J. Astrophys. Astr. (1984) 5, 79–98
For the Golden Jubilee of the Indian Academy of Sciences, representing a culture which has investigated cosmology for four millennia
Royal Institute of Technology, Stockholm, and University of California,
1. Pre-Galilean Cosmologies
1.1 Ancient Cosmological Myths
Cosmology began when man began to ask: What is beyond the horizon and what happened before the earliest event I can remember? The method of finding out was to ask those who had travelled very far; they reported what they had seen, and also what people they had met far away had told them about still more remote regions. Similarly, grandfather told about his young days and what his grandfather had told him and so on. But the information was always increasingly uncertain the more remote the regions and the times.
The increasing demand for knowledge about very remote regions and very early times was met by people who claimed they could give accurate information about the most distant regions and the earliest times. When asked how they could know all this they often answered that they had direct contact with the gods, and got revelations about the structure of the whole universe and how it was created. And some of these prophets were believed by large groups of people. Myths about the creation and structure of the universe were incorporated as essential parts of religious traditions.
In different cultures, the mythologies became drastically different, depending on the way the philosophical thinking developed and on the personalities of great prophets. In several of the world religions, both the universe and the gods were believed to the eternal; in others, the gods or one God created the universe. In some religions, there is no conflict between these views; initially the universe was identical with a god and the different members of his body developed into the different parts of the universe. In India during the Vedic period, the god Purusa was initially identical in the whole world, and part of his body became the Earth, other parts the Heaven; the Sun formed from his eyes and the Moon from his soul. In other philosophical-mythological schools, both Heaven and Earth are regarded as gods and as parents of gods. Sometimes one god—in India, Agni or Soma or Rudra—and sometimes all gods together are said to have generated or created the whole universe.
In Rigveda, there is a remarkable poem telling that originally “There was neither Aught nor Naught, no air nor sky beyond”. There was only “A self-supporting mass beneath, and energy above. Who knows, who ever told, from whence this vast creation rose? No gods had yet been born – who then can e’er the truth disclose?”
During the more than three millennia which have passed since the Vedic period, Indian mythology has developed a jungle of co-existing creeds, in part absorbed from neighbours, and in part from earlier cultures which had collapsed. The sophisticated mythological philosophy is, perhaps, somewhat less chaotic. There is a general tendency to consider the evolution of the universe as well as the human society to be periodic. Indeed, there is a hierarchy of periods. ? golden age, followed by a silver, a bronze and the present iron age (Kaliyuga) forms a Mahayuga of 54,000 years. A number of Mahayugas forms a larger period, and so on in steps up to the Kalpa or the day of Brahma, which is 4 × 109 years. This is only half an order of magnitude smaller than what according to the Big-Bang hypothesis should be the ‘age of the universe’.
However, there are 365 Brahma days in one Brahma year, and Brahma lives for 100 years, so the ancient Indians used time units which were four orders of magnitude longer than in the Big Bang. (Of course, when Brahma dies after his 100 years, he is immediately reborn). Indian estimates of the size of the world were not so fantastic.
Sometimes the figure10,000 yojanas is given, which means less than half the distance to the Moon. The Mediterranean-Middle East thinking was initially as closely related to the Indian mythologies as Greek, Latin, and Persian are related to Sanskrit. The way of life of the people speaking these languages was also similar. The battle of Kuruksetra and the battle before the walls of Ilion took place at about the same epoch and were fought in a similar way. The heroes spent day after day fighting, and at dusk they went back to their camps, drinking and bragging. Their gods took a decisive part in the fight. (By the way, in Scandinavian mythology, the Vikings who fell in battle came immediately to Valhalla, where they enjoyed the same type of daily life). In the same way, the Mediterranean mythology was initially similar with a golden, silver, bronze and iron age in sequence. However, the Greek cosmological philosophy which took the lead at the Greek cultural explosion around 500 B.C. did not develop like the Indian. First of all, the world remained very limited in time. Indeed, the guesses of the age of the world considered periods of some thousand years, which is only one micro-kalpa. On the other hand, the estimates of the size of the universe were not so different.
Not all the early cosmologies were so intimately connected with religion. The sages of China had no preconceived theories, and seem to have based their cosmological thinking more on phenomena which they observed. But the observations they could make did not suffice for any certain conclusions, and any more elaborate scenarios were no less speculative than those which originated from divine revelation to prophets.
1.2 Buddhist Cosmology
Buddhism developed views on cosmology which were drastically different from the other Indian cosmologies. As Buddhism is basically an agnostic religion, it does not deny the possible existence of gods, but it does not claim that there are any. The existence of gods is irrelevant to the aim of Buddhism, which is to find the right way to salvation, to the annihilation of desire, to the state of Nirvana.
As a logical consequence of this, when the Buddha was asked whether the universe was eternal or created he is reported to have answered in his characteristic style:
It is wrong to say that it is eternal.
It is wrong to say that it is created.
It is wrong to say that it is both eternal and created.
It is wrong to say that it is neither eternal nor created.
Perhaps this is an echo from the quoted Rigveda poem which probably derives from one millennium earlier: As man got his knowledge about the early states of the universe from prophets who got their knowledge directly from the gods, then no information could be gained about the epoch when the gods had not yet been born. Similarly, as the Buddha did not believe in gods—or in any case, did not care much about them—there was no possibility to get information about early cosmology.
Perhaps one could also find an echo two millennia later, when Descartes proclaimed: De omnibus est dubitandum (We should question everything). However, this is not altogether correct because Descartes had also inherited the Galilean scientific tradition according to which controversial issues should be settled by reference to experiment and observation. But there does not seem to be any basic logical conflict between Descartes and the agnosticism of Rigveda and the Buddha.
1.3 Rise of Mathematics
1.3.1 The Pythagoreans
A new element in the cosmological discussion was introduced by the rise of science and natural philosophy in Greece as a part of the cultural explosion around 500 B.C. The Greeks had absorbed astronomical knowledge both from the Mesopotamian and Egyptian cultures, and, as we have mentioned already, their mythology was genetically related to the Indian. The new element consisted of the rise of geometry, which to a large extent derived from Egypt, where it was of practical importance for land surveying. The Greeks developed this to the still unsurpassed masterpiece of logically stringent structure which we know as Euclidean geometry. It is questionable whether the beauty of the theorem of the regular polyhedrons will ever be surpassed. By a simple discussion which anyone can understand in a few minutes, the a priori surprising conclusion is reached that there are five and only five such bodies.
Strongly connected with this, a much wider breakthrough of new thinking was achieved by the Pythagoreans. They demonstrated that the basis of musical harmony was simple ratios of integers. It is quite understandable that this led to a philosophical optimism. The Pythagoreans tried to incorporate astronomy and cosmology as well into their philosophy. They claimed that astronomy should be to the eye what musical harmony was to the ear.
This was indeed a revolutionary idea. It was the first attempt to construct a comprehensive mathematical scheme of cosmology and to work out a synoptic view of the universe as a whole. One may say that its basic principle is that because the world was created by the gods, there must be a sublime order in its basic structure – even if many regrettable local disorders were obvious. According to the Pythagoreans, the most ‘perfect’ geometrical figure is the circle, and the most ‘perfect’ of all solid bodies is the sphere. Ergo the Earth must be a circular disk or a sphere, surrounded by a number of crystal spheres, on which the planets and the stars were located. Further, the most perfect motion was uniform motion. Ergo the crystal spheres must rotate with uniform velocity. This was necessary for the ‘harmony of the spheres.’
1.4 Relation between Theory and Observation
Neither the Pythagoreans nor Plato cared very much for a comparison with observations. The Pythagoreans formed a secret society with no real contact with the rest of Greek society. Indeed, traitors were severely punished. The rules of Plato’s Academy included: “Let none who has not learnt geometry enter here,” and he advised all scholars to “concentrate on the theoretical side of their subject and not spend endless trouble over physical measurements to the neglect of theoretical problems.”
This was in conformity with the general attitude of the intellectual aristocracy in Greece. The belief was that technology, including technological innovation, ought to be largely relegated to the lower classes, especially to slaves. It was degrading for a philosopher to get his hands dirty.
It has been suggested that this cleft between sophisticated theoretical thinking and practical work, including experiments, was the basic reason why the highly advanced science in ancient Greece never led to the scientific breakthrough which took place in Europe two millennia later.
1.4.1 The Ptolemaic System
When, in spite of Plato, observations began to attract interest, the Pythagorean cosmology seemed to be confirmed by observations in one respect: the outermost crystal sphere, the one on which the stars were fixed, did apparently move with a constant speed. This was just what could be expected because this sphere was the outermost one, closest to where the gods lived, and hence most divine. Unfortunately, the theory did not agree so well with observational results when applied to the planets, including the Sun and Moon. The Sun and the Moon sometimes moved more to the north, sometimes to the south, and a planet like Jupiter sometimes reversed its motion in relation to the stars.
It was obvious that something was wrong. But the basic principles—uniform motion and perfect geometrical figures—were sacrosanct and could not be given up even if they were in conflict with observations. Instead, very ingenious auxiliary ideas were forwarded. Planets are not directly fixed on the crystal spheres, but each is fixed on a small circle, an epicycle, which moved with a constant velocity with its centre fixed on the crystal sphere. For a time such theories looked promising, but better observations demonstrated that they were not accurate. The reaction of the scientists was to try to patch up an old fiction instead of asking themselves whether, after all, its basis was laid in truth. They tinkered instead of recreating. Hence, increasingly complicated additions to the system were made.
The result of this was the Ptolemaic system, which was worked out in the third century A.D. No less than 54 epicycles, eccentrics, etc., had been introduced. But at the same time, as it became more complicated, it became more sacrosanct. When an avalanche of religious fanaticism put the classical culture into a deep freeze for more than a millennium, it did not develop very much, and age made it still more sacrosanct. Criticism was dangerous, and it was a rare exception when the famous astronomer, King Alphonse X of Castile, complained about its degree of complexity: “Had I been present at the creation, I could have rendered profound advice.”
1.4.2 Astronomy, Astrology, and Myth
This mathematically based cosmology did not come into serious conflict with the ancient myths. They became to a certain extent incorporated, and a jungle grew up of mathematics, astronomy, astrology, and myths from many earlier cultures. Gods and spirits of all kinds began to settle on the crystal spheres, soon causing a population explosion. For example, one group of constellations depicts how Perseus saved Andromeda from Medusa, whose terrible head is represented by a variable star. Still more dramatic is the giant hunter Orion, who, followed by the Big Dog and the Small Dog, lifts his club against the red-eyed Bull.
The early motion of the Sun along the ecliptic was illustrated by a number of sun-myths. For example, when Heracles fought a bull and later a lion, this is thought to represent the Sun’s entry—on its walk along the zodiac—into the constellations Taurus and Leo. Another sun myth, in which Delilah cuts Samson’s hair from which his strength derives, tells us that in the fall, when the Sun enters the constellation Virgo, its rays lose their heating power and he becomes a captive for half a year, until spring, when he has regained his force.
This chaotic conglomeration of mathematics, astronomy (including cosmology), and myths from many religions has turned out to be a permanent ingredient in our culture. Today, after more than 2000 years, it has as much vitality as ever. Newspapers and periodicals usually have astrological columns; every jeweller sells pendants and pins with signs of the zodiac. From the point of view of our commercialized society, there are many more dollars in astrology than in astronomy.
1.5 Creation Ex Nihilo Versus Ungenerated Universe
The rise of the monotheistic religions meant that one of the gods became more important than the others; He became the Pharaoh, the dictator of the Heavens, God with capital ‘G’. He also became more important than the material world. He alone was eternal. He was not a product of the evolution of the universe, as in Rigveda. On the contrary, the whole world was a secondary structure created by Him. In the Bible the creation takes six days. It still has the character of bringing order into a pre-existing chaos. It was not until the first few centuries A.D. that creation was thought of as the production of the world ex nihilo (but this is never taught in the Bible). God had now become powerful enough to create the whole world by just pronouncing some magic words, or by his will-power.
Monotheistic religions have often a tendency to become fanatic. Certainly Christendom did so, at least during some periods. Tertullian said Credo quia absurdum (I believe because it is absurd). Hence there should be no serious attempt to reconcile religion and science. In the Aristotelian philosophy the material world was ‘ungenerated and indestructible’, a view which is not in conflict with some of the Rigvedic views. It was not until medieval times that Aristotle’s views were accommodated to the idea of creation ex nihilo essentially by Saint Thomas, who remodelled the Aristotelian philosophy in accordance with the requirements of ecclesiastical doctrine.
It is of interest to remember that even Saint Thomas confessed that reason could only be satisfied with the assumption that the world had no.beginning. “The doctrine of a beginning or the non-eternity of the world is to be received sola fide, as an act of pure faith in deference to authority.”
Not even the monotheistic religions were fatal to the old myths. The ‘pagan’ gods changed their names—some became devils, others became saints. In Italy, one pays homage to saints in the same places in the woods where earlier a nymph or a dryad used to live. They have only acquired more modern dress. Midwinter solstice was in ‘pagan’ times the festival of the Sun-god, and a fertility Moon-goddess was worshipped at the first full moon after the vernal equinox. These nice old traditions remain, even today, although with a modified meaning.
The ancient belief that the wandering stars governed the life of men was conserved and developed further. Astrology, mythology and religion formed an increasingly complicated, fascinating structure. The basic conflict between an omnipotent God and the old belief that our destiny is governed by the stars was patched over by the formula: Astra regunt hominem, sed regit astra Deus (Stars rule men, but God rules the stars) The scientific basis of the Ptolemaic system, viz., that the stars move according to certain mathematical laws, was forgotten.
1.6 Myth Versus Science; Mathematical Myths
The Ptolemaic system was initially a quite attractive theory but, during the centuries, it developed into a sacred and rigid structure increasingly impotent in incorporating new discoveries. The reason for this was that fundamentally the approach was not scientific but mythological.* The basic ideas were the perfect geometrical figures and uniform motion. The idea of building a world system on such general principles represented great progress, because earlier it had been generally believed that events in the world were governed by the will or the whimsies of gods. The Ptolemaic system did not necessarily question that the celestial system was created by the gods, but it claimed that they must have acted according to certain philosophical or mathematical principles which it was possible to analyze and understand. A sufficiently sophisticated mathematician might find out what the divine mathematic principles were.
The Ptolemaic system originated from what we may call a mathematical myth. The Pythagorean philosophy had a logical beauty which could well be called ‘divine.’ By pure abstract thinking the theoreticians claimed to have discovered the principles according to which the gods acted when they created the world. And when these principles were found, it was held that the world must be structured according to them. In a way, the demiurges had no choice; it was not even necessary that they existed. But not even observations of physical reality were necessary. The system was based on divine inspiration or logical-mathematical necessity. If Galileo claimed that in his telescope he saw celestial bodies or sunspots which a priori do not exist, it was his telescope and not the theoretical system which was wrong.
It is a semantic question whether a model initially deriving from ‘divine inspiration’ should be called a mytheven if it includes philosophical and mathematical elements. Some would no doubt prefer to call it, for example, ‘a priori metaphysics’.
But long before Galileo, new ideas had appeared in Islamic culture, which took the lead in science less than 100 years after the Hegira. In the twelfth century, Avaroës from Cordova claimed that the world is eternal—not created, but in a state of evolution (Singer 1959), a view which is similar to the hierarchical cosmology of today. In his impressive treatise Mugadema Ibn Khaldun (around 1400 AD) dared to oppose Plato’s view that the world could be explored by logical thinking alone. Indeed, he said that “logic is not a safe way of thinking, because of its tendency towards abstraction and its remoteness from the tangible world” (Baali & Ward 1981). This is similar to Bertrand Russell’s warning half a millenium later against ‘unaided reason’. Ibn Khaldun claimed explicitly that cosmology must be based on observations.
1.7 The Copernican System
The Ibn Khaldun idea had to hibernate for two hundred years until it reappeared in Europe, where it led to the well-known crisis which resulted in the victory of the Copernican heliocentric system (but after some time the latter had to abdicate in favour of a ‘galactocentric’ system).
1.8 The Tycho-Brahe Compromise
During the fight between the geocentric and the heliocentric cosmologies, an ingenious compromise was proposed by Tycho Brahe. His cosmology accepted that all the planets moved around the Sun, but the Sun (together with all the planets) moved around the Earth. (The Moon also moved around the Earth.) In this way he satisfied the observations which indicated that the planets moved around the Sun, but he conserved the sacrosanct geocentric cosmology. The Tycho-Brahe cosmology agreed with observations about as well as the Copernican cosmology. But it soon turned out that the basic issue was another. It was the survival or defeat of a sacrosanct myth. The myth had been sterile. It had not been able to predict a single new phenomenon which later was confirmed by observation.
(This is the first 7 of 20 pages in the complete published paper)