Let's assume there are two observers. Observer B is at rest and observer A is in a spaceship which has transparent walls. A draws line of 1 meter. When A arrives near B, B draws a line of 1 meter. And sees that A's 1 meter is shorter than own 1 meter. before forget i should say that meter is directed along motion. I hope i could explain well. My question is that how would A see B's line? shorter or longer? If answer is longer, it would be in conradict with relativity. But if answer is shorter, how could this be, it doesn't make sense.