Independent unit steps with uniformly random directions have zero mean. Cross terms cancel in the expected squared displacement, leaving one contribution per step; typical distance grows like the square root of elapsed steps.方向均匀随机的独立单位步长，均值为零。位移平方的期望中交叉项相消，每一步贡献一项，因此典型距离按步数的平方根增长。
Eight fixed sample paths unfold together. The gold circle has radius , an ensemble root-mean-square scale, not a boundary that confines individual walks.八条固定样本轨迹一起展开。金色圆半径为 ，表示总体均方根尺度，并非限制每条轨迹的边界。