To select a good reference frame to avoid some phys difficulty
As the reference frame based in this universe, the universe is secret enough in phys, like first explosion, huge action between mass and so on. To select the reference frame from this universe is to meet some phys difficulty. It is necessary to select another reference frame to avoid the light speed limit, relativity, no permitted to measurement and to seek truch in exceed light speed process easy.
It will be a good reference frame for phys future easy.