Imaginary Astronomies, Umberto Eco


 Imaginary Astronomies

I WOULD LIKE TO MAKE it clear straightaway that in talking about imaginary geographies and astronomies I will not be dealing with astrology. The history of astrology has continually crossed paths with that of astronomy, but the imaginary astronomies and geographies I will be talking about have all now been recognized as entirely imaginary or false, whereas businessmen and heads of state still turn to astrologers for guidance. Therefore astrology is not a science, whether exact or otherwise, but a religion (or a superstition—superstitions being other people’s religions), and as such cannot be demonstrated as true or false. It is only a question of faith, and in questions of faith it is always better not to get involved, if only out of respect for those who believe.

The imaginary geographies and astronomies I will be discussing were created by people of good faith who explored the sky and the earth as they saw them—and though they were wrong, we cannot doubt their good intentions. Yet those who are still involved in astrology today know perfectly well they are describing a sky that is different from that explored and defined by astronomy, and still they continue to behave as though their conception of the sky were true. There can be no sympathy for astrologers’ bad faith. They are not people who are deceived; they are deceivers. End of argument.

As a child I dreamed over atlases. I imagined journeys and adventures in exotic lands, or I thought of myself as a Persian conqueror traveling far into the steppes of central Asia, then descending toward the seas of the Sonda to build an empire stretching from Ecbatana to the island of Sakhalin. This is perhaps why as an adult I decided to visit all those places whose names had caught my imagination, like Samarkand or Timbuktu, the Alamo or the river Amazon, and all I am missing now are Mompracem1 and Casablanca.

My astronomical exploits have been more difficult, and always practiced vicariously. A friend of mine, a Czechoslovak exile who stayed at my house in the country during the 1970s and ’80s, built telescopes and explored the sky at night from the terrace, calling me out when he found anything of interest. I came to the conclusion that only I and Rudolf II of Prague had had the privilege of lodging a Bohemian astronomer permanently under our roof, but then the Berlin Wall came down and my Bohemian astronomer returned to Bohemia.

I have found consolation in my collection of antique books—I call it the Bibliotheca semiologica curiosa, lunatica, magica, et pneumatica—and it consists entirely of books that describe falsities. It includes the works of Ptolemy but not those of Galileo, and though as a child I dreamed up my journeys over the classic modern-day atlas, I now prefer to do it over maps of Ptolemaic origin.

Is this representation of the known world of that time an imaginary one? We need to distinguish between the various meanings of the word imaginary. Some astronomies have imagined a world based on pure speculation and mystical impulses—they tell us not what the visible cosmos looks like but what the invisible and spiritual forces are that pervade it. Other astronomies, though based on observation and experience, have nonetheless conceived explanations that we regard today as wrong. Look at the explanation that Athanasius Kircher gives for sunspots, in his Mundus subterraneus of 1665, as being puffs of steam from the surface of the star. Ingenuous, but ingenious. And to remain with Kircher, this is how he applied the principles of physics and mathematical calculus, in his Turris Babel of 1679, to show that it was impossible for the Tower of Babel to rise up to heaven. Beyond a certain height, having reached the same weight as the globe itself, the tower would have caused Earth’s axis to rotate 45 degrees.

THE SHAPE OF THE EARTH

Anaximenes, in the sixth century B.C.E., spoke of a terrestrial rectangle made of earth and water, framed by the ocean, which sailed around on a sort of cushion of compressed air.
It was fairly realistic for the ancients to believe the Earth was flat. For Homer it was a disc surrounded by ocean and covered by the canopy of the heavens, and it was a flat disc for Thales and for Hecataeus of Miletus. It seemed less realistic to think it was spherical, as Pythagoras did, for mystical and mathematical reasons. The Pythagoreans had elaborated a complex planetary system in which the Earth was not even at the center of the universe. The sun was also at the edge of it, and all the planetary spheres rotated around a central fire. Each rotating sphere, moreover, produced a sound from a range of musical notes, and to establish an exact correspondence between sounds and astronomical phenomena, a nonexistent planet, the Antichthon (Counter-Earth), was also introduced. In their mathematical and musical zeal (and in their scorn of sensory experience), the Pythagoreans had not considered that if each planet produced a sound from this range of notes, their planetary music would have produced a repugnant dissonance, as if a cat had suddenly jumped onto the keys of a piano. But we still find this idea more than a thousand years later in Boethius—and let us not forget that Copernicus was also inspired by mathematical-aesthetic principles.

Subsequent demonstrations of the Earth’s roundness, though, were based on empirical observations. Ptolemy, of course, knew that Earth was round; otherwise he wouldn’t have been able to divide it into 360 degrees of longitude. But Parmenides, Eudoxus, Plato, Aristotle, Euclid, and Archimedes had already understood this. And Eratosthenes knew it in the third century B.C.E., when he had calculated fairly accurately the length of Earth’s meridian, calculating the different inclination of the sun, at midday on the summer solstice, when it reflected into the bottom of the wells of Alexandria and Syene (now Aswan). But—so far as the Earth being flat—I must digress for a moment to say that there is not only a history of imaginary astronomy, but also an imaginary history of astronomy, which still survives today in many scientific circles, not to mention in popular opinion. Try an experiment. Ask any reasonably intelligent person what Christopher Columbus wanted to demonstrate when he decided to reach the East by way of the West, and what the learned men of Salamanca persistently denied. The answer, in most cases, will be that Columbus thought the Earth was round, while the learned men of Salamanca believed it was flat and that after a short distance the three caravels would fall off the edge into the cosmic abyss.

Nineteenth-century secular thought, irritated by the fact that the church had not accepted the heliocentric theory of the universe, attributed to Christian thought (both patristic and scholastic) the idea that the Earth was flat. This idea gained force during the campaign by supporters of Darwin against all forms of fundamentalism. They wanted to show that since the church was wrong about the Earth’s being round, it could be wrong about the origin of species. They therefore took advantage of the fact that the fourth-century Christian writer Lactantius (in his Divinae institutiones) had contested the pagan theories about the roundness of the Earth by arguing that the Bible describes the universe on the model of the tabernacle. It must therefore be rectangular in form, not least because Lactantius could not accept the existence of the Antipodes, where people would have to walk around upside-down.

Then it was discovered that a sixth-century Byzantine geographer, Cosmas Indicopleustes, in his Topografia Christiana, thinking once more of the biblical tabernacle, had claimed the cosmos was rectangular, with an arch over the flat floor of the Earth.

The curved vault remained hidden from our eyes by the stereoma, in other words, by the veil of the firmament. Beneath this was the ecumene, namely, all the land on which we live, which sits on the ocean and slopes imperceptibly and continually upward to the northwest. Here there is a mountain so high that it is lost to our view and its peak disappears among the clouds. The sun, moved by angels—who also control earthquakes, and the rains and all other atmospheric phenomena—passes in the morning from the east toward the meridian, in front of the mountain, lighting up the world, and in the evening it reaches the west and disappears behind the mountain. The reverse cycle is followed by the moon and by the stars.

Cosmas also shows us the Earth as if we were looking at it from above. There is the frame of the ocean, beyond which are the lands where Noah lived before the flood. Farthest east from these lands, separated from the ocean by regions inhabited by monstrous beings, is the earthly paradise. The Euphrates, Tigris, and Ganges spring from paradise. They pass under the ocean and flow out into the Persian Gulf. The Nile takes a more tortuous route via the antediluvian lands, it enters the ocean, continues its course into the low northern regions—more accurately, into the land of Egypt—and flows out into the Golfo Romaico, the Hellespont.

As Jeffrey Burton Russell has shown in his Inventing the Flat Earth (1991), many influential books on the history of astronomy still studied at school claim that Cosmas’s theory became the prevailing view throughout the Middle Ages. They also claim the medieval church taught that the Earth was a flat disc, with Jerusalem at the center, and that the works of Ptolemy remained unknown throughout the Middle Ages. The fact is, Cosmas’s text—written in Greek, a language the medieval Christian had forgotten—became known in the Western world only in 1706 and was published in English in 1897. No medieval writer knew of it.

A first-year pupil at a secondary school can easily work out that if Dante enters the funnel of hell and leaves from the other side, seeing unknown stars from the slopes of Mount Purgatory, this means he knew perfectly well that the Earth was round. But Origen, Saint Ambrose, Albertus the Great, Thomas Aquinas, Roger Bacon, and John of Holywood (to mention just a few) were all of the same view. The point of dispute at the time of Columbus was that the calculations made by the learned men of Salamanca were more accurate than his. They claimed that the Earth, which was certainly round, was larger than our Genoese voyager imagined, and it was therefore pure folly to try to circumnavigate it. Columbus, however, a fine navigator but a useless astronomer, thought the Earth was smaller than it was. Neither he nor the learned men of Salamanca, of course, suspected the existence of another continent between Europe and Asia. Though they were right, the doctors of Salamanca were wrong; and Columbus, though wrong, faithfully pursued his error and was right—through serendipity.

How did the idea develop that in the Middle Ages people thought the Earth was a flat disc? In the seventh century, Isidore of Seville (though hardly a model of scientific accuracy) calculated the equator to be eighty thousand rods long. Therefore, he thought the Earth was round. But among Isidore’s manuscripts is a diagram that influenced many representations of our planet, the so-called T-O map.

The upper part represents Asia—at the top because, according to legend, earthly paradise was to be found in Asia. The horizontal bar represents the Black Sea on one side and the Nile on the other, and the vertical bar is the Mediterranean, so that the quarter circle on the left represents Europe and that on the right, Africa. All around it is the great circle of the ocean.

The impression that the Earth was seen as a circle is given by the maps illustrating the Commentary on the Apocalypse by Beatus of Liébana. This text, written in the eighth century but illustrated by Mozarabic illuminators in later centuries, was to have a major influence on the art of the Romanesque abbeys and Gothic cathedrals—and its model is to be found in countless other illuminated manuscripts.

How was it possible for people who thought the Earth was round to draw maps showing it to be flat? The first explanation is that we do the same ourselves. Criticizing the flatness of these maps would be like criticizing the flatness of our modern-day atlas. It was a naive and conventional form of cartographic projection.

It could be pointed out that over the same centuries the Arabs had produced more accurate maps, though they had the bad habit of representing north at the bottom and south at the top. But we have to bear in mind other considerations. The first is suggested by Saint Augustine, who was well aware of the debate begun by Lactantius about the cosmos in the shape of a tabernacle, but was at the same time aware of the views of the ancients on the roundness of the globe. Augustine’s conclusion is that we should not place too much emphasis on the biblical description of the tabernacle because, as we know, the holy scriptures often speak through metaphor, and perhaps the Earth is round. But since knowledge about whether it is spherical or not doesn’t help us to save our souls, we can ignore the question.

This doesn’t mean, as has often been suggested, that there was no medieval astronomy. We need only cite the story of Gerbert d’Aurillac, the tenth-century pope Sylvester II, who in order to obtain a copy of Lucan’s Pharsalia promised an armillary sphere in exchange; not realizing that the Pharsalia had been left incomplete on Lucan’s death, upon receiving an incomplete manuscript he gave only half of the armillary sphere in exchange. This indicates the great attention given to classical culture during the early Middle Ages, but it also indicates the interest in astronomy at the time. Ptolemy’s Almagest and Aristotle’s De caelo were translated during the twelfth and thirteenth centuries. As we all know, astronomy was one of the subjects of the quadrivium taught in medieval schools, and in the eighth century John of Holywood’s Tractatus de sphaera mundi, based on Ptolemy, was to be the undisputed authority for centuries to come.

Yet it is also true that geographical and astronomical notions had long been confused by the ideas of authors such as Pliny or Solinus, for whom astronomy was certainly not of uppermost concern. The picture of the Ptolemaic cosmos, formed perhaps indirectly through other sources, was theologically most credible. Each element of the world, as Aristotle taught, had to remain in its proper natural place, from which it could be moved only by violence and not by nature. The natural place for the earthly element was the center of the world, whereas water and air had to remain in an intermediate position, and fire was at the edge. It was a reasonable and a reassuring picture, and this idea of the universe enabled Dante to imagine his journey into the three realms of the afterlife. 

And if this representation did not take account of all celestial phenomena, Ptolemy himself contrived to introduce adjustments and corrections, such as the theory of epicycles and deferents, according to which, in order to explain various astronomical phenomena such as accelerations, positions, retrograde motions, and the variations in distances of various planets, it was supposed that each planet rotates around the Earth along a larger circle, called the deferent, but also moves in a small circle, or epicycle, around a point C of its own deferent.

Lastly, the Middle Ages was a period of great travel, but with the roads in disrepair, great forests to pass through, and stretches of sea to be crossed at the mercy of buccaneers, there was no possibility of drawing adequate maps. They were purely indicative, like the instructions in the Pilgrim’s Guide at Santiago de Compostela, which said, more or less, “If you want to get from Rome to Jerusalem, head southward and ask along the way.” Now, try thinking of the rail maps you find with train timetables. No one could deduce the exact shape of Italy from that series of junctions, each perfectly clear in itself when you have to take a train from Milan to Livorno (and realize that you have to change at Genoa). The exact shape of Italy is of no interest to anyone traveling to that station.

The Romans built a series of roads that linked every city in the known world, but this is how those roads were represented in the map known as the Tabula Peutingeriana, named after the man who had rediscovered it in the fifteenth century. The upper part represents Europe, with Africa below, but we are in exactly the same situation as the railway map. From this map we can see the roads, our points of departure and arrival, but have absolutely no idea about the shape of Europe, or the Mediterranean, or Africa—and the Romans certainly had a much clearer notion of geography than this. They were not interested in the shape of the continents, but rather in whether, for example, there was a road that would take them from Marseille to Genoa.

Then again, medieval journeys were imaginary. The Middle Ages produced encyclopedias, Imagines mundi, whose authors tried as far as possible to satisfy the taste for wonder, writing about far-off, inaccessible lands, and these books are all written by people who had never seen the places they are describing—the force of tradition at that time was more important than experience. A map did not seek to represent the form of the Earth but to list cities and peoples along the way.

Once again, symbolic representation was more important than empirical representation. In many maps, the illuminator was most concerned about placing Jerusalem at the center of the Earth, rather than showing how to get there. Yet most maps of that period represent Italy and the Mediterranean fairly accurately.

One last consideration. Medieval maps did not have a scientific purpose but instead responded to the audience’s need for wonder, in rather the same way that popular magazines today show us that flying saucers exist and we are told on television that the pyramids were built by an extraterrestrial civilization. The creators of these maps looked up at the sky with the naked eye to see comets, which the imagination immediately transformed into something that (today) would confirm the existence of UFOs. On many fifteenth- and sixteenth-century maps with a reasonably accurate cartographic layout, mysterious monsters are depicted in the lands where they are supposed to live, and are reproduced on the map in a not entirely mythical fashion.
So let us not be too critical of medieval maps. It is with them that Marco Polo arrived in China, the Crusaders in Jerusalem, and perhaps the Irish or the Vikings in America.

A short aside—is it really true, as legend suggests, that the Vikings reached America? We all know that the real revolution in medieval navigation came with the invention of the stern-mounted hinged rudder. On Greek and Roman ships, as well as those of the Vikings and even those of William the Conqueror who landed on the English coast in 1066, the rudder consisted of two rear side-oars, operated in such a way as to set the intended direction of the boat. The system, apart from being fairly exhausting to use, made it practically impossible to maneuver large wooden vessels. Above all, it was impossible to sail against the wind; to do so, it was necessary to tack—to move the rudder so that each side of the boat faced alternately into the wind, first one side and then the other. Sailors therefore had to limit themselves to navigating close to shore, following the coastlines so that they could take shelter when the wind was unfavorable.

The Vikings (and the same was true for the Irish monks) could never, therefore, have sailed from Spain to Central America, as Columbus would later do. But the picture changes if we imagine they first took a route from Iceland to Greenland, and from there to the Canadian coast. Looking at a map, we can easily see how skilled mariners in longships could succeed (with who knows how many shipwrecks along the way) in reaching the far north of the American continent and perhaps the coast of Labrador.

THE SHAPE OF THE SKY

But let us leave the Earth and look at the sky. Aristarchus of Samos had advanced a heliocentric theory between the fourth and third centuries B.C.E., as Copernicus recorded. Plutarch tells us that Aristarchus was accused of impiety precisely because he had put the Earth in movement so as to explain, through earthly rotation, astronomical phenomena that could not otherwise be accounted for. Plutarch did not agree with this theory and Ptolemy later judged it “ridiculous.” Aristarchus was way ahead of his time, and perhaps he reached his conclusion for the wrong reasons. There again, the history of astronomy is curious. A great materialist such as Epicurus developed an idea that survived for so long that it was still being discussed by Gassendi in the seventeenth century, as well as appearing in Lucretius’s De rerum natura. He suggested that the sun, the moon, and the stars (for many very serious reasons) can be neither larger nor smaller than how they appear to our senses. So Epicurus judged the sun to have a diameter of about thirty centimeters.

Copernicus’s De revolutionibus orbium coelestium was published in 1543. We imagine the world was suddenly turned upside-down and we talk about the Copernican revolution. But Galileo’s Dialogo sopra i due massimi sistemi was published in 1632 (eighty-nine years later) and we know what opposition this met. There again, the astronomies of both Copernicus and Galileo were imaginary, since they were wrong about the nature of planetary orbits.

But the most rigorous of imaginary astronomies was that of Tycho Brahe, a great astronomer and Kepler’s teacher, who admitted that planets rotate around the sun—otherwise many astronomical phenomena could not be explained—but claimed that the sun and planets rotate around the Earth, which remains immobile at the center of the universe.

Brahe’s theory was taken seriously, for example, by the Jesuits and especially by Athanasius Kircher. Kircher was a cultured man and could no longer accept the Ptolemaic system. In an illustration of solar systems in his Iter extaticum coeleste (1660 edition), alongside the Platonic system and the Egyptian system he shows us the Copernican system, explaining it accurately, but adding this note: quem deinde secuti sunt pene omnes Mathematici Acatholici et nonnulli ex Catholicis, quibus nimirum ingenium et calamus prurit ad nova venditanda. This was later accepted by almost all non-Catholic and some Catholic mathematicians, namely those who evidently had a craving to peddle new ideas in their writings. Not being of that accursed breed, Kircher thus prefers Brahe.

There were, however, very strong arguments against the idea of an Earth that moves around the sun. In his Utriusque cosmi historia of 1617, Robert Fludd uses mechanical arguments to show that if you have to turn a wheel, like that of the celestial wheel, it is easier to make it turn by exercising a force around the circumference—the point among the spheres where the primum mobile was—than by acting on the center, where the foolish Copernicans would place the sun and every generating force of life and motion. Alessandro Tassoni, in his Dieci libri di pensieri diversi of 1627, lists a range of reasons why the movement of the Earth seemed inconceivable. I will quote two of them.

Argument of the Eclipse. By removing the Earth from the center of the universe, it has to be placed either below or above the moon. If we place it below, there will never be an eclipse of the sun since the moon, being above the sun and above the Earth, will never come between the Earth and the sun. If we place it above, there will never be an eclipse of the moon, since the Earth will never be able to come between it and the sun. And what is more, astronomy could no longer predict eclipses, since it bases its calculations on the movements of the sun, and if the sun does not move, such calculations would be in vain.

Argument of the Birds. If the Earth moves, birds flying westward would never be able to keep up with its rotation and would never go forward.

Descartes, who favored Galileo’s hypothesis but never had the courage to publish his opinions about it, had developed quite an interesting theory involving vortexes, or tourbillons, in Principia philosophiae (1644). He imagined that the heavens were liquid matter, like a sea, swirling about, forming eddies or whirlpools. These vortexes carry planets with them, and the Earth is carried in a vortex around the sun. But it is the vortex that moves. The Earth remains immobile in the vortex that carries it. Descartes was shrewd in setting out these astonishing explanations—a way of getting out of the impasse between the geocentric and heliocentric arguments—as a mere hypothesis, without having to dispute the truth recognized by the church.

As Apollinaire said, Pitié, pitié pour nous qui combattons aux frontières de l’illimité et de l’avenir, pitié pour nos péchés, pitié pour nos erreurs . . . These were times when the astronomer could still commit many serious mistakes, as happened to Galileo when, through his telescope, he discovered the rings of Saturn but could not work out what they were.

First of all he declares he has seen not one single star but three joined together in a straight line parallel to the equinoctial, and represents what he has seen as three small circles. In his later writing he suggests that Saturn may appear in the shape of an olive, and finally he no longer describes three bodies or an olive, but “two semi-ellipses with two very dark little triangles in the middle of the said figures” and draws Saturn to look very much like Mickey Mouse.

Only later would Huygens describe a ring.

AN INFINITY OF WORLDS

Roaming among worlds constructed by the imagination, the imaginary astronomy of our forebears, shaded with hints of the occult, was able to create a revolutionary idea: that of the plurality of worlds. It was an idea already present among the ancient atomists—in Democritus, Leucippus, Epicurus, and Lucretius. As Hippolytus tells us in his Philosophumena, if atoms are in continuous movement in the void, they cannot but produce infinite worlds, each different from the other; and some have neither sun nor moon, for others the stars appear larger than they do for us, and from others many more stars are seen. For Epicurus, it was a hypothesis that, since it could not be contradicted, had to be taken as true until shown to be false. In the words of Lucretius (De rerum natura, book II, lines 1050–51), “Nulla est finis: uti docui, res ipsaque per se / vociferatur, et elucet natura profundi” (“There is no limit; I have shown this, the facts speak for themselves, and the nature of the void is evident”). And he continues: “Thus it is increasingly necessary you recognize that other congregations of material bodies exist elsewhere in the universe, like this of our world, which the ether encircles in eager embrace” (lines 1064–66).

Both the void and the plurality of worlds were disputed by Aristotle and, as well as Aristotle, by great scholars such as Thomas Aquinas and Roger Bacon. But when it came to the debate over the infinita potentia Dei, suspicions about the plurality of worlds would be expressed by William of Ockham, Buridan, Nicole Oresme, and others. Nicholas of Cusa spoke about an infinity of worlds in the fifteenth century, and Giordano Bruno in the sixteenth century.

The deadly poison contained in this hypothesis would emerge more clearly when it gained support from the new epicureans, the seventeenth-century freethinkers. The idea of visiting other worlds, of finding other inhabitants there, was a far more dangerous heresy than the notion of heliocentricity. The infinity of worlds casts doubt on the uniqueness of redemption: Adam’s sin and Christ’s passion are either just minor episodes relevant to our world but not to other divine creatures, or else Golgotha would have to be repeated an infinite number of times on endless planets, removing the sublime uniqueness of the sacrifice of the Son of Man.

As Fontenelle would recall in his Entretiens sur la pluralité des mondes (1686), the suggestion was already there in the Cartesian theory of vortexes, because if every star sweeps its planets into a vortex, and the star is swept away by a larger vortex, it was possible to imagine in the sky an infinity of vortexes carrying an infinity of planetary systems.
The idea of the plurality of worlds heralded the beginning of modern science fiction in the seventeenth century, from the travels of Cyrano di Bergerac in the empires of the sun and of the moon, to Francis Godwin’s The Man in the Moone and John Wilkins’s Discovery of a World in the Moone. As to methods for takeoff, we have not yet reached Jules Verne. Cyrano, the first time, attaches to his body a great number of ampoules filled with dewdrops, and the heat of the sun, attracting the dewdrops, makes him rise. On a second occasion he uses a machine driven by firecrackers. Godwin, however, proposes an airplane ante litteram propelled by birds.

Science Fiction

Modern science fiction, from Verne to the twenty-first century, opens up another chapter of imaginary astronomies, in which theories of astronomy and scientific cosmology are taken to the extreme. My old pupil Renato Giovannoli has written a fascinating book on science in science fiction,2 in which he examines not only all the (often highly convincing) pseudoscientific theories developed in stories about the future, but also shows how science in science fiction consists of a fairly uniform body of ideas and topoi that return from narrator to narrator, with subsequent improvements and developments. These include Verne’s cannons loaded with nitroglycerin and Wells’s antigravitational rooms; time travel and the various techniques for space navigation; traveling while in a state of hibernation; the spaceship as a small, ecologically self-sufficient world, with hydroponic gardening systems; and the infinite variations on the Langevin paradox, whereby the astronaut returns from a voyage in space at the speed of light, only to find himself ten years younger than his twin brother. Robert A. Heinlein, for example, in Time for the Stars, wrote a story involving twins who communicate telepathically during the journey, but Tullio Regge, in his Cronache dell’universo, noted that if telepathic messages arrive instantly, the answer from the brother in space ought to arrive before the question.

Another recurring theme is that of hyperspace, which Heinlein, in Starman Jones, describes using a scarf as a model: “Here’s Mars . . . Here’s Jupiter. To go from Mars to Jupiter you have to go from here to here . . . But suppose I fold [the scarf] so that Mars is on top of Jupiter? What’s to prevent us just stepping across?” So science fiction has been off in search of abnormal parts of the universe where space can fold back on itself. It has also used scientific hypotheses, such as Einstein-Rosen bridges, black holes, and space-time wormholes. Kurt Vonnegut, in The Sirens of Titan, theorized about “chrono-synclastic infundibula,” tunnels in hyperspace, while others have invented tachyons, particles that move faster than light.3
All the problems of time travel have been discussed—with and without the time traveler meeting his own double (including the famous grandfather paradox, whereby if we go back in time and kill our grandfather before he gets married, perhaps we would disappear at that moment)—using also the concepts developed by scientists, such as Hans Reichenbach in The Direction of Time, in relation to closed causal chains whereby, at least in the subatomic world, A causes B, B causes C, and C causes A. Philip K. Dick, in Counter-Clock World, theorized about entropic inversion. The first part of Fredric Brown’s short story “The End” makes the supposition that time is a field and that the character Professor Jones has found a machine that reverses it. Jones presses the button, and the second part consists of the same words as the first, but in reverse order.

And finally, using the ancient theory of the infinity of worlds, writers have imagined parallel universes, so that Fredric Brown, in his novel What Mad Universe, reminds us that an infinite number of universes can exist at the same time: “There is, for example, a universe in which this exact scene is being repeated, except that you—or the equivalent of you—are wearing brown shoes instead of black ones . . . There are an infinite number of permutations on that variation, such as one in which you have a slight scratch on your left forefinger, and one in which you have purple horns . . .” But on the logic of possible worlds, philosophers such as D. K. Lewis, in Counterfactuals (1973), has also stated, “I emphatically do not identify possible worlds in any way with respectable linguistic entities; I take them to be respectable entities in their own right. When I profess realism about possible worlds, I mean to be taken literally . . . Our actual world is only one world among others . . . You believe in our actual world already. I ask you to believe in more things of that kind.”

How much separates science fiction from the science that preceded it or will come after it? Given that science fiction writers certainly read the work of scientists, how many scientists have nourished their imaginations reading science fiction? How many imaginary astronomies of science fiction are, or will remain, imaginary?

I have found a text by Thomas Aquinas (In primum sententiarum, distinction 8, article 1.2) in which he distinguishes two types of morphological relationship between cause and effect: cause can resemble effect, as a person resembles his portrait, or cause can be different from effect, as happens with fire that causes smoke; and in this second category of causes Aquinas includes the sun, which produces heat but is itself cold. We may laugh, since he reached this model from his theory of celestial spheres, but if one day cold fusion is taken seriously, might we have to reconsider this idea of Aquinas with more respect?

THE COLD SUN AND THE HOLLOW EARTH

Speaking of the cold sun, certain kinds of geo-astronomy have gone beyond the bounds of imagination into the realms of insanity, and yet seem to have influenced some very serious, though scarcely laudable, ideas and decisions.

In 1925, the theory of an Austrian pseudoscientist, Hanns Hörbiger, which was called the WEL, the Welteislehre or world ice theory, began to circulate within Nazi circles.4 This theory was to enjoy the support of men like Rosenberg and Himmler. But when Hitler rose to power Hörbiger was taken seriously even by some members of the scientific community, including people like Lenard, who had discovered x-rays with Röntgen.

According to Hörbiger, the cosmos was the theater of an eternal struggle between ice and fire, which produces not an evolution but an alternation of cycles, or epochs. An enormous hot body, millions of times larger than the sun, had once collided with an immense accumulation of cosmic ice. The mass of ice had penetrated into this incandescent body and, after having worked within it as a vapor for hundreds of millions of years, had made the whole thing explode. Various fragments were propelled into frozen space as well as into an intermediate zone, where they established the solar system. The moon, Mars, Jupiter, and Saturn are blocks of ice, and the Milky Way is a circle of ice—traditional astronomy purports that the Milky Way is made up of stars, but trick photography creates this illusion. Sunspots are produced by blocks of ice that break off from Jupiter.

The power of the original explosion is now diminishing and each planet does not revolve elliptically, as official science erroneously believes, but is (imperceptibly) spiraling toward the planet that most attracts it. At the end of the cycle in which we are living, the moon will move closer and closer to Earth, gradually raising the level of the oceans, submerging the tropics, and leaving only the highest mountains above water. The cosmic rays will become more powerful and will produce genetic mutations. In the end our own satellite will explode and be transformed into a ring of ice, water, and gas, which will then precipitate onto Earth. As the result of a complex series of events caused by the influence of Mars, Earth will also become a globe of ice and in the end will be reabsorbed by the sun. There will then be a new explosion and a new beginning. In the same way, the Earth in the past has already had, and then reabsorbed, three other satellites.

This cosmogony obviously presupposed a sort of eternal return, which harked back to ancient myths and epics. What Nazis today call “knowledge of tradition” was once again contrasted with the “false knowledge” of liberal and Jewish science. A glacial cosmogony, moreover, seemed very Nordic and Aryan. Pauwels and Bergier, in their Le matin des magiciens,5 attribute this great belief in the frozen origins of the cosmos to the faith, encouraged by Hitler, that their troops would cope very well in frozen Russia. But the authors also suggest that the need to test how cosmic ice would react had also delayed experiments on the V-1 flying bombs. Someone writing under the name of Elmar Brugg6 published a book in 1938 in which he paid tribute to Hörbiger as the twentieth-century Copernicus, claiming that the world ice theory explained the profound links between earthly events and cosmic forces and concluding that the silence on the part of democratic-Jewish science to Hörbiger’s ideas was a typical case of the conspiracy of mediocrity.

The fact that the Nazi party was surrounded by followers of magical, hermetic, and neo-Templaristic practices, such as the disciples of the Thule Gesellschaft founded by Rudolf von Sebottendorff, has already been amply studied.7

Another theory was taken seriously in Nazi circles: that the Earth is hollow and that we do not live outside, on the convex external crust, but inside, on the concave internal surface. This theory was first proposed in the early nineteenth century by a certain Captain John Cleves Symmes of Ohio, who wrote to various scientific societies, “To all the World: I declare that the earth is hollow and habitable within; containing a number of solid concentric spheres, one within the other, and that it is open at the poles twelve or sixteen degrees.” The wooden model of his universe can be seen today at the Academy of Natural Sciences in Philadelphia.

The theory was taken up again fifty years later by Cyrus Reed Teed, who declared that what we believe to be the sky is a mass of gas that fills the interior of the globe with areas of brilliant light. The sun, the moon, and the stars were not, he said, celestial globes but visual effects caused by various phenomena.

After the First World War the theory was introduced into Germany by Peter Bender, and then by Karl Neupert, who founded the movement based on the Hohlweltlehre, the hollow earth theory. According to some sources,8 the theory was taken seriously among members of the German hierarchy, and in certain parts of the German navy it was believed that the hollow earth theory made it possible to fix the positions of English ships more accurately because, if infrared rays were used, the curvature of the Earth would not have obscured observation. It is even said that some of the V-1 firings were wrong because the trajectory was calculated on the basis of a concave and not a convex land surface. If this is true, then the historical and providential utility of insane astronomies is perfectly apparent.

IMAGINARY GEOGRAPHY AND TRUE HISTORY

During the second half of the twelfth century, a letter reached the West telling how in the Far East, beyond the regions occupied by the Muslims, beyond those lands that the Crusaders had tried to take from the dominion of the infidels but had nonetheless returned to their dominion, there flourished a Christian kingdom, governed by the legendary Prester John, or Presbyter Johannes, re potentia et virtute dei et domini nostri Iesu Christi. The letter began as follows:

Hear and believe: I, Presbyter Johannes, the Lord of Lords, surpass all under heaven in virtue, in riches, and in power; seventy-two kings pay us tribute . . . In the three Indies our Magnificence rules, and our lands extend beyond India, where rests the body of the holy apostle Thomas; they reach toward the sunrise over the wastes, and extend toward deserted Babylon near the Tower of Babel . . . In our domains live elephants, dromedaries, camels, hippopotami, crocodiles, metagallinari, cametennus, tinsirete, panthers, onagers, red and white lions, white bears and blackbirds, mute cicadas, griffins, tigers, jackals, hyenas, wild oxen, centaurs, wild men, horned men, fauns, satyrs and women of the same species, pygmies, men with dogs’ heads, giants forty cubits tall, monocles, cyclopes, a bird called phoenix, and almost every kind of animal that lives beneath the vault of the heavens . . . In one of our provinces the river known as Indus flows. This river, whose source is in Paradise, winds its way along various branches through the entire province and in it are found natural stones, emeralds, sapphires, garnets, topazes, chrysolite, onyx, beryl, amethyst, sardonyx, and many other precious stones.

And so it went on, listing other wonders. Translated and paraphrased many times during the following centuries, up to the seventeenth century, and in various languages and versions, the letter was to be highly influential in the expansion of the Christian West toward the East. The idea that a Christian kingdom might exist beyond the Muslim lands justified all enterprises in expansion and exploration. Giovanni da Pian del Carpine, William of Rubruck, and Marco Polo all mentioned Prester John. Toward the middle of the fourteenth century, Prester John’s kingdom moved from a vague Orient toward Ethiopia when Portuguese mariners began their African campaign. Attempts to contact him were made in the fifteenth century by Henry IV of England, by the duc de Berry, and by Pope Eugene IV. In Bologna, at the time of the coronation of Emperor Charles V, there were still discussions about Prester John as a possible ally for the recapture of the Holy Sepulcher.

How did Prester John’s letter come into being, and what was its purpose? Perhaps it was a piece of anti-Byzantine propaganda, produced in the scriptoria of Frederick I, but the problem is not so much its origin as the way it was received. Through geographical fantasy a political project gradually gained strength. In other words, the specter evoked by some scribe inclined to forgery (a highly respectable literary genre at the time) was used as an excuse for expanding the Christian world toward Africa and Asia, a friendly gesture in supporting the white man’s burden.

And thus we have a case of imaginary geography that has produced real history. And it is not the only case. I would like to finish with the sixteenth-century Typus orbis terrarum by Ortelius.

Ortelius had already portrayed the American continent with remarkable precision, but he still thought, like many before and after, that Terra Australis, an immense cap covering the southern part of the planet, existed. It was in search of this hypothetical austral land that indefatigable mariners like Mendaña, Bougainville, Tasman, and Cook explored the Pacific. Thanks to an imaginary map, the real Australia, Tasmania, and New Zealand were eventually discovered.

Spare a thought, then, for those who fought at the frontiers of infinity and the future. Remember the greatness of those imaginary geographies and astronomies, and those errors that often bore fruit.

[Revised version of two lectures, one given in 2001 at a conference of astronomers and the other in 2002 at a conference of geographers.]

The end