Put some stuff on your table. Now take a pen and rotate it so that the things would be pushed away. Now you have more space on your table. Instead of those things now you have air of the atmosphere that ha gone to the place where things were.

This is gravity, particles spin (rotate), push things away and there is a replacement effect called gravity. When this happens with lots of things rotating the effect is more intense.

This is the theory that is now official because the Owner has adopted it. In case something better is shown I can revoke the theory. This would be done by myself, the smartest one on Earth.