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Cosmogeny
Cosmogony is any model concerning the origin of the cosmos or the universe. Overview Scientific theories In astronomy, cosmogony refers to 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 cosmological model of the early development of the universe is the Big Bang theory. Sean M. Carroll, who specializes in theoretical cosmology and field theory, explains two competing explanations for the origins of the singularity, which is the center of a space in which a characteristic is limitless. (One example of a singularity is the singularity of a black hole, where gravity becomes infinite.) It is generally accepted that the universe began at a point of singularity. When the singularity of the universe started to expand, the Big Bang occurred, which evidently began the universe. The other explanation, held by proponents such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmos
The cosmos (, ) is another name for the Universe. Using the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity. The cosmos, and understandings of the reasons for its existence and significance, are studied in cosmologya broad discipline covering scientific, religious or philosophical aspects of the cosmos and its nature. Religious and philosophical approaches may include the cosmos among spiritual entities or other matters deemed to exist outside the physical universe. Etymology The philosopher Pythagoras first used the term ''kosmos'' ( grc, κόσμος, Latinized ''kósmos'') for the order of the universe. Greek κόσμος "order, good order, orderly arrangement" is a word with several main senses rooted in those notions. The verb κοσμεῖν (''κοσμεῖν'') meant generally "to dispose, prepare", but especially "to order and arrange (troops for battle), to set (an army) in array"; also "to establish (a government or regime) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a result, it has no significant influence at the level of subatomic particles. However, gravity is the most significant interaction between objects at the macroscopic scale, and it determines the motion of planets, stars, galaxies, and even light. On Earth, gravity gives weight to physical objects, and the Moon's gravity is responsible for sublunar tides in the oceans (the corresponding antipodal tide is caused by the inertia of the Earth and Moon orbiting one another). Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Creation Myth
A creation myth (or cosmogonic myth) is a symbolic narrative of how the world began and how people first came to inhabit it., "Creation myths are symbolic stories describing how the universe and its inhabitants came to be. Creation myths develop through oral traditions and therefore typically have multiple versions." While in popular usage the term ''myth'' often refers to false or fanciful stories, members of cultures often ascribe varying degrees of truth to their creation myths. In the society in which it is told, a creation myth is usually regarded as conveying profound truthsmetaphorically, symbolically, historically, or literally. They are commonly, although not always, considered cosmogonical mythsthat is, they describe the ordering of the cosmos from a state of chaos or amorphousness. Creation myths often share several features. They often are considered sacred accounts and can be found in nearly all known religious traditions. They are all stories with a plot and charac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sumerian Creation Myth
The earliest record of a Sumerian creation myth, called The Eridu Genesis by historian Thorkild Jacobsen, is found on a single fragmentary tablet excavated in Nippur by the Expedition of the University of Pennsylvania in 1893, and first recognized by Arno Poebel in 1912. It is written in the Sumerian language and dated to around 1600 BCE. Other Sumerian creation myths from around this date are called the Barton Cylinder, the Debate between sheep and grain and the Debate between Winter and Summer, also found at Nippur. Summary The beginning of the tablet is lost, but the surviving portion begins by recounting how the gods An, Enlil, Enki, and Ninhursanga created the Sumerians and comfortable conditions for the animals to live and procreate. Kingship then descends from heaven, and the first cities are founded: Eridu, Bad-tibira, Larak, Sippar, and Shuruppak. After a missing section, we learn that the gods have decided not to save mankind from an impending flood. Zi-ud-sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ekpyrotic Universe
The ekpyrotic universe () is a physical cosmology, cosmological model of the early universe that explains the origin of the large-scale structure of the cosmos. The model has also been incorporated in the cyclic universe theory (or ekpyrotic cyclic universe theory), which proposes a complete cosmological history, both the past and future. Origins The original ekpyrotic model was introduced by Justin Khoury, Burt Ovrut, Paul Steinhardt and Neil Turok in 2001. Steinhardt created the name based on the Ancient Greek word ekpyrosis (ἐκπύρωσις, "conflagration"), which refers to a Stoicism, Stoic cosmological model in which the universe is caught in an eternal cycle of fiery birth, cooling and rebirth. The theory addresses the fundamental question that remains unanswered by the Big Bang inflationary model, "What happened before the Big Bang?" The explanation, according to the ekpyrotic theory, is that the Big Bang was actually a big bounce, a transition from a previous epo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inflation (cosmology)
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from seconds after the conjectured Big Bang singularity to some time between and seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate. The acceleration of this expansion due to dark energy began after the universe was already over 7.7 billion years old (5.4 billion years ago). Inflation theory was developed in the late 1970s and early 80s, with notable contributions by several theoretical physicists, including Alexei Starobinsky at Landau Institute for Theoretical Physics, Alan Guth at Cornell University, and Andrei Linde at Lebedev Physical Institute. Alexei Starobinsky, Alan Guth, and Andrei Linde won the 2014 Kavli Prize "for pioneering the theory of cosmic inflation." It was developed further in the ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Theory Landscape
The string theory landscape or landscape of vacua refers to the collection of possible false vacua in string theory,The number of metastable vacua is not known exactly, but commonly quoted estimates are of the order 10500. See M. Douglas, "The statistics of string / M theory vacua", ''JHEP'' 0305, 46 (2003). ; S. Ashok and M. Douglas, "Counting flux vacua", ''JHEP'' 0401, 060 (2004). together comprising a collective "landscape" of choices of parameters governing compactifications. The term "landscape" comes from the notion of a fitness landscape in evolutionary biology. It was first applied to cosmology by Lee Smolin in his book '' The Life of the Cosmos'' (1997), and was first used in the context of string theory by Leonard Susskind. Compactified Calabi–Yau manifolds In string theory the number of flux vacua is commonly thought to be roughly 10^, but could be 10^ or higher. The large number of possibilities arises from choices of Calabi–Yau manifolds and choices of gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartle–Hawking State
The Hartle–Hawking state is a proposal in theoretical physics concerning the state of the Universe prior to the Planck epoch. It is named after James Hartle and Stephen Hawking. Hartle and Hawking suggest that if we could travel backwards in time towards the beginning of the Universe, we would note that quite near what might otherwise have been the beginning, time gives way to space such that at first there is only space and no time. According to the Hartle–Hawking proposal, the Universe has no origin as we would understand it: the Universe was a singularity in both space and time, pre- Big Bang. However, Hawking does state "...the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago.", but that the Hartle-Hawking model is not the steady state Universe of Hoyle; it simply has no initial boundaries in time or space. Technical explanation The Hartle–Hawking state is the wave function of the U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barton Zwiebach
Barton Zwiebach (born ''Barton Zwiebach Cantor'', October 4, 1954) is a Peruvian string theorist and professor at the Massachusetts Institute of Technology. Work Zwiebach's undergraduate work was in Electrical Engineering at the Universidad Nacional de Ingeniería in Peru, from which he graduated in 1977. His graduate work was in physics at the California Institute of Technology. Zwiebach obtained his Ph.D. in 1983, working under the supervision of Murray Gell-Mann. He has held postdoctoral positions at the University of California, Berkeley, and at the Massachusetts Institute of Technology, where he became an assistant professor of physics in 1987, and a permanent member of the faculty in 1994. He is one of the world's leading experts in string field theory String or strings may refer to: *String (structure), a long flexible structure made from threads twisted together, which is used to tie, bind, or hang other objects Arts, entertainment, and media Films * Strings (1991 f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Quantum Cosmology
Loop quantum cosmology (LQC) is a finite, symmetry-reduced model of loop quantum gravity ( LQG) that predicts a "quantum bridge" between contracting and expanding cosmological branches. The distinguishing feature of LQC is the prominent role played by the quantum geometry effects of loop quantum gravity (LQG). In particular, quantum geometry creates a brand new repulsive force which is totally negligible at low space-time curvature but rises very rapidly in the Planck regime, overwhelming the classical gravitational attraction and thereby resolving singularities of general relativity. Once singularities are resolved, the conceptual paradigm of cosmology changes and one has to revisit many of the standard issues—e.g., the "horizon problem"—from a new perspective. Since LQG is based on a specific quantum theory of Riemannian geometry, geometric observables display a fundamental discreteness that play a key role in quantum dynamics: While predictions of LQC are very close to tho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M-theory
M-theory is a theory in physics that unifies all consistent versions of superstring theory. Edward Witten first conjectured the existence of such a theory at a string theory conference at the University of Southern California in 1995. Witten's announcement initiated a flurry of research activity known as the second superstring revolution. Prior to Witten's announcement, string theorists had identified five versions of superstring theory. Although these theories initially appeared to be very different, work by many physicists showed that the theories were related in intricate and nontrivial ways. Physicists found that apparently distinct theories could be unified by mathematical transformations called S-duality and T-duality. Witten's conjecture was based in part on the existence of these dualities and in part on the relationship of the string theories to a field theory called eleven-dimensional supergravity. Although a complete formulation of M-theory is not known, such a formu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Theory
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity. String theory is a broad and varied subject that attempts to address a number of deep questions of fundamental physics. String theory has contributed a number of advances to mathematical physics, which have been applied to a variety of problems in black hole physics, early universe cosmology, nuclear physics, and conde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
