Space 27667 226113158 2008-07-16T21:43:35Z ClueBot 4928500 Reverting possible vandalism by [[Special:Contributions/122.109.149.35|122.109.149.35]] to version by Ssnseawolf. False positive? [[User:ClueBot/FalsePositives|Report it]]. Thanks, [[User:ClueBot]]. (441884) (Bot) {{pp-move-vandalism|small=yes}} {{About||the space beyond Earth's atmosphere|Outer space|all other uses|Space (disambiguation)}} '''Space''' is the boundless extent within which [[matter]] is physically extended and [[Physical body|objects]] and [[event]]s have positions relative to one another<ref>[http://www.britannica.com/eb/article-9068962/space Britannica Online Encyclopedia: Space]</ref>. Physical space is often conceived in three [[linear]] [[dimension]]s, although modern [[physics|physicists]] usually consider it, with [[time]], to be part of the boundless four-dimensional continuum known as [[spacetime]]. In [[mathematics]] spaces with different numbers of dimensions and with different underlying structures can be examined. The concept of space is considered to be of fundamental importance to an understanding of the [[universe]] although disagreement continues between [[philosophy|philosophers]] over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. Many of the philosophical questions arose in the 17th century, during the early development of [[classical mechanics]]. In [[Isaac Newton|Isaac Newton's]] view, space was absolute - in the sense that it existed permanently and independently of whether there were any matter in the space.<ref>French and Ebison, Classical Mechanics, p. 1</ref> Other [[natural philosophy|natural philosophers]], notably [[Gottfried Leibniz]], thought instead that space was a collection of relations between objects, given by their [[distance]] and [[direction]] from one another. In the 18th century, [[Immanuel Kant]] described space and time as elements of a systematic framework which humans use to structure their experience. In the 19th and 20th centuries mathematicians began to examine [[non-Euclidean geometry|non-Euclidean geometries]], in which space can be said to be ''curved'', rather than ''flat''. According to [[Albert Einstein|Albert Einstein's]] [[theory of general relativity]], space around [[gravitational field]]s deviates from Euclidean space.<ref>Carnap, R. An introduction to the Philosophy of Science</ref> Experimental [[tests of general relativity]] have confirmed that non-Euclidean space provides a better model for explaining the existing laws of [[mechanics]] and [[optics]]. ==In philosophy== {{main|Philosophy of space and time}} Space has a range of definitions: *One view is that it is a fundamental part of the structure of the universe, a set of [[dimension]]s through which [[object (philosophy)|objects]] move. *A contrasting view is that ''space'' is part of a fundamental [[Abstract structure|abstract]] mathematical [[concept]]ual framework (together with [[time]] and [[number]]) within which we compare and [[quantity|quantify]] the distance between objects, their sizes, their shapes, and their speeds. In this view, ''space'' does not refer to any kind of entity that is a "container" that objects "move through". These opposing views are also relevant to definitions of time. Space is typically described as having three dimensions, see [[Three-dimensional space]] and that three numbers are needed to specify the size of any object and/or its location with respect to another location. Modern [[physics]] does not treat space and time as independent dimensions, but treats both as features of [[space-time]] &ndash; a conception that challenges intuitive notions of distance and time. An issue of [[philosophy|philosophical]] debate is whether space is an [[ontology|ontological]] entity itself, or simply a [[concept]]ual framework humans need to think (and talk) about the world. Another way to frame this is to ask, "Can space itself be measured, or is space part of the measurement system?" The same debate applies also to time, and an important formulation in both areas was given by [[Immanuel Kant]]. In his ''[[Critique of Pure Reason]]'', Kant described space as an ''[[A priori and a posteriori (philosophy)|a priori]]'' intuition that (together with another ''a priori'' intuition, time) allows us to comprehend sensual experience. Kant referred to such intuitions as ''[[noumenon|noumena]]'' and as ''things in themselves''. In Kant's view, neither space nor time are conceived of as [[Substance theory|substances]], but rather both are elements of a systematic [[framework]] we use to structure our experience. Spatial [[measurement]]s are used to quantify how far apart objects are, and temporal measurements are used to quantify how far apart [[Event (philosophy)|events]] occur. However, these measurements are applied by our minds to categorize what we sense and are not an inherent part of the thing in itself. Similar philosophical questions concerning space include: Is space absolute or purely relational? Does space have one correct geometry, or is the geometry of space just a convention? Historical positions in these debates have been taken by [[Isaac Newton]] (space is absolute), [[Gottfried Leibniz]] (space is relational), and [[Henri Poincaré]] (spatial geometry is a convention). Two important thought-experiments connected with these questions are: Newton's [[bucket argument]] and Poincaré's [[sphere-world]]. [[Image:Order-3 heptakis heptagonal tiling.png|thumb|right|A tiling of the plane with appropriate geometric distortion gives rise to unbounded hyperbolic geometry within a bounded space, this boundedness would not be visible to an inhabitant of the plane that was subject to the distortion]] However, attempts to prove the axioms continually failed, and finally it was discovered that multiple axioms could be constructed that gave different geometries, [[non-Euclidean geometry|non-Euclidean geometries]], but that appeared Euclidean at very small sizes. This raised the question whether the nature of space itself at large scales was Euclidean or not. In modern mathematics, spaces are frequently described as different types of [[manifold]]s which are spaces that locally approximate to Euclidean space and where the properties are defined largely on local connectedness of points that lie on the manifold. ==Physics== ===Classical mechanics=== {{Classical mechanics|cTopic=Fundamental concepts}} Space is one of the few [[fundamental]] quantities in [[physics]], meaning that it cannot be defined via other quantities because nothing more fundamental is known at the present. On the other hand, it can be related to other fundamental quantities. Thus, similar to other fundamental quantities (like [[time]] and [[mass]]), space can be explored via [[measurement]] and experiment. ===Astronomy=== {{main|Astronomy}} [[Astronomy]] is the science involved with the observation, explanation and measuring of objects in [[outer space]]. ===Relativity=== {{main|Theory of relativity}} Before [[Einstein]]'s work on relativistic physics, time and space were viewed as independent dimensions. Einstein's discoveries have shown that due to relativity of motion our space and time can be mathematically combined into one object &mdash; [[spacetime]]. It turns out that distances in [[Spacetime#Space-like_interval|space]] or in [[Spacetime#Time-like_interval|time]] separately are not invariant with respect to Lorentz coordinate transformations, but distances in Minkowski space-time along [[Spacetime#Space-time_intervals|space-time intervals]] are &mdash; which justifies the name. In addition, time and space dimensions should not be viewed as exactly equivalent in Minkowski space-time. One can freely move in space but not in time. Thus, time and space coordinates are treated differently both in [[special relativity]] (where time is sometimes considered an [[imaginary number|imaginary]] coordinate) and in [[general relativity]] (where different signs are assigned to time and space components of [[spacetime]] [[metric tensor|metric]]). Furthermore, from [[Einstein's general theory of relativity]], it has been shown that space-time is geometrically distorted- ''curved'' -near to gravitationally significant masses.<ref>chapters 8 and 9- John A. Wheeler "A Journey Into Gravity and Spacetime" Scientific American Library isbn = 0-7167-6034-7</ref> Experiments are ongoing to attempt to directly measure [[gravitational wave]]s. This is essentially solutions to the equations of general relativity which describe moving ripples of spacetime. Indirect evidence for this has been found in the motions of the [[Hulse-Taylor binary]] system. ===Cosmology=== {{main|Shape of the universe}} Relativity theory lead to the [[cosmology|cosmological]] question of what shape the universe is, and where space came from. It appears that space was created in the [[Big Bang]] and has been expanding ever since. The overall shape of space is not known, but space is known to be expanding very rapidly which is evident due to the [[Hubble expansion]]. ==Spatial measurement== {{main|Measurement}} The measurement of ''physical space'' has long been important. Although earlier societies had developed measuring systems, the [[SI|International System of Units]], (SI), is now the most common system of units used in the measuring of space, and is almost universally used within [[science]]. Currently, the standard space interval, called a standard meter or simply [[meter]], is defined as the [[speed of light|distance traveled by light in a vacuum]] during a time interval of exactly 1/299,792,458 of a second. This definition coupled with present definition of the [[second]] is based on the [[special theory of relativity]], that our [[space-time]] is a [[Minkowski space]].{{Fact|date=May 2008}}<!-- sounds very, very wrong, space-time isn't Minkowski, general relativity superceded special, and it isn't Minkowski space - Minkowski is flat---> ==Geography== [[Geography]] is the branch of science concerned with identifying and describing the [[Earth]], utilizing spatial awareness to try and understand why things exist in specific locations. [[Cartography]] is the mapping of spaces to allow better navigation, for visualization purposes and to act as a locational device. [[Geostatistics]] apply statistical concepts to collected spatial data in order to create an estimate for unobserved phenomena. Geographical space is often considered as [[land]], and can have a relation to [[ownership]] usage (in which space is seen as [[property]] or [[territory]]). While some cultures assert the rights of the individual in terms of ownership, other cultures will identify with a communal approach to land ownership, while still other cultures such as [[Australian Aboriginals]], rather than asserting ownership rights to land, invert the relationship and consider that they are in fact owned by the land. [[Spatial planning]] is a method of regulating the use of space at land-level, with decisions made at regional, national and international levels. Space can also impact on human and cultural behavior, being an important factor in [[architecture]], where it will impact on the design of buildings and structures, and on [[farming]]. Ownership of space is not restricted to land. Ownership of [[airspace]] and of [[International waters|waters]] is decided internationally. Other forms of ownership have been recently asserted to other spaces &mdash; for example to the [[radio]] bands of the electromagnetic [[spectrum]] or to [[cyberspace]]. [[Public space]] is a term used to define areas of land as collectively owned by the community, and managed in their name by delegated bodies; such spaces are open to all. While [[private property]] is the land culturally owned by an individual or company, for their own use and pleasure. [[Abstract space]] is a term used in [[geography]] to refer to a hypothetical space characterized by complete homogeneity. When modeling activity or behavior, it is a conceptual tool used to limit [[extraneous variables]] such as terrain. ==In psychology== The way in which space is perceived is an area which psychologists first began to study in the middle of the 19th century, and it is now thought by those concerned with such studies to be a distinct branch within [[psychology]]. Psychologists analyzing the perception of space are concerned with how recognition of an object's physical appearance or its interactions are perceived. Other, more specialized topics studied include [[amodal perception]] and [[object permanence]]. The [[perception]] of surroundings is important due to its necessary relevance to survival, especially with regards to [[hunting]] and [[self preservation]] as well as simply one's idea of [[personal space]]. Several space-related [[phobia]]s have been identified, including [[agoraphobia]] (the fear of open spaces), [[astrophobia]] (the fear of [[celestial]] space), [[claustrophobia]] (the fear of enclosed spaces), and [[cenophobia]] (the fear of empty spaces). ==See also== {{Wikiquote}} {{wiktionary}} *[[Aether theories]] *[[Cosmology]] *[[Curvature#3_dimensions:_Curvature_of_space|Curvature of space]] *[[Personal space]] *[[Shape of the universe]] *[[Space exploration]] *[[Spatial analysis]] ==References== {{reflist}} [[Category:Spacetime]] [[Category:Topology]] [[Category:Environments]] [[Category:Nothing]] [[ar:مكان (فيزياء)]] [[ca:Espai]] [[da:Rum]] [[de:Raum]] [[el:Χώρος]] [[es:Espacio]] [[eo:Spaco]] [[fa:فضا]] [[fr:Espace (notion)]] [[gl:Espazo]] [[ko:공간]] [[io:Spaco]] [[id:Ruang]] [[ia:Spatio]] [[it:Spazio]] [[he:מרחב]] [[hu:Tér]] [[mk:Простор]] [[nl:Ruimte (geografie)]] [[ja:空間]] [[uz:Fazo]] [[pl:Przestrzeń]] [[pt:Espaço]] [[ru:Пространство]] [[sq:Hapësira]] [[simple:Space]] [[sl:prostor]] [[fi:Avaruus]] [[sv:Rymden]] [[tr:Uzay]] [[uk:Простір]] [[bat-smg:Pluotmie]] [[zh:空间]]