Hello, I was wondering if perhaps someone could provide some insight as to the PhD program that would prepare me the best for what I would like to do research in one day. I am currently a mathematics undergrad with 2 semesters left. I am torn between getting a PhD in photonics, physics, and mathematics. Im just not sure which would be the best fit for my area of interest. The area I am interested in doing research is energy advancement i.e. anti-matter annihilation, fusion, photonic laser thrusters etc. Also, if one were to suggest say physics as the most appropriate for these areas of research, is there a particular area of physics that would be best? Mathematical physics? Particle physics? Theoretical physics? etc. Same with math, if one were to suggest math as an appropriate fit what would be better, applied or pure? Thank you for any and all honest feedback, I'm sure a lot of questions come through here like this, but I just can't seem to pick out which would benefit me the most in a research energy industry. Ideally I would like to go to graduate school in an area of mathematics, including mathematical physics, applied or pure math, and if one of these will get me into the above areas of research please let me know and which one, however, if an area of physics would be a better fit I would be more than willing to make the switch.