I want to be a professor in theoretical physics, but, people said that this position is limited. My question is, would a University recruit a excellent theoretical professor, even when there has been SO MANY theoretical physicist? I worry that, because theoretical physicists bring NO economic profit to the university, so the university may NOT want more theoretical physicist even when that person is really really good. Does good performance in phD guarantee a professorship? Another question, people said that to complete a phD needs 5 years (in USA). So, is it true that, to complete it within 3 years, is a VERY HARD job? Thanks, Twukwuw.