So you can see, if it's spinning on its own axis in this direction we'd call it spin up, where as this way it would be what we call spin down.

你们可以看到，如果它绕自己的轴朝这个方向转,我们就说它是自旋朝上，这个方向我们叫它自旋朝下。

麻省理工公开课 - 化学原理课程节选