Has there ever been an experiment to support the principle assumption of relativity? For example an experiment where an atomic clock is sent on a probe to , let's say, Pluto. We on earth get transmissions of the time on that ship and, after taking account of the light travel time delay, we compare that clock to one on earth. We should see that clock ticking slower than ours as we do with GPS satellites (minus the gravitational effect). The computer on board the ship would also be receiving transmissions of earth time. It would also post-process these and, according to relativity, it must see our clocks slowed in relation to its on board clock. This must be so as relativity forbids a preferred frame of reference, there's no way to tell if the ship is moving away from us or we are moving away from the ship. But I think the experiment would show that the on board computer would see our time ticking faster, not slower than it's own.If the experiment proved this, then there would be a way to determine who is actually moving in a relative velocity scenario just by comparing the relative time rate between the clocks in the two frames. The one clock that sees the other ticking faster is the clock on the relatively moving timeframe and the other is the relatively stationary timeframe. I assume there's a huge gaping hole in my logic and it's been brought up countless times in the past? Wouldn't this experiment settle if the basic assumption of relativity is correct or not based on experimental evidence?