Often wondered about this comment about magic. Say, for example, you showed an educated person from the dark ages a car, I think that would not be too hard to describe to remove the perceived magic. A method of transport etc etc. Maybe even an uneducated person. How far back do you have to go in the ignorance stakes? From my perspective, if an alien landed tomorrow and pointed to the sky and said they were from there, you would assume they travelled it somehow. My first thought would be, show us your engine, four pot or eight pot, where are the carbs etc etc not (insert Monty Python cliché) Burn em, they are a witch.....
PS, just google Shannon information theory. Pass me a couple of tin cans and some string... (actually, some of it rings a bell).