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1921 In Science
The year 1921 in science and technology involved some significant events, listed below. Astronomy and space science * Commencement of Gas Dynamics Laboratory the first Soviet research and development laboratory to focus on rocket technology. Cartography * Winkel tripel projection proposed. Chemistry * Étienne Biéler and James Chadwick publish a key paper on the strong interaction. * December 9 – Thomas Midgley discovers the effective anti-knocking properties of tetraethyllead, which is used in "leaded" gasoline (petrol). Exploration * Danish explorer Lauge Koch first sets foot on and names Kaffeklubben Island, the northernmost point of land on Earth. Mathematics * John Maynard Keynes publishes '' A Treatise on Probability''. * Marston Morse applies the Thue–Morse sequence to differential geometry. * Emmy Noether publishes ''Idealtheorie in Ringbereichen'', developing ideal ring theory, an important text in the field of abstract algebra. * First publication of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extreme Points Of Earth
This article lists extreme locations on Earth that hold geographical records or are otherwise known for their geophysical or meteorological superlatives. All of these locations are Earth-wide extremes; extremes of individual continents or countries are not listed. Latitude and longitude Northernmost * The northernmost point of land is the northern tip of Kaffeklubben Island, north of Greenland (), which lies slightly north of Cape Morris Jesup, Greenland (). Various shifting gravel bars lie farther north, the most famous being Oodaaq. There have been other islands more northern such as 83-42 and ATOW1996 but they have not been confirmed as permanent. Southernmost * The southernmost continental point of land outside Antarctica is in South America at Cape Froward, Magallanes Region, Chile (). * The southernmost point of (liquid) water is a bay on the Filchner–Ronne Ice Shelf along the coast of Antarctica (), about south of Berkner Island. ** The southernmost point ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicolae Paulescu
Nicolae Constantin Paulescu (; 30 October 1869 (O.S.) – 17 July 1931) was a Romanians, Romanian physiologist, professor of medicine, and politician, most famous for his work on diabetes, including patenting ''pancreine'' (a pancreatic extract containing insulin). The "pancreine" was an extract of bovine pancreas in salted water, after which some impurites were removed with hydrochloric acid and sodium hydroxide. Paulescu was also, with A. C. Cuza, co-founder of the National Christian Union and later, of the National-Christian Defense League, an early ultranationalist and anti-Semitic Romanian party. He was also a leading member of the militant religious fascist Iron Guard. Early life and education Born in Bucharest, he was the first of four children of Costache and Maria Paulescu. He displayed remarkable abilities as early as his first school years. He learned French language, French, Latin and Ancient Greek at an early age, so that a few years later he became fluent in all the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cairo Pentagonal Tiling
In geometry, a Cairo pentagonal tiling is a tessellation of the Euclidean plane by congruent convex pentagons, formed by overlaying two tessellations of the plane by hexagons and named for its use as a paving design in Cairo. It is also called MacMahon's net after Percy Alexander MacMahon, who depicted it in his 1921 publication ''New Mathematical Pastimes''. John Horton Conway called it a 4-fold pentille. Infinitely many different pentagons can form this pattern, belonging to two of the 15 families of pentagon tiling, convex pentagons that can tile the plane. Their tilings have varying symmetries; all are face-symmetric. One particular form of the tiling, dual to the snub square tiling, has tiles with the minimum possible perimeter among all pentagonal tilings. Another, overlaying two flattened tilings by regular hexagons, is the form used in Cairo and has the property that every edge is collinear with infinitely many other edges. In architecture, beyond Cairo, the Cairo tiling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percy Alexander MacMahon
Percy Alexander MacMahon (26 September 1854 – 25 December 1929) was an English mathematician, especially noted in connection with the partitions of numbers and enumerative combinatorics. Early life Percy MacMahon was born in Malta to a British military family. His father was a colonel at the time, retired in the rank of the brigadier. MacMahon attended the Proprietary School in Cheltenham. At the age of 14 he won a Junior Scholarship to Cheltenham College, which he attended as a day boy from 10 February 1868 until December 1870. At the age of 16 MacMahon was admitted to the Royal Military Academy, Woolwich and passed out after two years. Military career On 12 March 1873, MacMahon was posted to Madras, India, with the 1st Battery 5th Brigade, with the temporary rank of lieutenant. The Army List showed that in October 1873 he was posted to the 8th Brigade in Lucknow. MacMahon's final posting was to the No. 1 Mountain Battery with the Punjab Frontier Force at Kohat on the N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tractatus Logico-Philosophicus
The ''Tractatus Logico-Philosophicus'' (widely abbreviated and Citation, cited as TLP) is the only book-length philosophical work by the Austrian philosopher Ludwig Wittgenstein that was published during his lifetime. The project had a broad goal: to identify the relationship between language and reality, and to define the limits of science. Wittgenstein wrote the notes for the ''Tractatus'' while he was a soldier during World War I and completed it during a military leave in the summer of 1918. It was originally published in German in 1921 as ''Logisch-Philosophische Abhandlung'' (Logical-Philosophical Treatise). In 1922 it was published together with an English translation and a Latin title, which was suggested by G. E. Moore as homage to Baruch Spinoza's ''Tractatus Theologico-Politicus'' (1670). The ''Tractatus'' is written in an austere and succinct literary style, containing almost no arguments as such, but consists of 525 declarative statements altogether, which are hierarc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein ( ; ; 26 April 1889 – 29 April 1951) was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. From 1929 to 1947, Wittgenstein taught at the University of Cambridge. Despite his position, only one book of his philosophy was published during his entire life: the 75-page ''Logisch-Philosophische Abhandlung'' (''Logical-Philosophical Treatise'', 1921), which appeared, together with an English translation, in 1922 under the Latin title ''Tractatus Logico-Philosophicus''. His only other published works were an article, "Some Remarks on Logical Form" (1929); a book review; and a children's dictionary. #Works, His voluminous manuscripts were edited and published posthumously. The first and best-known of this posthumous series is the 1953 book ''Philosophical Investigations''. A 1999 survey among American university and college teachers ranked the ''Investigations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstract Algebra
In mathematics, more specifically algebra, abstract algebra or modern algebra is the study of algebraic structures, which are set (mathematics), sets with specific operation (mathematics), operations acting on their elements. Algebraic structures include group (mathematics), groups, ring (mathematics), rings, field (mathematics), fields, module (mathematics), modules, vector spaces, lattice (order), lattices, and algebra over a field, algebras over a field. The term ''abstract algebra'' was coined in the early 20th century to distinguish it from older parts of algebra, and more specifically from elementary algebra, the use of variable (mathematics), variables to represent numbers in computation and reasoning. The abstract perspective on algebra has become so fundamental to advanced mathematics that it is simply called "algebra", while the term "abstract algebra" is seldom used except in mathematical education, pedagogy. Algebraic structures, with their associated homomorphisms, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ideal (ring Theory)
In mathematics, and more specifically in ring theory, an ideal of a ring is a special subset of its elements. Ideals generalize certain subsets of the integers, such as the even numbers or the multiples of 3. Addition and subtraction of even numbers preserves evenness, and multiplying an even number by any integer (even or odd) results in an even number; these closure and absorption properties are the defining properties of an ideal. An ideal can be used to construct a quotient ring in a way similar to how, in group theory, a normal subgroup can be used to construct a quotient group. Among the integers, the ideals correspond one-for-one with the non-negative integers: in this ring, every ideal is a principal ideal consisting of the multiples of a single non-negative number. However, in other rings, the ideals may not correspond directly to the ring elements, and certain properties of integers, when generalized to rings, attach more naturally to the ideals than to the elem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emmy Noether
Amalie Emmy Noether (23 March 1882 – 14 April 1935) was a German mathematician who made many important contributions to abstract algebra. She also proved Noether's theorem, Noether's first and Noether's second theorem, second theorems, which are fundamental in mathematical physics. Noether was described by Pavel Alexandrov, Albert Einstein, Jean Dieudonné, Hermann Weyl and Norbert Wiener as the most important List of women in mathematics, woman in the history of mathematics. Transcribeonlineat the MacTutor History of Mathematics Archive. As one of the leading mathematicians of her time, she developed theories of ring (mathematics), rings, field (mathematics), fields, and algebras. In physics, Noether's theorem explains the connection between Symmetry (physics), symmetry and conservation laws. in . Noether was born to a Jewish family in the Franconian town of Erlangen; her father was the mathematician Max Noether. She originally planned to teach French and English after passin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Geometry
Differential geometry is a Mathematics, mathematical discipline that studies the geometry of smooth shapes and smooth spaces, otherwise known as smooth manifolds. It uses the techniques of Calculus, single variable calculus, vector calculus, linear algebra and multilinear algebra. The field has its origins in the study of spherical geometry as far back as classical antiquity, antiquity. It also relates to astronomy, the geodesy of the Earth, and later the study of hyperbolic geometry by Nikolai Lobachevsky, Lobachevsky. The simplest examples of smooth spaces are the Differential geometry of curves, plane and space curves and Differential geometry of surfaces, surfaces in the three-dimensional Euclidean space, and the study of these shapes formed the basis for development of modern differential geometry during the 18th and 19th centuries. Since the late 19th century, differential geometry has grown into a field concerned more generally with geometric structures on differentiable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thue–Morse Sequence
In mathematics, the Thue–Morse or Prouhet–Thue–Morse sequence is the binary sequence (an infinite sequence of 0s and 1s) that can be obtained by starting with 0 and successively appending the Boolean complement of the sequence obtained thus far. It is sometimes called the fair share sequence because of its applications to fair division or parity sequence. The first few steps of this procedure yield the strings 0, 01, 0110, 01101001, 0110100110010110, and so on, which are the prefixes of the Thue–Morse sequence. The full sequence begins: :01101001100101101001011001101001.... The sequence is named after Axel Thue, Marston Morse and (in its extended form) Eugène Prouhet. Definition There are several equivalent ways of defining the Thue–Morse sequence. Direct definition To compute the ''n''th element ''tn'', write the number ''n'' in binary. If the number of ones in this binary expansion is odd then ''tn'' = 1, if even then ''tn'' = 0. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
