> Another thing to remember is that Special Relativity makes *no* distinction between inertial reference frames. All are equally valid. Therefore, if I go out in a space ship towards Alpha Centauri at fifteen percent the speed of light (.15c), *you* can say that I am moving at .15c with respect to you, but *I* can also say that you and the whole Earth is receding from me at .15c--and I'd be just as right as you, as far as SR is concerned. I leave it as an exercise to the reader to find the apparent paradox in that statement with respect to time dilation ;-)

A challenge! The apparent paradox is that I, on planet Earth, will look at your ship's clock and observe that your clock is running more slowly than mine. Time, therefore must be moving faster for me than for you. However, you, in your ship, will look at my clock and observe that it's running more slowly than yours. Time must, you say, be moving faster for you than it is for me. Intuitively, we think both cannot be true. But the paradox is only apparent because both *are* true.