I'm finishing up the final drafts of my SOP for astronomy grad school, and I'm a little unclear on how detailed to be when it comes to research preferences. I've heard multiple suggestions, but in general I've been advised against naming a specific professor of interest unless you already have contact with that professor. As far as research interests go, though, how specific should I be? I don't want to commit completely to a research topic (because I really don't know) but I don't want to be too broad. I'm not really sure how to convey this in my writing (serious writers block). Any suggestions/advice? Thanks.