When a cool science fiction weapon sticks around for half a century and gathers more and more fans and more fiction, there will be people who put way too much thought into it. The lightsabers from Star Wars were born out of a cool special effect, but now everyone wants one, or at least wants to understand them.
What happens if you drop a lightsaber? Specifically, what happens if you drop one vertically, business end first, into the ground. Would it keep burning its way through the earth indefinitely? In the Star Wars universe, no, because there's a safety feature that disables the blade when it's not held. But there have been depictions of Jedi throwing lightsabers, so this feature apparently can be disabled. So what would happen in the real world? Rocket Riley goes through all the ways a lightsaber would act on earth, if there were such a thing. -via Laughing Squid