I'm confused on the different fields of physics. 14 years old and I"m very interested in this type of work, but I can't really decipher the difference between two fields which really interest me. Astrophysics and Theoretical physics. I have the definitions of the two and I've read about Theoretical Astrophysics but compared to actual Theoretical physics what does that entail? I've also read a lot about Quantum Physics and that really interests me as well. I've read a couple books by Dr. Michio Kaku and am especially interested in String theory and a possible theory of everything. So I guess my overall questions here is: based on the information given what do you think would be the best branch in physics for me to look into?