Okay, we can solve the special case where the corpuscles are confined

我们现在讨论的是处在同一平面的微粒子
to a plane, if you do it in two dimensions--

它们处在二维的空间
it's difficult mathematically in three dimensions--

三维空间在数学上难以处理
but you can do it in two dimensions.

但二维空间的就相对容易
And he gives a picture in this book, lke this,

汤姆斯在这本书上给了像这样的一张图
which is a solenoid magnet that attracts little needles

螺线状的磁铁对磁化的针产生吸引
that are magnetized, and those needles are stuck into corks,

针是插在软木塞里面的
which float in the water, right?

这样它们就能浮在水面上
So they have to,

这样一来
the corks have to stay at the level of the surface of the water.

针就可以处在同一个水平面上
So it's a two-dimensional problem.

问题就这样变成二维世界里的了
The needles are parallel, the magnets,

磁针在水里平行排列