Maybe "dunce" is the wrong word, but I'm pretty weak on stat mech/thermo. I've had a few courses in them but not to the point where I can understand anything but the most rudimentary basics (each time I took a course in them I happened to have been distracted with other things). I'm a thirdish year grad student specializing in gravity, and so far I'm learning GR pretty well. So how big of a concern should this be? Does it hinder my abilities as a physicist? Aren't thermo and stat mech such big, important subjects that you need to be well-versed in them to do any area of physics? Or is it normal for people with PhDs, like professors and postdocs, to be very weak in a big area of physics like this once they've gotten to the point where they start specializing? Thanks.