From the reference point outside, say "at rest," how much time passes on an object raveling at the speed of light?Einstein used this thought experiment: Imagine you are traveling on a beam of light away from and looking back at a clock tower. Do the hands of the clock move?
Is the tower moving at the same speed too? I always used to think of ti as a trick question while thinking of the movie "Around the World in Eighty Days" where the traveler, moving east, "gains" a day. Of course, it is all artificial. If I intentionally slow down my car does it mean the time slows down because it will take me much longer to cover the same distance?
We could also ask a more simple question: when you are dead does the time move? If not, does that mean you are "traveling" at the speed of light or that you are just dead? :)