英和和英

出典:『Wikipedia』 (2011/03/02 22:32 UTC 版)

英語による解説

引用

In standard cosmology, comoving distance and proper distance are two closely related distance measures used by cosmologists to define distances between objects. Proper distance roughly corresponds to where a distant object would be at a specific moment of cosmological time, measured using a long series of rulers stretched out from our position to the object's position at that time, and which can change over time due to the expansion of the universe. Comoving distance factors out the expansion of the universe, giving a distance that doesn't change over time, though it is defined to be equal to the proper distance at the present time.