Mary Poppins is the gatekeeper to the fifth dimension. She has a special way that she floats through the air with her umbrella. There are these particles all around us that are going in all directions and they move things. For the most part, they go downward and that is what causes gravity. The more massive the object is, the heavier it is. Well, Mary Poppins has a very small, massive section of matter in the tip of her umbrella that emits anti-particles. With this, she can control the opening of wormholes, which is in each object and is what keeps these particles refreshed in the universe by transporting them to the edge of the universe and letting them start over. These wormholes allow her to go to the fifth dimension and limbo and anywhere she wants. She even controls masses of things when she wants to.
This is an example of what I learned in Governor's School for the Sciences :-)