One of the interesting properties of cells that are in exponential growth is that the time to increase the cell number by a factor of 2 is always the same.

细胞有一个有趣的性质,那就是在指数增长阶段,细胞增长的速度,永远是以二为底数来增长的

耶鲁公开课 - 生物医学工程探索课程节选