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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Dirac large numbers hypothesis ： ウィキペディア英語版 Dirac large numbers hypothesis The Dirac large numbers hypothesis (LNH) is an observation made by Paul Dirac in 1937 relating ratios of size scales in the Universe to that of force scales. The ratios constitute very large, dimensionless numbers: some 40 orders of magnitude in the present cosmological epoch. According to Dirac's hypothesis, the apparent equivalence of these ratios might not be a mere coincidence but instead could imply a cosmology with these unusual features: *The strength of gravity, as represented by the gravitational constant, is inversely proportional to the age of the universe: $G\; \backslash propto\; 1/t\backslash ,$ *The mass of the universe is proportional to the square of the universe's age: $M\; \backslash propto\; t^2$. Neither of these two features has gained wide acceptance in mainstream physics. == Background == LNH was Dirac's personal response to a set of large number 'coincidences' that had intrigued other theorists at about the same time. The 'coincidences' began with Hermann Weyl (1919),〔 〕〔 〕〔 〕 who speculated that the observed radius of the universe, ''R''U, might also be the hypothetical radius of a particle whose rest energy is equal to the gravitational self-energy of the electron: :$\backslash frac\; \backslash approx\; \backslash frac\; \backslash approx\; 10^\; ,$ :$r\_e\; =\; \backslash frac\; ,$ :$r\_H\; =\; \backslash frac\; ,$ :$m\_H\; c^2\; =\; \backslash frac$ where ''r''e is the classical electron radius, ''m''e is the mass of the electron, ''m''H denotes the mass of the hypothetical particle, and ''r''H is its electrostatic radius. The coincidence was further developed by Arthur Eddington (1931)〔 〕 who related the above ratios to N, the estimated number of charged particles in the universe: :$\backslash frac\; \backslash approx\; \backslash sqrt\; \backslash approx\; 10^.$ In addition to the examples of Weyl and Eddington, Dirac was influenced also by the primeval-atom hypothesis of Georges Lemaître, who lectured on the topic in Cambridge in 1933.〔 The notion of a varying-G cosmology first appears in the work of Edward Arthur Milne a few years before Dirac formulated LNH. Milne was inspired not by large number coincidences but by a dislike of Einstein's general theory of relativity.〔 〕〔 〕 For Milne, space was not a structured object but simply a system of reference in which Einstein's conclusions could be accommodated by relations such as this: :$G\; =\; \backslash left(\backslash frac\backslash right)t,$ where ''M''U is the mass of the universe and ''t'' is the age of the universe in seconds. According to this relation, ''G'' increases over time. 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「Dirac large numbers hypothesis」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.