Science Fiction vs. Physics: The Lightsaber Question (opens in new tab)

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 app...