| 翻訳と辞書 |
| Quantification of randomness ： ウィキペディア英語版 |
Quantification of randomness
Randomness is an extremely ambiguous word not only in everyday language but also or even especially in science. Almost each branch of science has its own interpretation and hence own ways of handling the characteristic randomness. This confused situation is typical whenever there is no generally acknowledged unit defined for a characteristic.
The fact that there is no standard unit for randomness has strange consequences. For example, the probability that an interaction of a given kind will take place between a nucleus and an incident neutron is called cross-section or "effective cross-sectional area" and the unit for the probability is given as square centimeter.〔In nuclear physics often the non-SI unit ''barn'' is used where 1 ''barn'' = 10−24.〕
==Quantification==
Any characteristic in the physical world can adopt one out of a set of values. Quantification of a characteristic may have several meanings, however, according to the Free Dictionary it is used for "the act or process of assigning numbers to phenomena according to a rule".〔Free Dictionary ().〕 Accordingly, quantification of a characteristic means that the set of values of the characteristic is mapped on a suitable set of numbers. In other words, a characteristic is represented by a variable. The rules take care that all the relations like order, distance or a natural zero among the values of the characteristic are preserved within the obtained set of real numbers. An appropriate quantification necessitates therefore that the relations and hence the nature of the characteristic are sufficiently well understood. In physics metric characteristics〔A characteristic is called "metric", if there is a notion of distance (called a metric) defined among the elements of its set of values.〕 are of interest and quantification of a metric characteristic is obtained by selecting, for example, the values which are mapped on the real numbers 0 and 1, where the letter is called unit with a particular name like meter, mass or second.
An appropriate quantification of a characteristic is a difficult task as illustrated by the development of the International System of Units (SI). For example, the evolution of quantification of the characteristic "length" started in 1872 with deciding to produce a prototype of the metre. In 1892−93 the Michelson interferometer was used to determine the length of the metre in terms of the wavelength of the red line of cadmium. In 1960 the CGPM adopted a definition of the metre in terms of the wavelength in vacuum of the radiation corresponding to a transition between specified energy levels of the krypton 86 atom and finally in 1997 the CIPM modified the 1992 instructions for the practical realization of the definition by further reducing the uncertainties and increasing the number of recommended radiations from eight to twelve. However, work continues at the BIPM and elsewhere to identify those factors that at present limit the reproducibility of lasers as wavelength and frequency standards.〔The BIPM and the evolution of the definition of the metre, ().〕
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「Quantification of randomness」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|