One way to think about it, if we want to use a classical analogy, which often helps to give us an idea of what's going on, is the spin of an electron, we can picture it rotating on its own axis.

如果我们用一个，经典的比喻来考虑它的话，这经常会帮助我们建立起一些概念，就是我们可以把电子的，自旋想象是它绕着轴自转。

麻省理工公开课 - 化学原理课程节选

So that means that we don't have to worry about things like wave functions when we're talking about Lewis structures, but because they're so simple to use and because they so often predict the electron configuration of molecules accurately, we end up using them all the time in chemistry, so it's very valuable to know how to draw them correctly and to know how to work with them.

因此这也就意味着我们在讨论路易斯结构的时候,不需要担心波函数之类的东西，但是由于路易斯结构不仅简单易用,而且用它来预测分子的电子排布,经常可以得到非常精确的结果，结果我们在化学中一直都在用它，因此知道如何正确地画出并运用,路易斯结构是非常有价值的。

麻省理工公开课 - 化学原理课程节选

The most common one and the one we're going to use, is what's often called big Oh notation.

也就是我们即将用的方法,就是通常被叫做大O的方法，它叫大O并不是因为。

麻省理工公开课 - 计算机科学及编程导论课程节选

What we need to do is get rid of the Coulomb tag that we have - that's how we measure our electron charges - charge, and so we use this epsilon nought quite often, this permativity constant of a vacuum to make that conversion.

怎么量度电子电荷,所以我们会经常用到,这个epsilon，nought记号,这是真空中的介电常数,我们还要指出,这个介电常数。

麻省理工公开课 - 化学原理课程节选

And that's just a way of reminding you that we want to think carefully, but what are the things we're trying to measure when we talk about complexity here? It's both the size of the thing and how often are we going to use it? And there are some trade offs, but I still haven't said how I'm going to get an n log n sorting algorithm, and that's what I want to do today.

这只是在提醒你们我们要仔细的思考问题,但是当我们在讨论复杂性的时候,我们到底要衡量哪些东西？,是列表的大小和对其进行查找的频率吗？,这里面临一些取舍,但是我还没有说明,怎样得到一个n，log，n复杂度的排序算法,并且这是我今天想要讲的内容。

麻省理工公开课 - 计算机科学及编程导论课程节选