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Shkadov Thruster
Stellar engines are a class of hypothetical megastructures used to control the motion of a star system. The concept has been introduced by Badescu and Cathcart. Some variants use this energy to produce thrust, and thus accelerate a star and anything orbiting it in a given direction. The creation of such a system would make its builders a type-II civilization on the Kardashev scale. Classes Three classes of stellar engines have been defined. Class A (Shkadov thruster) One of the simplest examples of a stellar engine is the Shkadov thruster (named after Dr. Leonid Shkadov, who first proposed it), or a class-A stellar engine. Such an engine is a stellar propulsion system, consisting of an enormous mirror/light sail—actually a massive type of solar statite large enough to classify as a megastructure—which would balance gravitational attraction towards and radiation pressure away from the star. Since the radiation pressure of the star would now be ''asymmetrical'', i.e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class C Stellar Engine
Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently from such group phenomena as "types" or "kinds" * Class (set theory), a collection of sets that can be unambiguously defined by a property that all its members share * Hazard class, a dangerous goods classification * Social class, the hierarchical arrangement of individuals in society, usually defined by wealth and occupation * Working class, can be defined by rank, income or collar Arts, entertainment, and media * "The Class" (song), 1959 Chubby Checker song *Character class in role-playing games and other genres *Class 95 (radio station), a Singaporean radio channel Films * ''Class'' (film), 1983 American film * ''The Class'' (2007 film), 2007 Estonian film * ''The Class'' (2008 film), 2008 film (''Entre les murs'') Television * ''Class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term ''Milky Way'' is a translation of the Latin ', from the Greek ('), meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of , but only about 1,000 light years thick at the spiral arms (more at the bulg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronautical Federation
The International Astronautical Federation (IAF) is an international space advocacy organization based in Paris, and founded in 1951 as a non-governmental organization to establish a dialogue between scientists around the world and to lay the information for international space cooperation. It has over 390 members from 68 countries across the world. They are drawn from space agencies, companies, universities, professional associations, museums, government organizations and learned societies. The IAF organizes the annual International Astronautical Congress (IAC). As of 2019, Pascale Ehrenfreund has served as the president of the IAF. History After World War II, Heinz Gartmann, Gunter Loeser, and Heinz-Hermann Koelle formed the German Rocket Society. They contacted the British Interplanetary Society (BIS) and Groupement Astronautique Français. The French group's leader, Alexandre Ananoff, organized the First International Congress for Astronautics in Paris, France, in Sep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dyson Spheres In Popular Culture
Dyson spheres are theoretical constructs that harvest the entire energy output of a given star by completely enclosing it. They are named after physicist Freeman Dyson, who proposed the concept in 1960. A precursor to the concept of Dyson spheres was featured in the 1937 novel ''Star Maker'' by Olaf Stapledon. Fictional Dyson spheres are typically solid structures forming a continuous shell around the star in question, although Dyson himself considered that prospect mechanically implausible and instead proposed multiple separate objects independently orbiting the star. It is a type of Big Dumb Object. Dyson spheres are often a background element in fiction, such as in the 1964 novel '' The Wanderer'' by Fritz Leiber where aliens enclose multiple stars in this way. Dyson spheres are depicted in the 1975–1983 book series ''Saga of Cuckoo'' by Frederik Pohl and Jack Williamson, and one functions as the setting of Bob Shaw's 1975 novel '' Orbitsville'' and its sequels. Variations on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kurzgesagt
Kurzgesagt (; German for "In a nutshell" or "in a few words") is a German-made animation and design studio founded by Philipp Dettmer. The studio's YouTube channel focuses on minimalist animated educational content, using the flat and 3D design style. It discusses scientific, technological, political, philosophical, and psychological subjects. Narrated by Steve Taylor, videos on the channel are typically four to sixteen minutes, with many of them available in German through the channel ''Dinge Erklärt – Kurzgesagt,'' their Spanish channel ''En Pocas Palabras - Kurzgesagt,'' and some of their videos are also available in French, Hindi, Arabic, Brazilian Portuguese, Japanese and Korean. With over 19 million subscribers and over 160 videos, the studio's original English language channel was ranked as the world's 198th most subscribed as of 8 November 2022. History The Kurzgesagt YouTube channel was created on 10 July 2013, shortly after the founder, Philipp Dettmer, graduate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YouTube
YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the List of most visited websites, second most visited website, after Google Search. YouTube has more than 2.5 billion monthly users who collectively watch more than one billion hours of videos each day. , videos were being uploaded at a rate of more than 500 hours of content per minute. In October 2006, YouTube was bought by Google for $1.65 billion. Google's ownership of YouTube expanded the site's business model, expanding from generating revenue from advertisements alone, to offering paid content such as movies and exclusive content produced by YouTube. It also offers YouTube Premium, a paid subscription option for watching content without ads. YouTube also approved creators to participate in Google's Google AdSens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parsec
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond ( of a degree). This corresponds to astronomical units, i.e. 1\, \mathrm = 1/\tan \left( \ \mathrm \right)\, \mathrm. The nearest star, Proxima Centauri, is about from the Sun. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand. The word ''parsec'' is a portmanteau of "parallax of one second" and was coined by the British astronomer Herbert Hall Turner in 1913 to make calculations of astronomical distances from only raw observational data easy for astronomers. Partly for this reason, it is the unit preferred in astronomy and astrophysics, though the light-year remains prominent in popular s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen-14
There are three known stable isotopes of oxygen (8O): , , and . Radioactive isotopes ranging from to have also been characterized, all short-lived. The longest-lived radioisotope is with a half-life of , while the shortest-lived isotope is with a half-life of (though the half-lives of the neutron-unbound and are still unknown). List of isotopes , - , , style="text-align:right" , 8 , style="text-align:right" , 3 , , [] , proton emission, 2p , , (3/2−) , , , - , , style="text-align:right" , 8 , style="text-align:right" , 4 , , , 2p , , 0+ , , , - , rowspan=2, , rowspan=2 style="text-align:right" , 8 , rowspan=2 style="text-align:right" , 5 , rowspan=2, , rowspan=2, , β+ () , , rowspan=2, (3/2−) , rowspan=2, , rowspan=2, , - , β+p () , , - , , style="text-align:right" , 8 , style="text-align:right" , 6 , , , β+ , , 0+ , , , - , , style="text-align:right" , 8 , style="text-align:right" , 7 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bussard Ramjet
The Bussard ramjet is a theoretical method of spacecraft propulsion proposed in 1960 by the physicist Robert W. Bussard, popularized by Poul Anderson's novel ''Tau Zero'', Larry Niven in his ''Known Space'' series of books, Vernor Vinge in his ''Zones of Thought'' series, and referred to by Carl Sagan in the television series and book ''Cosmos''. Bussard proposed a ramjet variant of a fusion rocket capable of reasonable interstellar travel, using enormous electromagnetic fields (ranging from kilometers to many thousands of kilometers in diameter) as a ram scoop to collect and compress hydrogen from the interstellar medium. High speeds force the reactive mass into a progressively constricted magnetic field, compressing it until thermonuclear fusion occurs. The magnetic field then directs the energy into rocket exhaust, providing thrust. Feasibility Since the time of Bussard's original proposal, it has been discovered that the region surrounding the Solar System has a much lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Wind
The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni. Superposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface. At a distance of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illinois State University
Illinois State University (ISU) is a public university in Normal, Illinois. Founded in 1857 as Illinois State Normal University, it is the oldest public university in Illinois. The university emphasizes teaching and is recognized as one of the top ten largest producers of teachers in the US according to the American Association of Colleges of Teacher Education. It is classified among "R2: Doctoral Universities – High research activity". The university's athletic teams are members of the Missouri Valley Conference and the Missouri Valley Football Conference and are known as the "Redbirds," in reference to the state bird, the cardinal. History ISU was founded as a training school for teachers in 1857, the same year Illinois' first Board of Education was convened and two years after the Free School Act was passed by the state legislature. Among its supporters were judge and future Supreme Court Justice, David Davis and local businessman and land holder Jesse W. Fell whos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photovoltaic
Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially used for electricity generation and as photosensors. A photovoltaic system employs solar modules, each comprising a number of solar cells, which generate electrical power. PV installations may be ground-mounted, rooftop-mounted, wall-mounted or floating. The mount may be fixed or use a solar tracker to follow the sun across the sky. Photovoltaic technology helps to mitigate climate change because it emits much less carbon dioxide than fossil fuels. Solar PV has specific advantages as an energy source: once installed, its operation generates no pollution and no greenhouse gas emissions, it shows scalability in respect of power needs and silicon has large availability in the Earth's crust, although other materials required in PV system man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
