An anonymous reader writes PBS' It's OK to be Smart made this interesting video showing us what is and isn't physically realistic or possible in the space battles we've watched on TV and the movies. From the article: "You're probably aware that most sci-fi space battles aren't realistic. The original Star Wars' Death Star scene was based on a World War II movie, for example. But have you wondered what it would really be like to duke it out in the void? PBS is more than happy to explain in its latest It's Okay To Be Smart video. As you'll see below, Newtonian physics would dictate battles that are more like Asteroids than the latest summer blockbuster. You'd need to thrust every time you wanted to change direction, and projectiles would trump lasers (which can't focus at long distances); you wouldn't hear any sound, either."