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In astronomy, Al-Battani improved the measurements of Hipparchus, preserved in the translation of Ptolemy's Hè Megalè Syntaxis (The great treatise) translated as Almagest. Al-Battani also improved the precision of the measurement of the precession of the Earth's axis. The corrections made to the geocentric model by al-Battani, Ibn al-Haytham, Averroes and the Maragha astronomers such as Nasir al-Din al-Tusi, Mo'ayyeduddin Urdi and Ibn al-Shatir are similar to Copernican heliocentric model. Heliocentric theories may have also been discussed by several other Muslim astronomers such as Ja'far ibn Muhammad Abu Ma'shar al-Balkhi, Abu-Rayhan Biruni, Abu Said al-Sijzi, Qutb al-Din al-Shirazi, and Najm al-Dīn al-Qazwīnī al-Kātibī. |
Ibn Sina (Avicenna) is regarded as the most influential philosopher of Islam. He pioneered the science of experimental medicine and was the first physician to conduct clinical trials. His two most notable works in medicine are the Kitāb al-shifāʾ ("Book of Healing") and The Canon of Medicine, both of which were used as standard medicinal texts in both the Muslim world and in Europe well into the 17th century. Amongst his many contributions are the discovery of the contagious nature of infectious diseases, and the introduction of clinical pharmacology. |
An intellectual revitalization of Europe started with the birth of medieval universities in the 12th century. The contact with the Islamic world in Spain and Sicily, and during the Reconquista and the Crusades, allowed Europeans access to scientific Greek and Arabic texts, including the works of Aristotle, Ptolemy, Jābir ibn Hayyān, al-Khwarizmi, Alhazen, Avicenna, and Averroes. European scholars had access to the translation programs of Raymond of Toledo, who sponsored the 12th century Toledo School of Translators from Arabic to Latin. Later translators like Michael Scotus would learn Arabic in order to study these texts directly. The European universities aided materially in the translation and propagation of these texts and started a new infrastructure which was needed for scientific communities. In fact, European university put many works about the natural world and the study of nature at the center of its curriculum, with the result that the "medieval university laid far greater emphasis on science than does its modern counterpart and descendent." |
At the beginning of the 13th century, there were reasonably accurate Latin translations of the main works of almost all the intellectually crucial ancient authors, allowing a sound transfer of scientific ideas via both the universities and the monasteries. By then, the natural philosophy contained in these texts began to be extended by notable scholastics such as Robert Grosseteste, Roger Bacon, Albertus Magnus and Duns Scotus. Precursors of the modern scientific method, influenced by earlier contributions of the Islamic world, can be seen already in Grosseteste's emphasis on mathematics as a way to understand nature, and in the empirical approach admired by Bacon, particularly in his Opus Majus. Pierre Duhem's provocative thesis of the Catholic Church's Condemnation of 1277 led to the study of medieval science as a serious discipline, "but no one in the field any longer endorses his view that modern science started in 1277". However, many scholars agree with Duhem's view that the Middle Ages were a period of important scientific developments. |
The first half of the 14th century saw much important scientific work being done, largely within the framework of scholastic commentaries on Aristotle's scientific writings. William of Ockham introduced the principle of parsimony: natural philosophers should not postulate unnecessary entities, so that motion is not a distinct thing but is only the moving object and an intermediary "sensible species" is not needed to transmit an image of an object to the eye. Scholars such as Jean Buridan and Nicole Oresme started to reinterpret elements of Aristotle's mechanics. In particular, Buridan developed the theory that impetus was the cause of the motion of projectiles, which was a first step towards the modern concept of inertia. The Oxford Calculators began to mathematically analyze the kinematics of motion, making this analysis without considering the causes of motion. |
In 1348, the Black Death and other disasters sealed a sudden end to the previous period of massive philosophic and scientific development. Yet, the rediscovery of ancient texts was improved after the Fall of Constantinople in 1453, when many Byzantine scholars had to seek refuge in the West. Meanwhile, the introduction of printing was to have great effect on European society. The facilitated dissemination of the printed word democratized learning and allowed a faster propagation of new ideas. New ideas also helped to influence the development of European science at this point: not least the introduction of Algebra. These developments paved the way for the Scientific Revolution, which may also be understood as a resumption of the process of scientific inquiry, halted at the start of the Black Death. |
The renewal of learning in Europe, that began with 12th century Scholasticism, came to an end about the time of the Black Death, and the initial period of the subsequent Italian Renaissance is sometimes seen as a lull in scientific activity. The Northern Renaissance, on the other hand, showed a decisive shift in focus from Aristoteleian natural philosophy to chemistry and the biological sciences (botany, anatomy, and medicine). Thus modern science in Europe was resumed in a period of great upheaval: the Protestant Reformation and Catholic Counter-Reformation; the discovery of the Americas by Christopher Columbus; the Fall of Constantinople; but also the re-discovery of Aristotle during the Scholastic period presaged large social and political changes. Thus, a suitable environment was created in which it became possible to question scientific doctrine, in much the same way that Martin Luther and John Calvin questioned religious doctrine. The works of Ptolemy (astronomy) and Galen (medicine) were found not always to match everyday observations. Work by Vesalius on human cadavers found problems with the Galenic view of anatomy. |
The willingness to question previously held truths and search for new answers resulted in a period of major scientific advancements, now known as the Scientific Revolution. The Scientific Revolution is traditionally held by most historians to have begun in 1543, when the books De humani corporis fabrica (On the Workings of the Human Body) by Andreas Vesalius, and also De Revolutionibus, by the astronomer Nicolaus Copernicus, were first printed. The thesis of Copernicus' book was that the Earth moved around the Sun. The period culminated with the publication of the Philosophiæ Naturalis Principia Mathematica in 1687 by Isaac Newton, representative of the unprecedented growth of scientific publications throughout Europe. |
The Age of Enlightenment was a European affair. The 17th century "Age of Reason" opened the avenues to the decisive steps towards modern science, which took place during the 18th century "Age of Enlightenment". Directly based on the works of Newton, Descartes, Pascal and Leibniz, the way was now clear to the development of modern mathematics, physics and technology by the generation of Benjamin Franklin (1706–1790), Leonhard Euler (1707–1783), Mikhail Lomonosov (1711–1765) and Jean le Rond d'Alembert (1717–1783), epitomized in the appearance of Denis Diderot's Encyclopédie between 1751 and 1772. The impact of this process was not limited to science and technology, but affected philosophy (Immanuel Kant, David Hume), religion (the increasingly significant impact of science upon religion), and society and politics in general (Adam Smith, Voltaire), the French Revolution of 1789 setting a bloody cesura indicating the beginning of political modernity[citation needed]. The early modern period is seen as a flowering of the European Renaissance, in what is often known as the Scientific Revolution, viewed as a foundation of modern science. |
The Romantic Movement of the early 19th century reshaped science by opening up new pursuits unexpected in the classical approaches of the Enlightenment. Major breakthroughs came in biology, especially in Darwin's theory of evolution, as well as physics (electromagnetism), mathematics (non-Euclidean geometry, group theory) and chemistry (organic chemistry). The decline of Romanticism occurred because a new movement, Positivism, began to take hold of the ideals of the intellectuals after 1840 and lasted until about 1880. |
The scientific revolution is a convenient boundary between ancient thought and classical physics. Nicolaus Copernicus revived the heliocentric model of the solar system described by Aristarchus of Samos. This was followed by the first known model of planetary motion given by Johannes Kepler in the early 17th century, which proposed that the planets follow elliptical orbits, with the Sun at one focus of the ellipse. Galileo ("Father of Modern Physics") also made use of experiments to validate physical theories, a key element of the scientific method. |
In 1687, Isaac Newton published the Principia Mathematica, detailing two comprehensive and successful physical theories: Newton's laws of motion, which led to classical mechanics; and Newton's Law of Gravitation, which describes the fundamental force of gravity. The behavior of electricity and magnetism was studied by Faraday, Ohm, and others during the early 19th century. These studies led to the unification of the two phenomena into a single theory of electromagnetism, by James Clerk Maxwell (known as Maxwell's equations). |
The beginning of the 20th century brought the start of a revolution in physics. The long-held theories of Newton were shown not to be correct in all circumstances. Beginning in 1900, Max Planck, Albert Einstein, Niels Bohr and others developed quantum theories to explain various anomalous experimental results, by introducing discrete energy levels. Not only did quantum mechanics show that the laws of motion did not hold on small scales, but even more disturbingly, the theory of general relativity, proposed by Einstein in 1915, showed that the fixed background of spacetime, on which both Newtonian mechanics and special relativity depended, could not exist. In 1925, Werner Heisenberg and Erwin Schrödinger formulated quantum mechanics, which explained the preceding quantum theories. The observation by Edwin Hubble in 1929 that the speed at which galaxies recede positively correlates with their distance, led to the understanding that the universe is expanding, and the formulation of the Big Bang theory by Georges Lemaître. |
In 1938 Otto Hahn and Fritz Strassmann discovered nuclear fission with radiochemical methods, and in 1939 Lise Meitner and Otto Robert Frisch wrote the first theoretical interpretation of the fission process, which was later improved by Niels Bohr and John A. Wheeler. Further developments took place during World War II, which led to the practical application of radar and the development and use of the atomic bomb. Though the process had begun with the invention of the cyclotron by Ernest O. Lawrence in the 1930s, physics in the postwar period entered into a phase of what historians have called "Big Science", requiring massive machines, budgets, and laboratories in order to test their theories and move into new frontiers. The primary patron of physics became state governments, who recognized that the support of "basic" research could often lead to technologies useful to both military and industrial applications. Currently, general relativity and quantum mechanics are inconsistent with each other, and efforts are underway to unify the two. |
Modern chemistry emerged from the sixteenth through the eighteenth centuries through the material practices and theories promoted by alchemy, medicine, manufacturing and mining. A decisive moment came when 'chymistry' was distinguished from alchemy by Robert Boyle in his work The Sceptical Chymist, in 1661; although the alchemical tradition continued for some time after his work. Other important steps included the gravimetric experimental practices of medical chemists like William Cullen, Joseph Black, Torbern Bergman and Pierre Macquer and through the work of Antoine Lavoisier (Father of Modern Chemistry) on oxygen and the law of conservation of mass, which refuted phlogiston theory. The theory that all matter is made of atoms, which are the smallest constituents of matter that cannot be broken down without losing the basic chemical and physical properties of that matter, was provided by John Dalton in 1803, although the question took a hundred years to settle as proven. Dalton also formulated the law of mass relationships. In 1869, Dmitri Mendeleev composed his periodic table of elements on the basis of Dalton's discoveries. |
The synthesis of urea by Friedrich Wöhler opened a new research field, organic chemistry, and by the end of the 19th century, scientists were able to synthesize hundreds of organic compounds. The later part of the 19th century saw the exploitation of the Earth's petrochemicals, after the exhaustion of the oil supply from whaling. By the 20th century, systematic production of refined materials provided a ready supply of products which provided not only energy, but also synthetic materials for clothing, medicine, and everyday disposable resources. Application of the techniques of organic chemistry to living organisms resulted in physiological chemistry, the precursor to biochemistry. The 20th century also saw the integration of physics and chemistry, with chemical properties explained as the result of the electronic structure of the atom. Linus Pauling's book on The Nature of the Chemical Bond used the principles of quantum mechanics to deduce bond angles in ever-more complicated molecules. Pauling's work culminated in the physical modelling of DNA, the secret of life (in the words of Francis Crick, 1953). In the same year, the Miller–Urey experiment demonstrated in a simulation of primordial processes, that basic constituents of proteins, simple amino acids, could themselves be built up from simpler molecules. |
Geology existed as a cloud of isolated, disconnected ideas about rocks, minerals, and landforms long before it became a coherent science. Theophrastus' work on rocks, Peri lithōn, remained authoritative for millennia: its interpretation of fossils was not overturned until after the Scientific Revolution. Chinese polymath Shen Kua (1031–1095) first formulated hypotheses for the process of land formation. Based on his observation of fossils in a geological stratum in a mountain hundreds of miles from the ocean, he deduced that the land was formed by erosion of the mountains and by deposition of silt. |
Geology did not undergo systematic restructuring during the Scientific Revolution, but individual theorists made important contributions. Robert Hooke, for example, formulated a theory of earthquakes, and Nicholas Steno developed the theory of superposition and argued that fossils were the remains of once-living creatures. Beginning with Thomas Burnet's Sacred Theory of the Earth in 1681, natural philosophers began to explore the idea that the Earth had changed over time. Burnet and his contemporaries interpreted Earth's past in terms of events described in the Bible, but their work laid the intellectual foundations for secular interpretations of Earth history. |
Modern geology, like modern chemistry, gradually evolved during the 18th and early 19th centuries. Benoît de Maillet and the Comte de Buffon saw the Earth as much older than the 6,000 years envisioned by biblical scholars. Jean-Étienne Guettard and Nicolas Desmarest hiked central France and recorded their observations on some of the first geological maps. Aided by chemical experimentation, naturalists such as Scotland's John Walker, Sweden's Torbern Bergman, and Germany's Abraham Werner created comprehensive classification systems for rocks and minerals—a collective achievement that transformed geology into a cutting edge field by the end of the eighteenth century. These early geologists also proposed a generalized interpretations of Earth history that led James Hutton, Georges Cuvier and Alexandre Brongniart, following in the steps of Steno, to argue that layers of rock could be dated by the fossils they contained: a principle first applied to the geology of the Paris Basin. The use of index fossils became a powerful tool for making geological maps, because it allowed geologists to correlate the rocks in one locality with those of similar age in other, distant localities. Over the first half of the 19th century, geologists such as Charles Lyell, Adam Sedgwick, and Roderick Murchison applied the new technique to rocks throughout Europe and eastern North America, setting the stage for more detailed, government-funded mapping projects in later decades. |
Midway through the 19th century, the focus of geology shifted from description and classification to attempts to understand how the surface of the Earth had changed. The first comprehensive theories of mountain building were proposed during this period, as were the first modern theories of earthquakes and volcanoes. Louis Agassiz and others established the reality of continent-covering ice ages, and "fluvialists" like Andrew Crombie Ramsay argued that river valleys were formed, over millions of years by the rivers that flow through them. After the discovery of radioactivity, radiometric dating methods were developed, starting in the 20th century. Alfred Wegener's theory of "continental drift" was widely dismissed when he proposed it in the 1910s, but new data gathered in the 1950s and 1960s led to the theory of plate tectonics, which provided a plausible mechanism for it. Plate tectonics also provided a unified explanation for a wide range of seemingly unrelated geological phenomena. Since 1970 it has served as the unifying principle in geology. |
In 1847, Hungarian physician Ignác Fülöp Semmelweis dramatically reduced the occurrency of puerperal fever by simply requiring physicians to wash their hands before attending to women in childbirth. This discovery predated the germ theory of disease. However, Semmelweis' findings were not appreciated by his contemporaries and came into use only with discoveries by British surgeon Joseph Lister, who in 1865 proved the principles of antisepsis. Lister's work was based on the important findings by French biologist Louis Pasteur. Pasteur was able to link microorganisms with disease, revolutionizing medicine. He also devised one of the most important methods in preventive medicine, when in 1880 he produced a vaccine against rabies. Pasteur invented the process of pasteurization, to help prevent the spread of disease through milk and other foods. |
Perhaps the most prominent, controversial and far-reaching theory in all of science has been the theory of evolution by natural selection put forward by the British naturalist Charles Darwin in his book On the Origin of Species in 1859. Darwin proposed that the features of all living things, including humans, were shaped by natural processes over long periods of time. The theory of evolution in its current form affects almost all areas of biology. Implications of evolution on fields outside of pure science have led to both opposition and support from different parts of society, and profoundly influenced the popular understanding of "man's place in the universe". In the early 20th century, the study of heredity became a major investigation after the rediscovery in 1900 of the laws of inheritance developed by the Moravian monk Gregor Mendel in 1866. Mendel's laws provided the beginnings of the study of genetics, which became a major field of research for both scientific and industrial research. By 1953, James D. Watson, Francis Crick and Maurice Wilkins clarified the basic structure of DNA, the genetic material for expressing life in all its forms. In the late 20th century, the possibilities of genetic engineering became practical for the first time, and a massive international effort began in 1990 to map out an entire human genome (the Human Genome Project). |
The discipline of ecology typically traces its origin to the synthesis of Darwinian evolution and Humboldtian biogeography, in the late 19th and early 20th centuries. Equally important in the rise of ecology, however, were microbiology and soil science—particularly the cycle of life concept, prominent in the work Louis Pasteur and Ferdinand Cohn. The word ecology was coined by Ernst Haeckel, whose particularly holistic view of nature in general (and Darwin's theory in particular) was important in the spread of ecological thinking. In the 1930s, Arthur Tansley and others began developing the field of ecosystem ecology, which combined experimental soil science with physiological concepts of energy and the techniques of field biology. The history of ecology in the 20th century is closely tied to that of environmentalism; the Gaia hypothesis, first formulated in the 1960s, and spreading in the 1970s, and more recently the scientific-religious movement of Deep Ecology have brought the two closer together. |
Political science is a late arrival in terms of social sciences[citation needed]. However, the discipline has a clear set of antecedents such as moral philosophy, political philosophy, political economy, history, and other fields concerned with normative determinations of what ought to be and with deducing the characteristics and functions of the ideal form of government. The roots of politics are in prehistory. In each historic period and in almost every geographic area, we can find someone studying politics and increasing political understanding. |
In Western culture, the study of politics is first found in Ancient Greece. The antecedents of European politics trace their roots back even earlier than Plato and Aristotle, particularly in the works of Homer, Hesiod, Thucydides, Xenophon, and Euripides. Later, Plato analyzed political systems, abstracted their analysis from more literary- and history- oriented studies and applied an approach we would understand as closer to philosophy. Similarly, Aristotle built upon Plato's analysis to include historical empirical evidence in his analysis. |
An ancient Indian treatise on statecraft, economic policy and military strategy by Kautilya and Viṣhṇugupta, who are traditionally identified with Chāṇakya (c. 350–-283 BCE). In this treatise, the behaviors and relationships of the people, the King, the State, the Government Superintendents, Courtiers, Enemies, Invaders, and Corporations are analysed and documented. Roger Boesche describes the Arthaśāstra as "a book of political realism, a book analysing how the political world does work and not very often stating how it ought to work, a book that frequently discloses to a king what calculating and sometimes brutal measures he must carry out to preserve the state and the common good." |
With the fall of the Western Roman Empire, there arose a more diffuse arena for political studies. The rise of monotheism and, particularly for the Western tradition, Christianity, brought to light a new space for politics and political action[citation needed]. During the Middle Ages, the study of politics was widespread in the churches and courts. Works such as Augustine of Hippo's The City of God synthesized current philosophies and political traditions with those of Christianity, redefining the borders between what was religious and what was political. Most of the political questions surrounding the relationship between Church and State were clarified and contested in this period. |
Historical linguistics emerged as an independent field of study at the end of the 18th century. Sir William Jones proposed that Sanskrit, Persian, Greek, Latin, Gothic, and Celtic languages all shared a common base. After Jones, an effort to catalog all languages of the world was made throughout the 19th century and into the 20th century. Publication of Ferdinand de Saussure's Cours de linguistique générale created the development of descriptive linguistics. Descriptive linguistics, and the related structuralism movement caused linguistics to focus on how language changes over time, instead of just describing the differences between languages. Noam Chomsky further diversified linguistics with the development of generative linguistics in the 1950s. His effort is based upon a mathematical model of language that allows for the description and prediction of valid syntax. Additional specialties such as sociolinguistics, cognitive linguistics, and computational linguistics have emerged from collaboration between linguistics and other disciplines. |
The basis for classical economics forms Adam Smith's An Inquiry into the Nature and Causes of the Wealth of Nations, published in 1776. Smith criticized mercantilism, advocating a system of free trade with division of labour. He postulated an "invisible hand" that regulated economic systems made up of actors guided only by self-interest. Karl Marx developed an alternative economic theory, called Marxian economics. Marxian economics is based on the labor theory of value and assumes the value of good to be based on the amount of labor required to produce it. Under this assumption, capitalism was based on employers not paying the full value of workers labor to create profit. The Austrian school responded to Marxian economics by viewing entrepreneurship as driving force of economic development. This replaced the labor theory of value by a system of supply and demand. |
In the 1920s, John Maynard Keynes prompted a division between microeconomics and macroeconomics. Under Keynesian economics macroeconomic trends can overwhelm economic choices made by individuals. Governments should promote aggregate demand for goods as a means to encourage economic expansion. Following World War II, Milton Friedman created the concept of monetarism. Monetarism focuses on using the supply and demand of money as a method for controlling economic activity. In the 1970s, monetarism has adapted into supply-side economics which advocates reducing taxes as a means to increase the amount of money available for economic expansion. |
The above "history of economics" reflects modern economic textbooks and this means that the last stage of a science is represented as the culmination of its history (Kuhn, 1962). The "invisible hand" mentioned in a lost page in the middle of a chapter in the middle of the to "Wealth of Nations", 1776, advances as Smith's central message.[clarification needed] It is played down that this "invisible hand" acts only "frequently" and that it is "no part of his [the individual's] intentions" because competition leads to lower prices by imitating "his" invention. That this "invisible hand" prefers "the support of domestic to foreign industry" is cleansed—often without indication that part of the citation is truncated. The opening passage of the "Wealth" containing Smith's message is never mentioned as it cannot be integrated into modern theory: "Wealth" depends on the division of labour which changes with market volume and on the proportion of productive to Unproductive labor. |
The end of the 19th century marks the start of psychology as a scientific enterprise. The year 1879 is commonly seen as the start of psychology as an independent field of study. In that year Wilhelm Wundt founded the first laboratory dedicated exclusively to psychological research (in Leipzig). Other important early contributors to the field include Hermann Ebbinghaus (a pioneer in memory studies), Ivan Pavlov (who discovered classical conditioning), William James, and Sigmund Freud. Freud's influence has been enormous, though more as cultural icon than a force in scientific psychology. |
The final decades of the 20th century have seen the rise of a new interdisciplinary approach to studying human psychology, known collectively as cognitive science. Cognitive science again considers the mind as a subject for investigation, using the tools of psychology, linguistics, computer science, philosophy, and neurobiology. New methods of visualizing the activity of the brain, such as PET scans and CAT scans, began to exert their influence as well, leading some researchers to investigate the mind by investigating the brain, rather than cognition. These new forms of investigation assume that a wide understanding of the human mind is possible, and that such an understanding may be applied to other research domains, such as artificial intelligence. |
Ibn Khaldun can be regarded as the earliest scientific systematic sociologist. The modern sociology, emerged in the early 19th century as the academic response to the modernization of the world. Among many early sociologists (e.g., Émile Durkheim), the aim of sociology was in structuralism, understanding the cohesion of social groups, and developing an "antidote" to social disintegration. Max Weber was concerned with the modernization of society through the concept of rationalization, which he believed would trap individuals in an "iron cage" of rational thought. Some sociologists, including Georg Simmel and W. E. B. Du Bois, utilized more microsociological, qualitative analyses. This microlevel approach played an important role in American sociology, with the theories of George Herbert Mead and his student Herbert Blumer resulting in the creation of the symbolic interactionism approach to sociology. |
American sociology in the 1940s and 1950s was dominated largely by Talcott Parsons, who argued that aspects of society that promoted structural integration were therefore "functional". This structural functionalism approach was questioned in the 1960s, when sociologists came to see this approach as merely a justification for inequalities present in the status quo. In reaction, conflict theory was developed, which was based in part on the philosophies of Karl Marx. Conflict theorists saw society as an arena in which different groups compete for control over resources. Symbolic interactionism also came to be regarded as central to sociological thinking. Erving Goffman saw social interactions as a stage performance, with individuals preparing "backstage" and attempting to control their audience through impression management. While these theories are currently prominent in sociological thought, other approaches exist, including feminist theory, post-structuralism, rational choice theory, and postmodernism. |
Computer science, built upon a foundation of theoretical linguistics, discrete mathematics, and electrical engineering, studies the nature and limits of computation. Subfields include computability, computational complexity, database design, computer networking, artificial intelligence, and the design of computer hardware. One area in which advances in computing have contributed to more general scientific development is by facilitating large-scale archiving of scientific data. Contemporary computer science typically distinguishes itself by emphasising mathematical 'theory' in contrast to the practical emphasis of software engineering. |
As an academic field, history of science began with the publication of William Whewell's History of the Inductive Sciences (first published in 1837). A more formal study of the history of science as an independent discipline was launched by George Sarton's publications, Introduction to the History of Science (1927) and the Isis journal (founded in 1912). Sarton exemplified the early 20th-century view of the history of science as the history of great men and great ideas. He shared with many of his contemporaries a Whiggish belief in history as a record of the advances and delays in the march of progress. The history of science was not a recognized subfield of American history in this period, and most of the work was carried out by interested scientists and physicians rather than professional historians. With the work of I. Bernard Cohen at Harvard, the history of science became an established subdiscipline of history after 1945. |
Much of the study of the history of science has been devoted to answering questions about what science is, how it functions, and whether it exhibits large-scale patterns and trends. The sociology of science in particular has focused on the ways in which scientists work, looking closely at the ways in which they "produce" and "construct" scientific knowledge. Since the 1960s, a common trend in science studies (the study of the sociology and history of science) has been to emphasize the "human component" of scientific knowledge, and to de-emphasize the view that scientific data are self-evident, value-free, and context-free. The field of Science and Technology Studies, an area that overlaps and often informs historical studies of science, focuses on the social context of science in both contemporary and historical periods. |
Humboldtian science refers to the early 19th century approach of combining scientific field work with the age of Romanticism sensitivity, ethics and aesthetic ideals. It helped to install natural history as a separate field, gave base for ecology and was based on the role model of scientist, naturalist and explorer Alexander von Humboldt. The later 19th century positivism asserted that all authentic knowledge allows verification and that all authentic knowledge assumes that the only valid knowledge is scientific. |
The mid 20th century saw a series of studies relying to the role of science in a social context, starting from Thomas Kuhn's The Structure of Scientific Revolutions in 1962. It opened the study of science to new disciplines by suggesting that the evolution of science was in part sociologically determined and that positivism did not explain the actual interactions and strategies of the human participants in science. As Thomas Kuhn put it, the history of science may be seen in more nuanced terms, such as that of competing paradigms or conceptual systems in a wider matrix that includes intellectual, cultural, economic and political themes outside of science. "Partly by selection and partly by distortion, the scientists of earlier ages are implicitly presented as having worked upon the same set of fixed problems and in accordance with the same set of fixed canons that the most recent revolution in scientific theory and method made seem scientific." |
Further studies, e.g. Jerome Ravetz 1971 Scientific Knowledge and its Social Problems referred to the role of the scientific community, as a social construct, in accepting or rejecting (objective) scientific knowledge. The Science wars of the 1990 were about the influence of especially French philosophers, which denied the objectivity of science in general or seemed to do so. They described as well differences between the idealized model of a pure science and the actual scientific practice; while scientism, a revival of the positivism approach, saw in precise measurement and rigorous calculation the basis for finally settling enduring metaphysical and moral controversies. However, more recently some of the leading critical theorists have recognized that their postmodern deconstructions have at times been counter-productive, and are providing intellectual ammunition for reactionary interests. Bruno Latour noted that "dangerous extremists are using the very same argument of social construction to destroy hard-won evidence that could save our lives. Was I wrong to participate in the invention of this field known as science studies? Is it enough to say that we did not really mean what we meant?" |
(デジモン Dejimon, branded as Digimon: Digital Monsters, stylized as DIGIMON), short for "Digital Monsters" (デジタルモンスター Dejitaru Monsutā), is a Japanese media franchise encompassing virtual pet toys, anime, manga, video games, films and a trading card game. The franchise focuses on Digimon creatures, which are monsters living in a "Digital World", a parallel universe that originated from Earth's various communication networks. In many incarnations, Digimon are raised by humans called "Digidestined" or "Tamers", and they team up to defeat evil Digimon and human villains who are trying to destroy the fabric of the Digital world. |
The franchise was first created in 1997 as a series of virtual pets, akin to—and influenced in style by—the contemporary Tamagotchi or nano Giga Pet toys. The creatures were first designed to look cute and iconic even on the devices' small screens; later developments had them created with a harder-edged style influenced by American comics. The franchise gained momentum with its first anime incarnation, Digimon Adventure, and an early video game, Digimon World, both released in 1999. Several seasons of the anime and films based on them have aired, and the video game series has expanded into genres such as role-playing, racing, fighting, and MMORPGs. Other media forms have also been released. |
Digimon was first conceived as a virtual pet toy in the vein of Tamagotchis and, as such, took influence from Tamagotchis' cute and round designs. The small areas of the screens (16 by 16 pixels) meant that character designers had to create monsters whose forms would be easily recognizable. As such, many of the early Digimon—including Tyrannomon, the first one ever created—were based on dinosaurs. Many further designs were created by Kenji Watanabe, who was brought in to help with the "X-Antibody" creatures and art for the Digimon collectible card game. Watanabe was one influenced by American comics, which were beginning to gain popularity in Japan, and as such began to make his characters look stronger and "cool." The character creation process, however, has for most of the franchise's history been collaborative and reliant on conversation and brainstorming. |
Digimon hatch from types of eggs which are called Digi-Eggs (デジタマ, Dejitama?). In the English iterations of the franchise there is another type of Digi-Egg that can be used to digivolve, or transform, Digimon. This second type of Digi-Egg is called a Digimental (デジメンタル, Dejimentaru?) in Japanese. (This type of Digi-Egg was also featured as a major object throughout season 2 as a way of Digivolution available only to certain characters at certain points throughout the season.) They age via a process called "Digivolution" which changes their appearance and increases their powers. The effect of Digivolution, however, is not permanent in the partner Digimon of the main characters in the anime, and Digimon who have digivolved will most of the time revert to their previous form after a battle or if they are too weak to continue. Some Digimon act feral. Most, however, are capable of intelligence and human speech. They are able to digivolve by the use of Digivices that their human partners have. In some cases, as in the first series, the DigiDestined (known as the 'Chosen Children' in the original Japanese) had to find some special items such as crests and tags so the Digimon could digivolve into further stages of evolution known as Ultimate and Mega in the dub. |
The first Digimon anime introduced the Digimon life cycle: They age in a similar fashion to real organisms, but do not die under normal circumstances because they are made of reconfigurable data, which can be seen throughout the show. Any Digimon that receives a fatal wound will dissolve into infinitesimal bits of data. The data then recomposes itself as a Digi-Egg, which will hatch when rubbed gently, and the Digimon goes through its life cycle again. Digimon who are reincarnated in this way will sometimes retain some or all their memories of their previous life. However, if a Digimon's data is completely destroyed, they will die. |
Digimon started out as digital pets called "Digital Monsters", similar in style and concept to the Tamagotchi. It was planned by WiZ and released by Bandai on June 26, 1997. The toy began as the simple concept of a Tamagotchi mainly for boys. The V-Pet is similar to its predecessors, with the exceptions of being more difficult and being able to fight other Digimon v-pets. Every owner would start with a Baby Digimon, train it, evolve it, take care of it, and then have battles with other Digimon owners to see who was stronger. The Digimon pet had several evolution capabilities and abilities too, so many owners had different Digimon. In December, the second generation of Digital Monster was released, followed by a third edition in 1998. |
"Digimon" are "Digital Monsters". According to the stories, they are inhabitants of the "DigiWorld", a manifestation of Earth's communication network. The stories tell of a group of mostly pre-teens, who accompany special Digimon born to defend their world (and ours) from various evil forces. To help them surmount the most difficult obstacles found within both realms, the Digimon have the ability to evolve (Digivolve) In this process, the Digimon change appearance and become much stronger, often changing in personality as well. The group of children who come in contact with the Digital World changes from series to series. |
As of 2011, there have been six series — Digimon Adventure, the follow-up sequel Digimon Adventure 02, Digimon Tamers, Digimon Frontier, Digimon Data Squad and Digimon Fusion. The first two series take place in the same fictional universe, but the third, fourth, fifth and sixth each occupy their own unique world. Each series is commonly based on the original storyline but things are added to make them unique. However, in Tamers, the Adventure universe is referred to as a commercial enterprise — a trading card game in Japan, plus a show-within-a-show in the English dub. It also features an appearance by a character from the Adventure universe. In addition, each series has spawned assorted feature films. Digimon still shows popularity, as new card series, video games, and movies are still being produced and released: new card series include Eternal Courage, Hybrid Warriors, Generations, and Operation X; the video game, Digimon Rumble Arena 2; and the previously unreleased movies Revenge of Diaboromon, Runaway Locomon, Battle of Adventurers, and Island of Lost Digimon. In Japan, Digital Monster X-Evolution, the eighth TV movie, was released on January 3, 2005, and on December 23, 2005 at Jump Festa 2006, the fifth series, Digimon Savers was announced for Japan to begin airing after a three-year hiatus of the show. A sixth television series, Digimon Xros Wars, began airing in 2010, and was followed by a second season, which started on October 2, 2011 as a direct sequel to Digimon Xros Wars. |
The first Digimon television series, which began airing on March 7, 1999 in Japan on Fuji TV and Kids Station and on August 14, 1999 in the United States on Fox Kids dubbed by Saban Entertainment for the North American English version. Its premise is a group of 7 kids who, while at summer camp, travel to the Digital World, inhabited by creatures known as Digital Monsters, or Digimon, learning they are chosen to be "DigiDestined" ("Chosen Children" in the Japanese version) to save both the Digital and Real World from evil. Each Kid was given a Digivice which selected them to be transported to the DigiWorld and was destined to be paired up with a Digimon Partner, such as Tai being paired up with Agumon and Matt with Gabumon. The children are helped by a mysterious man/digimon named Gennai, who helps them via hologram. The Digivices help their Digimon allies to Digivolve into stronger creatures in times of peril. The Digimon usually reached higher forms when their human partners are placed in dangerous situations, such as fighting the evil forces of Devimon, Etemon and Myotismon in their Champion forms. Later, each character discovered a crest that each belonged to a person; Tai the Crest of Courage, Matt the Crest of Friendship, Sora the Crest of Love, Izzy the Crest of Knowledge, Mimi the Crest of Sincerity, Joe the Crest of Reliability, T.K. the Crest of Hope, and later Kari the Crest of Light which allowed their Digimon to digivolve into their Ultimate forms. The group consisted of seven original characters: Taichi "Tai" Kamiya, Yamato "Matt" Ishida, Sora Takenouchi, Koushiro "Izzy" Izumi, Mimi Tachikawa, Joe Kido, and Takeru "T.K." Takaishi. Later on in the series, an eighth character was introduced: Hikari "Kari" Kamiya (who is Taichi's younger sister). |
The second Digimon series is direct continuation of the first one, and began airing on April 2, 2000. Three years later, with most of the original DigiDestined now in high school at age fourteen, the Digital World was supposedly secure and peaceful. However, a new evil has appeared in the form of the Digimon Emperor (Digimon Kaiser) who as opposed to previous enemies is a human just like the DigiDestined. The Digimon Emperor has been enslaving Digimon with Dark Rings and Control Spires and has somehow made regular Digivolution impossible. However, five set Digi-Eggs with engraved emblems had been appointed to three new DigiDestined along with T.K. and Kari, two of the DigiDestined from the previous series. This new evolutionary process, dubbed Armor Digivolution helps the new DigiDestined to defeat evil lurking in the Digital World. Eventually, the DigiDestined defeat the Digimon Emperor, more commonly known as Ken Ichijouji on Earth, only with the great sacrifice of Ken's own Digimon, Wormmon. Just when things were thought to be settled, new Digimon enemies made from the deactivated Control Spires start to appear and cause trouble in the Digital World. To atone for his past mistakes, Ken joins the DigiDestined, being a DigiDestined himself, with his Partner Wormmon revived to fight against them. They soon save countries including France and Australia from control spires and defeat MaloMyotismon (BelialVamdemon), the digivolved form of Myotismon (Vamdemon) from the previous series. They stop the evil from destroying the two worlds, and at the end, every person on Earth gains their own Digimon partner. |
The third Digimon series, which began airing on April 1, 2001, is set largely in a "real world" where the Adventure and Adventure 02 series are television shows, and where Digimon game merchandise (based on actual items) become key to providing power boosts to real Digimon which appear in that world. The plot revolves around three Tamers, Takato Matsuki, Rika Nonaka, and Henry Wong. It began with Takato creating his own Digimon partner by sliding a mysterious blue card through his card reader, which then became a D-Power. Guilmon takes form from Takato's sketchings of a new Digimon. (Tamers’ only human connection to the Adventure series is Ryo Akiyama, a character featured in some of the Digimon video games and who made an appearance in some occasions of the Adventure story-line.) Some of the changes in this series include the way the Digimon digivolve with the introduction of Biomerge-Digivolution and the way their "Digivices" work. In this series, the Tamers can slide game cards through their "Digivices" and give their Digimon partners certain advantages, as in the card game. This act is called "Digi-Modify" (Card Slash in the Japanese version). The same process was often used to Digivolve the Digimon, but as usual, emotions play a big part in the digivolving process. Unlike the two seasons before it and most of the seasons that followed, Digimon Tamers takes a darker and more realistic approach to its story featuring Digimon who do not reincarnate after their deaths and more complex character development in the original Japanese. The anime has become controversial over the decade, with debates about how appropriate this show actually is for its "target" audience, especially due to the Lovecraftian nature of the last arc. The English dub is more lighthearted dialogue-wise, though still not as much as previous series. |
The fourth Digimon series, which began airing on April 7, 2002, radically departs from the previous three by focusing on a new and very different kind of evolution, Spirit Evolution, in which the human characters use their D-Tectors (this series' Digivice) to transform themselves into special Digimon called Legendary Warriors, detracting from the customary formula of having digital partners. After receiving unusual phone messages from Ophanimon (one of the three ruling Digimon alongside Seraphimon and Cherubimon) Takuya Kanbara, Koji Minamoto, Junpei Shibayama, Zoe Orimoto, Tommy Himi, and Koichi Kimura go to a subway station and take a train to the Digital World. Summoned by Ophanimon, the Digidestined realize that they must find the ten legendary spirits and stop the forces of Cherubimon from physically destroying the Digital World. After finding the ten spirits of the Legendary Warriors and defeating Mercurymon, Grumblemon, Ranamon, and Arbormon, they finally end up fighting Cherubimon hoping to foil his effort to dominate the Digital World. After the defeat of Cherubimon, the Digidestined find they must face an even greater challenge as they try to stop the Royal Knights—Dynasmon and Crusadermon—from destroying the Digital World and using the collected data to revive the original ruler of the Digital World: the tyrannical Lucemon. Ultimately the Digidestined fail in preventing Lucemon from reawakening but they do manage to prevent him from escaping into the Real World. In the final battle, all of the legendary spirits the digidestined have collected thus far merge and create Susanoomon. With this new form, the digidestined are able to effectively defeat Lucemon and save the Digital World. In general, Frontier has a much lighter tone than that of Tamers, yet remains darker than Adventure and Adventure 02. |
After a three-year hiatus, a fifth Digimon series began airing on April 2, 2006. Like Frontier, Savers has no connection with the previous installments, and also marks a new start for the Digimon franchise, with a drastic change in character designs and story-line, in order to reach a broader audience. The story focuses on the challenges faced by the members of D.A.T.S. ("Digital Accident Tactics Squad"), an organization created to conceal the existence of the Digital World and Digimon from the rest of mankind, and secretly solve any Digimon-related incidents occurring on Earth. Later the D.A.T.S. is dragged into a massive conflict between Earth and the Digital World, triggered by an ambitious human scientist named Akihiro Kurata, determined to make use of the Digimon for his own personal gains. The English version was dubbed by Studiopolis and it premiered on the Jetix block on Toon Disney on October 1, 2007. Digivolution in Data Squad requires the human partner's DNA ("Digital Natural Ability" in the English version and "Digisoul" in the Japanese version) to activate, a strong empathy with their Digimon and a will to succeed. 'Digimon Savers' also introduces a new form of digivolving called Burst Mode which is essentially the level above Mega (previously the strongest form a digimon could take). Like previously in Tamers, this plot takes on a dark tone throughout the story and the anime was aimed, originally in Japan, at an older audience consisting of late teens and people in their early twenties from ages 16 to 21. Because of that, along with the designs, the anime being heavily edited and localized for western US audiences like past series, and the English dub being aimed mostly toward younger audiences of children aged 6 to 10 and having a lower TV-Y7-FV rating just like past dubs, Studiopolis dubbed the anime on Jetix with far more edits, changes, censorship, and cut footage. This included giving the Japanese characters full Americanized names and American surnames as well as applying far more Americanization (Marcus Damon as opposed to the Japanese Daimon Masaru), cultural streamlining and more edits to their version similar to the changes 4Kids often made (such as removal of Japanese text for the purpose of cultural streamlining). Despite all that, the setting of the country was still in Japan and the characters were Japanese in the dub. This series was the first to show any Japanese cultural concepts that were unfamiliar with American audiences (such as the manju), which were left unedited and used in the English dub. Also despite the heavy censorship and the English dub aimed at young children, some of the Digimon's attacks named after real weapons such as RizeGreymon's Trident Revolver are not edited and used in the English dub. Well Go USA released it on DVD instead of Disney. The North American English dub was televised on Jetix in the U.S. and on the Family Channel in Canada. |
Three and a quarter years after the end of the fifth series, a new sixth series was confirmed by Bandai for the Digimon anime, its official name of the series revealed in the June issue of Shueisha's V Jump magazine being Digimon Xros Wars. It began airing in Japan on TV Asahi from July 6, 2010 onwards. Reverting to the design style of the first four series as well as the plot taking on the younger, lighter tone present in series one, two and four throughout the story. The story follows a boy named Mikey Kudō (Taiki Kudo in Japan) who, along with his friends, ends up in the Digital World where they meet Shoutmon and his Digimon friends. Wielding a digivice known as a Fusion Loader (Xros Loader in Japan), Mikey is able to combine multiple Digimon onto one to enhance his power, Shoutmon being the usual core of the combination, using a technique known as 'DigiFuse' (Digi-Xros in Japan). Forming Team Fusion Fighters (Team Xros Heart in Japan), Mikey, Shoutmon and their friends travel through the Digital World to liberate it from the evil Bagra Army, led by Bagramon(Lord Bagra in English), and Midnight, a shady group led by AxeKnightmon with Nene as a figurehead before joining the Fusion Fighters. The Fusion Fighters also finds themselves at odds with Blue Flare, led by Christopher Aonuma (Kiriha Anouma in Japan). The second arc of Xros Wars was subtitled The Evil Death Generals and the Seven Kingdoms. It saw the main cast reshuffled with a new wardrobe while Angie (Akari in Japan) and Jeremy (Zenjiro in Japan) stay behind in the Human World; thus making Mikey, Christopher and Nene the lead protagonists as they set off to face the Seven Death Generals of the Bagra Army and AxeKnightmon's new pawn: Nene's brother Ewan (Yuu in Japan). A new evolution known as Super Digivolution was introduced at the end of the first arc. The English dub of the series began airing on Nickelodeon on September 7, 2013, which is produced by Saban Brands. |
On August 17, 2011, Shueisha's V-Jump magazine announced a sequel set one year later, a third arc of Xros Wars subtitled The Young Hunters Who Leapt Through Time, which aired from October 2, 2011 to March 25, 2012, following on from the previous arc. It focuses on a new protagonist, Tagiru Akashi and his partner Gumdramon who embark on a new journey with an older Mikey, Shoutmon, an older Ewan and the revived Damemon, along with other new comrades as they deal with a hidden dimension that lies between the Human World and the Digital World called DigiQuartz. The series finale reintroduces the heroes of the previous five seasons as they all come together and help the current heroes in the final battle due to the fact that the DigiQuartz is essentially a tear in Space and Time, allowing all of the Digimon universes to converge. |
A new Digimon series was announced 30 months after the end of Digimon Fusion at a 15th anniversary concert and theater event for the franchise in August 2014. The series announced the return of the protagonists from the original Digimon Adventure series, most of them now as high school students. A countdown clicking game was posted on the show's official website, offering news when specific clicks were met. On December 13, 2014 the series title and a key visual featuring character designs by Atsuya Uki were revealed with Keitaro Motonaga announced as director with a tentative premiere date of Spring, 2015. However, on May 6, 2015, it was announced that tri. would not be a television series, but rather a 6-part theatrical film series. The films are being streamed in episodic format outside Japan by Crunchyroll and Hulu from the same day they premiere on Japanese theaters. |
The series is set three years after the events of Digimon Adventure 02, when Digimon who turn rogue by a mysterious infection appear to wreak havoc in the Human World. Tai and the other DigiDestined from the original series reunite with their partners and start fighting back with support from the Japanese government, while Davis, Yolei, Cody and Ken are defeated by a powerful enemy called Alphamon and disappear without a trace. Tai and the others also meet another DigiDestined called Meiko Mochizuki and her partner Meicoomon who become their friends, until Meicoomon turns hostile as well and flees after an encounter with Ken, who reappears suddenly, once again as the Digimon Emperor. The film series also feature several DigiDestined having their partners Digivolve up to the Mega level for the first time, a feat only Tai and Matt had achieved previously. |
There have been nine Digimon movies released in Japan. The first seven were directly connected to their respective anime series; Digital Monster X-Evolution originated from the Digimon Chronicle merchandise line. All movies except X-Evolution and Ultimate Power! Activate Burst Mode have been released and distributed internationally. Digimon: The Movie, released in the U.S. and Canada territory by Fox Kids through 20th Century Fox on October 6, 2000, consists of the union of the first three Japanese movies. |
The European publishing company, Panini, approached Digimon in different ways in different countries. While Germany created their own adaptations of episodes, the United Kingdom (UK) reprinted the Dark Horse titles, then translated some of the German adaptations of Adventure 02 episodes. Eventually the UK comics were given their own original stories, which appeared in both the UK's official Digimon Magazine and the official UK Fox Kids companion magazine, Wickid. These original stories only roughly followed the continuity of Adventure 02. When the comic switched to the Tamers series the storylines adhered to continuity more strictly; sometimes it would expand on subject matter not covered by the original Japanese anime (such as Mitsuo Yamaki's past) or the English adaptations of the television shows and movies (such as Ryo's story or the movies that remained undubbed until 2005). In a money saving venture, the original stories were later removed from Digimon Magazine, which returned to printing translated German adaptations of Tamers episodes. Eventually, both magazines were cancelled. |
The Digimon series has a large number of video games which usually have their own independent storylines with a few sometimes tying into the stories of the anime series or manga series. The games consists of a number of genres including life simulation, adventure, video card game, strategy and racing games, though they are mainly action role-playing games. The games released in North America are: Digimon World, Digimon World 2, Digimon World 3, Digimon World 4, Digimon Digital Card Battle, Digimon Rumble Arena, Digimon Rumble Arena 2, Digimon Battle Spirit, Digimon Battle Spirit 2, Digimon Racing, Digimon World DS, Digimon World Data Squad, Digimon World Dawn and Dusk, Digimon World Championship, and Digimon Masters. |
In 2011, Bandai posted a countdown on a teaser site. Once the countdown was finished, it revealed a reboot of the Digimon World series titled Digimon World Re:Digitize. An enhanced version of the game released on Nintendo 3DS as Digimon World Re:Digitize Decode in 2013. Another role-playing game by the name Digimon Story: Cyber Sleuth is set for release in 2015 for PlayStation Vita. It is part of the Digimon Story sub-series, originally on Nintendo DS and has also been released with English subtitles in North America. |
A glacier (US /ˈɡleɪʃər/ or UK /ˈɡlæsiə/) is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. |
On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges on every continent except Australia, and on a few high-latitude oceanic islands. Between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earth's land surface. Continental glaciers cover nearly 13,000,000 km2 (5×10^6 sq mi) or about 98 percent of Antarctica's 13,200,000 km2 (5.1×10^6 sq mi), with an average thickness of 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers. |
Glacial ice is the largest reservoir of freshwater on Earth. Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. Within high altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater. |
Glacial bodies larger than 50,000 km2 (19,000 sq mi) are called ice sheets or continental glaciers. Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of fresh water, enough that if both melted, global sea levels would rise by over 70 m (230 ft). Portions of an ice sheet or cap that extend into water are called ice shelves; they tend to be thin with limited slopes and reduced velocities. Narrow, fast-moving sections of an ice sheet are called ice streams. In Antarctica, many ice streams drain into large ice shelves. Some drain directly into the sea, often with an ice tongue, like Mertz Glacier. |
Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin and Ellesmere Islands in Canada, Southeast Alaska, and the Northern and Southern Patagonian Ice Fields. As the ice reaches the sea, pieces break off, or calve, forming icebergs. Most tidewater glaciers calve above sea level, which often results in a tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by the climate change than those of other glaciers. |
Thermally, a temperate glacier is at melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below freezing point from the surface to its base, although the surface snowpack may experience seasonal melting. A sub-polar glacier includes both temperate and polar ice, depending on depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is often described by the temperature at its base alone. A cold-based glacier is below freezing at the ice-ground interface, and is thus frozen to the underlying substrate. A warm-based glacier is above or at freezing at the interface, and is able to slide at this contact. This contrast is thought to a large extent to govern the ability of a glacier to effectively erode its bed, as sliding ice promotes plucking at rock from the surface below. Glaciers which are partly cold-based and partly warm-based are known as polythermal. |
Glaciers form where the accumulation of snow and ice exceeds ablation. The area in which a glacier forms is called a cirque (corrie or cwm) - a typically armchair-shaped geological feature (such as a depression between mountains enclosed by arêtes) - which collects and compresses through gravity the snow which falls into it. This snow collects and is compacted by the weight of the snow falling above it forming névé. Further crushing of the individual snowflakes and squeezing the air from the snow turns it into 'glacial ice'. This glacial ice will fill the cirque until it 'overflows' through a geological weakness or vacancy, such as the gap between two mountains. When the mass of snow and ice is sufficiently thick, it begins to move due to a combination of surface slope, gravity and pressure. On steeper slopes, this can occur with as little as 15 m (50 ft) of snow-ice. |
Glaciers are broken into zones based on surface snowpack and melt conditions. The ablation zone is the region where there is a net loss in glacier mass. The equilibrium line separates the ablation zone and the accumulation zone; it is the altitude where the amount of new snow gained by accumulation is equal to the amount of ice lost through ablation. The upper part of a glacier, where accumulation exceeds ablation, is called the accumulation zone. In general, the accumulation zone accounts for 60–70% of the glacier's surface area, more if the glacier calves icebergs. Ice in the accumulation zone is deep enough to exert a downward force that erodes underlying rock. After a glacier melts, it often leaves behind a bowl- or amphitheater-shaped depression that ranges in size from large basins like the Great Lakes to smaller mountain depressions known as cirques. |
The top 50 m (160 ft) of a glacier are rigid because they are under low pressure. This upper section is known as the fracture zone and moves mostly as a single unit over the plastically flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in the fracture zone. Crevasses form due to differences in glacier velocity. If two rigid sections of a glacier move at different speeds and directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 46 m (150 ft) deep but in some cases can be 300 m (1,000 ft) or even deeper. Beneath this point, the plasticity of the ice is too great for cracks to form. Intersecting crevasses can create isolated peaks in the ice, called seracs. |
Crevasses can form in several different ways. Transverse crevasses are transverse to flow and form where steeper slopes cause a glacier to accelerate. Longitudinal crevasses form semi-parallel to flow where a glacier expands laterally. Marginal crevasses form from the edge of the glacier, due to the reduction in speed caused by friction of the valley walls. Marginal crevasses are usually largely transverse to flow. Moving glacier ice can sometimes separate from stagnant ice above, forming a bergschrund. Bergschrunds resemble crevasses but are singular features at a glacier's margins. |
Mean speeds vary greatly, but is typically around 1 m (3 ft) per day. There may be no motion in stagnant areas; for example, in parts of Alaska, trees can establish themselves on surface sediment deposits. In other cases, glaciers can move as fast as 20–30 m (70–100 ft) per day, such as in Greenland's Jakobshavn Isbræ (Greenlandic: Sermeq Kujalleq). Velocity increases with increasing slope, increasing thickness, increasing snowfall, increasing longitudinal confinement, increasing basal temperature, increasing meltwater production and reduced bed hardness. |
A few glaciers have periods of very rapid advancement called surges. These glaciers exhibit normal movement until suddenly they accelerate, then return to their previous state. During these surges, the glacier may reach velocities far greater than normal speed. These surges may be caused by failure of the underlying bedrock, the pooling of meltwater at the base of the glacier — perhaps delivered from a supraglacial lake — or the simple accumulation of mass beyond a critical "tipping point". Temporary rates up to 90 m (300 ft) per day have occurred when increased temperature or overlying pressure caused bottom ice to melt and water to accumulate beneath a glacier. |
In glaciated areas where the glacier moves faster than one km per year, glacial earthquakes occur. These are large scale temblors that have seismic magnitudes as high as 6.1. The number of glacial earthquakes in Greenland peaks every year in July, August and September and is increasing over time. In a study using data from January 1993 through October 2005, more events were detected every year since 2002, and twice as many events were recorded in 2005 as there were in any other year. This increase in the numbers of glacial earthquakes in Greenland may be a response to global warming. |
Ogives are alternating wave crests and valleys that appear as dark and light bands of ice on glacier surfaces. They are linked to seasonal motion of glaciers; the width of one dark and one light band generally equals the annual movement of the glacier. Ogives are formed when ice from an icefall is severely broken up, increasing ablation surface area during summer. This creates a swale and space for snow accumulation in the winter, which in turn creates a ridge. Sometimes ogives consist only of undulations or color bands and are described as wave ogives or band ogives. |
Glaciers are present on every continent and approximately fifty countries, excluding those (Australia, South Africa) that have glaciers only on distant subantarctic island territories. Extensive glaciers are found in Antarctica, Chile, Canada, Alaska, Greenland and Iceland. Mountain glaciers are widespread, especially in the Andes, the Himalayas, the Rocky Mountains, the Caucasus, and the Alps. Mainland Australia currently contains no glaciers, although a small glacier on Mount Kosciuszko was present in the last glacial period. In New Guinea, small, rapidly diminishing, glaciers are located on its highest summit massif of Puncak Jaya. Africa has glaciers on Mount Kilimanjaro in Tanzania, on Mount Kenya and in the Rwenzori Mountains. Oceanic islands with glaciers occur on Iceland, Svalbard, New Zealand, Jan Mayen and the subantarctic islands of Marion, Heard, Grande Terre (Kerguelen) and Bouvet. During glacial periods of the Quaternary, Taiwan, Hawaii on Mauna Kea and Tenerife also had large alpine glaciers, while the Faroe and Crozet Islands were completely glaciated. |
The permanent snow cover necessary for glacier formation is affected by factors such as the degree of slope on the land, amount of snowfall and the winds. Glaciers can be found in all latitudes except from 20° to 27° north and south of the equator where the presence of the descending limb of the Hadley circulation lowers precipitation so much that with high insolation snow lines reach above 6,500 m (21,330 ft). Between 19˚N and 19˚S, however, precipitation is higher and the mountains above 5,000 m (16,400 ft) usually have permanent snow. |
Even at high latitudes, glacier formation is not inevitable. Areas of the Arctic, such as Banks Island, and the McMurdo Dry Valleys in Antarctica are considered polar deserts where glaciers cannot form because they receive little snowfall despite the bitter cold. Cold air, unlike warm air, is unable to transport much water vapor. Even during glacial periods of the Quaternary, Manchuria, lowland Siberia, and central and northern Alaska, though extraordinarily cold, had such light snowfall that glaciers could not form. |
Glacial abrasion is commonly characterized by glacial striations. Glaciers produce these when they contain large boulders that carve long scratches in the bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks, lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock. |
Glacial moraines are formed by the deposition of material from a glacier and are exposed after the glacier has retreated. They usually appear as linear mounds of till, a non-sorted mixture of rock, gravel and boulders within a matrix of a fine powdery material. Terminal or end moraines are formed at the foot or terminal end of a glacier. Lateral moraines are formed on the sides of the glacier. Medial moraines are formed when two different glaciers merge and the lateral moraines of each coalesce to form a moraine in the middle of the combined glacier. Less apparent are ground moraines, also called glacial drift, which often blankets the surface underneath the glacier downslope from the equilibrium line. |
Before glaciation, mountain valleys have a characteristic "V" shape, produced by eroding water. During glaciation, these valleys are widened, deepened, and smoothed, forming a "U"-shaped glacial valley. The erosion that creates glacial valleys eliminates the spurs of earth that extend across mountain valleys, creating triangular cliffs called truncated spurs. Within glacial valleys, depressions created by plucking and abrasion can be filled by lakes, called paternoster lakes. If a glacial valley runs into a large body of water, it forms a fjord. |
At the start of a classic valley glacier is a bowl-shaped cirque, which has escarped walls on three sides but is open on the side that descends into the valley. Cirques are where ice begins to accumulate in a glacier. Two glacial cirques may form back to back and erode their backwalls until only a narrow ridge, called an arête is left. This structure may result in a mountain pass. If multiple cirques encircle a single mountain, they create pointed pyramidal peaks; particularly steep examples are called horns. |
Some rock formations in the path of a glacier are sculpted into small hills called roche moutonnée, or "sheepback" rock. Roche moutonnée are elongated, rounded, and asymmetrical bedrock knobs that can be produced by glacier erosion. They range in length from less than a meter to several hundred meters long. Roche moutonnée have a gentle slope on their up-glacier sides and a steep to vertical face on their down-glacier sides. The glacier abrades the smooth slope on the upstream side as it flows along, but tears loose and carries away rock from the downstream side via plucking. |
Large masses, such as ice sheets or glaciers, can depress the crust of the Earth into the mantle. The depression usually totals a third of the ice sheet or glacier's thickness. After the ice sheet or glacier melts, the mantle begins to flow back to its original position, pushing the crust back up. This post-glacial rebound, which proceeds very slowly after the melting of the ice sheet or glacier, is currently occurring in measurable amounts in Scandinavia and the Great Lakes region of North America. |
Comcast Corporation, formerly registered as Comcast Holdings,[note 1] is an American multinational mass media company and is the largest broadcasting and largest cable company in the world by revenue. It is the second largest pay-TV company after the AT&T-DirecTV acquisition, largest cable TV company and largest home Internet service provider in the United States, and the nation's third largest home telephone service provider. Comcast services U.S. residential and commercial customers in 40 states and the District of Columbia. The company's headquarters are located in Philadelphia, Pennsylvania. |
Comcast operates multiple cable-only channels (including E! Entertainment Television, the Golf Channel, and NBCSN), over-the-air national broadcast network channels (NBC and Telemundo), the film production studio Universal Pictures, and Universal Parks & Resorts, with a global total of nearly 200 family entertainment locations and attractions in the U.S. and several other countries including U.A.E., South Korea, Russia and China, with several new locations reportedly planned and being developed for future operation. Comcast also has significant holding in digital distribution (thePlatform). In February 2014 the company agreed to merge with Time Warner Cable in an equity swap deal worth $45.2 billion. Under the terms of the agreement Comcast was to acquire 100% of Time Warner Cable. However, on April 24, 2015, Comcast terminated the agreement. |
Comcast has been criticized for multiple reasons. The company's customer satisfaction often ranks among the lowest in the cable industry. Comcast has violated net neutrality practices in the past; and, despite Comcast's commitment to a narrow definition of net neutrality, critics advocate a definition of which precludes distinction between Comcast's private network services and the rest of the Internet. Critics also point out a lack of competition in the vast majority of Comcast's service area; there is limited competition among cable providers. Given Comcast's negotiating power as a large ISP, some suspect that Comcast could leverage paid peering agreements to unfairly influence end-user connection speeds. Its ownership of both content production (in NBCUniversal) and content distribution (as an ISP) has raised antitrust concerns. These issues, in addition to others, led to Comcast being dubbed "The Worst Company in America" by The Consumerist in 2014 and 2010. |
Comcast is sometimes described as a family business. Brian L. Roberts, Chairman, President, and CEO of Comcast, is son of co-founder Ralph Roberts. Roberts owns or controls just over 1% of all Comcast shares but all of the Class B supervoting shares, which gives him an "undilutable 33% voting power over the company". Legal expert Susan P. Crawford has said this gives him "effective control over its [Comcast's] every step". In 2010, he was one of the highest-paid executives in the United States, with total compensation of about $31 million. |
The company is often criticized by both the media and its own staff for its less upstanding policies regarding employee relations. A 2012 Reddit post written by an anonymous Comcast call center employee eager to share their negative experiences with the public received attention from publications including The Huffington Post. A 2014 investigative series published by The Verge involved interviews with 150 of Comcast's employees. It sought to examine why the company has become so widely criticized by its customers, the media and even members of its own staff. The series claimed part of the problem is internal and that Comcast's staff endures unreasonable corporate policies. According to the report: "customer service has been replaced by an obsession with sales; technicians are understaffed while tech support is poorly trained; and the company is hobbled by internal fragmentation." A widely read article penned by an anonymous call center employee working for Comcast appeared in November 2014 on Cracked. Titled "Five Nightmares You Live While Working For America's Worst Company," the article also claimed that Comcast is obsessed with sales, doesn't train its employees properly and concluded that "the system makes good customer service impossible." |
Comcast has also earned a reputation for being anti-union. According to one of the company's training manuals, "Comcast does not feel union representation is in the best interest of its employees, customers, or shareholders". A dispute in 2004 with CWA, a labor union that represented many employees at Comcast's offices in Beaverton, Oregon, led to allegations of management intimidating workers, requiring them to attend anti-union meetings and unwarranted disciplinary action for union members. In 2011, Comcast received criticism from Writers Guild of America for its policies in regards to unions. |
Despite these criticisms, Comcast has appeared on multiple "top places to work" lists. In 2009, it was included on CableFAX magazine's "Top 10 Places to Work in Cable", which cited its "scale, savvy and vision". Similarly, the Philadelphia Business Journal awarded Comcast the silver medal among extra-large companies in Philadelphia, with the gold medal going to partner organization, Comcast-Spectacor. The Boston Globe found Comcast to be that city's top place to work in 2009. Employee diversity is also an attribute upon which Comcast receives strong marks. In 2008, Black Enterprise magazine rated Comcast among the top 15 companies for workforce diversity. Comcast was also named a "Top 2014 Workplace" by the Washington Post in their annual feature. |
The book value of the company nearly doubled from $8.19 a share in 1999 to $15 a share in 2009. Revenues grew sixfold from 1999's $6 billion to almost $36 billion in 2009. Net profit margin rose from 4.2% in 1999 to 8.4% in 2009, with operating margins improving 31 percent and return on equity doubling to 6.7 percent in the same time span. Between 1999 and 2009, return on capital nearly tripled to 7 percent. Comcast reported first quarter 2012 profit increases of 30% due to increase in high-speed internet customers. In February 2014, Comcast generated 1.1 billion in revenue during the first quarter due to the Sochi Olympics,. |
With $18.8 million spent in 2013, Comcast has the seventh largest lobbying budget of any individual company or organization in the United States. Comcast employs multiple former US Congressmen as lobbyists. The National Cable & Telecommunications Association, which has multiple Comcast executives on its board, also represents Comcast and other cable companies as the fifth largest lobbying organization in the United States, spending $19.8 million in 2013. Comcast was among the top backers of Barack Obama's presidential runs, with Comcast vice president David Cohen raising over $2.2 million from 2007 to 2012. Cohen has been described by many sources as influential in the US government, though he is no longer a registered lobbyist, as the time he spends lobbying falls short of the 20% which requires official registration. Comcast's PAC, the Comcast Corporation and NBCUniversal Political Action Committee, is the among the largest PACs in the US, raising about $3.7 million from 2011-2012 for the campaigns of various candidates for office in the United States Federal Government. Comcast is also a major backer of the National Cable and Telecommunications Association Political Action Committee, which raised $2.6 million from 2011-2012. Comcast spent the most money of any organization in support of the Stop Online Piracy and PROTECT IP bills, spending roughly $5 million to lobby for their passage. |
In 1963, Ralph J. Roberts in conjunction with his two business partners, Daniel Aaron and Julian A. Brodsky, purchased American Cable Systems as a corporate spin-off from its parent, Jerrold Electronics, for US $500,000. At the time, American Cable was a small cable operator in Tupelo, Mississippi, with five channels and 12,000 customers. Storecast Corporation of America, a product placement supermarket specialist marketing firm, was purchased by American Cable in 1965. With Storecast being a Muzak client, American Cable purchased its first Muzak franchise of many in Orlando, Florida. |
In 1994, Comcast became the third largest cable operator in the United States with around 3.5 million subscribers following its purchase of Maclean-Hunter's American division for $1.27 billion. The company's UK branch, Comcast UK Cable Partners, goes public while constructing a cable telecommunications network. With five other media companies, the corporation becomes an original investor in The Golf Channel. Following a bid in 1994 for $2.1 billion, Comcast increased its ownership of QVC from 15.5% of stock to a majority, in a move to prevent QVC from merging with CBS. Comcast later sold its QVC shares in 2004 to Liberty Media for $7.9 billion. |
Comcast sold Comcast Cellular to SBC Communications in 1999 for $400 million, releasing them from $1.27 billion in debt. Comcast acquired Greater Philadelphia Cablevision in 1999. In March 1999, Comcast offered to buy MediaOne for $60 billion. However, MediaOne decided to accept AT&T Corporation's offer of $62 billion instead. Comcast University started in 1999 as well as Comcast Interactive Capital Group to make technology and Internet related investments taking its first investment in VeriSign. |
In 2001, Comcast announced it would acquire the assets of the largest cable television operator at the time, AT&T Broadband, for US$44.5 billion. The proposed name for the merged company was "AT&T Comcast", but the companies ultimately decided to keep only the Comcast name. In 2002, Comcast acquired all assets of AT&T Broadband, thus making Comcast the largest cable television company in the United States with over 22 million subscribers. This also spurred the start of Comcast Advertising Sales (using AT&T's groundwork) which would later be renamed Comcast Spotlight. As part of this acquisition, Comcast also acquired the National Digital Television Center in Centennial, Colorado as a wholly owned subsidiary, which is today known as the Comcast Media Center. |
On February 11, 2004, Comcast announced a $54 billion bid for The Walt Disney Company, as well as taking on $12 billion of Disney's debt. The deal would have made Comcast the largest media conglomerate in the world. However, after rejection by Disney and uncertain response from investors, the bid was abandoned in April. The main reason for the buyout attempt was so that Comcast could acquire Disney's 80 percent stake in ESPN, which a Comcast executive called "the most important and valuable asset" that Disney owned. |
On April 8, 2005, a partnership led by Comcast and Sony Pictures Entertainment finalized a deal to acquire MGM and its affiliate studio, United Artists, and create an additional outlet to carry MGM/UA's material for cable and Internet distribution. On October 31, 2005, Comcast officially announced that it had acquired Susquehanna Communications a South Central Pennsylvania, -based cable television and broadband services provider and unit of the former Susquehanna Pfaltzgraff company, for $775 million cash. In this deal Comcast acquired approximately 230,000 basic cable customers, 71,000 digital cable customers, and 86,000 high-speed Internet customers. Comcast previously owned approximately 30 percent of Susquehanna Communications through affiliate company Lenfest. In December 2005, Comcast announced the creation of Comcast Interactive Media, a new division focused on online media. |
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