yea he does but im sure he talks , he talks with people, especially historians, astronomers, chemists, writers, you name it, why im saying that? dreaming is one thing but getting inspiration is quite another, i argue that you can have one without another...
i mean , think about it, with a 'higher status' as a film producer you'd enjoy access to talk with these people right? if you're a no body you could dream a little but not this much to encompass all the means to make another 'world' more realistic, back to the OP and Luca connection, im pretty sure he didnt justr dreamt it , he read it somewhere or talked with astonomoer, but then again Albert Einstein could be right too, imagination is more powerful than knowledge...