Suppose you were in a craft travelling at 0.5c towards an alien planet. That alien planet has been sending out TV broadcasts for the past hundred years. Those broadcasts are moving towards your craft at c. Will those broadcasts play at twice the speed? Is this what is meant by 'time dilation at relativistic speeds'? That massless particles from the rest frame are hitting you at twice the rate? Or, rather, the information carried by those particles seems to be twice as fast? Wouldn't that make dilation directional? And how about if you were moving away from Earth at 0.5c. Would the TV broadcasts play at half the speed? Furthermore, what is the rate of 'time slowing down in relation to the rest frame' as you approach c? I mean, if 1s = 1s at 0c, then what would 1s be at 0.25c? 0.5c? 0.75c? Is there a function that covers this? Just a little something that popped into my head the other day when I heard about the SETI signal.