theuniverse, and to _know_ by supported proofs that it has a doublemovement,--daily about itself, and yearly about the Sun. From that timeonly, from the time of Copernicus, Galileo, Kepler, and Newton, has realastronomy existed.
And yet again, that was but a beginning, for the great remodeller of theworld's system, Copernicus himself, had no suspicion of the Earth'sother motions, or of the distances of the stars. It is only in our owncentury that the first measurements of the distances of the stars couldbe made, and it is only in our day that sidereal discoveries haveafforded us the necessary data by which we might endeavor to account forthe forces which maintain the equilibrium of creation.
The ancient idea of endless roots attributed to the Earth, evidentlyleft much to be desired to minds anxious to go to the bottom of things.It is absolutely impossible for us to conceive of a material pillar, asthick and as wide as you like (of the diameter of the Earth, forexample), sinking down into the infinite; just as one cannot admit thereal existence of a stick which should have but one end. No matter howfar our mind goes down towards the base of such a material pillar, thereis a point where it can see the end of it. The difficulty had beenobviated by materializing the celestial sphere and putting the Earthinside it, occupying all its lower portion. But in the first place itbecame difficult to adjust the motion of the stars, and on the otherhand this material universe itself, enclosed in an immense crystalglobe, was held up by nothing, since the infinite must extend allaround, beneath it, as well as above. Investigating minds were at firstobliged to free themselves from the vulgar idea of weight.
Isolated in space like a child's balloon floating in the air, and moreabsolutely too, for the balloon is carried by aerial waves, while worldsgravitate in the void, the Earth is a toy for the invisible cosmicforces which it obeys,--a real soap-bubble, sensitive to the faintestbreath. Besides, we can easily judge of it by looking at the same timeat the whole of the _eleven_ principal motions of the Earth, by which itis moved. Perhaps they will help us to find that "fixed point" which ourphilosophical ambition asks for.
Thrown around the Sun at a distance of 37,000,000 leagues, and making atthis distance its annual revolution around the luminous star, itconsequently moves at the rate of 643,000 leagues per day; that is,26,800 leagues an hour, or 29,450 metres per second. This speed iseleven hundred times more rapid than an express train going at the rateof a hundred kilometres an hour. It is a ball, going with a rapidityseventy-five times greater than that of a bomb, always hurrying on, butnever reaching its goal. In 365 days, 6 hours, 9 minutes, and 10seconds, the terrestrial projectile has returned to the same point ofits orbit relative to the Sun, and continues its flight. The Sun, on itspart, is moving in space, following a line oblique to the plane of theEarth's annual motion,--a line drawn towards the constellation ofHercules. The result is, that instead of describing an exact circle, theEarth describes a spiral, and has never passed over the same road twicein its existence. To its motion of annual revolution around the Sunthere is added perpetually, as a second motion, that of the Sun itself,which draws it, with all the solar system, into an oblique descenttowards the constellation of Hercules.
During all this time our little globe pirouettes around itself everytwenty-four hours, and gives us the daily succession of days andnights,--diurnal rotation: third motion.
It does not turn upright upon itself, like a top, which would bevertical on a table, but is inclined, as everybody knows, by 23 deg. 27'.This inclination, too, is not always the same; it varies from year toyear, from age to age, oscillating slowly by secular periods. That is afourth kind of motion.
The orbit in which our planet yearly travels around the Sun is notcircular, but elliptical. This ellipse itself also varies from year toyear, and from century to century; sometimes it approaches thecircumference of a circle, sometimes it lengthens out to a greateccentricity. It is like an elastic ring, which can be bent more or lessout of shape. Fifth complication in the Earth's motion.
This ellipse itself i
Here is a seventh. We said just now that our globe's axis of rotation isinclined, and everybody knows that the imaginary prolongation of thisaxis points towards the polar star. This axis itself is not fixed. Itrevolves in 25,765 years, keeping its inclination of 22 to 24 degrees,so that its prolongation describes a circle of 44 to 48 degrees indiameter--according to the epoch--on the celestial sphere around thepole of the ecliptic. It is in consequence of this displacement of thepole that Vega, in twelve thousand years, will again become the polarstar, as she was fourteen thousand years ago. Seventh kind of movement.
An eighth motion, due to the action of the Moon on the equatorialswelling of the Earth, that of nutation, causes the pole of the equatorto describe a small ellipse in eighteen years and eight months.
A ninth, due also to the attraction of our satellite, incessantlychanges the position of the globe's centre of gravity and the Earth'splace in space. When the Moon is in front of us, she accelerates thespeed of the globe; when she is behind, she retards us, on thecontrary, like a check-rein,--a monthly complication which is added toall the others.
When the Earth passes between the Sun and Jupiter, the attraction of thelatter, in spite of its distance of 155,000,000 leagues, makes itdeviate by 2 m. 10 sec. from its absolute orbit. The attraction of Venusmakes it deviate 1 m. 25 sec. the other way. Saturn and Mars also actupon it, but more feebly. These are exterior disturbances, which make upa tenth kind of correction to add to the motion of our celestial barque.
The whole of the planets weigh about one seven hundredth part of theweight of the Sun; the centre of gravity around which the Earth annuallyturns is not in the very centre of the Sun, but far from the centre, andoften even outside of the solar globe. Now, absolutely speaking, theEarth does not turn around the Sun; but the two heavenly bodies, Sun andEarth, turn about their common centre of gravity. Thus the centre of ourplanet's annual motion is constantly changing place, and we may add thiseleventh complication to the others. We might even add many others tothese; but the preceding ones are enough to make the degree oflightness and delicacy of our floating island appreciated, subject, aswe have seen, to all the fluctuations of celestial influences.Mathematical analysis goes very far beyond this summary statement. Ithas found that the Moon alone, which seems to turn so peacefully aboutus, has more than sixty distinct motions.
The expression is therefore not exaggerated: our planet is but theplaything of the cosmic forces which accompany it in the meadows of thesky, and it is the same with everything existing in the universe. Matteris meekly obedient to force.
Where, then, is the fixed point which we desire for our support?
Our planet, then, formerly supposed to be at the base of the universe,is in fact kept up at a distance by the Sun, which makes the Earthgravitate about it with a speed corresponding to that distance. Thisspeed, caused by the solar mass itself, keeps our planet at the samemean distance from the central star. A lesser speed would make theweight predominate, and would lead to the Earth's falling into the Sun;a greater speed, on the contrary, would progressively and infinitelysend our planet away from its life-giving focus. But at the speedresulting from gravitation, our wandering home remains suspended inpermanent stability, just as the Moon is upheld in space by the force ofthe Earth's gravity, which makes it circulate about the Earth with thespeed requisite to maintain it constantly at the same mean distance. TheEarth and the Moon thus form a planetary couple in space which sustaineach other in perpetual equilibrium under the supreme domination ofsolar attraction. If the Earth existed alone in the universe, it wouldbe forever motionless in the void, wherever it had been placed, with nopower to descend or rise or change its position in any way whatsoever;these very expressions--to rise, descend, left or right--having noabsolute sense whatever. If this same Earth, while existing alone, hadreceived any impetus whatever, had been thrown with any speed in anydirection, it would have whirled away forever in a straight line in thatdirection, never being able to stop or to slacken its pace or change itsmotion. It would have been the same thing if the Moon had existed alonewith it; they would both have turned about their common centre ofgravity, fulfilling their destiny in the same place in space, flyingtogether, following the direction in which they had been thrown. The Sunexisting and being the centre of its system, the Earth, all the planetsand their satellites, are dependent upon it, and to it their destiny isirrevocably bound.
Is the fixed point that we are seeking, the solid base which we seem toneed to insure the stability of the universe, to be found in thatcolossal and heavy globe, the Sun?
Assuredly not, since the Sun itself is not in repose, for it is bearingus and all its system away towards the constellation of Hercules.
Does our Sun gravitate around an immense sun whose attraction extends toit and controls its destinies as it controls that of the planets? Doinvestigations in sidereal astronomy lead us to believe that a star ofsuch magnitude can exist in a direction situated at right angles withour course towards Hercules? No; our Sun is influenced by siderealattraction, but no one star appears to overpower all the others andreign sovereign over our central star.
Although it may be perfectly admissible, or rather certain, that the sunnearest to ours, the star Alpha Centauri, and our own Sun feel theirmutual attraction; although this star may be situated at about 90degrees from our tangent towards Hercules, and, more than that, in theplane of the principal stars, passing by Perseus, Capella, Vega,Aldebaran, and the Southern Cross; and although the proper motion ofthis neighboring sun may be turned sensibly in the opposite directionfrom ours,--yet we could not consider these two systems as forming onecouple analogous to that of the double stars; in the first place,because all the known double-star systems are composed of stars muchnearer to each other, and then because in the immensity of the orbitdescribed, according to this hypothesis, the attraction of theneighboring stars could not be considered as remaining withoutinfluence; and lastly, because the actual rates of speed with whichthese two suns are moved are much less great than those which wouldresult from their mutual attraction.
The little constellation of Perseus, especially, might very well exert amore powerful action than that of the Pleiades, or than any other groupof stars, and be the fixed point, the centre of gravity, of the motionsof our Sun, of Alpha Centauri, and the neighboring stars, inasmuch asthe cluster of Perseus is not only at right angles with the tangent ofour movement towards Hercules, but also in the great circle of theprincipal stars and precisely at the intersection of this circle withthe Milky Way. But here another factor comes in, of more importance thanall the preceding ones,--this Milky Way, with its eighteen millions ofsuns, of which it would assuredly be audacious to seek the centre ofgravity.
But what is the whole entire Milky Way, after all, compared with themilliards of stars which our mind contemplates in the bosom of thesidereal universe? Is not this Milky Way itself moving like anarchipelago of floating islands? Is not every resolvable nebula, eachcluster of stars, a Milky Way in motion under the action of thegravitation of other universes, which call to it and appeal to itthrough the infinite night?
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Our thoughts are transported from star to star, from system to system,from region to region, in the presence of unfathomable grandeurs, insight of celestial motions whose speed we are but just beginningproperly to value, but which already surpasses all conception. Theproper annual motion of the sun Alpha Centauri exceeds 188 millions ofleagues per year. The proper motion of the 61st of Cygnus (second sun inthe order of distances) is equivalent to 370 millions of leagues peryear, or about one million of leagues per day. The star Alpha Cygnicomes to us in a direct line at a speed of 500 milli
What projectiles! They are suns thousands and millions of times heavierthan the Earth, launched through the unfathomable void with giddy ratesof speed, revolving in immensity under the influence of the gravitationof all the stars of the universe. And these millions and thousandmillions of suns, planets, clusters of stars, nebulae, worlds in theirinfancy, worlds near their end, rush with equal velocity towards goalsof which they are ignorant, with an energy and intensity of actionbefore which gunpowder and dynamite are like the breath of sleepingbabes.
And thus everything hurries on through all eternity perhaps, withoutbeing able ever to reach the unexisting limits of infinity.... Motion,activity, light, life everywhere. Happily so, without doubt. If allthese innumerable suns, planets, earths, moons, comets, were fixed andimmovable, petrified kings in their eternal tombs, how much moreformidable, but also more mournful, would be the aspect of such auniverse! Can you imagine the whole creation stopped, benumbed,mummified? Is not such an idea unbearable? Is there not somethingfunereal about it?
What causes these motions? What maintains them? What regulates them?Universal gravitation, invisible force, which the visible universe (whatwe call matter) obeys. A body attracted from infinity by the Earth wouldattain a velocity of 11,300 metres per second; just as a body thrownfrom the Earth with that speed would never fall again. A body attractedby the Sun from the infinite would attain a speed of 608,000 metres; anda body thrown by the Sun with that swiftness would never return to itspoint of departure. Clusters of stars may give us velocities much moreremarkable still, but which are explained by the theory of gravitation.A glance at a map of the proper motions of the stars is enough to makeone understand the variety and grandeur of these motions.
* * * * *
Thus the stars, the suns, the planets, the worlds, the shooting-stars,the meteoric stones, in short all the bodies which constitute this vastuniverse, rest, not on solid bases, as the childish and primitiveconception of our fathers seemed to require, but _upon invisible andimmaterial forces_ which govern their motions. These milliards ofcelestial bodies have their respective movements for the purpose ofstability, and mutually lean upon each other across the void whichseparates them. The mind which could eliminate time and space would seethe Earth, the planets, the Sun, the stars, rain down from a limitlesssky in all imaginable directions, like the drops carried away by thewhirlwinds of a gigantic tempest, and drawn, not by a common basis, butby the attraction of each and all; each one of these cosmic drops, eachone of these worlds, each one of these suns, is whirled away at a speedso rapid that the flight of cannon-balls is but rest in comparison: itis not one hundred, nor five hundred, nor a thousand metres persecond,--it is ten thousand, twenty, fifty, a hundred, and even two orthree hundred thousand metres _per second_!
How is it that there are no meetings in the midst of all this motion?Perhaps there may be some,--the "temporary stars," which appear to riseagain from their ashes, would seem to indicate it. But as a matter offact, it would be difficult for meetings to occur, because space isimmense, relatively to the celestial bodies, and because the motion bywhich each body is animated entirely prevents it from submittingpassively to the attraction of another body and falling upon it; itkeeps its own motion, which cannot be destroyed, and glides around thefocus which attracts it, as a butterfly would obey the attraction of aflame without burning itself in it. Besides, absolutely speaking, thesemotions are not "rapid."
Indeed, everything runs, flies, falls, rolls, rushes through the void,but at such respective distances that it all appears to be at rest. Ifwe wanted to place in a frame, the size of Paris, the stars whosedistances have been measured up to the present time, the nearest starwould be placed at two kilometres from the Sun, from which the Earthwould be distant one centimetre, Jupiter at five centimetres, andNeptune at thirty centimetres. The 61st of Cygnus would be at fourkilometres, Sirius at ten kilometres, the polar star at twenty-sevenkilometres, etc.; and the immense majority of the stars would remainoutside the department of the Seine. Well, to give to all theseprojectiles their relative motions, the Earth would take a year to runthrough its orbit of a centimetre radius, Jupiter twelve years to runthrough his of five centimetres, and Neptune one hundred and sixty-fiveyears. The proper motions of the Sun and stars would be of the samenature; that is to say, all would appear to be at rest, even under themicroscope. Urania reigns with calmness and serenity in the immensity ofthe universe.
So the constitution of the sidereal universe is just like that of thebodies which we call material. All bodies, organic or inorganic, man,animal, plant, stone, iron, bronze, are composed of molecules which arein perpetual motion, and which do not touch one another. Each one ofthese atoms is infinitely small, and invisible not only to the eye, notonly to the microscope, but even to thought; since it is possible thatthese atoms may be centres of force. It has been calculated that in thehead of a pin there are not less than eight sextillions of atoms,--thatis, eight thousand milliards of milliards,--and that in one centimetreof cubic air there are not less than a sextillion of molecules. Allthese atoms, all these molecules, are in motion under the influence ofthe forces which govern them; and as compared with their dimensions,great distances separate them. We may even believe that there is inprinciple but one kind of atoms, and that it is the number of primitiveatoms, essentially simple and homogeneous, their modes of arrangement,and their motions, which constitute the diversity of molecules; amolecule of gold, of iron, would not differ from a molecule of sulphur,of oxygen, of hydrogen, etc., except in the number, the disposition, andthe motion of the primitive atoms which compose it: each molecule wouldbe a system, a microcosm.
But whatever may be the idea that one conceives of the innerconstitution of bodies, the truth is now recognized and indisputablethat the fixed point for which our imagination has been seeking, existsnowhere. Archimedes can vainly call for a point of support, that he maylift the world. _Worlds, like atoms, rest on the invisible_, onimmaterial force; everything moves, urged on by attraction, and as if insearch of that fixed point which flies as it is pursued, and which doesnot exist, since in the infinite the centre is everywhere and nowhere.So-called positive minds, which assert with so much assurance that"Matter reigns alone, with its properties," and who smile disdainfullyat the researches of thinkers, should first tell us what they mean bythat famous word "matter." If they did not stop at the surface ofthings, if they even suspected that appearances hid intangiblerealities, they would doubtless be a little more modest.
To us, who seek the truth with no jealousy of system, it seems that theessence of matter remains as mysterious as the essence of force; thevisible universe not being in the least what it appears to be to oursenses. In fact, that visible universe is composed of invisible atoms;it rests upon the void, and the forces which govern it are in themselvesimmaterial and invisible. It would be less bold to think that matterdoes not exist, that all is dynamism, than to pretend to affirm theexistence of an exclusively material universe. As to the materialsupport of the world, it disappeared--a somewhat interestingobservation--precisely with the conquest of Mechanics, which proclaimthe triumph of the invisible. The fixed point vanishes in the universalbalance of powers, in the ideal harmony of ether vibrations; the moreone seeks it, the less one finds it; and the last effort of our thoughthas for a last support, for supreme reality, the Infinite.