Hello! What can a first year PhD student (in an American university) do, research related, in the field of Theoretical (mainly high-energy) physics? I know in the USA you need to start research from the first semester of PhD (even if you formally choose a definite field of research at the end of your second year). I did research in several areas, mostly experimental and there you can more or less get started, without understanding all the details behind what is going on (I mean in the beginning), but for theoretical physics, you need to know this stuff (QFT, GR etc.) and this stuff is usually not even taught in the first year of PhD (in the first year for a PhD you usually need to take EM, CM, QM and Stat Mech). So what kind of work can a student doing theoretical physics do, without previously knowing these topics (which realistically speaking take quite a while to master)? Thank you!