We are able to predict, measure and mathematically demonstrate time dilation, but are we able to explain 'why' it happens? what would be that explanation?
Edit1
Think the question backwards:
After some time traveling in space they noticed that the clock that was on the shuttle was always running a few seconds back... they also noticed that the difference was larger when the traveling speed was greater... So why, the faster we travel, "slower" time passes?
Edit2
People keep saying "it is because it is" (or something like that)... so Time Dilation is a Axiom?