Ancient astronomers and philosophers, medieval and Renaissance developed many different theories about the dynamics of celestial spheres . They explain the motions of the various fields in their materials, the external movers such as the heavenly intelligence, and internal movements such as the soul of impressed motives or powers. Most of these models are qualitative, although some of them incorporate quantitative analysis related to speed, motive strength and resistance.
Video Dynamics of the celestial spheres
The celestial material and its natural movement
In considering the physics of the sky, scholars follow two different views of the composition of the material of celestial balls. For Plato, the celestial regions are made "mostly from fire" because of the mobility of fire. Then Platonists, like Plotinus, maintain that even though fire moves naturally upward in a straight line toward a natural place on the edges of the universe, when it arrives there, it will rest or move naturally in a circle. This account is compatible with Aristotle's meteorology from the fiery region of the upper air, dragged beneath the moon's circular motion. For Aristotle, however, the ball itself is made entirely of a special fifth element, Aether (?????), a bright and uncontaminated upper atmosphere where the gods dwell, different from the crowded ones. lower atmosphere, Aer (???). While the four terrestrial elements (earth, water, air, and fire) bring out the generation and destruction of natural substances through their mutual transformation, the aether is immutable, moving always in a uniformly uniform motion uniquely matched to the heavenly balls, the eternal. Earth and water have a natural weight ( gravitas ), which they declare by moving downward toward the center of the universe. Fire and air have natural light ( levitas ), so they move upward, away from the center. Aether, because it is not heavy or light, moves naturally around the center.
Maps Dynamics of the celestial spheres
Causes of celestial movement
As early as Plato, philosophers consider heaven to be displaced by immaterial agents. Plato believed that the cause was the soul of the world, created according to mathematical principles, which governed the daily movement of the sky (Sama movement) and the opposite movements of the planets along the zodiac (Different movements). Aristotle proposed the existence of an unassailable divine activator acting as the ultimate cause; celestial spheres imitate the movers, as best they can, by moving in a uniform circular motion. In his book Metaphysics Aristotle argues that immovable movers will be required to ensure every individual movement in heaven. While establishing that the number of spheres, and thus the deity, subject to revisions by astronomers, he estimates the total as 47 or 55, depending on whether one follows the model of Eudoxus or Callippus. In Heaven , Aristotle presents an alternate view of the eternal circular movement as the movement itself, in the way of the soul of Plato's world, which lends support to three principles of celestial movement: the internal, external, immovable, and celestial material (ether).
Greek translator later
In the planet's hypothesis, Ptolemy (c.90-168) rejects the Aristotelian concept of an external prime mover, while maintaining that the planet has a soul and moves with a voluntary movement. Each planet sends motive emissions that direct its own motion and the relative and epicycle movements that make up its system, just as a bird sends emissions to its nerves that direct the movement of its legs and wings.
John Philoponus (490-570) considers that heaven is made of fire, not of ether, but maintains that the circular motion is one of two natural movements of fire. In the theological work, In the Creation of the World, he denies that heaven is moved by a soul or an angel, proposing that "it is not impossible that God, who created all this imparts the motive power to the Moon, the Sun, and other stars - such as the tendency for heavy and light bodies, and movements because of the internal soul for all living things - so that angels do not forcibly transfer them. "This is interpreted as a concept application the impetus for the movement of the heavenly spheres. In a previous commentary on Aristotle Physics, Philoponus compares the strength or innate nature responsible for the rotation of the sky to the forces or innate nature that caused the fall of the stone.
Islamic Translator
The Islamic philosophers al-Farabi (c.872-c.950) and Avicenna (c.980-1037), following Plotinus, claim that Aristotle's movers, called Intelligence, emerge through a series of emanations beginning with God. The first intelligence comes from God, and from the first intelligence radiates its sphere, soul, and second intelligence. The process continues down through the heavenly balls to the Moon ball, its soul, and the last intelligence. They assume that every ball is moved steadily by its soul, trying to imitate the perfection of its intelligence. Avicenna states that in addition to his intelligence and soul, each ball is also driven by a natural tendency ( mayl ).
An interpreter of Aristotle from Muslim Spain, al-Bitruji (w.C.1024), proposes a radical transformation of astronomy that removes epicles and eccentricities, in which the heavenly spheres are driven by a single, immobile motion at the edges of the universe. They move in a "natural nonviolent movement". The driving force is reduced by increasing the distance from the rim so that the lower balls lag behind in their daily movement around the Earth; This power reaches even as far as the ball of water, producing waves.
The more influential for future Christian thinkers is the teaching of Averroes (1126-1198), who agrees with Avicenna that intelligence and soul combine to move the ball but reject the concept of emanation. Considering how the soul acts, it maintains that the soul moves the ball effortlessly, since the celestial material has no inclination for opposite movements.
Later in this century, mutakallim Adud al-Din al-Iji (1281-1355) rejected the principle of uniform and circular motion, following Ash'ari's doctrine of atomism, which states that all physical effects are directly caused by the will of God. than with natural causes. He argues that the heavenly spheres are "imaginary objects" and "more distant than cobwebs". His view was challenged by al-Jurjani (1339-1413), who argued that even if the celestial sphere "has no external reality, yet they are the things that are properly imagined and according to what [there is] in the actuality".
Medieval Western Europe
In the early Middle Ages, Plato's description of the heavens was dominant among European philosophers, which led to Christian thinkers questioning the role and nature of the soul of the world. With the restoration of Aristotle's works in the twelfth and thirteenth centuries, Aristotle's views replaced earlier Platonism, and a whole new set of questions about the immovable relations of movers to the fields and to God emerged.
In the early phases of the restoration of the Western Aristotle, Robert Grosseteste (c.1175-1253), influenced by medieval Platonism and by astronomy al-Bitruji, rejects the idea that heaven is driven by the soul or intelligence. Adam Marsh (c.1200-1259) The treatise On Ebb and the Flow of the Sea, previously associated with Grosseteste, defends al-Bitruji's opinion that the heavenly spheres and oceans are driven by peripheral devices. movers whose movements are weakened by distance.
Thomas Aquinas (c.1225-1274), following Avicenna, interprets Aristotle to mean that there are two immaterial substances responsible for the movement of each celestial sphere, the soul which is an integral part of the sphere, and the intelligence separated from its sphere. The soul shares the motion of the sphere and causes the ball to move through love and its desire for a separate, unmoved intelligence. Avicenna, al-Ghazali, Moses Maimonides, and most Christian scholastic philosophers identified Aristotle's intelligence with the angels of revelation, thus associating an angel with each ball. In addition, Aquinas rejects the idea that celestial bodies are displaced by internal properties, similar to the weight and light that move the terrestrial body. Connecting souls to spheres is theologically controversial, because it can make them animals. After the Curse of 1277, most of the philosophers came to reject the idea that the balls of heaven had a soul.
Robert Kilwardby (c 1215-1279) discusses three alternative explanations of the movement of the heavenly spheres, rejecting the view that celestial bodies are animated and moved by their own spirit or soul, or that celestial bodies are driven by angel spirits, which organizes and moves it. He maintains, on the contrary, that "celestial bodies are displaced by their natural tendency which is similar to weight". Just as the heavy body is naturally driven by its own weight, which is an intrinsically active principle, the celestial bodies are naturally driven by the same intrinsic principle. Because the sky is a ball, the only movement that can be natural to them is rotation. The idea of ​​Kilwardby had previously been held by another Oxford scholar, John Blund (c.1175-1248).
In two slightly different discussions, John Buridan (c.1295-1358) states that when God created the heavenly spheres he begins to move them, impressing in them a circular impulse that will not be damaged or diminished, since there is no tendency to other movements or any resistance in the celestial territory. He notes that this will allow God to rest on the seventh day, but he leaves this problem to be solved by theologians.
Nicole Oresme (c.1323-1382) describes the movement of the sphere in terms of traditional acts of intelligence but notes that, contrary to Aristotle, some intelligences are moved; for example, the intelligence that drives the Moon epicycle shares the moon ball movement in which the epicycle is embedded. He attributes the motion of the ball to the proportion of motive force to the impressed resistance in each ball when God created the heavens. In discussing the moving power relations of intelligence, ball resilience, and circular velocity, he says "this ratio should not be called the ratio of resistance forces except by analogy, since intelligence moves with willÃ,... and the sky does not hold it."
According to Grant, except for Oresme, scholastic thinkers do not consider the power-resistance model to be applied appropriately to the movements of celestial bodies, although some, such as Bartholomeus Amicus, think analogously in terms of strength and endurance. At the end of the Middle Ages, a common opinion among philosophers that celestial bodies are displaced by external intelligence, or angels, and not by some kind of internal drive.
Drive and Copernicanism
Although Nicolaus Copernicus (1473-1543) altered Aristotelian Ptolemaic and cosmological astronomy by moving the Earth from the center of the universe, it maintained both the traditional model of the celestial sphere and the medieval Aristotelian view of the cause of its movement. Copernicus followed Aristotle to maintain that the circular motion was natural for the shape of the ball. However, he also seems to have accepted traditional philosophical beliefs that the balls were driven by external drivers.
Cosmology Johannes Kepler (1571-1630) abolished the heavenly spheres, but he argued that the planets were displaced both by the external motive force, which he discovered in the Sun, and the motive soul associated with each planet. In the early manuscripts discussing the motions of Mars, Kepler considers the Sun to cause the circular motion of the planet. He then attributes the motion to the inner and outer planets, which transforms his entire movement from circle to oval, to a soul that moves on this planet because it is "not a natural movement, but more than animate." In various writings, Kepler often associate a kind of intelligence with innate motive abilities associated with the stars.
After the occurrence of Copernicanism, the planets began to appear as the body moves freely through a very fine medium. Although many scholastics continue to maintain that intelligence is a celestial driver, they now associate intelligence with the planets themselves, rather than with celestial balls.
See also
- Non-moving moves
- the hierarchy of Christian angels
Note
References
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Secondary sources
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