I'm working on a Physics BS and in my junior year. After this semester, I'll start the upper level physics courses. This semester is my last for non-math or science courses, but I am also taking Differential Equations. I currently work about 20 hours/week. Next semester, my classes will be Modern Physics I, Vector Analysis, and Introduction to PDE. Each semester henceforth is full of upper level physics courses and I need a senior level math course to complete my minor. I want to continue working part-time, but is 20 hours too much? I know these physics courses are conceptually heavy, not necessarily work heavy. I like to have time to absorb the material and actually learn it and not be rushed each week, etc. Thanks for any thoughts.