Hi there.. I have been away from PF for a long time now. But I need some guidance and I have come back here. I am describing all the fields that I believe I have some degree of interest in, and now I need to decide which one to take up for a Phd. I am currently doing a Masters in Theoretical Physics. It has a lot of Particle Physics theory related courses like RQFT, Quantum THeory: path intergrals, MQFT, Standard Model.I have taken the first two courses already, I am not sure if I understand them properly or not, but I enjoyed doing calculations for Feynman diagrams. Also, I had a course in particle physics, that was based on experimental aspect. Well, I somehow do not like experimental work and hence didn't appreciate this course at all. It sounded a lot like facts nd less of explanation to all those weird things. Other than Particle Theory, I have keen interest in foundation of Quantum Mechanics, but all my professors have said it has no scope, not for a PhD. They have suggested Quantum Optics and Information. I looked at the work going on in these fields and it seems to be inclined towards experimental side. I believe, I have interest in Optics... as in how photon interacts with matter and all the amazing properties of light, but as far as I know there not much in this.Further, I am not so sure about using the Quantum ideas to develop Quantum computers...this doesn't fascinate me much. I possibly have a little interest in Materials as well. That is because I worked with Ferroeletric and Piezoelectric material. I am quite interested to study the phase transition in different materials. This leads me to Statistical Physics and its applications. I think I want this as well. So, in short, it feels like I want to study everything. Thus choosing one and leaving the rest seems difficult. I need you people to tell me if there is a group that works on materials theoretically, applying QED type Feynman Diagrams to study the interaction of Light with it.. what will such a group be called? And what category will it fall under? Or if reading my post you think I have interest in something else, I am willing to hear it. Also, I haven't specifically mentioned any sub topic in these field because I don't know much about that. I know, just by reading the things i have said no one can clearly tell me how to really decide my PhD field. But I m looking for a different point of view on this. Any help is appreciated. Thanks for reading so much..