So what will happen? Well, some of these guys will evaporate and some of these guys will evaporate and they will begin moving. But they won't move directly from this point to this point. They will move via a crooked path because of something called the mean free path because there are air molecules present. And these air molecules will create collisions. And this green molecule, for example, will first collide with this guy, then move here, close the wall, then collide with this guy, and so on until it gets to some point here.