I am a little confused about the Galilean transforms. If I have t'=[itex]\gamma[/itex]t Is t ALWAYS the frame of reference that we are in? i.e. If a spacecraft is moving away from Earth, and I wanted to measure the time taken on the spacecraft to reach some distance, would t be the variable I should look for? If yes, does the length contraction formula (l'=[itex]\gamma[/itex]l) work the same way? i.e. If I had two men at rest, a distance d from each other, and a spacecraft flies past and I want to measure the distance someone on the spacecraft travels - would l be the variable I wanted to find? Help would be greatly appreciated!