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Didicosm
"Didicosm" is a science-fiction short story by Australian writer Greg Egan, first published in ''Analog'' in July/August 2023. Plot As a child, her father shows Charlotte the night sky and wants her to realize the truth about the endless worlds and possibilities in the universe. In one of his books, he read about the idea of the universe repeating, but with changes occurring and later uses this thought to rationalize his own suicide. After her mother dies as well, Charlotte is brought to her grandmother and later wants to find the correct topology of the universe, which turns out to be a didicosm ( Hantzsche-Wendt manifold). Her own student later comes up with a theoretical explanation involving quantum gravity, concluding this shape is indeed canonical due to being the only platycosm with a finite first homology group. Charlotte returns to her partner thinking that she lives in the best possible universe. Background While the 3-torus (T^3=\mathbb R^3/\mathbb Z^3), also o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greg Egan
Greg Egan (born 20 August 1961) is an Australian science fiction writer and mathematician, best known for his works of hard science fiction. Egan has won multiple awards including the John W. Campbell Memorial Award, the Hugo Award, and the Locus Award. Life and work Egan holds a Bachelor of Science degree in mathematics from the University of Western Australia. He published his first work in 1983. He specialises in hard science fiction stories with mathematical and quantum ontology themes, including the nature of consciousness. Other themes include genetics, simulated reality, posthumanism, mind uploading, sexuality, artificial intelligence, and the superiority of rational naturalism to religion. He often deals with complex technical material, like new physics and epistemology. He is a Hugo Award winner (with eight other works shortlisted for the Hugos) and has also won the John W. Campbell Memorial Award for Best Science Fiction Novel. His early stories feature strong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hantzsche–Wendt Manifold
The Hantzsche–Wendt manifold, also known as the HW manifold or didicosm, is a compact space, compact, orientable, flat manifold, flat 3-manifold, first studied by Walter Hantzsche and Hilmar Wendt in 1934. It is the only closed flat 3-manifold with first Betti number zero. Its holonomy group is \mathbb_2^2. It has been suggested as a possible shape of the universe because its complicated geometry can obscure the features in the cosmic microwave background that would arise if the universe is a closed flat manifold, such as the 3-torus. Construction The HW manifold can be built from two cubes that share a face. One construction proceeds as follows: # The top and bottom faces are glued to one another. # One of the remaining sides is glued to the opposite side with a 180° rotation. # One of the remaining faces on the top cube is glued to the matching face of the bottom cube, reflected across an axis parallel to the long axis of the double-cube. # Repeat step 3 for the remaining pair ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexei Starobinsky
Alexei Alexandrovich Starobinsky (; 19 April 1948 – 21 December 2023) was a Soviet and Russian-Jewish theoretical physicist and cosmologist. He was a pioneer of the theory of cosmic inflation, for which he received the 2014 Kavli Prize in Astrophysics together with Alan Guth and Andrei Linde. Born in Moscow, Starobinsky obtained a degree in physics from Moscow State University in 1972 and a doctorate in theoretical and mathematical physics from the Landau Institute for Theoretical Physics in 1975, the latter under the supervision of Yakov Zeldovich. Starobinsky remained at the Landau Institute, becoming its principal research scientist in 1997 and holding this position until his death. While still a doctoral student, in 1973 he showed that, according to the uncertainty principle, rotating black holes must emit particles. This work led to Stephen Hawking conjecturing Hawking radiation. In 1979, he became the first to propose a model of cosmic inflation, postulating what ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tangent Online
''Tangent Online'' is an online magazine launched in its online incarnation in 1997, though it began as a print magazine in 1993. ''Tangent Online'' is edited by Dave Truesdale, with web-hoster Eric James Stone. The magazine covers reviews of science fiction and fantasy short fiction as well as providing classic interviews, articles, and editorials. According to Sam Moskowitz, ''Tangent'' was the first of its kind in the history of the SF field (going back to its official inception in 1926) to review short science fiction and fantasy exclusively. Reception Paul Di Filippo of '' Sci Fi Weekly'' reviewed the site as "a one-stop clearinghouse for information on the good, the bad and the ugly in the short-story jungle." Awards From 1997 through 1999, ''Tangent'' was nominated each year for the Hugo Award for Best Fanzine. In 2002, ''Tangent Online'' received sixth place for the Locus Award for Best Website and nominated for the Hugo Award The Hugo Award is an annual liter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shape Of The Universe
In physical cosmology, the shape of the universe refers to both its local and global geometry. Local geometry is defined primarily by its curvature, while the global geometry is characterised by its topology (which itself is constrained by curvature). General relativity explains how spatial curvature (local geometry) is constrained by gravity. The global topology of the universe cannot be deduced from measurements of curvature inferred from observations within the family of homogeneous general relativistic models alone, due to the existence of locally indistinguishable spaces with varying global topological characteristics. For example; a multiply connected space like a 3 torus has everywhere zero curvature but is finite in extent, whereas a flat simply connected space is infinite in extent (such as Euclidean space). Current observational evidence ( WMAP, BOOMERanG, and Planck for example) imply that the observable universe is spatially flat to within a 0.4% margin of error o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cosmological Model
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate.For an overview, see Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood. Physical cosmology, as it is now understood, began in 1915 with the development of Albert Einstein's general theory of relativity, followed by major observational discoveries in the 1920s: first, Edwin Hubble discovered that the universe contains a huge number of external galaxies beyond the Milky Way; then, work by Vesto Slipher and others showed that the universe is expanding. These advances made it possi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moscow
Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents within the city limits, over 19.1 million residents in the urban area, and over 21.5 million residents in Moscow metropolitan area, its metropolitan area. The city covers an area of , while the urban area covers , and the metropolitan area covers over . Moscow is among the world's List of largest cities, largest cities, being the List of European cities by population within city limits, most populous city entirely in Europe, the largest List of urban areas in Europe, urban and List of metropolitan areas in Europe, metropolitan area in Europe, and the largest city by land area on the European continent. First documented in 1147, Moscow became the capital of the Grand Principality of Moscow, which led the unification of the Russian lan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landau Institute For Theoretical Physics
Landau (), officially Landau in der Pfalz (, ), is an autonomous (''kreisfrei'') town surrounded by the Südliche Weinstraße ("Southern Wine Route") district of southern Rhineland-Palatinate, Germany. It is a university town (since 1990), a long-standing cultural centre, and a market and shopping town, surrounded by vineyards and wine-growing villages of the Palatinate wine region. Landau lies east of the Palatinate forest, on the German Wine Route. It contains the districts (''Ortsteile'') of Arzheim, Dammheim, Godramstein, Mörlheim, Mörzheim, Nussdorf, Queichheim, and Wollmesheim. History and other settings Landau was first mentioned as a settlement in 1106. It was in the possession of the counts of Leiningen-Dagsburg-Landeck, whose arms, differenced by an escutcheon of the Imperial eagle, served as the arms of Landau until 1955. The town was granted a charter in 1274 by King Rudolf I of Germany, who declared the town a Free Imperial Town in 1291; nevertheless Prince-Bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yakov Zeldovich
Yakov Borisovich Zeldovich (, ; 8 March 1914 – 2 December 1987), also known as YaB, was a leading Soviet people, Soviet Physics, physicist of Belarusians, Belarusian origin, who is known for his prolific contributions in physical Physical cosmology, cosmology, physics of Plasma physics, thermonuclear reactions, combustion, and Fluid dynamics, hydrodynamical phenomena. From 1943, Zeldovich, a self-taught physicist, started his career by playing a crucial role in the development of the former Soviet atomic bomb project, Soviet program of nuclear weapons. In 1963, he returned to academia to embark on pioneering contributions on the fundamental understanding of the Black hole thermodynamics, thermodynamics of black holes and expanding the scope of physical cosmology. Biography Early life and education Yakov Zeldovich was born into a History of the Jews in Belarus, Belarusian Jewish family in his grandfather's house in Minsk. However, in mid-1914, the Zeldovich family moved to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-torus
The three-dimensional torus, or 3-torus, is defined as any topological space that is homeomorphic to the Cartesian product of three circles, \mathbb^3 = S^1 \times S^1 \times S^1. In contrast, the usual torus is the Cartesian product of only two circles. The 3-torus is a three-dimensional compact manifold with no boundary. It can be obtained by "gluing" the three pairs of opposite faces of a cube, where being "glued" can be intuitively understood to mean that when a particle moving in the interior of the cube reaches a point on a face, it goes through it and appears to come forth from the corresponding point on the opposite face, producing periodic boundary conditions. Gluing only one pair of opposite faces produces a solid torus while gluing two of these pairs produces the solid space between two nested tori. In 1984, Alexei Starobinsky and Yakov Zeldovich at the Landau Institute in Moscow proposed a cosmological model where the shape of the universe In physical cosmolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller islands. It has a total area of , making it the list of countries and dependencies by area, sixth-largest country in the world and the largest in Oceania. Australia is the world's flattest and driest inhabited continent. It is a megadiverse countries, megadiverse country, and its size gives it a wide variety of landscapes and Climate of Australia, climates including deserts of Australia, deserts in the Outback, interior and forests of Australia, tropical rainforests along the Eastern states of Australia, coast. The ancestors of Aboriginal Australians began arriving from south-east Asia 50,000 to 65,000 years ago, during the Last Glacial Period, last glacial period. By the time of British settlement, Aboriginal Australians spoke 250 distinct l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
