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The Planet-Girded Suns: Man's View of Other Solar Systems  by Sylvia Engdahl (1974) ~ Page 3 of 8 |
Chapter Two
(Please read the Introduction
if you haven't yet seen it.)Historians do not know to what extent the growth of belief in other worlds was due to Bruno’s influence. It is difficult to determine because when he was sentenced to burn, it was also decreed that his books should be burned, and people who belonged to the Catholic Church were forbidden to read them. Naturally, some hid copies and read them anyway, but they could scarcely quote from them approvingly in their own writings. Most Protestants did not want to quote Bruno either, since they were equally opposed to many of the religious ideas he had expressed. The idea of an infinite universe filled with inhabited worlds flourished as part of Copernican astronomy; but as to just how it became a tenet of Copernicanism, there are mysterious gaps. Seventeenth-century writers who favored it treated it as a common idea that was already widely discussed.
It is frequently said that the discovery that the earth is not in the physical center of the universe was upsetting to people because they considered the center the place of greatest dignity. Scholars who have studied medieval beliefs in detail, however, point out that this is not true. The center was not thought to be a position of honor by Aristotelians; it was the lowest place. It was the farthest from heaven and the closest to hell—in fact hell was presumed to occupy the exact center. Furthermore, the earth was supposed to be composed of elements inferior to those found in the celestial spheres surrounding it. Both Christian and Jewish philosophers wrote a great deal about how small, base and corrupt Earth was in comparison to those spheres. One of the things that angered people most about the new cosmology was its assertion that heavenly bodies themselves were imperfect. Galileo, in his first book about his telescopic discoveries, wrote, “We shall prove the earth to be a wandering body surpassing the moon in splendor, and not the sink of all dull refuse of the universe.” Such statements were considered by some to be blasphemous.
Most modern historians therefore feel that the Copernican theory was not a threat to man’s dignity, at least not at first. Even the concept of the earth’s motion served to suggest that Earth shared the “perfection” associated with the circles in which celestial bodies were thought to move. Nevertheless, the cosmology that developed from the Copernican theory—which was often called “the new philosophy”—did strike a blow to human pride. It did so by implying that man was not the center of the universe in a spiritual sense: in other words, that this world is not the only one of importance, and that the universe does not exist merely for man’s benefit. In addition, it taught something much more frightening than the removal of Earth from the physical center of the universe. It taught that the universe has no center at all.
Bruno, and other philosophers who speculated about infinity, had not found the idea of no center frightening. The majority of people who tried to envision an infinite universe felt differently. They wanted a neat, orderly cosmos with a plan they could understand. They were deeply disturbed at the thought of space going on and on forever, with stars scattered here and there at unpredictable distances from each other. There are still people today who are frightened by the vastness of space; some of them think that if no clear pattern is apparent in it, then no pattern exists. Some believe that such a universe reduces man to total insignificance. These feelings were far worse among seventeenth-century people, who were suddenly told that the arrangement of things was not as it had been pictured for countless generations. The French philosopher Blaise Pascal spoke for many with his famous statement, “The eternal silence of these infinite spaces terrifies me.”
Perhaps that was one reason why the controversy about the new cosmology focused upon the theory of Copernicus. Perhaps people did not like to talk about the other things. The solar system was closer to home, and it was a less upsetting topic of debate. Moreover, it was obvious that if the earth was not a planet that revolved around the sun, none of the other issues would need to be raised. Whether or not this was the case (and there is no way of really knowing) the advocates of the “new philosophy” were called Copernicans, although most of them believed things Copernicus had never suggested. Also, their opponents started to place more and more emphasis on the assertion that the movement of the earth was contrary to the Bible: an assertion that had rarely been taken seriously before the full implications of the Copernican theory were seen. However, not everyone interpreted the Bible in the same way, and many people felt that it did not say anything with which Copernicanism did not fit.
The conflict between the old and new cosmologies should not be viewed as a conflict between religion and science. Many scientists were Aristotelians, and they resisted Copernicanism because it was not compatible with the current theories of physics. On the other hand, the Copernicans believed that nothing found to be true could be contrary to religion; they considered truth about the arrangement of the universe as vital to religion itself as to astronomy.
Part of the trouble was that religion, in that era, was mixed up with politics. For more than a hundred years Catholics had fought against Protestants and Protestant sects had fought against each other. Anything that weakened the authority of an established church also endangered the kings who belonged to it. It was a turbulent time, and there were sincere theologians who felt that uneducated people would lose their faith if the church’s teachings about the universe were allowed to be challenged. Especially they felt that it was the place of the church to decide what the Bible meant. One of the biggest issues between Catholics and Protestants concerned the right to interpret the Bible; when Copernican scientists like Galileo began to write their own interpretations, they were attacking the church not with scientific fact, but with competition in its own field.
Their attack on orthodox physics was even more audacious. Aristotelian scientists argued that if the earth moved there would be a wind strong enough to blow down trees, that birds could not fly fast enough to keep up, and that the world itself might be torn apart. There were also technical, mathematical arguments backed by sound logic. The unproven assumptions demanded by the new cosmology seemed less justifiable than those of the old. For example, it was correctly reasoned that slight differences in the positions of the stars should be observed if the earth revolved around the sun. Since no such differences could be measured, it had to be assumed that the stars were much farther away than had been thought, and therefore much larger. To many, these assumptions were unnecessary and unreasonable—more unreasonable than revolution of the sky. After all, man’s senses proclaimed that the earth did stand still; there was no observational evidence that it did not. Nor was there any physical theory to explain its motions, or those of any planet. What caused such motions, and what kept them regular? The Aristotelians had a detailed explanation based on the crystal spheres; the Copernicans, at first, could offer none.
The first scientific evidence for the fact that stars are suns, and that moons and planets are worlds, came in 1609 when Galileo first looked at the heavenly bodies through a telescope. Galileo himself did not believe in worlds outside our solar system—at least he never said that he did. However, he was arrested by the Inquisition for teaching Copernican theory as fact, and unlike Bruno he did recant. He retracted his criticism of Aristotelian cosmology. It has been suggested that his memory of Bruno’s fate may have had something to do with this; but the two cases are not comparable. Galileo honestly agreed with the Catholic Church in most religious matters, and he was therefore in the position of having to choose between his religion and what the telescope showed. He knew that the telescope’s evidence would not be affected by his denial of it. If Bruno had recanted, his ideas would have been discredited, since he had nothing but his own words to support them. That was not true of Galileo. People went on looking in telescopes despite his recantation, and meanwhile, he was able to complete further important work.
Galileo’s book Dialogue Concerning the Two Chief World Systems did a great deal to publicize Copernican ideas, perhaps more than it would have if it had not been banned. His greatest contribution to science was not that book, however. More significant was his role in developing a new theory of physics. Among the other seventeenth-century scientists most influential in the development of physics were Kepler, Descartes, and Newton, of whom more will be said later. All these men believed in the existence of other inhabited worlds, but without their work as physicists and mathematicians, their new philosophy of the universe would never have gained acceptance. Only by overcoming the valid objections of traditional science could Copernicanism advance.
As, gradually, it did advance, the larger implications Bruno had seen took hold. These implications frightened people, yet at the same time fascinated them. Not so long before, Columbus and other explorers had discovered a “New World” on the opposite side of the earth. The church had previously taught that there could be no inhabitants there, and had been forced to revise its teachings, a fact that believers in plurality of worlds lost no opportunity to point out. If there were unknown lands in one place, why not in another? To the average man, who knew nothing of philosophers and their arguments, the idea of an “upside down” continent was scarcely less strange than that of a distant planet.
The old ways of viewing the world were too deeply shaken to be preserved. Though thoughtful people were disturbed by the revolutionary new cosmology, many were drawn to it despite their fears. Possibly some who voiced the loudest objections were the most attracted underneath; it is often so when traditions lose their power.
The traditional conception of the universe lost its power to symbolize religious faith. But faith itself was neither lost nor separated from astronomy. Soon, in fact, the idea of extrasolar worlds became a symbol of the wisdom and majesty of God.
That change, of course, did not take place overnight. The controversy lasted for many years, years during which steady progress was being made in astronomical science.
It was Johannes Kepler who first abandoned the assumption that all heavenly bodies move in perfect circles. His laws of planetary motion were a great advance. Kepler, however, did not accept the idea of an infinite universe without a center. He was convinced that the sun was the center, and to Galileo he wrote, “From none of the fixed stars can such a view of the universe be obtained as is possible from our earth.” He also wrote that he rejoiced that the telescope had not discovered any planets revolving around other stars, saying that this freed him from great fear that had gripped him when he first heard about Galileo’s book. Kepler referred to Bruno’s belief in infinite worlds as “that dreadful philosophy.” He meant, literally, that it filled him with dread, for his own theory of the universe was an orderly one based on a symbolic correspondence between the positions of the planets and geometrical shapes.
Yet Kepler did not lack mental daring. He not only believed that the moon and planets of our own solar system were inhabited, but made the first serious suggestion that man would someday travel to those planets. “As soon as somebody demonstrates the art of flying,” he said in his letter to Galileo, “settlers from our species of man will not be lacking . . . Given ships or sails adapted to the breezes of heaven, there will be those who will not shrink from even that vast expanse . . . Does God the Creator . . . lead mankind, like some growing youngster gradually approaching maturity, step by step from one stage of knowledge to another? . . . How far has the knowledge of nature progressed, how much is left, and what may men of the future expect?”
One of the best-known and earliest protests against the Catholic decree that Copernicanism could be taught only as a mathematical calculating device was the Defense of Galileo by Thomas Campanella, who wrote it while confined in a dungeon. Campanella, like Bruno, was a monk and had been accused of heresy; but his prison sentence was the result of involvement in political conspiracy. The church did not object to the publication of his book, which was a detailed, impartial analysis of the arguments on both sides of the question that pertained to religion. (Not being a scientist, Campanella did not discuss the issue of physics.) In particular, he pointed out that past theologians had made statements supporting plurality of worlds, and supporting interpretations of the Bible that did not rule out motion of the earth or life on other planets. He did not say that he himself believed any aspects of the new cosmology, but he declared that it was a mistake to suppress such ideas. His book was read and quoted for many years by educated men throughout Europe.
Two other very influential books were written in 1638 and 1640 by John Wilkins, a bishop of the Church of England. They were titled The Discovery of a New World; or, a Discourse tending to prove that there may be another habitable World in the Moon, with a Discourse concerning the Possibility of a Passage thither and A Discourse concerning a New Planet; tending to prove that it is probable that our Earth is one of the Planets. These were long books discussing the religious objections to existence of other worlds in detail, as well as the possible nature of the moon’s inhabitants. The chapter headings give a good idea of the contents: they include, for instance, “That a plurality of worlds doth not contradict any principle of reason or faith;” “That the heavens do not consist of any such pure matter which can privilege them from the like change and corruption as these inferior bodies are liable unto;” and even, “That it is possible for some of our posterity to find out a conveyance to this other world, and if there be inhabitants there, to have commerce with them.”
In this last chapter Bishop Wilkins said, “I do seriously, and upon good grounds, affirm it possible to make a flying chariot. The perfecting of such an invention would be of such excellent use, that it were enough not only to make a man famous, but the age also wherein he lives. For besides the strange discoveries that it might occasion in this other world, it would be also of inconceivable advantage for travelling, above any other conveyance that is now in use.”
It may seem strange that he imagined moonships being invented before planes and used for air travel as an afterthought. But science had not yet defined the difference between air and space. There was no real need for a “flying chariot” merely to get to the other side of the earth; only passage to another world demanded a means of flight. And while such voyages were sometimes described in fiction, seventeenth-century science fiction was intended mainly as satire. Very few people shared Bishop Wilkins’ optimism in regard to flight as an actual possibility.
Although Bishop Wilkins wrote chiefly about the moon, he did imply a belief in other inhabited solar systems too. In answer to the contention that God could have had no purpose for making the stars as large and far away as the Copernican theory assumed, he asked the purpose of stars visible only through a telescope, and said, “Though scripture do tell us that these things were made for our use, yet it does not tell us that this is their only end. It is not impossible, but that there may be elsewhere some other inhabitants, by whom these lesser stars may be more plainly discerned.” With this comment, Bishop Wilkins introduced an idea that dominated thought about other worlds for at least two and a half centuries: the idea of the purpose of those worlds.
Under the old view it was assumed that God made everything for the use of man. But actually religion had never taught that man should consider himself of supreme importance in relation to God. The eighth psalm declares, “What is man, that thou art mindful of him?” and this had been pondered for hundreds of years before people began quoting it—as they soon did—in connection with the vastness of the universe. Once the existence of telescopic stars became undeniable, the idea of each star having inhabited planets was quickly accepted. Though there were holdouts against Copernicanism—such as Alexander Ross, who in answer to Bishop Wilkins’ books published one entitled The New Planet no Planet, or, the Earth no Wandering Star except in the Wandering Heads of the Galileans—everyone who did adopt the new cosmology adopted the idea of extrasolar worlds as an integral part of it. In fact, many who had not favored it were converted by their conviction that stars could not have been made without any purpose.
In general, people felt that an uninhabited world, or a star that gave light to no worlds, would be useless by any standard imaginable. In 1678 Ralph Cudworth, in a book called The True Intellectual System of the Universe, wrote, “Now it is not reasonable to think that all this immense vastness should lie waste, desert, and uninhabited, and have nothing in it that could praise the Creator thereof, save only this one small spot of Earth.” It was that argument, more than any other, that turned churches from opponents of belief in extraterrestrial life into its most ardent defenders. But religious leaders were not the only ones who used the argument. Scientists used it, too. Without data to work from, their theories were based entirely on their reasoning; and the thought of a useless sun or planet struck them as wholly unreasonable.
Scientific theories of other solar systems took quite a while to develop. Kepler and Galileo, the founders of the necessary physics, concentrated on our solar system alone. Not until the middle of the seventeenth century were the essential features of the new cosmology proclaimed by a major scientist: the French philosopher and mathematician, Rene Descartes.
Descartes was a Catholic, and although he was also a Copernican, was unwilling to defy the edicts of his church. When he heard that Galileo’s book had been condemned, he was astonished, for he saw nothing wrong in it; but he decided not to publish the book on Copernicanism that he himself had just finished. Some feel he was afraid to do so; others have pointed out that since he was a Frenchman and lived in Protestant-dominated Holland he could scarcely have feared the Inquisition, which had power only in Italy and Spain. It seems more likely that he merely wanted to keep his works off the prohibited list. Descartes’ ideas about cosmology did not involve the concept around which the religious opposition had become centered. He did not believe that the earth moved; instead, he believed that all celestial bodies were at rest in a moving sky. According to his “Theory of Vortices,” which he set forth in his Principles of Philosophy ten years after Galileo’s trial, all space was filled with invisible fluid matter that moved planets around suns in whirlpool currents. The earth itself did not move any more than do people who sleep aboard a ship that is carrying them across the ocean.
To the modern mind this may seem as if Descartes was trying to get around the opposition to Copernicanism on a technicality. Some historians have interpreted it that way, but there is no doubt that he sincerely believed in the fluid vortices. He had strong reasons for such a belief; philosophers had long taught that a void, or empty space, could not exist, and a basic principle of Aristotelian physics was nature’s “abhorrence of a vacuum.” The vortex theory of Descartes was the first attempt to provide a physical explanation for the Copernicans’ system of planetary motion. Its aim was to remove the main stumbling block to acceptance of that system by science; the fact that it circumvented religious opposition too may have been coincidental. Descartes did not avoid the underlying issues, those more basic to religion than motion of the earth. Though he called the universe “indefinite” rather than “infinite” in size, his system assumed that all stars were the centers of vortices and that all probably had planets. Because this system met little strong hostility from either theologians or scientists, the Cartesians—as Descartes’ followers were called—were credited with originating plurality of extrasolar worlds as a modern astronomical concept. The earlier speculators like Bruno were almost forgotten.
Today, Descartes is better known for his contributions to philosophy than those to science. Yet his theory was dominant in cosmology for many decades—in some countries, for more than a century. Some have said that its supremacy delayed acceptance of the more accurate theory of Newton; but though this may be true, it is doubtful whether people would have accepted Newton’s ideas if Descartes’ had not preceded them. The Cartesian vortex theory could not be attacked on the basis of traditional objections to Copernicanism. Furthermore, it could be easily pictured and understood. It was based on a principle that exerted great influence not only on astronomy but on all science: the principle that the universe is like a machine. Mechanism is no longer a tenet of scientific theory, for it is now known to be a much oversimplified view of physical phenomena. Yet even today a mechanical picture is the only kind some people can visualize.
The theory of Sir Isaac Newton, discoverer of the law of gravitation, was less mechanical than Cartesianism. That was people’s chief objection to it. The idea that planets were suspended in empty space, and kept in orbit by an invisible force from the sun, was not only incredible to them; it sounded like a step back to supernaturalism. Philosophers, scientists and mathematicians called gravity an “occult” force. They viewed it in much the same way as many still view ESP. That gravity should act at a distance, without any material connection between two celestial bodies, seemed no less impossible than telepathic communication seems to today’s most conservative scientists.
Newton’s book Mathematical Principles of Natural Philosophy, which was first published in 1687, is one of the most famous and important ones in the history of science. It became the foundation of both modern astronomy and modern physics. Because its mathematical laws of planetary motion explained things that could be explained in no other way, the Newtonian system eventually superseded the Cartesian system. But the change came slowly, particularly outside Newton’s native land of England. Even Newton himself was reluctant to accept the idea of space being a void, for it was not compatible with his own theories about light waves and colors.
Although he discovered more controlling principles of the physical universe than any man before him, Newton felt deeply frustrated by his inability to find a single pattern that offered answers for everything. “To myself,” he admitted, “I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.”
Others rated Newton far more highly than this. In his later life, and especially in the years immediately following his death, he was venerated as the greatest scientist the world had yet known. He proved that the movement of heavenly bodies was governed by exact, changeless laws. He restored people’s faith in a universe ruled by order, order no less immutable than that of the revolving Aristotelian spheres. The concept of extrasolar worlds revealing God’s glory was therefore closely associated with his name. Before that happened, however, people were convinced by the Cartesians that such worlds did exist.
The books of Descartes and Newton, like those of great scientists today, were technical ones full of mathematics. In addition, some were written in Latin, for scholars of that time still used Latin when they wished to be understood by colleagues in many countries. Ordinary people did not read such books any more than they would now read Einstein’s presentation of the theory of relativity. The controversies about cosmology had little effect on the average man, and still less on the average woman, since it was not the custom for women to study philosophy and science. But in 1686 a book appeared that was, in its own way, an even more influential one than Newton’s. This book, which has been called the first “popular science” book ever written, was the work of a Frenchman, Bernard de Fontenelle [pictured above], and its title was Conversations on the Plurality of Worlds.
There had been other books on the new astronomy for laymen, but Fontenelle’s was vastly more entertaining. It was meant not only for students and literary men, but for people in high society. In France, noblewomen did discuss science with gentlemen at social gatherings. The book took the form of conversations between two lovers: a Marquise—or Countess—and a Parisian philosopher with whom she was strolling through a French garden by starlight. Romance was a courtly, formal affair in seventeenth-century France. If readers found amusement in the eagerness of the Countess to learn astronomy, it was due less to the occasion than to the mere fact that she was a lady.
Fashionable ladies of lesser rank were not amused; they were entranced. In England especially, the Countess became their ideal. Within two years after its publication the book had been translated twice into English, one translation being by a woman, and there were many later editions as well as translations into various European languages. It remained a best-seller until well into the eighteenth century, despite the fact that it was based on the outdated vortex theory of Descartes.
The quotations that follow (including the spelling and punctuation) are taken from a translation made by John Glanvill in 1688. This was the form in which most English-speaking people first became familiar with the idea of inhabited planets outside our solar system:
The Countess was very impatient to know what would become of the fix’d Stars; are they inhabited, says she, as the Planets are, or are they not inhabited? What shall we do with’em? You may soon guess, said I; the fix’d Stars cannot be less distant from the Earth than fifty millions of leagues; nay, if you anger an Astronomer, he will set’em further . . . In a word, all the fix’d Stars are so many Suns.The Countess and her philosopher did not neglect to speak of love occasionally in the midst of their scientific discussion. Fontenelle managed to use arguments that he felt would be meaningful to ladies who, presumably, had little experience with the reasoning of scholars. Thus when the Countess inquired as to whether it was an absolute necessity that every star have planets, she was answered as follows:I perceive, says the Countess, where you would carry me; you are going to tell me, that if the fix’d Stars are so many Suns, and our Sun the centre of a Vortex that turns round him, why may not every fix’d Star be the centre of a Vortex that turns round the fix’d Star? Our Sun enlightens the Planets; why may not every fix’d Star have Planets to which they give light? You have said it, I reply’d, and I will not contradict you.
You have made the Universe so large, says she, that I know not where I am, or what will become of me; what is it all to be divided into heaps confusedly, one among another? Is every Star the centre of a Vortex, as big as ours? . . . I protest it is dreadful. Dreadful, Madam, said I; I think it very pleasant, when the Heavens were a little blue Arch, stuck with Stars, methought the Universe was too strait and close, I was almost stifled for want of Air.
You present me with a kind of Perspective of so vast a length, said the Countess, that no Eye can reach to the end of it . . . The Inhabitants of the Planets which are in other Vortex’s . . . are sunk into so great a depth, that tho’ I do all I can to see them, yet I must confess I can hardly perceive’em . . . We scarce know where we are in the midst of so many Worlds; for my own part, I begin to see the Earth so fearfully little, that I believe from henceforth, I shall never be concern’d at all for any thing: That we so eagerly desire to make ourselves great, that we are always designing, always troubling & harassing our selves, is certainly because we are ignorant of what these Vortex’s are.
Madam, said I, since we are in the humour of mingling amorous Follies with our most serious Discourses, I must tell you, that in Love and the Mathematicks People reason alike: Allow never so little to a Lover, yet presently after you must grant him more; nay more and more, which will at last go a great way: In like manner, grant but a Mathematician one little Principle, he immediately draws a consequence from it, to which you must necessarily assent . . . These two sorts of People, Lovers and Mathematicians, will always take more than you give’em.Reasoning like this, based on extending analogies, was the chief foundation for scientific ideas about other solar systems. Even the belief that their purpose must be habitation arose from the conviction that habitation was the purpose of the earth. As Fontenelle phrased it, “You grant that when two things are like one another in all those things that appear to you, it is possible they may be like one another in those things that are not visible, if you have not some good reason to believe otherwise.”Now this way of arguing have I made use of. The Moon, say I, is inhabited, because she is like the Earth; and the other planets are inhabited, because they are like the Moon; I find the fix’d Stars to be like our Sun, therefore I attribute to them what is proper to that: You are now gone too far to be able to retreat, therefore you must go forward with a good grace.
At the time Fontenelle wrote, scientists had no reason to believe that
not all planets were alike. There had not been much serious speculation
about the nature of other worlds’ inhabitants, or about possible
differences in their environments. His philosopher did tell the
Countess, “So near together are the Vortex’s of the Milky way, that
the People in one World may talk and shake hands with those of another; at
least I believe the Birds of one World may easily fly into another; and that
Pigeons may be train’d up to carry Letters.” He also suggested
that on these worlds so many nearby suns would be visible that there would
be no night. However, more prudently than many later writers, he concluded
his remarks with, “I think I have said enough for a Man that was never
out of his own Vortex.”
Lots more that I have written, or collected, about space! |
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