我们可以在宇宙里遥远的地方测量阿尔法常数，从而通过研究这些原子光谱线回到过去。

And alpha is something that we can measure at distant places in the universe and thereby back in time by looking at these atomic spectral lines.

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为了确定在任一给出的位置的alpha常数的强度，科学家们测量了不同原子的电子从一个能级跃迁到另一能级的频率。

To determine how strong the alpha constant was in any given spot, the scientists measured the frequency at which electrons in various atoms would hop from one energy level to the next.

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平均光子数、场模与原子耦合常数的变化对光子统计性质的影响也很明显；

The influences of the atom-field coupling constant and the mean photon number on the statistic properties of photon are noticeable.

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It is joules per atom. Or, if you multiply by Avogadro's number then you will get joules per mole.

焦耳每个原子，或者，如果乘以,阿伏伽德罗常数你会得到焦耳数每摩尔。

麻省理工公开课 - 固态化学导论课程节选

And what I am going to do is say start with this ion, add up the energy associated with the interactions between that ion and everybody else in the row and then multiply it by Avogadro's number, because that is the number of atoms there are in a row.

接下来我要从这一离子开始，加上相互作用的能量，也就是这一离子,和其它所有在这一行的离子之间的能量,再乘以阿伏加德罗常数，因为这是在一行的原子的数量。

麻省理工公开课 - 固态化学导论课程节选

We're going to get to more complicated atoms eventually where we're going to have more than one electron in it, but when we're talking about a single electron atom, we know that the binding energy is equal to the negative of the Rydberg constant over n squared, so it's only depends on n.

我们以后会讲到，更加复杂的情况,那时候,不只有一个原子，但当我们讲，单个原子的时候，我们知道结合能，等于,负的Rydberg常数,除以n平方，所以它仅仅由n决定的。

麻省理工公开课 - 化学原理课程节选