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Ekpyrotic universe

Ekpyrotic universe
The ekpyrotic universe, or ekpyrotic scenario, is a cosmological model of the origin and shape of the universe. The name comes from a Stoic term ekpyrosis (Ancient Greek ἐκπύρωσις ekpurōsis) meaning conflagration or in Stoic usage "conversion into fire".[1] The ekpyrotic model of the universe is an alternative to the standard cosmic inflation model for the very early universe; both models accommodate the standard Big Bang Lambda-CDM model of our universe.[2][3] The ekpyrotic model is a precursor to, and part of, some cyclic models. The ekpyrotic model came out of work by Neil Turok and Paul Steinhardt and maintains that the universe did not start in a singularity, but came about from the collision of two branes. This collision avoids the primordial singularity and superluminal expansion of spacetime while preserving nearly scale-free density fluctuations and other features of the observed universe. See also[edit] Notes and references[edit] Further reading[edit] P.

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Diffeomorphism The image of a rectangular grid on a square under a diffeomorphism from the square onto itself. Definition[edit] Given two manifolds M and N, a differentiable map f : M → N is called a diffeomorphism if it is a bijection and its inverse f−1 : N → M is differentiable as well. Ultimate fate of the universe The ultimate fate of the universe is a topic in physical cosmology. Many possible fates are predicted by rival scientific theories, including futures of both finite and infinite duration. Once the notion that the universe started with a rapid inflation nicknamed the Big Bang became accepted by the majority of scientists,[1] the ultimate fate of the universe became a valid cosmological question, one depending upon the physical properties of the mass/energy in the universe, its average density, and the rate of expansion.

Cosmological principle Astronomer William Keel explains: The cosmological principle is usually stated formally as 'Viewed on a sufficiently large scale, the properties of the Universe are the same for all observers.' This amounts to the strongly philosophical statement that the part of the Universe which we can see is a fair sample, and that the same physical laws apply throughout. In essence, this in a sense says that the Universe is knowable and is playing fair with scientists.[1] The cosmological principle contains three implicit qualifications and two testable consequences. The first implicit qualification is that "observers" means any observer at any location in the universe, not simply any human observer at any location on Earth: as Andrew Liddle puts it, "the cosmological principle [means that] the universe looks the same whoever and wherever you are

Shape of the Universe The shape of the universe is the local and global geometry of the universe, in terms of both curvature and topology (though, strictly speaking, it goes beyond both). When physicsist describe the universe as being flat or nearly flat, they're talking geometry: how space and time are warped according to general relativity. When they talk about whether it open or closed, they're referring to its topology.[1] Although the shape of the universe is still a matter of debate in physical cosmology, based on the recent Wilkinson Microwave Anisotropy Probe (WMAP) measurements "We now know that the universe is flat with only a 0.4% margin of error", according to NASA scientists. [2] Theorists have been trying to construct a formal mathematical model of the shape of the universe. In formal terms, this is a 3-manifold model corresponding to the spatial section (in comoving coordinates) of the 4-dimensional space-time of the universe. Two aspects of shape[edit] Local geometry (spatial curvature)[edit]

Hindu cycle of the universe See also Hindu units of measurement. This is similar to the Cyclical Universe Theory in physical cosmology. The Big Bang is described as the birth of the universe (Brahma), the life of the universe then follows (Vishnu), and the Big Crunch would be described as the destruction of the universe (Shiva). Multiverse (religion) In religion a multiverse is the concept of a plurality of universes. Some religious cosmologies propose that the cosmos is not the only one that exists. The concept of infinite worlds is mentioned in the Apannaka Jataka: Quintessence (physics) In physics, quintessence is a hypothetical form of dark energy postulated as an explanation of the observation of an accelerating rate of expansion of the Universe announced in 1998. It has been proposed by some physicists to be a fifth fundamental force. Quintessence differs from the cosmological constant explanation of dark energy in that it is dynamic, that is, it changes over time, unlike the cosmological constant which always stays constant. It is suggested that quintessence can be either attractive or repulsive depending on the ratio of its kinetic and potential energy.

Hindu cosmology In Hindu cosmology the universe is cyclically created and destroyed. The Hindu literature, such as Vedas, Puranas, cites the creation of universe. They describe the aspects of evolution, astronomy, etc. Buddhist cosmology Buddhist cosmology is the description of the shape and evolution of the Universe according to the Buddhist scriptures and commentaries. Introduction[edit] The self-consistent Buddhist cosmology which is presented in commentaries and works of Abhidharma in both Theravāda (31 planes, Sakwala Vibhanga) and Mahāyāna traditions, is the end-product of an analysis and reconciliation of cosmological comments found in the Buddhist sūtra and vinaya traditions. No single sūtra sets out the entire structure of the universe. Kalpa Vibhangaya However, in several sūtras the Buddha describes other worlds and states of being, and other sūtras describe the origin and destruction of the universe.