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·八戒· 發表於 2012-7-9 21:10
咱倆說的是兩回事兒。你說的「抽象」就屬於純「理論」上的抽象,而不是現實的抽象。因為真實世界所有物質 ...
我想也是.我們說的 "圓","抽象", "原子半徑", "Angstrom", "精確","精度"都不是一回事. 所以建議先把語言文字定義清楚了, 然後再判斷對錯. 比如"原子半徑", wiki 定義如下:
The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the nucleus to the boundary of the surrounding cloud of electrons. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius.
Despite these conceptual difficulties, under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 angstroms. Therefore, the radius of an atom is more than 10,000 times the radius of its nucleus (1–10 fm),[2] and less than 1/1000 of the wavelength of visible light (400–700 nm). |
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