Actually, the analogy is rather correct. They both describe highly improbable events. The gas molecules in the air don't know anything about the room's overall

Actually, the analogy is rather correct. They both describe highly improbable events. The gas molecules in the air don't know anything about the room's overall pressure, and don't individually obey any "pneumatic" laws. Pressure, in essence, is just a huge amount of molecules bouncing off a surface. The air in a room is usually very evenly distributed, because it would be extremely unlikely that all the molecules happened to be in the same half. Here's a link that might explain it better: http://webs.morningside.edu/slaven/physics/entropy/entropy3.html http://webs.morningside.edu/slaven/physics/entropy/entropy3....