Physicist Andy Howell recently gave a talk about the science of Star Wars and wrote up a summary of it for Ain’t It Cool News. Topics covered include binary star systems, droids, the Death Star, and lightsabers:
Of course, we still don’t know how to make a lightsaber. One big problem is confining plasma (if that is even what it is), into some tube. But a bigger problem is the amount of energy required. We can actually calculate this from clues in the movies!
In Episode I, Qui-Gon jabs his lightsaber into a door, and melts part of it. That’s just basic physics! To melt something, you have to raise its temperature to the melting point, and you can calculate how much energy that takes using the specific heat capacity of a material.