Because of the physics of diffusion it doesn't go linearly with distance.

由于扩散现象的物理特性,它和距离不是线性相关的

耶鲁公开课 - 生物医学工程探索课程节选

So one way to think about it is, is the expected distance from her of the winning candidates, is: with probability of a half it's herself so that's nothing, No distance, and with probability of a half it's two places away.

所以一种考虑的方法是,预期她与获胜者的距离是,由于她有一半获胜的机会所以没有成本,没有距离,且,距她两个位置远的人有另一半获胜的机会

耶鲁公开课 - 博弈论课程节选

These details aren't important, it is described in your book, but the thing that is important to know is that diffusion occurs fast over short distances, but because of the physics of diffusion it occurs slowly over longer distances.

这些具体细节无关轻重,书上都有,重点是你要明白,距离越短扩散越快,由于扩散现象的物理特性,距离越长扩散越慢

耶鲁公开课 - 生物医学工程探索课程节选