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<!DOCTYPE html> <html lang="en"> <head> <title>CATHOLIC ENCYCLOPEDIA: Universe</title><script src="https://dtyry4ejybx0.cloudfront.net/js/cmp/cleanmediacmp.js?ver=0104" async="true"></script><script defer data-domain="newadvent.org" src="https://plausible.io/js/script.js"></script><link rel="canonical" href="https://www.newadvent.org/cathen/15183a.htm"> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="description" content="Presents a history of astronomy"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"><link rel="alternate" type="application/rss+xml" title="RSS" href="http://feeds.newadvent.org/bestoftheweb?format=xml"><link rel="icon" href="../images/icon1.ico" type="image/x-icon"><link rel="shortcut icon" href="../images/icon1.ico" type="image/x-icon"><meta name="robots" content="noodp"><link type="text/css" rel="stylesheet" href="../utility/screen6.css" media="screen"></head> <body class="cathen" id="15183a.htm">  <br/> <div id="capitalcity"><table summary="Logo" cellpadding=0 cellspacing=0 width="100%"><tr valign="bottom"><td align="left"><a href="../"><img height=36 width=153 border="0" alt="New Advent" src="../images/logo.gif"></a></td><td align="right"> <form id="searchbox_000299817191393086628:ifmbhlr-8x0" action="../utility/search.htm">  <input type="hidden" name="safe" value="active"> <input type="hidden" name="cx" value="000299817191393086628:ifmbhlr-8x0"/> <input type="hidden" name="cof" value="FORID:9"/>  <label for="searchQuery" id="searchQueryLabel">Search:</label> <input id="searchQuery" name="q" type="text" size="25" aria-labelledby="searchQueryLabel"/>  <label for="submitButton" id="submitButtonLabel" class="visually-hidden">Submit Search</label> <input id="submitButton" type="submit" name="sa" value="Search" aria-labelledby="submitButtonLabel"/> </form> <table summary="Spacer" cellpadding=0 cellspacing=0><tr><td height="2"></td></tr></table> <table summary="Tabs" cellpadding=0 cellspacing=0><tr> <td bgcolor="#ffffff"></td> <td class="tab"><a class="tab_color_on_beige" href="../"> Home </a></td> <td class="tab"><a class="tab_white_on_color" href="../cathen/index.html"> Encyclopedia </a></td> <td class="tab"><a class="tab_color_on_beige" href="../summa/index.html"> Summa </a></td> <td class="tab"><a class="tab_color_on_beige" href="../fathers/index.html"> Fathers </a></td> <td class="tab"><a class="tab_color_on_beige" href="../bible/gen001.htm"> Bible </a></td> <td class="tab"><a class="tab_color_on_beige" href="../library/index.html"> Library </a></td> </tr></table> </td> </tr></table><table summary="Alphabetical index" width="100%" cellpadding=0 cellspacing=0><tr><td class="bar_white_on_color"> <a href="../cathen/a.htm"> A </a><a href="../cathen/b.htm"> B </a><a href="../cathen/c.htm"> C </a><a href="../cathen/d.htm"> D </a><a href="../cathen/e.htm"> E </a><a href="../cathen/f.htm"> F </a><a href="../cathen/g.htm"> G </a><a href="../cathen/h.htm"> H </a><a href="../cathen/i.htm"> I </a><a href="../cathen/j.htm"> J </a><a href="../cathen/k.htm"> K </a><a href="../cathen/l.htm"> L </a><a href="../cathen/m.htm"> M </a><a href="../cathen/n.htm"> N </a><a href="../cathen/o.htm"> O </a><a href="../cathen/p.htm"> P </a><a href="../cathen/q.htm"> Q </a><a href="../cathen/r.htm"> R </a><a href="../cathen/s.htm"> S </a><a href="../cathen/t.htm"> T </a><a href="../cathen/u.htm"> U </a><a href="../cathen/v.htm"> V </a><a href="../cathen/w.htm"> W </a><a href="../cathen/x.htm"> X </a><a href="../cathen/y.htm"> Y </a><a href="../cathen/z.htm"> Z </a> </td></tr></table></div> <div id="mobilecity" style="text-align: center; "><a href="../"><img height=24 width=102 border="0" alt="New Advent" src="../images/logo.gif"></a></div>  <div id="mi5"><span class="breadcrumbs"><a href="../">Home</a> > <a href="../cathen">Catholic Encyclopedia</a> > <a href="../cathen/u.htm">U</a> > Systems of the Universe</span></div> <div id="springfield2"> <div class='catholicadnet-728x90' id='cathen-728x90-top' style='display: flex; height: 100px; align-items: center; justify-content: center; '></div> <h1>Systems of the Universe</h1> <p><em><a href="https://gumroad.com/l/na2"><strong>Please help support the mission of New Advent</strong> and get the full contents of this website as an instant download. Includes the Catholic Encyclopedia, Church Fathers, Summa, Bible and more  all for only $19.99...</a></em></p> <p>Universe (or "world") is here taken in the <a href="../cathen/02025a.htm">astronomical</a> sense, in its narrower or wider meanings, from our terrestrial planet to the stellar universe. The term "systems" restricts the view to the general structure and motions of the heavenly bodies, but comprises all the ages of the world the present, past, and future.</p> <h2 id="section1">Historic times of the universe</h2> <p>The present system, in the widest sense of the term, forms the subject of universal cosmography. Descriptions of this kind were made by Lambert, the two Herschels, Laplace, Newcomb, and others. The present section treats only of the solar system, and in particular of the disputed theories of Ptolemy and <a href="../cathen/04352b.htm">Copernicus</a>, and the <a href="../cathen/12454c.htm">proofs</a> in favour of the latter.</p> <h3 id="A">Ptolemaic and Copernican systems</h3> <p><em>(1) Greek astronomy</em></p> <p>The earliest astronomical systems are found in the Greek school. No planetary system can be discerned in Chinese or Babylonian records.</p> <p>The <a href="../cathen/02025a.htm">astronomical</a> <a href="../cathen/08673a.htm">knowledge</a> of the Greeks shows three periods. Its infancy is represented by Philolaus and Eudoxus, of the fifth and fourth century B.C. The earth is the common centre of the universe, within the celestial sphere of the fixed stars. The great luminaries, sun and moon, and the five planets have each their concentric spheres, upon which they slide in two directions, longitude and latitude, keeping constantly the same distance from the earth.</p> <div class="CMtag_300x250" style="display: flex; height: 300px; align-items: center; justify-content: center; "></div> <p>The flourishing period of Greek <a href="../cathen/02025a.htm">astronomy</a> extends from Heraclides Ponticus in the fourth century B.C. to Hipparchus in the second. Observation was made its basis. The different degrees of brilliancy observed in the nearest planets, Mercury, Venus, and Mars, at the times of the opposition and conjunction with the sun, pointed to heliocentric orbits, and analogy demanded the same arrangement for Jupiter and Saturn. The hypothesis was then established, probably by Heraclides himself, that the sun revolved annually, with the five planets, around the earth, while the moon remained on her sphere as before. Heraclides also made an important step in advance by asserting the diurnal rotation of the earth. His system was afterwards known as that of Tycho Brahé. Even the annual motion of the earth around the sun is mentioned by Heraclides as held by some of his contemporaries. The heliocentric system was certainly pronounced and defended by Aristarchus of <a href="../cathen/13421c.htm">Samos</a>, although his writings are lost, and known only through Archimedes, whose works were published a year after <a href="../cathen/04352b.htm">Copernicus's</a> death (Basle, 1544).</p> <p>The period of decline had commenced when Hipparchus flashed up as the last genius among the Greek astronomers. The precession of the equinoxes, which he discovered, was made to fit the geocentric system, then prevailing, only a century after Aristarchus. The <a href="../cathen/12025c.htm">philosophical</a> <a href="../cathen/13554b.htm">schools</a>, in particular the <a href="../cathen/14299a.htm">Stoics</a>, began to prefer <a href="../cathen/02018e.htm">astrology</a> to observational <a href="../cathen/02025a.htm">astronomy</a>. The geometrical <a href="../cathen/08673a.htm">knowledge</a> that apparent or relative motion remains unaffected by an interchange of its component motions, as was correctly demonstrated by Apollonius, paved the way to the confusion of the solar system. It must be remembered that the apparent planetary motions are epicyclical, each planet revolving in its own orbit, the epicycle, around the sun, and with the sun, as centre of the epicycle, apparently around the earth in a common orbit, which is called the deferent orbit. These are the correct <a href="../cathen/07630a.htm">ideas</a>, and will ever form the basis of spherical <a href="../cathen/02025a.htm">astronomy</a>.</p> <p>The decadence of <a href="../cathen/02025a.htm">astronomical</a> concepts among the Greek <a href="../cathen/12025c.htm">philosophers</a> appeared in two ways: First, they applied the geometrical fiction of Apollonius to the physical planetary system, supposing that the epicycle must always be the smaller of the two components in apparent motion; and, secondly, they believed that a physical planet could revolve, all alone, around a fictitious point in space. For the outer planets, Mars, Jupiter, and Saturn, the apparent orbit of the sun is the smaller component-the common deferent orbit. It cannot be made the epicycle, without introducing into the system three new circles each with a fictitious centre. This was done, but worse was to come for the inner planets, Venus and Mercury. There was no need for them to dislodge the common deferent circle, or solar orbit, as it was larger than the two planetary epicycles. And yet the centre of the deferent was moved from the sun towards the earth, at the cost of introducing into the system two new circles and two ideal centres of motion. The precession of the equinoxes discovered by Hipparchus even lent support to the concept of fictitious pivots. It seemed to swing the pole of the ecliptic around the pole of the celestial sphere. In this shape the Greek system of the heavenly bodies came down to posterity during the second century of our era through Ptolemy's Syntax . The two fundamental propositions of the geocentric system viz. that the earth has no axial rotation and no translation in space form the sixth chapter of the first book. The Syntax did not pass directly from the Alexandrian <a href="../cathen/13554b.htm">school</a> to <a href="../cathen/05607b.htm">Europe</a>. Greek <a href="../cathen/02025a.htm">astronomy</a> made its round through <a href="../cathen/14399a.htm">Syria</a>, <a href="../cathen/11712a.htm">Persia</a>, and Tatary, under Albategnius Ibn-Yunis, Ulugh-Beg. The Ptolemaic system was accepted by the Arabic astronomers without criticism and was made known in <a href="../cathen/05607b.htm">Europe</a> through their translations. An unintelligible Latin Almagest had taken the place of the Greek Syntax and rested like a tombstone on <a href="../cathen/05607b.htm">European</a> <a href="../cathen/02025a.htm">astronomy</a>.</p> <p><em>(2) European astronomy</em></p> <p>New <a href="../cathen/02025a.htm">astronomical</a> life awoke in the fifteenth century in <a href="../cathen/06484b.htm">Germany</a>. <a href="../cathen/11060b.htm">Nicholas of Cusa</a> rejected the axioms of Ptolemy Peurbach and Muller restored the text of Ptolemy's Syntax and <a href="../cathen/04352b.htm">Copernicus</a> made it his life-work to disentangle the cycles and epicycles of the Greek system. The task of <a href="../cathen/04352b.htm">Copernicus</a> was harder than that of his predecessor Aristarchus on account of the unanimous acceptance of the geocentric system for more than a thousand years. The first book of <a href="../cathen/04352b.htm">Copernicus's</a> great work <em>On the Revolutions of the Celestial Bodies</em> is directed against the Ptolemaic axioms on the centre of the universe and the stability of the earth. He rightly observes that the universe has no geometrical centre. He then gives clear definitions of relative and apparent motion and applies the Apollonian principle of interchanging the component motions in the opposite sense of Ptolemy. The complex heavenly machinery was explained by a triple motion of the earth one around its axis another around the sun and a third a conical motion around the axis of the ecliptic in periods of respectively one day, one year, and 25,816 years. Ptolemy's negative arguments against a moving earth were answered in a masterly manner:</p> <div class="bulletlist"><ul><li>It had been objected that a disastrous centrifugal force would be created on the surface of the earth. <a href="../cathen/04352b.htm">Copernicus</a> retorts that a far greater centrifugal force must be admitted in the outer planets and the fixed stars if they revolved around the earth.</li><li>The resistance of the atmosphere which it was urged would sweep away every object from a moving earth was disposed of by <a href="../cathen/04352b.htm">Copernicus</a> exactly as it is today: each planet condenses and carries its own atmosphere.</li><li>A third difficulty was raised about <a href="../cathen/10733a.htm">necessary</a> changes in the appearance of the constellations or in modern language about large parallaxes of the stars when viewed from opposite points of the earth's orbit. <a href="../cathen/04352b.htm">Copernicus</a> correctly thought the stars so far away as to make the terrestrial orbit comparatively too small to show any effect in the instruments then available.</li></ul></div> <div class="CMtag_300x250" style="display: flex; height: 300px; align-items: center; justify-content: center; "></div> <p>The negative arguments of Ptolemy being dispelled there remained only one positive argument in favour of <a href="../cathen/04352b.htm">Copernicus</a>.</p> <p><em>(3) Reaction to Copernicus</em></p> <p>The simplicity of the heliocentric system had sufficient weight to convince a genius like <a href="../cathen/04352b.htm">Copernicus</a>. He never called his system an hypothesis. The first who exercised censorship on the work <em>De revolutionibus</em> was the Reformer, Osiander. Dreading the opposition of the <a href="../cathen/15678b.htm">Wittenberg</a> <a href="../cathen/13554b.htm">school</a> he put the word <em>Hypothesis</em> on the title-page and substituted for the preface of <a href="../cathen/04352b.htm">Copernicus</a> one of his own-all without authorization. It was more than half a century later that the Congregation of the Index pointed out nine sentences that had either to be omitted or expressed hypothetically before the book might be read freely by all.</p> <p>The argument of simplicity was greatly strengthened by Kepler when he discovered the ellipticity of planetary orbits. <a href="../cathen/04352b.htm">Copernicus</a> had found by long years observation that the inequalities of planetary motion could not be accounted for, after Ptolemaic fashion by simply placing the circular orbits excentrically. Not being prepared to abandon the circle he resorted to small epicycles. Their final removal greatly enhanced the simplicity of the <a href="../cathen/04352b.htm">Copernican</a> system. Then came the discoveries of the aberration of light and of stellar parallaxes. While they appeared as natural consequences of the orbital motion of the earth they threw on the Ptolemaic system the condemnation of an almost <a href="../cathen/08004a.htm">infinite</a> complexity. The fixed stars were recognized to vibrate in double ellipses their major axes parallel to the ecliptic in periods of exactly one year. The double ellipses are the images of the terrestrial orbit projected on the celestial sphere by the parallactic displacement of the stars and by the finite velocity of light. The former kind is much the smaller of the two and in most cases dwindles to immeasurable dimensions. Some twelve hundred of them have actually been observed. The aberration-ellipses have their apparent major axes all of equal length. The geocentric system not only has no explanation for these phenomena, but cannot even represent them without two epicycles for each star in the <a href="../cathen/06079b.htm">firmament</a>. The <a href="../cathen/04352b.htm">Copernican</a> argument of simplicity thereby received an overwhelming corroboration.</p> <h3 id="B">Direct proofs of the Copernican system</h3> <p>While the argument of greater simplicity is only an indirect criterion between the two opposing systems mechanics has furnished more direct <a href="../cathen/12454c.htm">proofs</a>. <a href="../cathen/04352b.htm">Copernicus</a> actually had them in mind when he maintained that centrifugal force in a daily rotating celestial sphere would have to be enormous that the atmosphere is condensed around the terrestrial globe and that single planets cannot revolve around fictitious points that have no physical meaning. Kepler was too much preoccupied with geometrical studies and with the favourite <a href="../cathen/07630a.htm">idea</a> of cosmical harmonics (<em>Harmonices mundi</em>) to recognize in the common focus of his elliptical orbits a governing power. It was reserved for Newton and Laplace to formulate the mechanical <a href="../cathen/09053a.htm">laws</a> of celestial motion.</p> <p><em>(1) The annual revolution of the earth around the sun is a necessary consequence of celestial mechanics.</em></p> <p>(a) Newton computed from the velocity and distance of our satellite the amount of attraction that the earth must exercise upon it to maintain its orbital revolution. Learning then from French geometers the exact dimensions of the earth he found the force that keeps the moon in her orbit to be identical with terrestrial gravity divided by the square of the distance from the centre. The discovery led to the computation of the masses of sun and planets inclusive of the earth the latter turning out more than three hundred thousand times lighter than the sun. The mechanical conclusion is that the lighter body revolves around the heavier and not the reverse; or, in more scientific language that both revolve around their common centre of gravity which in this case lies inside the solar sphere.</p> <p>(b) Our satellite furnishes another more direct <a href="../cathen/12454c.htm">proof</a> of the annual revolution of the earth. Carl Braun shows in the Wochenschrift für Astronomie X (1867) 193 that the moon is attracted nearly three times more forcibly by the sun than by the earth. Our satellite would therefore leave us unless we revolved with it around the sun. The earth is only able to give the annual lunar orbit a serpentine shape so as to have the satellite alternately outside and inside her own orbit.</p> <p>(c) Newton also alludes to comets and shows that in the Ptolemaic system each of them needs an epicycle parallel to the ecliptic to turn its orbit towards the sun. With our present cometary <a href="../cathen/08673a.htm">knowledge</a> of comets the argument can be made stringent. Numerous comets have their orbits well determined. Over two hundred of them have passed the ecliptic within the earth's orbit, and some, like Halley's comet at its last appearance, almost in line between sun and earth. Most of the comets, including Halley's, come to us from distances beyond the orbit of Neptune. Now, computation shows that they all have their common focus in the sun and that the earth is, as a rule, outside their orbits. In the case of Halley's comet the earth was, at one time, even on the convex side of the orbit. The mechanical conclusion is as follows: If, without any regard to the earth, the comets obey the sun, the earth must do the</p> <p><em>(2) The daily rotation of the earth</em></p> <p>The daily rotation of the earth around its axis is demonstrated in many ways. Once the annual revolution is <a href="../cathen/12454c.htm">proved</a>, the daily rotation becomes a matter of course. If the earth has not the power to swing the sun around its own centre once a year, it will be far less able to do so in one day; and if it cannot swing around one sun, what could it do with the countless suns of the universe? Yet, we have direct and special <a href="../cathen/12454c.htm">proofs</a> of the diurnal rotation. They all rest on mechanics, partly celestial, partly terrestrial. Celestial mechanics has turned into <a href="../cathen/12454c.htm">proofs</a> what formerly seemed to be difficulties. This occurred in the case of stellar parallaxes, the absence of which had been objected by Ptolemy, and the existence of which was shown by Bessel. The precession of the equinoxes also has changed its role. Laplace showed it to be due to the action of the sun on the protuberant equatorial regions of the rotating earth. The similar result of the action of the moon upon the earth is called nutation. Laplace's demonstration was based upon the flatness of the earth, which had been measured in the seventeenth century, and was also theoretically <a href="../cathen/04674a.htm">deduced</a> by him from the existence of centrifugal force. We have here a complex reverse of roles. The consequences of centrifugal force, so strongly urged against diurnal rotation by Ptolemy, turned out to be the cause of precession, known to Hipparchus, and of several phenomena, discovered only after the time of <a href="../cathen/04352b.htm">Copernicus</a>. Precession was still a matter of special difficulty to <a href="../cathen/04352b.htm">Copernicus</a>, and the one of the three terrestrial motions that he could not explain. To him it was the resultant of two annual, slightly different, conical rotations of opposite direction, to which no cause could be assigned.</p> <p>So much about the <a href="../cathen/12454c.htm">proofs</a> from celestial mechanics. There are others, by means of instruments, so-called laboratory experiments. They commenced immediately after the time of <a href="../cathen/06342b.htm">Galilei</a> and seem to have received the impulse from his trial. The experiments may be classified chronologically in five periods or groups. From 1640 to 1770 they were crude trials without result. The years from 1790 to 1831 were a period of experiments with falling bodies. The twenty years from 1832 to 1852 were a time of pendulum experiments. Then followed a period, 1852-80, of experiments with more elaborate apparatus; and the last, since 1902, may be called that of modern methods.</p> <div class="bulletlist"><ul><li>The first period is represented by the names of Calignon, <a href="../cathen/10209b.htm">Mersenne</a>, Viviani, and Newton. Calignon (1643) experimented with plumb lines, without knowing what their variations should tell. <a href="../cathen/10209b.htm">Mersenne</a> (1643) had pieces of artillery directed to the zenith, rightly expecting a westerly deviation of the balls. <a href="../cathen/06156c.htm">Foucault's</a> pendulum experiment was materially forestalled by Viviani at Florence (1661) and <a href="../cathen/12204b.htm">Poleni</a> at Padua (1742), but was not formally understood. The easterly deviation of falling bodies was explicitly announced by Newton, but unsuccessfully tried by Hooke (1680). <a href="../cathen/06342b.htm">Galilei</a> had alluded to it before, in his "Dialogo" (Opere, VII 1897), in a contradictory manner. In one place (p. 170) he denied the possibility of the experiment, in another (p. 259) he affirmed it. Lalande missed the opportunity of first making Newton's experiment at the <a href="../cathen/11480c.htm">Paris</a> observatory. The <a href="../cathen/07462a.htm">honour</a> was reserved to Abbate Guglielmini.</li><li>The second period comprises the experiments with falling bodies, made by Guglielmini at Bologna (1790-2), by Benzenberg at <a href="../cathen/07121b.htm">Hamburg</a> (1802) and Schlebusch (1804), and by Reich at <a href="../cathen/06264a.htm">Freiburg</a> (1831) The general drift of the balls towards the east side of the meridian was unmistakable. It <a href="../cathen/12454c.htm">proved</a> the rotation of the earth from west to east, but only in a qualitative manner. Quantitative <a href="../cathen/12454c.htm">proofs</a> were obtained in the next period.</li><li>Three kinds of pendulum experiments filled the third period. The horizontal pendulum was invented and tried by <a href="../cathen/07215b.htm">Hengler</a>, in 1832, for the effects of the centrifugal force. The instrument is still waiting for a more delicate manipulator. <a href="../cathen/06156c.htm">Foucault's</a> vertical pendulum dates from 1851, and was tried first in a cellar, then in the <a href="../cathen/11480c.htm">Paris</a> Observatory, and last in the Pantheon. The deviation of the pendulum from the original vertical plane was clockwise, as expected by <a href="../cathen/06156c.htm">Foucault</a>, but no quantitative measures were ever published by him. They were made in many places, chiefly in large <a href="../cathen/03438a.htm">cathedrals</a>. The best results known are those of <a href="../cathen/13669a.htm">Secchi</a> in <a href="../cathen/13164a.htm">Rome</a> (1851) and of Garthe in Cologne (1852). <a href="../cathen/13669a.htm">Secchi</a> experimented in San Ignazio, in presence of many Italian scientists, and Garthe in the <a href="../cathen/03438a.htm">cathedral</a>, before <a href="../cathen/06405a.htm">Cardinal Geissel</a>, royal princes, and numerous spectators. The counterproof in the southern hemisphere, where the deviation of the pendulum must be counter-clockwise, has not been made to this day. The attempt at Rio de Janeiro (1851) cannot be regarded as such. A conical pendulum was set in motion by Bravais in the same meridian room of the observatory and in the same year as the vertical pendulum of <a href="../cathen/06156c.htm">Foucault</a>. The experiment had the advantage of being reversible. Swinging clockwise, the pendulum appeared to move faster than in the opposite sense, for the reason that the theodolite, in which it was observed, followed the rotation of the earth. Two pendulums used simultaneously, and moving in opposite directions, yielded the correct value of the diurnal rotation within a tenth of one per cent, a result never reached by <a href="../cathen/06156c.htm">Foucault's</a> pendulum.</li><li>The second half of the nineteenth century, the fourth period, is remarkable for complicated experiments and profound theories. The instruments were the gyroscope and the compound pendulum. The invention of the former is due to <a href="../cathen/06156c.htm">Foucault</a>, and furnished a new <a href="../cathen/12454c.htm">proof</a> of the diurnal rotation. It was constructed by him in three forms: the universal, the vertical, and the horizontal gyroscope, so called according to their degrees of freedom. The vertical gyroscope was perfected by Gilbert (1878) into his barogyroscope, while the horizontal gyroscope was lately introduced on warships as an <a href="../cathen/02025a.htm">astronomical</a> compass. The <a href="../cathen/12454c.htm">proofs</a> of <a href="../cathen/06156c.htm">Foucault</a> and Gilbert could only be qualitative, for want of electric motors. The delicate experiment made in 1879 with the compound pendulum by Kamerlingh Onnes, comprises those of <a href="../cathen/06156c.htm">Foucault</a> and Bravais as special cases, and in general all the movements between the plane and the circular pendulum vibrations (see "Specola Vaticana", I, 1911, Appendix 1).</li><li>The fifth and last period of experiments falls within the early twentieth century and presents no less than four <a href="../cathen/12454c.htm">proofs</a>, all widely different among themselves. The difficult experiment with falling bodies was brought within the walls of the physical laboratory by E. H. Hall in 1902. Under improved facilities, a fall of only twenty-three metres showed the easterly deviation better than all the preceding trials with heights from three to seven times as large. In 1904 the gyroscope was made to yield quantitative results by Föppl. An electric motor gave to a double wheel of 160 pounds a speed of over two thousand turns a minute. The rotation of the earth was strong enough to deviate the horizontal axis, which was suspended on a triple wire, six and a half degrees from the primevertical. A novel scheme had been tried by Perrot in 1859. He made a liquid flow through the central orifice of a circular vessel, and rendered the currents visible by means of floating dust. We have to take his word, that the currents were spiral-shaped, and ran counter-clockwise. The experiment was repeated by Tumlirz in <a href="../cathen/15417a.htm">Vienna</a> (1908), and its result photographed and compared with theory. While the experiments of Hall, Föppl, and Tumlirz are repetitions of former ones, with improved methods, the next <a href="../cathen/12454c.htm">proof</a> of the diurnal rotation is new as an experiment, although forecast in the <a href="../cathen/07630a.htm">idea</a> by Poinsot as early as 1851. It was carried out at the <a href="../cathen/15309a.htm">Vatican Observatory</a> in 1909. Its principle is that of equal areas described in equal times, applied to a horizontal beam suspended in form of a torsion balance, on which heavy masses can be moved. The shifting of the masses from extremity to centre will make the beam turn faster than the earth; the opposite will happen in the reverse case. The last <a href="../cathen/12454c.htm">proof</a> had never been proposed before, and consists in observing the thread of the Atwood machine in a telescope. Viewed in the meridian, the thread of the falling weight is seen to come down east of the plumb-line, but viewed in the prime vertical it remains exactly plumb. This experiment was likewise carried out at the <a href="../cathen/15309a.htm">Vatican Observatory</a> in 1912 (see "Specola Vaticana", I, 1911, appendix II, 1912).</li></ul></div> <div class="CMtag_300x250" style="display: flex; height: 300px; align-items: center; justify-content: center; "></div> <p>Some writers have expressed surprise that <a href="../cathen/03449a.htm">Catholic</a> scientists were allowed to take part in the experiments, e.g. that Bonfioli, domestic <a href="../cathen/12386b.htm">prelate</a> to <a href="../cathen/12131a.htm">Pius VI</a> assisted Guglielmini in measuring the impressions of the balls on the plate of wax, or that <a href="../cathen/13669a.htm">Secchi</a> demonstrated the rotation of the earth in <a href="../cathen/13164a.htm">Rome</a> "before all the people" (Wolf, "Handbuch", I, <a href="../cathen/15770b.htm">Zurich</a>, 1890, no. 262 c). We must remember, however, that what was condemned in a former age was not the experiment but a then gratuitous assertion. </p> <h2 id="section2">Past and future of the world</h2> <p>How the world has developed into its present shape, and how it will pass out of it, <a href="../cathen/13598b.htm">science</a> may never tell. <a href="../cathen/04405c.htm">Cosmogony</a> is the accepted name for all the hypotheses on the past (from <em>kosmos</em> world, and <em>gignesthai</em> to originate). A corresponding form from the Greek, to designate the speculations on the future of the world, cosmothany (world's death), has been used; more correct formations are perhaps: cosmophthory (<em>phthora</em>, corruption) or cosmodysy (<em>dysis, occasus</em>, decline). <em>World</em> must here be taken in all its narrower or wider meanings, as earth, solar system, stellar system, universe.</p> <h3 id="A">Cosmogony</h3> <p>No <a href="../cathen/04405c.htm">cosmogony</a> can really claim to be a scientific theory or even hypothesis, in the proper sense of a systematic development of the details from a definite number of assumed principles. Proposition and rejection are alike vague and uncertain, and must be so, as processes of extrapolation from laboratory <a href="../cathen/09053a.htm">laws</a> to the fabric of the Creator.</p> <p>For more information on mythical cosmogony, the reader is referred to the article <a href="../cathen/04405c.htm">COSMOGONY</a>. For Biblical <a href="../cathen/04405c.htm">cosmogony</a>, see <a href="../cathen/07310a.htm">HEXAEMERON</a>.</p> <h3 id="B">Cosmodysy</h3> <p>This is the proposed name for all the hypotheses on the future of the world. The literature on cosmodysy is far less extensive than that on <a href="../cathen/04405c.htm">cosmogony</a>. The youth of the world seems to exert a stronger charm on human speculation than its old age and decline. There does not seem to exist any mythical cosmodysy, and very little can be found on scientific cosmodysies. So much the more explicit and detailed is Biblical cosmodysy (see <a href="../cathen/08549a.htm">DIVINE JUDGMENT</a>, IV). And yet, from a scientific point of view, the prospective conclusion from the known premises of the present world would seem to be better warranted than retrospective speculations upon cosmical conditions entirely unknown.</p> <p>One such theory is the extinction theory. This theory rests on a certain irreversible process, common to all natural phenomena, called entropy. While the sum total of cosmical energy is supposed to remain constant, the amount of potential energy is steadily diminishing. It is the unstable condition of potential energy that animates all activity in the universe. Drifting as it is towards stability, it will end in exhaustion and repose. The process is not reversible and consequently not cyclical. Applying it to the earth but abstracting from organic life, it will mean the extinction of its interior plutonic power and of its rotary speed. The raising and shifting of continents, the continual tremors, occasional earthquakes and volcanic eruptions, the gradual shrinkage of the crust and the wandering of the polar ice caps, are so many irretrievable losses of potential energy.</p> <p>Our scanty <a href="../cathen/13598b.htm">science</a> of cosmodysy might be a temptation to look for further information in the Scripture. Will the darkening of sun and moon, and the falling of stars, lend support to the extinction theory, for instance? The like question may be raised in <a href="../cathen/04405c.htm">cosmogony</a>. Can Genesis be consulted to decide between the various hypotheses?</p> <p>The answer is given by an attempt, made three centuries ago, in cosmography. The Scriptural decision of the controversy, whether the solar system be geocentric or heliocentric, was bound to be a failure either way. <a href="../cathen/04405c.htm">Cosmogonic</a> revelation was given to impress on the <a href="../cathen/09580c.htm">human race</a> its physical and moral dependency upon the Creator. Likewise has cosmodysic revelation the purpose of holding out to <a href="../cathen/09580c.htm">mankind</a> the final administration of <a href="../cathen/08571c.htm">justice</a>. Purely scientific curiosity will find no satisfaction in Scripture.</p> <div class='catholicadnet-728x90' id='cathen-728x90-bottom' style='display: flex; height: 100px; align-items: center; justify-content: center; '></div> <div class="pub"><h2>About this page</h2><p id="apa"><strong>APA citation.</strong> <span id="apaauthor">Hagen, J.</span> <span id="apayear">(1912).</span> <span id="apaarticle">Systems of the Universe.</span> In <span id="apawork">The Catholic Encyclopedia.</span> <span id="apapublisher">New York: Robert Appleton Company.</span> <span id="apaurl">http://www.newadvent.org/cathen/15183a.htm</span></p><p id="mla"><strong>MLA citation.</strong> <span id="mlaauthor">Hagen, John.</span> <span id="mlaarticle">"Systems of the Universe."</span> <span id="mlawork">The Catholic Encyclopedia.</span> <span id="mlavolume">Vol. 15.</span> <span id="mlapublisher">New York: Robert Appleton Company,</span> <span id="mlayear">1912.</span> <span id="mlaurl"><http://www.newadvent.org/cathen/15183a.htm>.</span></p><p id="transcription"><strong>Transcription.</strong> <span id="transcriber">This article was transcribed for New Advent by Tomas Hancil and Joseph P. Thomas.</span> <span id="dedication"></span></p><p id="approbation"><strong>Ecclesiastical approbation.</strong> <span id="nihil"><em>Nihil Obstat.</em> October 1, 1912. Remy Lafort, S.T.D., Censor.</span> <span id="imprimatur"><em>Imprimatur.</em> +John Cardinal Farley, Archbishop of New York.</span></p><p id="contactus"><strong>Contact information.</strong> The editor of New Advent is Kevin Knight. My email address is webmaster <em>at</em> newadvent.org. Regrettably, I can't reply to every letter, but I greatly appreciate your feedback — especially notifications about typographical errors and inappropriate ads.</p></div> </div> <div id="ogdenville"><table summary="Bottom bar" width="100%" cellpadding=0 cellspacing=0><tr><td class="bar_white_on_color"><center><strong>Copyright © 2023 by <a href="../utility/contactus.htm">New Advent LLC</a>. 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