The bonds are like one and a half angstroms.

一个化学键的长度大约有1.5埃
So it's like a part in a thousand,

所以他们精确到了千分之一
is the precision to which the positions of the atoms is known.

也就是我们所知的原子位置的精度
But those positions are average positions,

但这些原子的位置只是个平均值
because the atoms are constantly in motion, vibrating.

因为原子是不停运动的它们会振动
In fact, the typical vibration amplitude,which depends on --

而原子的振幅一般来说取决于
an atom that's off on the end of something is more floppy than one

处在分子末端的原子比连结很多键的原子
that's held in by a lot of bonds in various directions,

比如那些在笼里的原子
in a cage sort of thing

要柔软的多
But typically they're vibrating by about 0.05 angstroms,

但总的来说它们的振幅在约0.05埃
which is twenty-five times as big as the precision

是所知的原子平均位置精度的
to which the position of the average is known.

25倍