The world shows to us as something into which we can go forward.
The world is empty for us before we effectively go forward into it.
Though to go forward belongs to us, our advance gets a meaning only by receiving content from those parts of the world through which we go.
Thus, world can be defined as the intercross between our advance and those things we meet while going forward.
In this way, we need not a physical theory for grasping the relativity of the world.
The contrary belief is the common image that we belong or are included into the world. Though common, that image is ever external to our personal experience of the world.
Besides, it is always based on the wrong conception according to which what we know about world is precisely what everybody knows. In this case, we take the geographical representations of the world as images able to replace the personal experience into it.