(From a friend one mine; I'm just hosting this here.)
Issue 1: Relativity of Simultaneousness:
Your buddy Einstein is riding the interstellar express train. All the lights are off, but just as it passes your observation platform, he turns on a lamp in the middle of the train. You and he have taken bets on which end of the train, front or back, will light up first. As expected, your video cameras on the platform record the rear of the train lighting up first, since, as the light spreads out from the original location of the lamp, the rear of the train moves slightly closer to the source, while the front end is moving away. However, Einstein reports that his equipment shows both ends lit up simultaneously.
Both of you are correct. In your reference frame the events "light reaches front of train" and "light reaches rear of train" are not simultaneous, even though in Einstein's they are are.