For me it's been definitely physics. In the high school I read a lot of divulgative material on the subject, and thought I was rather knowledgeable. Then I started to study it in the university... and roughly during the middle of my Ph.D. I felt I was ready to discuss it again. I'm still in the valley for music, probably: I thought I knew a lot because I knew a lot about rock music, and at the moment I'm trying to slowly fill my enormous gap in jazz and classical music,