What Are The Major Theories Explaining The Disappearance Of Trains?

A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be scientific, belong to a non-scientific discipline, or no discipline at all. Depending on the context, a theory's assertions might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings. In modern science, the term "theory" refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with scientific method, and fulfilling the criteria required by modern science. Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction ("falsify") of it. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge, in contrast to more common uses of the word "theory" that imply that something is unproven or speculative (which in formal terms is better characterized by the word hypothesis). Scientific theories are distinguished from hypotheses, which are individual empirically testable conjectures, and from scientific laws, which are descriptive accounts of the way nature behaves under certain conditions. Theories guide the enterprise of finding facts rather than of reaching goals, and are neutral concerning alternatives among values.: 131  A theory can be a body of knowledge, which may or may not be associated with particular explanatory models. To theorize is to develop this body of knowledge.: 46 The word theory or "in theory" is sometimes used erroneously by people to explain something which they individually did not experience or test before. In those instances, semantically, it is being substituted for another concept, a hypothesis. Instead of using the word "hypothetically", it is replaced by a phrase: "in theory". In some instances the theory's credibility could be contested by calling it "just a theory" (implying that the idea has not even been tested). Hence, that word "theory" is very often contrasted to "practice" (from Greek praxis, πρᾶξις) a Greek term for doing, which is opposed to theory. A "classical example" of the distinction between "theoretical" and "practical" uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.An explanation is a set of statements usually constructed to describe a set of facts which clarifies the causes, context, and consequences of those facts. This description may establish rules or laws, and may clarify the existing rules or laws in relation to any objects, or phenomena examined.Explanation, in philosophy, is a set of statements that makes intelligible the existence or occurrence of an object, event, or state of affairs. Among the most common forms of explanation are causal explanation; deductive-nomological explanation, which involves subsuming the explanandum under a generalization from which it may be derived in a deductive argument (e.g., “All gases expand when heated; this gas was heated; therefore, this gas expanded”); and statistical explanation, which involves subsuming the explanandum under a generalization that gives it inductive support (e.g., “Most people who use tobacco contract cancer; this person used tobacco; therefore, this person contracted cancer”). Explanations of human behaviour typically appeal to the subject’s beliefs and desires, as well as other facts about him, and proceed on the assumption that the behaviour in question is rational (at least to a minimum degree). Thus an explanation of why the subject removed his coat might cite the fact that the subject felt hot, that the subject desired to feel cooler, and that the subject believed that he would feel cooler if he took off his coat.Disappearance may refer to: Forced disappearance, when an organization forces a person to vanish from public viewA train is a form of rail transport consisting of a series of connected vehicles that generally run along a railroad (or railway) track to transport passengers or cargo (also known as "freight" or "goods"). The word train comes from the Old French trahiner, derived from the Latin trahere meaning 'to pull, to draw'.Motive power for a train is provided by a separate locomotive or individual motors in a self-propelled multiple unit. The term "engine" is often used as an alternative to locomotive. Although historically steam propulsion dominated, the most common types of locomotive are diesel and electric, the latter supplied by overhead wires or additional rails. Trains can also be hauled by horses, pulled by engine or water-driven cable or wire winch, run downhill using gravity, or powered by pneumatics, gas turbines or electric batteries. The track usually consists of two running rails with a fixed spacing, which may be supplemented by additional rails such as electric conducting rails ("third rail") and rack rails. Monorails and maglev guideways are also occasionally used.Passenger trains include passenger-carrying vehicles and can often be very long and fast. High-speed rail systems began expanding rapidly in the late 20th century, and this remains a major subject of further development. The term "light rail" is sometimes used to refer to a modern tram system, but it may also mean an intermediate form between a tram and a train, similar to a heavy rail rapid transit system. Freight (goods) trains use freight cars (or wagons/trucks) to transport goods or materials (cargo). It is possible to carry passengers and freight in the same train using a mixed consist. Rail cars and machinery that are used for the maintenance and repair of tracks, are termed "maintenance of way" equipment; these may be assembled into maintenance of way trains. Similarly, dedicated trains may be used to provide support services to stations along a train line, such as garbage or revenue collection.