*Ahem* All right folks, here's some lightsaber tech for you. First of all, lightsaber blades aren't just single beams of energy- they're arcs. The blade is generated by channeling power through a refractive crystal, and when it leaves the emitter guard it passes between two power couplings, one positive and one negative. This causes the blade to curve around and back in on itself, creating what's really an endless ring of energy. This 'ring' is so thin the space between the sides is nonexistant, and thus it appears to be a solid blade. But it's not, and that's why the blade 'stops' instead of going on and on to infinity. Because of the 'ring' nature of a lightsaber blade, energy is kept within the infinite loop of the blade itself. Thus, a lightsaber blade does not generate heat just humming in the air. Another result of this is that a lightsaber does not expend power unless it cuts something- because the 'ring' is broken. Then it will generate heat- intense heat, explaining why Qui-Gon was quite capable of melting the blast doors on the Trade Federation starship in Episode I. Lightsabers are thus incredibly efficient, and lightsabers found in ancient Jedi tombs, thousands of years old, are often still in working condition. And that's my Star Wars Science for the day. Always brush your teeth, kids!