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Cosmic Microwave Background Spectral Distortions
CMB spectral distortions are tiny departures of the average cosmic microwave background (CMB) frequency spectrum from the predictions given by a perfect black body. They can be produced by a number of standard and non-standard processes occurring at the early stages of cosmic history, and therefore allow us to probe the standard picture of cosmology. Importantly, the CMB frequency spectrum and its distortions should not be confused with the CMB anisotropy power spectrum, which relates to spatial fluctuations of the CMB temperature in different directions of the sky. Overview The energy spectrum of the CMB is extremely close to that of a perfect blackbody with a temperature of 2.7255 K. This is expected because in the early Universe matter and radiation are in thermal equilibrium. However, at redshifts z<2\times10^6, several mechanisms, both standard and non-standard, can modify the CMB spectrum and introduce departures from a blackbody spectrum. These departures ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmic Microwave Background
In Big Bang cosmology the cosmic microwave background (CMB, CMBR) is electromagnetic radiation that is a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all space. It is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination when the first atoms were formed. With a traditional optical telescope, the space between stars and galaxies (the background) is completely dark (see: Olbers' paradox). However, a sufficiently sensitive radio telescope shows a faint background brightness, or glow, almost uniform, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1965 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Big Bang
The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the earliest known periods through its subsequent large-scale form. These models offer a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure. The overall uniformity of the Universe, known as the flatness problem, is explained through cosmic inflation: a sudden and very rapid expansion of space during the earliest moments. However, physics currently lacks a widely accepted theory of quantum gravity that can successfully model the earliest conditions of the Big Bang. Crucially, these models are compatible with the Hubble–Lemaître law—the observation that the farther away a galaxy is, the faster it is m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teide Observatory
Teide Observatory ( es, Observatorio del Teide), IAU code 954, is an astronomical observatory on Mount Teide at , located on Tenerife, Spain. It has been operated by the Instituto de Astrofísica de Canarias since its inauguration in 1964. It became one of the first major international observatories, attracting telescopes from different countries around the world because of the good astronomical seeing conditions. Later the emphasis for optical telescopes shifted more towards Roque de los Muchachos Observatory on La Palma. Telescopes Solar telescopes *Solar Vacuum Tower Telescope (VTT): 70 cm diameter. Operated by the Kiepenheuer Institute of Solar Physics, Freiburg (Germany). Installed in 1989. *THEMIS Solar Telescope: 90 cm diameter, built 1996, operated by Italy and France. *GREGOR Solar Telescope: 1.5 m, operated by a Germany, German consortium. In operation since May 2012. *A node of the Birmingham Solar Oscillations Network (BiSON), operated by the Universit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARCADE
Arcade most often refers to: * Arcade game, a coin-operated game machine ** Arcade cabinet, housing which holds an arcade game's hardware ** Arcade system board, a standardized printed circuit board * Amusement arcade, a place with arcade games * Arcade (architecture), a series of adjoining arches * Shopping mall, one or more buildings forming a complex of shops, also sometimes called a shopping arcade Arcade or The Arcade may also refer to: Places Greece *Arcades (Crete), a town and city-state of ancient Crete, Greece Italy * Arcade, Italy, a town and commune in the region of Veneto United States * Arcade Building (Asheville, North Carolina) * Arden-Arcade, California * Arcade, Georgia, a city in Jackson County * Arcade (village), New York * Arcade (town), New York * The Arcade (Oak Bluffs, Massachusetts), a historic site in Oak Bluffs, Massachusetts * The Arcade (Providence, Rhode Island), a historic shopping center * Arcade, Texas Arts and entertainment Books and comics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decoupling (cosmology)
In cosmology, decoupling refers to a period in the development of the universe when different types of particles fall out of thermal equilibrium with each other. This occurs as a result of the expansion of the universe, as their interaction rates decrease (and mean free paths increase) up to this critical point. The two verified instances of decoupling since the Big Bang which are most often discussed are photon decoupling and neutrino decoupling, as these led to the cosmic microwave background and cosmic neutrino background, respectively. Photon decoupling is closely related to recombination, which occurred about 378,000 years after the Big Bang (at a redshift of ''z'' = ), when the universe was a hot opaque ("foggy") plasma. During recombination, free electrons became bound to protons (hydrogen nuclei) to form neutral hydrogen atoms. Because direct recombinations to the ground state (lowest energy) of hydrogen are very inefficient, these hydrogen atoms generally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerma (physics)
In radiation physics, kerma is an acronym for "kinetic energy released per unit mass" (alternately, "kinetic energy released in matter", "kinetic energy released in material",, or "kinetic energy released in materials"), defined as the sum of the initial kinetic energies of all the charged particles liberated by uncharged ionizing radiation (i.e., indirectly ionizing radiation such as photons and neutrons) in a sample of matter, divided by the mass of the sample. It is defined by the quotient K = \operatorname\!E_\text/\operatorname\!m. Units The SI unit of kerma is the gray (Gy) (or joule per kilogram), the same as the unit of absorbed dose. However, kerma can be different from absorbed dose, depending on the energies involved. This is because ionization energy is not accounted for. While kerma approximately equals absorbed dose at low energies, kerma is much higher than absorbed dose at higher energies, because some energy escapes from the absorbing volume in the form of brem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrophysics And Space Science
''Astrophysics and Space Science'' is a bimonthly peer-reviewed scientific journal covering astronomy, astrophysics, and space science and astrophysical aspects of astrobiology. It was established in 1968 and is published by Springer Science+Business Media. From 2016 to 2020 the editors-in-chief were both Prof. Elias Brinks and Prof. Jeremy Mould. Since 2020 the sole editor-in-chief is Prof. Elias Brinks. Other editors-in-chief in the past have been Zdeněk Kopal (Univ. of Manchester) (1968-1993) and Michael A. Dopita (Australian National University) (1994-2015). Abstracting and indexing The journal is abstracted and indexed in the following databases: According to the ''Journal Citation Reports'', the journal has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bose–Einstein Statistics
In quantum statistics, Bose–Einstein statistics (B–E statistics) describes one of two possible ways in which a collection of non-interacting, indistinguishable particles may occupy a set of available discrete energy states at thermodynamic equilibrium. The aggregation of particles in the same state, which is a characteristic of particles obeying Bose–Einstein statistics, accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium. The theory of this behaviour was developed (1924–25) by Satyendra Nath Bose, who recognized that a collection of identical and indistinguishable particles can be distributed in this way. The idea was later adopted and extended by Albert Einstein in collaboration with Bose. The Bose–Einstein statistics applies only to the particles not limited to single occupancy of the same state – that is, particles that do not obey the Pauli exclusion principle restrictions. Such particles have integer values of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planckian Distribution
In physics, Planck's law describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature , when there is no net flow of matter or energy between the body and its environment. At the end of the 19th century, physicists were unable to explain why the observed spectrum of black-body radiation, which by then had been accurately measured, diverged significantly at higher frequencies from that predicted by existing theories. In 1900, German physicist Max Planck heuristically derived a formula for the observed spectrum by assuming that a hypothetical electrically charged oscillator in a cavity that contained black-body radiation could only change its energy in a minimal increment, , that was proportional to the frequency of its associated electromagnetic wave. This resolved the problem of the ultraviolet catastrophe predicted by classical physics. This discovery was a pioneering insight of modern physics and is of fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Distortions In The Early Universe New
''Spectral'' is a 2016 3D military science fiction, supernatural horror fantasy and action-adventure thriller war film directed by Nic Mathieu. Written by himself, Ian Fried, and George Nolfi from a story by Fried and Mathieu. The film stars James Badge Dale, Max Martini, Emily Mortimer, Clayne Crawford and Bruce Greenwood. The film was released worldwide on December 9, 2016 on Netflix. On February 1, 2017, Netflix released a prequel graphic novel of the film called ''Spectral: Ghosts of War'' which was made available digitally through the website ComiXology. Plot DARPA researcher Dr. Mark Clyne flies from Virginia to Moldova, the current deployment location of the US military in the ongoing Moldovan War, to be consulted on one of his creations, a line of hyperspectral imaging goggles that have been issued to troops there. After arriving at a US military airbase on the outskirts of Chișinău, he meets with US Army General (United States), General Orland and Central Intellige ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
