Comment by rfhjt

So space expands itself at every point at a certain rate. There is an elephant in the room here: how do all the parts in space coordinate to expand at about the same steady rate? Why don't we see radically different expansion rates in different parts of the universe, e.g. stars on the left are getting further apart 10x faster than those on the right? We often use the air balloon analogy, but an air ballool is inflated by the same force which equally applies to every part of the balloon. My point is that, there is probably a simple underlying mechanism that drives space expansion and the clever nature of this mechanism would explain the relativity axiom used in GTR.