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For more information on cosmology, visit Britannica.com.
The study of the origin and structure of the universe.
The world view and belief system of a community based upon their understanding of order in the universe.
Buddhism inherited much of its traditional cosmology from common Indian lore, and in certain basic respects is consistent with the concepts of modern science, particularly in conceiving the universe to be vastly greater in space and time than it was envisaged to be in the West. The world (loka) in its broadest sense includes the whole cosmos, but within this there are smaller units knows as ‘world-systems’ (lokadhātu), which correspond roughly to solar systems. Such a unit consists of the sun and moon, Mt. Meru, four continents, four oceans, the four great Kings (lokapāla, caturmahārāja), and the sevenfold heavenly spheres. One thousand of these units together forms a ‘small world system’, and the ‘medium’ and ‘large’ systems are each one thousand times greater than the one below. These larger world systems correspond roughly to the modern concept of a galaxy. The cosmos is believed to be infinite in space and also in time, although it passes through immense cycles of evolution and decline. In the post-canonical period of Pāli literature, the term lokadhātu is replaced by cakkavāḷa (Sanskrit, cakravāla), and more elaborate details are added to the traditional accounts. Cosmologies among Buddhists outside India tend to be based on the Indian model, although local cultural influences often modify the original blueprint.
Modern Cosmological Theories
Present models of the universe hold two fundamental premises: the cosmological principle and the dominant role of gravitation. Derived by Hubble, the cosmological principle holds that if a large enough sample of galaxies is considered, the universe looks the same from all positions and in all directions in space. The second point of agreement is that gravitation (or an antigravitation force, called dark energy) is the most important force in shaping the universe. According to Einstein's general theory of relativity, which is a geometric interpretation of gravitation, matter produces gravitational effects by actually distorting the space about it; the curvature of space is described by a form of non-Euclidean geometry. A number of cosmological theories satisfy both the cosmological principle and general relativity. The two main theories are the big-bang hypothesis and the steady-state hypothesis, with many variations on each basic approach.
The Steady-State Theory
According to the steady-state theory, now of historical interest only, the universe expands, but new matter is continuously created at all points in space left by the receding galaxies. The theory implies that the universe has always expanded, with no beginning or end, at a uniform rate and that it always will expand and maintain a constant density.
The Big-Bang Theory
According to big-bang theories, at the beginning of time, all of the matter and energy in the universe was concentrated in a very dense state, from which it “exploded,” with the resulting expansion continuing until the present. This “big bang” is dated between 10 and 20 billion years ago. In this initial state, the universe was very hot and contained a thermal soup of quarks, electrons, photons, and other elementary particles. The temperature rapidly decreased, falling from 1013 degrees Kelvin after the first microsecond to about one billion degrees after three minutes. As the universe cooled, the quarks condensed into protons and neutrons, the building blocks of atomic nuclei. Some of these were converted into helium nuclei by fusion; the relative abundance of hydrogen and helium is used as a test of the theory. After many millions of years the expanding universe, at first a very hot gas, thinned and cooled enough to condense into individual galaxies and then stars.
Several spectacular discoveries since 1950 have shed new light on the problem. Optical and radio astronomy complemented each other in the discovery of the quasars and the radio galaxies. It is believed that the energy reaching us now from some of these objects was emitted not long after the creation of the universe. Further evidence for the big-bang theory was the discovery in 1965 that a cosmic background noise is received from every part of the sky. This background radiation has the same intensity and distribution of frequencies in all directions and is not associated with any individual celestial object. It has a black body temperature of 2.7K (−270°C) and is interpreted as the electromagnetic remnant of the primordial fireball, stretched to long wavelengths by the expansion of the universe. More recently, the analysis of radiation from distant celestial objects detected by artificial satellites has given additional evidence for the big-bang theory.
Development of Modern Cosmology
The earliest pre-Ptolemaic theories assumed that the earth was the center of the universe (see Ptolemaic system). With the acceptance of the heliocentric, or sun-centered, theory (see Copernican system), the nature and extent of the solar system began to be realized. The Milky Way, a vast collection of stars separated by enormous distances, came to be called a galaxy and was thought to constitute the entire universe with the sun at or near its center. By studying the distribution of globular star clusters the American astronomer Harlow Shapley was able to give the first reliable indication of the size of the galaxy and the position of the sun within it. Modern estimates show it to have a diameter of about 100,000 light-years with the sun toward the edge of the disk, about 28,000 light-years from the center.
During the first two decades of the 20th cent. astronomers came to realize that some of the faint hazy patches in the sky, called nebulae, are not within our own galaxy, but are separate galaxies at great distances from the Milky Way. Willem de Sitter of Leyden suggested that the universe began as a single point and expands without end. After studying the red shift (see Doppler effect) in the spectral lines of the distant galaxies, the American astronomers Edwin Hubble and M. L. Humason concluded that the universe is expanding, with the galaxies appearing to fly away from each other at great speeds. According to Hubble's law, the expansion of the universe is approximately uniform. The greater the distance between any two galaxies, the greater their relative speed of separation.
At the end of the 20th cent. the study of very distant supernovas led to the belief that the cosmic expansion was accelerating. To explain this cosmologists postulated a repulsive force, dark energy, that counteracts gravity and pushes galaxies apart. It also appears that the universe has been expanding at different rates over its cosmic history. This led to a variation of the big-bang theory in which, under the influence of gravity, the expansion slowed initially and then, under the influence of dark energy, suddenly accelerated. It is estimated that this “cosmic jerk” occurred five billion years ago, about the time the solar system was formed. This theory postulates a flat, expanding universe with a composition of c.70% dark energy, c.30% dark matter, and c.0.5% bright stars.
A number of questions must be answered, however, before cosmologists can establish a single, comprehensive theory. The expansion rate and age of the universe must be established. The nature and density of the missing mass, the dark matter and dark energy that is far more abundant than ordinary, visible matter, must be identified. The total mass of the universe must be determined to establish whether it is sufficient to support an equilibrium condition—a state in which the universe will neither collapse of its own weight nor expand into diminishing infinity. Such an equilibrium is called “omega equals one,” where omega is the ratio between the actual density of the universe and the critical density required to support equilibrium. If omega is greater than one, the universe would have too much mass and its gravity would cause a cosmic collapse. If omega is less than one, the low-density universe would expand forever. Today the most widely accepted picture of the universe is an omega-equals-one system of hundreds of billions of galaxies, many of them clustered in groups of hundreds or thousands, spread over a volume with a diameter of at least 10 billion light-years and all receding from each other, with the speeds of the most widely separated galaxies approaching the speed of light. On a more detailed level there is great diversity of opinion, and cosmology remains a highly speculative and controversial science.
Bibliography
See D. W. Sciama, Modern Cosmology and the Dark Matter Problem (1993); J. D. Barrow, The Origin of the Universe (1994); P. Coles and F. Lucchin, Cosmology: The Origin and Evolution of Cosmic Structure (1995); M. S. Longair, Our Evolving Universe (1996); B. Green, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (2000); S. Hawking, The Universe in a Nutshell (2001); R. P. Kirshner, The Extravagant Universe: Exploding Stars, Dark Energy, and Accelerating Cosmos (2002); S. Singh, Big Bang: The Origin of the Universe (2005).
During the fifteenth century, the cosmological systems of the Epicurean atomists, Plato, and the Stoics were known from antiquity, but the cosmology that was taught in universities throughout Europe was that of Aristotle, as augmented by Ptolemy. By the beginning of the eighteenth century a new cosmology, associated with the names of Copernicus, Kepler, Galileo, Descartes, and Newton, had almost completely replaced the earlier consensus. The present article considers the cosmologies of these main figures and reviews changes in historians' understanding of the causes of the scientific revolution.
Aristotle's Cosmos
Aristotle's cosmos was finite, spherical, and full. Its outer boundary was a sphere carrying the fixed stars. Its center was the Earth, and the sphere carrying the Moon divided the cosmos into a terrestrial portion and a celestial portion. The region beneath the Moon consisted of four elements, each endowed with the tendency to return to its natural place by a motion along a radius of the cosmos. The element Earth tended to seek the center; water moved naturally to a sphere surrounding the central globe of Earth; air sought a sphere concentric to water, and fire, which in its pure form was quite transparent, would naturally move to the region above the air and beneath the Moon. The general structure of the world reflected its elementary constitution, with most earth covered by water and both inner elements covered by air. Only the sphere of fire was not directly observable, although it was a theoretical necessity. Mixing and transmutation created complex combinations of elements, such as people, plants, and animals. Changes in the proportions of the four elements explained terrestrial change, especially growth and decay.
By contrast, the heavens consisted of a single element, ether, which was already in its natural place, and moved naturally in a circle, at constant speed, around the central earth. Deprived of the opportunity for transmutation or mixing of elements, the heavens were incapable of physical change. The order of the heavenly bodies was determined partly by observation and partly by convention. Eclipses and occultations made it clear that the Moon was the closest heavenly body and the fixed stars were the most distant. Mars, Jupiter, and Saturn could be ordered according to their periods of return, with the longest being the farthest away. However, the periods of return for the remaining planets and the Sun were not distinguishable. The locations of the five known planets were divided by the zone occupied by the Sun, and, beyond the Moon, an ordering of Mercury, followed by Venus, followed by the sun became conventional.
The heavens consisted of nested concentric shells. A single heavenly body was confined within and carried by each shell. Physically, the heavenly bodies were believed to be denser regions in the ether. During the fifteenth and sixteenth centuries, followers of Averroes (Ibn Rushd) and Ptolemy violently disagreed over the inner structure of these shells.
In the Almagest Ptolemy had introduced a system of moving circles carrying other circles to explain the details of planetary motion. In the Planetary Hypotheses he introduced a corresponding set of physical models, which Arabic commentators presented as sets of hollow orbs carrying smaller spheres within them. These, in turn, carried individual planets. Ptolemaic astronomers assumed that the orb clusters for different planets fitted perfectly inside one another, and were thereby able to calculate the distances of planets, including the Sun, and their relative sizes. But most importantly, Ptolemy's mathematical apparatus allowed the calculation of planetary positions with an accuracy sufficient, for example, to predict eclipses of the Sun and Moon, and approximate conjunctions and other planetary alignments important in astrology. These models were presented in Georg Peurbach's Theoricae novae planetarum (c. 1474), which rapidly became a standard text. Averroists objected to the eccentric circles and epicycles used by their rivals on the grounds that they were not strictly centered on the Earth. They proposed that planets were carried by a series of nested orbs, exactly concentric to the Earth, but, as late as the 1530s, attempts to construct predictive models failed. Copernicus was exposed to both viewpoints during his education.
The New Cosmologies
Motivated by a desire to establish an absolute order for the planets, Copernicus moved the center of the cosmos to the Sun (On the Revolutions of the Heavenly Spheres, 1543). In other respects, his cosmology was conservative. He continued to assume that the planets were carried by orbs and that the sphere of fixed stars was the boundary of a finite universe, although his shift of center created large and inexplicable gaps between orbs, and especially between the outermost planet, Saturn, and the fixed stars. These gaps were later explained by Kepler using the geometrical construction introduced in the Mysterium Cosmographicum (1596). The immediate reaction, led by astronomers at the Lutheran University of Wittenberg, was to adapt Copernicus's new models to an Earth-centered system and to reject his cosmology on physical and scriptural grounds.
To remove Aristotle's cosmology, it was necessary to undermine his account of the construction of the heavens. Two major factors began this process: the revival of Stoic physics and precise observations of comets. Aristotle had taught that comets, which appeared and vanished at irregular intervals, must be long-lasting fires in the region below the Moon, because there could be no change in the heavens. In 1572 a nova suggested that change did occur in the heavens. Attempts to measure comets' distances placed them in the heavens. At the same time, the revival of Stoic physics suggested that the heavens might be filled by a continuous fluid rather than Aristotle's solid spheres. Tycho Brahe in Denmark and Michael Maestlin in Germany both measured precise distances for a comet that appeared in 1577. Both concluded that the comet had moved through a series of Aristotle's Earth-centered spheres and that any spheres must be centered on the Sun. Maestlin became a Copernican, later teaching his ideas to Johannes Kepler. But Brahe was unable to accept the motion of the Earth and developed a new cosmology in which the Earth remained the center, the Moon and Sun circled the Earth, and the remaining planets circled the Sun. To avoid the overlap his system created between the orbs of Mars and the Sun, Brahe adopted fluid heavens in which celestial spheres were no more than geometrical boundaries.
Today, Johannes Kepler is credited with discovering the three laws of planetary motion that bear his name, but his innovations were not generally accepted until Isaac Newton showed that they followed from his own theory. Kepler introduced the modern concept of an orbit, located the cause of planetary motion in the Sun, and replaced the circles of traditional astronomy with ellipses, but he continued to regard the fixed stars as the boundary of a finite universe. Like Tycho, he adopted a theory that made the substance of the heavens a fluid. The unprecedented accuracy of his astronomical tables advertised the importance of his insights after his death in 1630.
Galileo Galilei, by contrast, preserved many features of traditional cosmology. He never adopted Kepler's ellipses and denied that comets were celestial objects. However, his telescopic discoveries offered a host of new observational evidence supporting Copernicus. Jupiter's moons showed that the Averroists were wrong in demanding a single center of rotation for the cosmos. Sunspots and the observation of terrestrial features on the Moon showed that the heavens were not changeless and suggested that a single physics should embrace both heavens and Earth. The cycle of phases displayed by Venus showed that it, at least, circled the Sun. It was possible to accommodate all of these innovations in a modified Aristotelian scheme (as postulated by Du Chevreul in 1623), but the motions of comets and their implications for the substance of the heavens were unaccounted for. In the climate created by the Catholic Church's condemnation of Copernicanism in 1616 and 1633, Tycho Brahe's system became the most attractive option to anyone wishing to reconcile religious orthodoxy, traditional physics, and new astronomical discoveries. Jesuits exported it to China, and it was taught in Northern European universities into the eighteenth century.
Galileo's later work helped revive the ancient theory that matter was composed of atoms, a viewpoint that was being developed by Beeckman, Gassendi, and Descartes. The latter delayed publishing an atomistic cosmology because of Galileo's condemnation. In Le Monde, finished in 1633, but not published until 1664, Descartes described a cosmos filled by vortices of atoms. Stars naturally formed at the center of each vortex, while matter falling onto their surface caused sunspots. A large enough quantity of infalling material formed a crust over the entire star, which then became free of its vortex and wandered through the heavens, appearing as a comet. When finally captured by another vortex, the comet became a planet. Descartes therefore explained many new discoveries in a single scheme that was inherently heliocentric, although the sun was now just one among many vortex centers scattered throughout space.
Newton's synthesis (1689) provided a detailed mathematical physics that unified the heavens and the Earth. The planets were now held in place not by vortices, but by universal gravitation. Comets were divided into returning and nonreturning, and the reappearance of Halley's comet in 1758 was a highly visible success. With the general acceptance of Newton's system, cosmology assumed a form that persisted until the early twentieth century. As with Descartes, the Sun was identified as a star. The planets with their attendant satellites were bound to the Sun, but were not unique; other stars were assumed to be the centers of other planetary systems. Comets were definitely celestial, although only the determination of the numerical value of Newton's Universal Gravitational Constant allowed the recognition of their diminutive mass in comparison to planets or stars. Newton's First Law required that inertial motion continue indefinitely and implied a universe that was infinite in space.
The Nature of the Scientific Revolution
The changes in cosmology just described have often been taken as the centerpiece of an event known as the scientific revolution, usually described as the replacement of Aristotle's scientific system with modern mathematical physics, based on experimental evidence. But recent historiography has tended to emphasize continuity with earlier achievements. It is now clear that the modern conception of experiment developed over a long period, with important changes beginning in the sixteenth century with the work of astronomers and early mathematical physicists. Kepler's unification of physics and mathematical astronomy became an important precedent, although it was more important with hindsight, after the development of new mathematical techniques for doing physics by Descartes, Newton, and their contemporaries. The work of Boyle and other members of the early Royal Society, as well as members of similar institutions in France and Italy, also contributed, although the modern conception of experiment did not emerge until the power of the new mathematical methods had been reconciled with the empiricism advocated by Bacon, a process that continued from Newton's career through the development of mathematical physics in France during the Enlightenment. Galileo's use of experiment resembles the earlier, rather than the later, concept. He was clearly not the originator of the experimental method, and modern research also demonstrates that his ideas on physics and scientific method in general were transformations of existing ideas rather than complete novelties.
Recent historians also give a more equal role to noncanonical sciences such as alchemy and astrology in the development of modern science. Alchemy clearly contributed to the replacement of Aristotle's theory of the terrestrial elements. Astrology remained important as the main motive for the study of astronomy and cosmology because of applications including medical diagnosis and treatment, weather prediction, and political planning. Although most practitioners followed the great Lutheran reformer and educator Philipp Melanchthon in believing that the heavens predisposed rather than compelled terrestrial events, casting horoscopes was a professional skill prized by the patrons of Tycho Brahe, Kepler, and Galileo. Alchemy was gradually transformed, first into the phlogiston theories of Stahl and his contemporaries, and then into the modern discipline of chemistry at the hands of Lavoisier. The disappearance of astrology lacks a generally agreed explanation. In England, at least, its public suppression may have had less to do with the development of the new science and new scientific societies after the Civil War than with the fact that its supporters were on the losing side after the Restoration of Charles II.
The supposed warfare between science and religion is now recognized to be largely a fiction of late-nineteenth-century historiography. Both Catholic and Protestant churches were active in supporting and sometimes opposing the new science. During the sixteenth century, for example, followers of Melanchthon arranged for the publication of Copernicus's work and actively spread his ideas, although, initially, they accepted his mathematical astronomy and rejected his cosmology. The trial of Galileo in 1633 cannot be attributed solely to his defense of Sun-centered cosmology. Other factors may include the dynamics of patronage (Galileo's patron Ciampoli offended the pope; other supporters had died) and internal church politics (the potential rebellion of a Spanish faction over the pope's handling of the Counter-Reformation). The condemnation of Copernicanism, and especially the outbreak of the Thirty Years' War in 1618, created new difficulties, but the Jesuit order of the Catholic Church remained at the forefront of scientific research. Kepler and Newton both saw their religious beliefs as integral to, rather than separable from, their scientific work.
The importance of new career paths and new scientific institutions has qualified earlier accounts of the scientific revolution. Copernicus was a lowly member of the Catholic hierarchy, who, until almost the end of his life, pursued his research essentially in private. His earliest supporters were university teachers, like Melanchthon's followers at Wittenberg and Maestlin at Tübingen. But his most important successors were courtiers whose research was supported by patronage. Tycho Brahe was financed by the king of Denmark, and later the Holy Roman emperor, who also supported his successor Kepler. Galileo moved from a university post to the court of the Medici in Florence, where he did his most important work. The first scientific societies appeared during the seventeenth century and provided new avenues of scientific communication, including published proceedings and journals, and new forms of support for scientists. In later life, Newton dominated the Royal Society of London. But the acceptance of Newton's system in Germany, and especially in France, followed the adoption of the new science as an intellectual fashion by the upper classes throughout Europe. This process depended upon the ascendancy of another social forum, the salon, where, for the first time since antiquity, women made major contributions to science.
The scientific revolution was not the work of a few great men, nor the result of changes that occurred only in the mathematical sciences, or in sciences that still exist today. It was not the result of the sudden appearance of the modern conception of experiment, nor did it come about because of any early separation between science and religion. There are profound differences between the content, method, and structure of the sciences from the origin to the close of the early modern period, but these changes are now regarded as the result of a complex combination of intellectual, theological, social, and institutional causes.
Bibliography
Primary Sources
Aiton, E. J. "Peurbach's Theoricae Novae Planetarum:A Translation with Commentary." Osiris, 2nd series, 3 (1987): 5–44.
Brahe, Tycho. De Mundi Eetherei Recentioribus Phaenomenis. Uraniborg, 1588. Tycho's book on comets and his new cosmic scheme.
Chevreul, Jacques du. Sphaera. Paris, 1623. Contains an Aristotelian cosmic scheme that accommodates all Galileo's telescopic discoveries. (See also Ariew, below.)
Copernicus, Nicolaus. On the Revolutions of the Heavenly Spheres. Translated by A. M. Duncan. New York, 1976. Translation of De Revolutionibus Orbium Coelestium (1543).
Galilei, Galileo. Dialogue Concerning the Two Chief World Systems, Ptolemaic & Copernican. Translated by Stillman Drake. Berkeley, 1967. English translation of Dialogo sopra i due massimi sistemi del mondo, Tolemaico e Copernicano (1632), the work for which Galileo was condemned.
Goldstein, Bernard R. "The Arabic Version of Ptolemy's Planetary Hypotheses." Transactions of the American Philosophical Society 57 (1967), Part 4. Presents Ptolemy's physical models.
Descartes, René. The World and Other Writings. Translated by Stephen Gaukroger. Cambridge, U.K., 1998. English versions of Le monde de Mr Descartes; ou, Le traite de la lumiere. Paris, 1664.
Ptolemy's Almagest. Translated by G. J. Toomer. New York, 1984. Ptolemy's main work on mathematical astronomy. (See also Goldstein, above.)
Secondary Sources
Aiton, E. J. The Vortex Theory of Planetary Motions. London, 1972. Cartesian cosmology.
Ariew, Roger. Descartes and the Last Scholastics. Ithaca, N.Y, 1999. Presents Descartes in the context of Aristotelian responses to the new philosophy and science, including the work of Du Chevreul.
Barker, Peter, and Roger Ariew, eds. Revolution and Continuity: Essays in the History and Philosophy of Early Modern Science. Washington, D.C., 1991. Appraises the alleged discontinuity between medieval and modern science.
Biagioli, Mario. Galileo Courtier: The Practice of Science in the Culture of Absolutism. Chicago, 1993.
Dear, Peter. Revolutionizing the Sciences: European Knowledge and its Ambitions, 1500–1700. Princeton, 2001. Sound introduction that balances the contributions of canonical and noncanonical sciences.
Densmore, Dana. Newton's Principia: The Central Argument. Santa Fe, N.M., 1995. Translation, with notes, and expanded proofs of key mathematical arguments in Principia Mathematica (1687).
Osler, Margaret J., ed. Rethinking the Scientific Revolution. Cambridge, U.K., 2000. New historiography for early modern science.
Sutton, Geoffrey V. Science for a Polite Society: Gender, Culture, and the Demonstration of Enlightenment. Boulder, Colo., 1995. The social framework of Cartesian and Enlightenment science.
Westman, Robert S. "The Astronomer's Role in the Sixteenth Century: A Preliminary Survey." History of Science 18 (1980): 105–147. Classic study of the transition from university support to patronage support in early modern science.
—PETER BARKER
A system of beliefs that seeks to describe or explain the origin and structure of the universe. A cosmology attempts to establish an ordered, harmonious framework that integrates time, space, the planets, stars, and other celestial phenomena. In so-called primitive societies, cosmologies help explain the relationship of human beings to the rest of the universe and are therefore closely tied to religious beliefs and practices. In modern industrial societies, cosmologies seek to explain the universe through astronomy and mathematics.
The branch of science dealing with the large-scale structure, origins, and development of the universe. (See astronomy and Big Bang theory.)
Cosmology, from the Greek: κοσμολογία (cosmologia, κόσμος (cosmos) order + λογος (logos) word, reason, plan) is the quantitative (usually mathematical) study of the Universe in its totality, and by extension, humanity's place in it. Though the word cosmology is recent (first used in 1730 in Christian Wolff's Cosmologia Generalis), study of the Universe has a long history involving science, philosophy, esotericism, and religion.
In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology by bringing observations and mathematical tools to analyze the universe as a whole; in other words, in the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scale and at the earliest moments, is generally understood to begin with the big bang (possibly combined with cosmic inflation) - an expansion of space from which the Universe itself is thought to have emerged ~13.7 ± 0.2 billion (109) years ago[1] . From its violent beginnings and until its various speculative ends, cosmologists propose that the history of the Universe has been governed entirely by physical laws.
Between the domains of religion and science, stands the philosophical perspective of metaphysical cosmology. This ancient field of study seeks to draw intuitive conclusions about the nature of the universe, man, god and/or their relationships based on the extension of some set of presumed facts borrowed from spiritual experience and/or observation.
Cosmology is often an important aspect of the origin beliefs of religions and mythologies that seek to explain the existence and nature of reality. In some cases, views about the creation (cosmogony) and destruction (eschatology) of the universe play a central role in shaping a framework of religious cosmology for understanding humanity's role in the universe.
A more contemporary distinction between religion and philosophy, esoteric cosmology is distinguished from religion in its less tradition-bound construction and reliance on modern "intellectual understanding" rather than faith, and from philosophy in its emphasis on spirituality as a formative concept.
There are many historical cosmologies:
“…the universe itself acts on us as a random, inefficient, and yet in the long run effective, teaching machine. …our way of looking at the universe has gradually evolved through a natural selection of ideas.” —Steven Weinberg [2]
The following table outlines the significant historical cosmologies in chronological order.
| NAME | Author & Date | Classification | REMARKS |
|---|---|---|---|
| Brahmanda (Earliest known model) | Ancient Hindu Rig-Veda treatise on cosmology | Cyclical or oscillating. Infinite in time. | The universe is a cosmic egg that cycles between expansion and total collapse. It expanded from a concentrated form —a point called a Bindu. The universe, as a living entity, is bound to the perpetual cycle of birth, death, and rebirth |
| Atomist universe | Anaxagoras (500-428 B.C.) & later Epicurus | Infinite in extent | The universe contains only two things: an infinite number of tiny seeds, or atoms, and the void of infinite extent. All atoms are made of the same substance, but differ in size and shape. Objects are formed from atom aggregations and decay back into atoms. Incorporates Leucippus’ principle of causality: ”nothing happens at random; everything happens out of reason and necessity.” The universe was not ruled by gods. |
| Stoic universe | Stoics 3rd & 4th c. B.C. | Island universe | The cosmos is finite and surrounded by an infinite void. It is in a state of flux, as it pulsates in size and periodically passes through upheavals and conflagrations. |
| Aristotelian universe | Aristotle (384-322 B.C.) | Geocentric, static, steady state, finite | Spherical earth is surrounded by concentric celestial spheres. Universe exists unchanged throughout eternity. Contains a 5th element called aether (later known as quintessence). |
| Aristarchean universe | Aristarchus of Samos (circa 280 B.C.) | Heliocentric | Earth rotates daily on its axis and revolves annually about the sun in a circular orbit. Sphere of fixed stars is centered about the sun. |
| Ptolemaic model (based on the Aristotelian universe) | Claudius Ptolemaeus
(2nd century A.D.) |
Geocentric | Universe orbits about a stationary Earth. Planets move in circular epicycles, each having a center that moved in a larger circular orbit (called an eccentric or a deferent) around a center-point near the Earth. The use of equants added another level of complexity and allowed astronomers to predict the positions of the planets. The most successful universe model of all time, using the criterion of longevity. Almagest (the Great System). |
| Copernican universe | Nicolaus Copernicus 1543 | Heliocentric | The ancient Aristarchean universe rediscovered.
Revolutions of the Celestial Spheres. |
| Static Newtonian | Sir Isaac Newton (1642-1727) | Static (evolving), steady state, infinite | Every particle in the universe attracts every other particle. Matter on the large scale is uniformly distributed. Gravitationally balanced but UNSTABLE. |
| Cartesian Vortex universe | René Descartes
17th century |
Static (evolving), steady state, infinite | A system of huge swirling whirlpools of aethereal or fine matter produces what we would call gravitational effects. His vacuum was not empty. All space was filled with matter that swirled around in large and small vortices. |
| Hierarchical universe | Immanuel Kant, Johann Lambert 1700s | Static (evolving), steady state, infinite | Matter is clustered on ever larger scales of hierarchy. Matter is endlessly being recycled. |
| Einstein Universe with a cosmological constant | Albert Einstein 1917 | Static (nominally). Bounded (finite) | “Matter without motion.” Contains uniformly distributed matter. Uniformly curved spherical space; based on Riemann’s hypersphere. Curvature is set equal to Λ. In effect Λ is equivalent to a repulsive force which counteracts gravity. UNSTABLE. |
| De Sitter universe | Willem de Sitter 1917 | Expanding flat space.
Steady state. Λ > 0 |
“Motion without matter.” Only apparently static. Based on Einstein’s General Relativity. Space expands with constant acceleration. Scale factor (radius of universe) increases exponentially, i.e. constant inflation. |
| MacMillan | William MacMillan 1920s | Static &
steady state |
New matter is created from radiation. Starlight is perpetually recycled into new matter particles. |
| Friedmann universe of spherical space | Alexander Friedmann 1922 | Spherical expanding space.
k= +1 ; no Λ |
Positive curvature. Curvature constant k = +1
Expands then recollapses. Spatially closed (finite). |
| Friedmann universe of hyperbolic space | Alexander Friedmann 1924 | Hyperbolic expanding space.
k= -1 ; no Λ |
Negative curvature. Said to be infinite (but ambiguous). Unbounded. Expands forever. |
| Dirac large numbers hypothesis | Paul Dirac 1930s | Expanding | Demands a large variation in G, which decreases with time. Gravity weakens as universe evolves. |
| Friedmann zero-curvature, aka the Einstein-DeSitter universe | Einstein & DeSitter 1932 | Expanding flat space.
k= 0 ; Λ = 0 Critical density |
Curvature constant k = 0. Said to be infinite (but ambiguous). ‘Unbounded cosmos of limited extent.’ Expands forever. ‘Simplest’ of all known universes. Named after but not considered by Friedmann. Has a deceleration term q =½ which means that its expansion rate slows down. |
| Georges Lemaître
the original Big Bang. aka Friedmann-Lemaître Model |
Georges Lemaître 1927-29 | Expansion
Λ > 0 Λ > |Gravity| |
Λ is positive and has a magnitude greater than Gravity. Universe has initial high density state (‘primeval atom’). Followed by a two stage expansion. Λ is used to destabilize the universe. (Lemaître is considered to be the father of the big bang model.) |
| Oscillating universe
(aka Friedmann-Einstein; was latter’s 1st choice after rejecting his own 1917 model) |
Favored by Friedmann
1920s |
Expanding and contracting in cycles | Time is endless and beginningless; thus avoids the beginning-of-time paradox. Perpetual cycles of big bang followed by big crunch. |
| Eddington | Arthur Eddington 1930 | first Static
then Expands |
Static Einstein 1917 universe with its instability disturbed into expansion mode; with relentless matter dilution becomes a DeSitter universe. Λ dominates gravity. |
| Milne universe of kinematic relativity | Edward Milne, 1933, 1935;
William H. McCrea, 1930s |
Kinematic expansion with NO space expansion | Rejects general relativity and the expanding space paradigm. Gravity not included as initial assumption. Obeys cosmological principle & rules of special relativity. The Milne expanding universe consists of a finite spherical cloud of particles (or galaxies) that expands WITHIN flat space which is infinite and otherwise empty. It has a center and a cosmic edge (the surface of the particle cloud) which expands at light speed. His explanation of gravity was elaborate and unconvincing. For instance, his universe has an infinite number of particles, hence infinite mass, within a finite cosmic volume. |
| Friedmann-Lemaître-Robertson-Walker class of models | Howard Robertson, Arthur Walker, 1935 | Uniformly expanding | Class of universes that are homogenous and isotropic. Spacetime separates into uniformly curved space and cosmic time common to all comoving observers. The formulation system is now known as the FLRW or Robertson-Walker metrics of cosmic time and curved space. |
| Steady-state expanding (Bondi & Gold) | Herman Bondi, Thomas Gold 1948 | Expanding, steady state, infinite | Matter creation rate maintains constant density. Continuous creation out of nothing from nowhere. Exponential expansion. Deceleration term q = -1. |
| Steady-state expanding (Hoyle) | Fred Hoyle 1948 | Expanding, steady state; but unstable | Matter creation rate maintains constant density. But since matter creation rate must be exactly balanced with the space expansion rate the system is unstable. |
| Ambiplasma | Hannes Alfvén 1965 Oskar Klein | Cellular universe, expanding by means of matter-antimatter annihilation | Based on the concept of plasma cosmology. The universe is viewed as meta-galaxies divided by double layers —hence its bubble-like nature. Other universes are formed from other bubbles. Classified as quasi-cellular because ongoing cosmic matter-antimatter annihilations keep the bubbles separated and moving apart preventing them from interacting. |
| Brans-Dicke | Carl H. Brans; Robert H. Dicke | Expanding | Based on Mach’s principle. G varies with time as universe expands. “But nobody is quite sure what Mach’s principle actually means.” |
| Cosmic inflation | Alan Guth 1980 | Big Bang with modification to solve horizon problem and flatness problem. | Based on the concept of hot inflation. The universe is viewed as a multiple quantum flux —hence its bubble-like nature. Other universes are formed from other bubbles. Classified as quasi-cellular because ongoing cosmic expansion kept the bubbles separated and moving apart preventing them from interacting. |
| Eternal Inflation (a multiply universe) | Andreï Linde 1983 | Big Bang with cosmic inflation | A multiverse, based on the concept of cold inflation, in which inflationary events occur at random each with independent initial conditions; some expand into bubble universes supposedly like our entire cosmos. Bubbles nucleate in a spacetime foam. |
| Cyclic model | Paul Steinhardt; Neil Turok 2002 | Expanding and contracting in cycles; M theory. | Two parallel orbifold planes or M-branes collide periodically in a higher dimensional space. With quintessence or dark energy |
Table Notes: the term “static” simply means not expanding and not contracting. Symbol G represents Newton’s gravitational constant; Λ (Lambda) is the cosmological constant.
Physical cosmology is the branch of physics and astrophysics that deals with the study of the physical origins of the Universe and the nature of the Universe on its very largest scales. In its earliest form it was what is now known as celestial mechanics, the study of the heavens. The Greek philosophers Aristarchus of Samos, Aristotle and Ptolemy proposed different cosmological theories. In particular, the geocentric Ptolemaic system was the accepted theory to explain the motion of the heavens until Nicolaus Copernicus, and subsequently Johannes Kepler and Galileo Galilei proposed a heliocentric system in the 16th century. This is known as one of the most famous examples of epistemological rupture in physical cosmology.
With Isaac Newton and the 1687 publication of Principia Mathematica, the problem of the motion of the heavens was finally solved. Newton provided a physical mechanism for Kepler's laws and his law of universal gravitation allowed the anomalies in previous systems, caused by gravitational interaction between the planets, to be resolved. A fundamental difference between Newton's cosmology and those preceding it was the Copernican principle that the bodies on earth obey the same physical laws as all the celestial bodies. This was a crucial philosophical advance in physical cosmology.
Modern scientific cosmology is usually considered to have begun in 1917 with Albert Einstein's publication of his final modification of general relativity in the paper "Cosmological Considerations of the General Theory of Relativity," (although this paper was not widely available outside of Germany until the end of World War I). General relativity prompted cosmogonists such as Willem de Sitter, Karl Schwarzschild and Arthur Eddington to explore the astronomical consequences of the theory, which enhanced the growing ability of astronomers to study very distant objects. Prior to this (and for some time afterwards), physicists assumed that the Universe was static and unchanging. In parallel to this dynamic approach to cosmology, a debate was unfolding regarding the nature of the cosmos itself. On the one hand, Mount Wilson astronomer Harlow Shapley championed the model of a cosmos made up of the Milky Way star system only. Heber D. Curtis, on the other hand, suggested spiral nebulae were star systems in their own right, island universes. This difference of ideas came to a climax with the organization of the Great Debate at the meeting of the (US) National Academy of Sciences in Washington on 26 April 1920. The resolution of the debate on the structure of the cosmos came with the detection of novae in the Andromeda galaxy by Edwin Hubble in 1923 and 1924. Their distance established spiral nebulae well beyond the edge of the Milky Way and as galaxies of their own. Subsequent modeling of the universe explored the possibility that the cosmological constant introduced by Einstein in his 1917 paper may result in an expanding universe, depending on its value. Thus the big bang theory was proposed by the Belgian priest Georges Lemaître in 1927 which was subsequently corroborated by Edwin Hubble's discovery of the red shift in 1929 and later by the discovery of the cosmic microwave background radiation by Arno Penzias and Robert Woodrow Wilson in 1964. These findings were a first step to rule out some of many alternative physical cosmologies.
Recent observations made by the COBE and WMAP satellites observing this background radiation have effectively, in many scientists' eyes, transformed cosmology from a highly speculative science into a predictive science, as these observations matched predictions made by a theory called Cosmic inflation, which is a modification of the standard big bang theory. This has led many to refer to modern times as the "Golden age of cosmology". [3]
In philosophy and metaphysics, cosmology deals with the world as the totality of space, time and all phenomena. Historically, it has had quite a broad scope, and in many cases was founded in religion. The ancient Greeks did not draw a distinction between this use and their model for the cosmos. However, in modern use it addresses questions about the Universe which are beyond the scope of science. It is distinguished from religious cosmology in that it approaches these questions using philosophical methods (e.g. dialectics). Modern metaphysical cosmology tries to address questions such as:
Many world religions have origin beliefs that explain the beginnings of the Universe and life. Often these are derived from scriptural teachings and held to be part of the faith's dogma, but in some cases these are also extended through the use of philosophical and metaphysical arguments.
In some origin beliefs, the universe was created by a direct act of a god or gods who are also responsible for the creation of humanity (see creationism). In many cases, religious cosmologies also foretell the end of the Universe, either through another divine act or as part of the original design.
Many religions accept the findings of physical cosmology, in particular the big bang, and some, such as the Roman Catholic Church, have embraced it as suggesting a philosophical first cause. Others have tried to use the methodology of science to advocate for their own religious cosmology, as in intelligent design or creationist cosmologies.
Many esoteric and occult teachings involve highly elaborate cosmologies. These constitute a "map" of the Universe and of states of existences and consciousness according to the worldview of that particular doctrine. Such cosmologies cover many of the same concerns also addressed by religious and philosophical cosmology, such as the origin, purpose, and destiny of the Universe and of consciousness and the nature of existence. For this reason it is difficult to distinguish where religion or philosophy end and esotericism and/or occultism begins.
Common themes addressed in esoteric cosmology are emanation, involution, evolution, epigenesis, planes of existence,
hierarchies of spiritual beings, cosmic cycles (e.g., cosmic year, Yuga), yogic or
spiritual disciplines, and references to
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Français (French)
n. - cosmologie
Deutsch (German)
n. - Kosmologie, (Wissenschaft über den Ursprung und die Entstehung des Universums)
Ελληνική (Greek)
n. - κοσμολογία
Português (Portuguese)
n. - cosmologia (f)
Español (Spanish)
n. - cosmología
Svenska (Swedish)
n. - kosmologi
中文（简体） (Chinese (Simplified))
宇宙哲学, 宇宙论
中文（繁體） (Chinese (Traditional))
n. - 宇宙哲學, 宇宙論
العربيه (Arabic)
(الاسم) علو الكون, الكونيات
עברית (Hebrew)
n. - מדע היקום
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