it does not matter if you are on a fast space ship or on the ground here - velocity is the same. Gravity is the same, Mass is the same. But the 'difference' changes it all and that has nothing to do with physics it is perspective. Geometry. How you view it from your point. The angle of shift - that is defined by the shift in the 4D space time grid.
They call this relativity - but what is it comes down to speed/velocity never changes just he angles of perspective!!!!!!!!!!!!