Harmy said:
Well, the cave question was obviously answered in the EU - and in the good one (at lest for me) too. It's explained in Zahn's Thrawn trilogy, and the answer is quite cool IMHO but I won't post it, I don't want to stop anyone's imagination by an official explanation. If you want to know, I'm sure you can find out for yourselves :-)
I've never considered the EU "official" in any way whatsoever. Feel free to post whatever you like, it won`t dull my imagination one bit ;)