Pressure can exist in a container of gas even if there is no gravity. From kinetic theory of gases it is assumed that pressure exists due to momentum transfer between molecules and the wall. Suppose I have a closed container on Earth at sea level filled with air. Now I carried it to zero gravity facility. I maintained all other thermodynamic parameter like volume and temperature. Now pressure should decrease as gravitational force is not pulling individual gas molecules. Therefore there should be less momentum of particles so the pressure. Please just give me insight to my thought whether I am current or not?