redshift time does'nt flow in any direction its more like multiple ripples in a large pond you can start on one wave and end up on an entirely different one. Case in point you can go to the point in space earth occupied last week the earth itself is'nt there anymore in 3d space time but if you knew how to to negotiate the ripples in time caused by causality you can find the 4th point of reference you need to navigate to to the past also although much trickier if you can calculate the possible events of the next week you could navigate the future point of the earth effectively visiting the future. Disclaimer: dont try this with your home PC unless you like to cook eggs on it..