Sorry, strange question, but let's do a thought experiment: if a train was moving at near light speed and hit a slow moving object on the tracks, would the two timelines synchronize? since the train is moving at near light speed, according to relativity, time on the train would slow down relative to stationary objects. However, once they hit, it would not be possible that they would be in the same timeline because such a synchronization would mean that in effect, time travel would be possible. but if the timelines are not synchronized, wouldn't we have a strange state of affairs where two different timelines existed side by side??