"Electives" in grad school? Hello PF, I am an undergrad student majoring in one of the STEM field. I have a strong interest in particle physics, but I am not really interested in any other discipline of physics. For this reason, I don't think going to grad school in physics is not a realistic option. But I still want to take particle physics courses as electives I have seen some professors' profiles where some of their research interest is related, but not quite exact. (like physics & differential geometry or finance & analysis) - well, I don't think they are good examples for my point, but... hope you get my point So I was wondering, while in grad school, if I could take undergrad prerequisites courses for particle physics, (intermedieate mechanics, quantum physics, mathematical physics), particle physics courses themselves.