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1900 In Science
The year 1900 in science and technology involved some significant events, listed below. Aeronautics * July 2 – The first rigid airship flight is made by the LZ1 designed by Ferdinand von Zeppelin. * c. October 3 – The Wright brothers begin their first manned glider experimental flights at Kitty Hawk, North Carolina and failed for the first few attempts Chemistry * Moses Gomberg identifies the first organic radical (according to the modern definition), triphenylmethyl radical. * Johannes Rydberg refines the expression for observed hydrogen line wavelengths. Earth sciences * Richard Dixon Oldham distinguishes between primary, secondary and tertiary waveforms as recorded by seismometers. Exploration * American explorer Robert Peary first sights Kaffeklubben Island, the northernmost point of land on Earth. Genetics * Hugo de Vries publishes the results of his experiments in Mendelian inheritance. Mathematics * Max Dehn introduces two examples of Dehn plane and the Deh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for scientific reasoning is tens of thousands of years old. The earliest written records in the history of science come from Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes. After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages, but was preserved in the Muslim world during the Islamic Golden Age and later by the efforts of Byzantine Greek scholars who brought Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehn Invariant
In geometry, the Dehn invariant is a value used to determine whether one polyhedron can be cut into pieces and reassembled ("dissection problem, dissected") into another, and whether a polyhedron or its dissections can Honeycomb (geometry), tile space. It is named after Max Dehn, who used it to solve Hilbert's third problem by proving that not all polyhedra with equal volume could be dissected into each other. Two polyhedra have a dissection into polyhedral pieces that can be reassembled into either one, if and only if their volumes and Dehn invariants are equal. A polyhedron can be cut up and reassembled to tile space if and only if its Dehn invariant is zero, so having Dehn invariant zero is a necessary condition for being a space-filling polyhedron. The Dehn invariant of a self-intersection-free flexible polyhedron is invariant as it flexes. The Dehn invariant is zero for the cube but nonzero for the other Platonic solids, implying that the other solids cannot tile space and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehn Plane
In geometry, Max Dehn introduced two examples of planes, a semi-Euclidean geometry and a non-Legendrian geometry, that have infinitely many lines parallel to a given one that pass through a given point, but where the sum of the angles of a triangle is at least . A similar phenomenon occurs in hyperbolic geometry, except that the sum of the angles of a triangle is less than . Dehn's examples use a non-Archimedean field, so that the Archimedean axiom is violated. They were introduced by and discussed by . Dehn's non-archimedean field Ω(''t'') To construct his geometries, Dehn used a non-Archimedean ordered Pythagorean field Ω(''t''), a Pythagorean closure of the field of rational functions R(''t''), consisting of the smallest field of real-valued functions on the real line containing the real constants, the identity function ''t'' (taking any real number to itself) and closed under the operation \omega \mapsto \sqrt . The field Ω(''t'') is ordered by putting ''x'' >&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Max Dehn
Max Wilhelm Dehn (November 13, 1878 – June 27, 1952) was a German mathematician most famous for his work in geometry, topology and geometric group theory. Born to a Jewish family in Germany, Dehn's early life and career took place in Germany. However, he was forced to retire in 1935 and eventually fled Germany in 1939 and emigrated to the United States. Dehn was a student of David Hilbert, and in his habilitation in 1900 Dehn resolved Hilbert's third problem, making him the first to resolve one of Hilbert's well-known 23 problems. Dehn's students include Ott-Heinrich Keller, Ruth Moufang, Wilhelm Magnus, and the artists Dorothea Rockburne and Ruth Asawa. Biography Dehn was born to a family of Jewish origin in Hamburg, Imperial Germany. He studied the foundations of geometry with Hilbert at Göttingen in 1899, and obtained a proof of the Jordan curve theorem for polygons. In 1900 he wrote his dissertation on the role of the Legendre angle sum theorem in axiomatic geome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mendelian Inheritance
Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularized by William Bateson. These principles were initially controversial. When Mendel's theories were integrated with the Boveri–Sutton chromosome theory of inheritance by Thomas Hunt Morgan in 1915, they became the core of classical genetics. Ronald Fisher combined these ideas with the theory of natural selection in his 1930 book ''The Genetical Theory of Natural Selection'', putting evolution onto a mathematical footing and forming the basis for population genetics within the modern evolutionary synthesis. History The principles of Mendelian inheritance were named for and first derived by Gregor Johann Mendel, a nineteenth-century Moravian monk who formulated his ideas after conducting simple hybridisation experiments with pea plants (' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hugo De Vries
Hugo Marie de Vries () (16 February 1848 – 21 May 1935) was a Dutch botanist and one of the first geneticists. He is known chiefly for suggesting the concept of genes, rediscovering the laws of heredity in the 1890s while apparently unaware of Gregor Mendel's work, for introducing the term "mutation", and for developing a mutation theory of evolution. Early life De Vries was born in 1848, the eldest son of Gerrit de Vries (1818–1900), a lawyer and deacon in the Mennonite congregation in Haarlem and later Prime Minister of the Netherlands from 1872 until 1874, and Maria Everardina Reuvens (1823–1914), daughter of a professor in archaeology at Leiden University. His father became a member of the Dutch Council of State in 1862 and moved his family over to The Hague. From an early age Hugo showed much interest in botany, winning several prizes for his herbariums while attending gymnasium in Haarlem and The Hague. In 1866 he enrolled at the Leiden University to major in botan ... [...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 on Earth is the Geographic North Pole, in the Arctic Ocean. ** 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 point on Earth and the southernmost point on land is the Geographic South Pole, which is on the continent of Antarctica. ** The southernmost continental point of land outside Antarctica is in South America at Cap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaffeklubben Island
Kaffeklubben Island or Coffee Club Island ( da, Kaffeklubben Ø; kl, Inuit Qeqertaat) is an uninhabited island lying off the northern tip of Greenland. It contains the northernmost undisputed point of land on Earth. Discovery The first recorded sighting of Kaffeklubben Island was made by American explorer Robert Peary in 1900; however, the island was not visited until 1921. When the Danish explorer Lauge Koch set foot on the island, it received its name after the coffee club in the University of Copenhagen Geological Museum. In 1969, a Canadian team calculated that its northernmost tip is farther north than Cape Morris Jesup, the northernmost point of mainland Greenland, thus claiming its record as the most northerly point on land. Since its record as the northernmost point of land was established, several gravel banks have been discovered in the sea to the north of the island, such as Oodaaq, 83-42, and ATOW1996; however, there is debate as to whether such gravel banks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Peary
Robert Edwin Peary Sr. (; May 6, 1856 – February 20, 1920) was an American explorer and officer in the United States Navy who made several expeditions to the Arctic in the late 19th and early 20th centuries. He is best known for, in April 1909, leading an expedition that claimed to be the first to have reached the geographic North Pole. Explorer Matthew Henson, part of the expedition, is thought to have reached what they believed to be the North Pole narrowly before Peary. Peary was born in Cresson, Pennsylvania, but, following his father's death at a young age, was raised in Portland, Maine. He attended Bowdoin College, then joined the United States Coast and Geodetic Survey as a draftsman. He enlisted in the navy in 1881 as a civil engineer. In 1885, he was made chief of surveying for the Nicaragua Canal, which was never built. He visited the Arctic for the first time in 1886, making an unsuccessful attempt to cross Greenland by dogsled. In the Peary expedition to Green ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford Dictionary Of National Biography
The ''Dictionary of National Biography'' (''DNB'') is a standard work of reference on notable figures from British history, published since 1885. The updated ''Oxford Dictionary of National Biography'' (''ODNB'') was published on 23 September 2004 in 60 volumes and online, with 50,113 biographical articles covering 54,922 lives. First series Hoping to emulate national biographical collections published elsewhere in Europe, such as the '' Allgemeine Deutsche Biographie'' (1875), in 1882 the publisher George Smith (1824–1901), of Smith, Elder & Co., planned a universal dictionary that would include biographical entries on individuals from world history. He approached Leslie Stephen, then editor of the ''Cornhill Magazine'', owned by Smith, to become the editor. Stephen persuaded Smith that the work should focus only on subjects from the United Kingdom and its present and former colonies. An early working title was the ''Biographia Britannica'', the name of an earlier eightee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
