One of the things I love best about being a writer is that it's an excuse to learn a lot of things. Because when you're building a world, especially a world where six impossible things regularly happen before breakfast, you don't want to throw the reader out of the story on a mundane detail (or the application of that mundane detail to a weird-world situation, like the Great Zombie Erection Debate of Clarion 2008. And yes, the mind reels at the potential search string that will bring traffic to my blog. Sorry guys, no immediate plans for zombie porn here.)
Er, moving on.
I like learning things. I went to grad school not so much because I wanted to collect fancy strings of letters after my name, but because I wanted to learn things, and continuing to get degrees seemed like the best way to do that at the time. (Being a writer is better. No one makes you learn the Rule Against Perpetuities. I cannot remember exactly which of our text books a friend's husband shot after our first year, but I really hope it was property law.)
My point. Oh, that I had a point, and might someday get to it... My point is get the details right. Sometimes, of course, you can't. My research for the current book involves Milton and Aquinas and Augustine and Teilhard de Chardin and John Chrysostom and Oliver Sacks and some musicians and calling my medically trained sister to ask her questions like "what do you know about brains?" (I think she liked that better than the last book, when I asked her questions like how long it took for someone to bleed out, and where to stab someone if you just want their arm to stop working for a little while.) I'm going to get things wrong, and there will be unanswerable questions (Like the one I asked on Twitter earlier because I need to deal with the order versus chaos problem in this book, and it was making my brain hurt to think about it all by myself.)
Because you have to believe in your world enough to bring it forth from the void of the white page, and the best key to belief is knowledge.