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Celestial Spheres
The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others. In these celestial models, the apparent motions of the fixed stars and planets are accounted for by treating them as embedded in rotating spheres made of an aetherial, transparent fifth element ( quintessence), like gems set in orbs. Since it was believed that the fixed stars were unchanging in their positions relative to one another, it was argued that they must be on the surface of a single starry sphere. Context In modern thought, the orbits of the planets are viewed as the paths of those planets through mostly empty space. Ancient and medieval thinkers, however, considered the celestial orbs to be thick spheres of rarefied matter nested one within the other, each one in complete contact with the sphere above it and the sphere below.Lindberg, ''Beginnings of Western Science'', p. 251. When schol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Kepler
Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his Kepler's laws of planetary motion, laws of planetary motion, and his books ''Astronomia nova'', ''Harmonice Mundi'', and ''Epitome Astronomiae Copernicanae'', influencing among others Isaac Newton, providing one of the foundations for his theory of Newton's law of universal gravitation, universal gravitation. The variety and impact of his work made Kepler one of the founders and fathers of modern astronomy, the scientific method, Natural science, natural and modern science. He has been described as the "father of science fiction" for his novel ''Somnium (novel), Somnium''. Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Hans Ulrich von Eggenberg, Prince Hans Ulrich von Eggenberg. Lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concentric Spheres
The cosmological model of concentric (or homocentric) spheres, developed by Eudoxus of Cnidus, Eudoxus, Callippus, and Aristotle, employed celestial spheres all geocentric model, centered on the Earth. In this respect, it differed from the epicycle, epicyclic and eccentric models with multiple centers, which were used by Ptolemy and other mathematical astronomers until the time of Copernicus. Origins of the concept of concentric spheres Eudoxus of Cnidus was the first astronomer to develop the concept of concentric spheres. He was originally a student at Plato's academy and is believed to have been influenced by the cosmological speculations of Plato and Pythagoras."Eudoxus of Cnidus." Complete Dictionary of Scientific Biography. Vol. 4. Detroit: Charles Scribner's Sons, 2008. 465–467. Gale Virtual Reference Library. Web. 2 June 2014. He came up with the idea of homocentric spheres in order to explain the perceived inconsistent motions of the planets and to develop a uniform mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timaeus (dialogue)
''Timaeus'' (; , ) is one of Plato's dialogues, mostly in the form of long monologues given by Critias and Timaeus, written 360 BC. The work puts forward reasoning on the possible nature of the physical world and human beings and is followed by the dialogue '' Critias''. Participants in the dialogue include Socrates, Timaeus, Hermocrates, and Critias. Some scholars believe that it is not the Critias of the Thirty Tyrants who appears in this dialogue, but his grandfather, also named Critias. At the beginning of the dialogue, the absence of another, unknown dialogue participant, present on the day before, is bemoaned. It has been suggested from some traditions— Diogenes Laertius (VIII 85) from Hermippus of Smyrna (3rd century BC) and Timon of Phlius ( 320 – 235 BC)—that ''Timaeus'' was influenced by a book about Pythagoras, written by Philolaus, although this assertion is generally considered false. Introduction The dialogue takes place the day after Socrates de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parmenides
Parmenides of Elea (; ; fl. late sixth or early fifth century BC) was a Pre-Socratic philosophy, pre-Socratic ancient Greece, Greek philosopher from Velia, Elea in Magna Graecia (Southern Italy). Parmenides was born in the Greek colony of Velia, Elea to a wealthy and illustrious family. The exact date of his birth is not known with certainty; on the one hand, according to the Doxography, doxographer Diogenes Laërtius, Parmenides flourished in the period immediately preceding 500 BC, which would place his year of birth around 540 BC; on the other hand, in the dialogue ''Parmenides (dialogue), Parmenides'' Plato portrays him as visiting Athens at the age of 65, when Socrates was a young man, , which, if true, suggests a potential year of birth of . Parmenides is thought to have been in his prime (or "floruit") around 475 BC. The single known work by Parmenides is a philosophical poem in dactylic hexameter verse whose original title is unknown but which is often referred to as '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenophanes
Xenophanes of Colophon ( ; ; – c. 478 BC) was a Greek philosopher, theologian, poet, and critic of Homer. He was born in Ionia and travelled throughout the Greek-speaking world in early classical antiquity. As a poet, Xenophanes was known for his critical style, writing poems that are considered among the first satires. He composed elegiac couplets that criticised his society's traditional values of wealth, excesses, and athletic victories. He criticised Homer and the other poets in his works for representing the gods as foolish or morally weak. His poems have not survived intact; only fragments of some of his work survive in quotations by later philosophers and literary critics. Xenophanes is seen as one of the most important pre-Socratic philosophers. A highly original thinker, Xenophanes sought explanations for physical phenomena such as clouds or rainbows without references to divine or mythological explanations, but instead based on first principles. He distinguished ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pythagoras
Pythagoras of Samos (; BC) was an ancient Ionian Greek philosopher, polymath, and the eponymous founder of Pythagoreanism. His political and religious teachings were well known in Magna Graecia and influenced the philosophies of Plato, Aristotle, and, through them, Western philosophy. Modern scholars disagree regarding Pythagoras's education and influences, but most agree that he travelled to Croton in southern Italy around 530 BC, where he founded a school in which initiates were allegedly sworn to secrecy and lived a communal, ascetic lifestyle. In antiquity, Pythagoras was credited with mathematical and scientific discoveries, such as the Pythagorean theorem, Pythagorean tuning, the five regular solids, the theory of proportions, the sphericity of the Earth, the identity of the morning and evening stars as the planet Venus, and the division of the globe into five climatic zones. He was reputedly the first man to call himself a philosopher ("lover of wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaximenes Of Miletus
Anaximenes of Miletus (; ; ) was an Ancient Greece, Ancient Greek, Pre-Socratic philosophy, Pre-Socratic philosopher from Miletus in Anatolia (modern-day Turkey). He was the last of the three philosophers of the Ionian School (philosophy), Milesian School, after Thales of Miletus, Thales and Anaximander. These three are regarded by historians as the first philosophers of the Western world. Anaximenes is known for his belief that air is the ''arche'', or the basic element of the universe from which all things are created. Little is known of Anaximenes's life and work, as all of his original texts are lost. Historians and philosophers have reconstructed information about Anaximenes by interpreting texts about him by later writers. All three Milesian philosophers were monists who believed in a single foundational source of everything: Anaximenes believed it to be air, while Thales and Anaximander believed it to be water and Apeiron, an undefined infinity, respectively. It is generally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmogony
Cosmogony is any model concerning the origin of the cosmos or the universe. Overview Scientific theories In astronomy, cosmogony is the study of the origin of particular astrophysical objects or systems, and is most commonly used in reference to the origin of the universe, the Solar System, or the Earth–Moon system. The prevalent physical cosmology, cosmological scientific theory, model of the early development of the universe is the Big Bang theory. Sean M. Carroll, who specializes in Physical cosmology, theoretical cosmology and Field (physics), field theory, explains two competing explanations for the origins of the Gravitational singularity, singularity, which is the center of a space in which a characteristic is limitless (one example is the singularity of a black hole, where gravity is the characteristic that becomes infinite). It is generally accepted that the universe began at a point of singularity. When the universe started to expand, the Big Bang occurred, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sphere Of Fire
Sphere of fire is the name given in Ptolemaic astronomy to the sphere intervening between, and separating, the Earth and the Moon. Traditional concept Building on Empedocles's vision of the world as a four-level cake of stacked fundamental elements - earth, water, air and fire - with fire at the top, Aristotle saw the sublunary world as surmounted by the sphere of fire. Aristotle's conception became prevalent in the Hellenic world, and was given a distance scale by Ptolemy: “taking the radius of the spherical surface of the Earth and the water as the unit, the radius of the spherical sphere which surrounds the air and fire is 33, the radius of the lunar sphere is 64....”. The Middle Ages broadly inherited the concept of the four elements of earth, water, air and fire arranged in concentric spheres about the earth as centre: as the purest of the four elements, fire - and the sphere of fire - stood highest in the ascending sequence of the '' scala naturae'', and closest to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaximander
Anaximander ( ; ''Anaximandros''; ) was a Pre-Socratic philosophy, pre-Socratic Ancient Greek philosophy, Greek philosopher who lived in Miletus,"Anaximander" in ''Chambers's Encyclopædia''. London: George Newnes Ltd, George Newnes, 1961, Vol. 1, p. 403. a city of Ionia (in modern-day Turkey). He belonged to the Milesian school and learned the teachings of his master Thales. He succeeded Thales and became the second master of that school where he counted Anaximenes of Miletus, Anaximenes and, arguably, Pythagoras amongst his pupils. Little of his life and work is known today. According to available historical documents, he is the first philosopher known to have written down his studies, although only one fragment of his work remains. Fragmentary testimonies found in documents after his death provide a portrait of the man. Anaximander was an early proponent of science and tried to observe and explain different aspects of the universe, with a particular cosmogony, interest in its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greece
Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically related city-states and communities. Prior to the Roman period, most of these regions were officially unified only once under the Kingdom of Macedon from 338 to 323 BC. In Western history, the era of classical antiquity was immediately followed by the Early Middle Ages and the Byzantine period. Three centuries after the decline of Mycenaean Greece during the Bronze Age collapse, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and the colonization of the Mediterranean Basin. This was followed by the age of Classical Greece, from the Greco-Persian Wars to the death of Alexander the Great in 323 BC, and which included the Golden Age of Athens and the Peloponnesian War. The u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
