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A number of independent lines of research depict the universe, including the social organization of living creatures which is of particular interest to humans, as systems, or networks, of relationships. In physics and philosophy, a relational theory is a framework to understand reality or a physical system in such a way that the positions and other properties of objects are only meaningful relative to other objects. In a relational spacetime theory, space does not exist unless there are objects in it; nor does time exist without events. Space can be defined through the relations among the objects that it contains considering their variations through time. The relational point of view was advocated in cosmological physics by Gottfried Wilhelm Leibniz, Ernst Mach (in his Mach's principle). Although Albert Einstein was impressed by Mach's principle, he did not fully incorporate it into his general theory of relativity. Several attempts have been made to formulate a full Machian theory, but none has as yet succeeded in gaining broad acceptance. For example, see Brans–Dicke theory. Basic physics has assumed and characterized distinctive regimes of relationships. For common examples, gases, liquids and solids are characterized as systems of objects which have among them relationships of distinctive types. Gases contain elements which vary continuously in their spatial relationships as among themselves. In liquids component elements vary continuously as to angles as between themselves, but are restricted as to spatial dispersion. In solids both angles and distances are circumscribed. These systems of relationships, where relational states are relatively uniform, bounded and distinct from other relational states in their surroundings, are often characterized as phases of matter, as set out in this encyclopedia in Phase (matter) These examples are only a few of the sorts of relational regimes which can be identified, made notable by their relative simplicity and ubiquity in the universe. Such Relational systems, or regimes, can be seen as defined by reductions in degrees of freedom among the elements of the system. This diminution in degrees of freedom in relationships among elements is characterized as correlation. In the commonly observed transitions between phases of matter, or phase transitions, the progression of less ordered, or more random, to more ordered, or less random, systems is recognized as the result of correlational processes (e.g. gas to liquid, liquid to solid). In the reverse of this process, transitions from a more-ordered state to a less ordered state, as from ice to liquid water, are accompanied by the disruption of correlations. Correlational processes have been observed at several levels. For example, atoms are fused in suns, building up aggregations of nucleons, which we recognize as complex and heavy atoms. Atoms, both simple and complex, aggregate into molecules. In life a variety of molecules form extremely complex dynamically ordered living cells. Over evolutionary time multicellular organizations developed as dynamically ordered aggregates of cells. Multicellular organisms have over evolutionary time developed correlated activities forming what we term social groups. Etc. Thus, as is reviewed below, correlation, i.e. ordering, processes have been tiered through several levels, reaching from quantum mechanics upward through complex, dynamic, 'non-equilibrium', systems, including living systems. == Quantum Mechanics == Lee Smolin〔''The Life of the Cosmos'', Lee Smolin, Oxford University Press, 1997〕 proposes a system of "knots and networks" such that "the geometry of space arises out of a … fundamental quantum level which is made up of an interwoven network of … processes".〔Smolin, supra. p. 283〕 Smolin and a group of like minded researchers have devoted a number of years to developing a loop quantum gravity basis for physics, which encompasses this relational network viewpoint. Carlo Rovelli initiated development of a system of views now called Relational quantum mechanics. This concept has at its foundation the view that all systems are quantum systems, and that each quantum system is defined by its relationship with other quantum systems with which it interacts. The physical content of the theory is not to do with objects themselves, but the relations between them. As Rovelli puts it: "''Quantum mechanics is a theory about the physical description of physical systems relative to other systems, and this is a complete description of the world''".〔Rovelli, C. (1996), "Relational quantum mechanics", ''International Journal of Theoretical Physics'', 35: 1637-1678.〕 Rovelli has proposed that each interaction between quantum systems involves a ‘measurement’, and such interactions involved reductions in degrees of freedom between the respective systems, to which he applies the term correlation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Relational order theories」の詳細全文を読む スポンサード リンク
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