We might criticize special effects for overstaying their welcome on occasion, but without CGI and crazy miniature work, we wouldn't have space battles. Watching spaceships shoot lasers and blow up is among the greatest, basest pleasures of movies. Even the Star Wars prequels, superfluous as they may be, have a few entertaining space fights. Color us saddened if unsurprised that these scenes are very scientifically inaccurate.
As part of his It's Okay to Be Smart series, PBS's Joseph Shoer produced a six-minute video (embedded above) explaining how movie-magic space combat would work in a scientifically accurate setting. Too many factors, especially speed-of-light travel and the feasibility of weaponized lasers, prevent the possibility of flashy movie-style battles. He suggests that realistically, space combat would resemble a war from the 1800s, with cannon-like projectiles and sluggish communications.
So why do the movies get it wrong? Shoer argues that many early science fiction films were in fact reflections on modern war, and their combat scenes stylistically mimicked classic cinematic depictions of aerial dogfights. He juxtaposes footage of the famous Death Star battle scene from Star Wars alongside clips from The Dam Busters (HU DVD 7519), and it's hard to argue against that visual evidence.
If you like sci-fi, have a few minutes to spare, and don't mind a little cheesiness, check this video out. Hopefully it won't ruin your enjoyment of "pew pew pew" in the future