Let's say I have a 5m3 cube of air and right next to it a 5m3 vacuum. Does the cube of air have potential energy? According to that, the potential energy would be converted into kinetic energy when the cube of air and the vacuum were joined. Would vacuum energy be the initial potential energy of the air? And apparently (I read in a thread here) that vacuum energy constant will double in 11 billion years? Does that mean that the cube of air in 11 billion years will have more potential vacuum energy? Doesn't really make a lot of sense in the big picture.