Studies have been done in the city of New York where you can-- if you live in Manhattan you can actually get a very nice metric of how far apart people live from each other in city blocks. Right?

纽约市就做过这类实验,在纽约-,如果你生活在曼哈顿,你能准确地测量,生活不同街道的人相互距离多远？

耶鲁公开课 - 心理学导论课程节选

First there was the observation by Michelson who back in the late 1880s had done very precise interferal metric measurements of the hydrogen lines and had observed that the 656 nanometer line 3 associated with the transition of n equals 3 to n equals 2 was, in fact, a doublet.

首先是麦克逊,在1880年底的观察,他以公制单位对氢原子的光谱线,作了准确的，无其他因素干扰的，测量,发现当n值由3变为2时,会同时得到波长为656纳米的谱线3,实际上是有两条线。

麻省理工公开课 - 固态化学导论课程节选