Remember in Flatland how the sphere touches the square's insides and then pulls him out of his plane? Well, what prevents normal occurences and forces, such as wind or gravity, from doing the same. For example, wouldn't a wind moving perpendicular to Flatland brush against the square's insides and be very painful? Or, couldn't a stronger wind knock him out of the plane?
Now, take this to the next level. Could a tetral wind injure us, or blow us out of realmspace? And, if it can, can it be assumes that there is no wind outside our "realm"?
Seldon