Time dilation... but for who?? I was reading Einstein's postulate that if two bodies A and B are moving relative to one another it is impossible to truely discern whether one of the bodies is stationary and the other is moving (i.e. we can only speak of their relative motion). However, special relativity claims that as a body approaches light speed, time (for that body) slows down. But this seems to contradict the postulate that motion is always relative. If motion can only be described in relative terms, then wouldn't time slow down for both bodies compared with the other?