Can we build a lightsaber?
I've been wanting to ask this one for a looong time... My sons (Lucas and Tristan) are Star Wars fans, and asked me if it was possible to make a real lightsaber. I said no, of course, but when they asked me WHY NOT?... I couldn't give them a thorough scientific explanation. Please help, Naked Scientists!
Dave - Depends exactly what you mean by lightsaber. Producing a kind of beam of light which is coming out of an object which is incredibly powerful and can cut through things, that's not impossible. But we certainly couldn't get anything nearly as powerful as that. We can't get laser that powerful in anything like that size of container, but we can get lasers which will cut through things within the size of a house, but we'll ignore the size issue at the moment. But the problem is making light suddenly stop at the end of the sort of 2-foot length, unless you put a mirror there it just wouldn't and also, light doesn't interact with other light, so you can't have sword fights with them. They would just go straight through each other and not affect each other. You might conceivably be able to make a plasma sabre so you could somehow constrain some very, very hot plasma into a tube magnetically or something conceivably. I think it would be difficult but just about possible, but certainly not with light.