Hi everyone, I apologize for the long post, and the fact that it may not be written with perfect grammar and spelling since I am not a native English speaker. I am an engineering student from France, and I am interested in pursuing a PhD in physics in the near future. It's been a week that I've been sending e-mails to a lot of universities regarding the research opportunities they have, but I haven't been getting a lot of helpful answers. Maybe it is because my questions are not clear enough, but anyway, I am hoping I can finally find what I want on this forum. My main interest lies in space exploration and I'd like to build a company with ambitious goals in this domain. But I don't want to follow the Musk-like entrepreneurial path : I'm passionate about science (really, I love it, be it mathematics, physics or anything else), and if I am to be at the head of a science company, I want to be an expert to understand what's going on and recruit the best people. Hence my desire to get a PhD in physics. There are two subjects that I would like to conduct graduate research in, but I can't find what I should do for neither of them. Please, note that I am not asking for help to decide between the two subjects. What I would like is to get more insight into the two of them. 1) Controlled nuclear fusion I am really excited by the quest for man-made sustained nuclear fusion. I would really like to conduct graduate research on how to make compact nuclear fusion reactors, maybe create new plasma confinement methods, find new techniques to improve inertial confinement methods, find some new ways to initiate a fusion reaction and sustained it, etc. My problem is that I don't know what program I should apply to in order to conduct such research. Should it be the nuclear engineering department ? They are generally focused on fission reactors and the engineering aspect of them so I feel like this would not be the right choice. Should it be plasma physics ? Nuclear physics ? What do you think ? 2) Einstein field equation and warp field experiments I am also curious about space-time physics. I have heard of the Alcubierre metric and what it would imply for space travel. I am also aware of the limitations of this mathematical model and that many physicists believe it will be proven infeasible (being aware doesn't mean I understand any of it). However, as far as I know, this is still a valid solution to Einstein field equation. What should I do to learn about this field of physics and do research in it ? I would like to conduct research on some similar models, suggest new ones, or imagine some lab experiments that would confirm or invalidate these model. To my understanding, there are not many scientists doing research in this field right now. I have only heard of Sonny White at NASA and he hasn't been bringing anything to the table yet. Should I apply for cosmology ? Something else ? Would I be better off studying mathematics since it's all about differential geometry ? And finally the common question : where ? Where in the US or in GB. Where can I find the best course material in these two domains, as well as the best advisors ? So far I have thought of Berkeley, Caltech, the MIT, Stanford, University of Chicago, University of Washington... But it is hard for an international student to sort things out. If you could answer any of these questions, this would be of great help to me. Indeed, you may have noticed that I am completely lost right now. Anything you could say will help me. Thank you in advance.