It cannot be done and man harms himself by attempting to do it. To butt against God's natural laws brings physical punishment and death to those who do it. Man must conform to God's laws and not go against them. By learning and following them he will gain natural strength and permanent happiness. A difference in density causes Penetrability.
Lesser density is volume and greater density is mass.
Mass falls toward volume which causes pressure. Space made vacant by falling mass creates a vacuum, or space with lesser density, which draws to it substances of greater density and this process is Suction. As mass falls toward a Suction point it leaves a Suction point behind which draws mass from another point and so on eternally. That is why matter does not always fall in the same direction. Suction and Pressure is the power of movement, no substance could move without it.