Now, if this, if the inside was replaced with, say, salad or liquid, I wouldn't be able to push it without changing the volume. Notice how when I'm pushing this I'm not really affecting the volume too much, right? And that's why I'm able to push it, I'm compressing it. And the reason for that is this following idea. Now, the volume of the inside of the ball is much greater than the volume that is taken up by these molecules. In other words, any two molecules at any given time are very far apart.