the type of person who fails his physics coursesHer . Haven ' t failed a class yet , but grades don ' t mean much . how much better he understands quantum mechanics than everyone else ? I don ' t understand quantum mechanics at all , and I never said I did . It isn ' t my field of study within physics . I wouldn ' t dare to argue any point in physics unless I had a PhD in the area , because I ' m aware of just how little I know . Memorising a formula doesn ' t make you smart . Of course not . Understanding it ' s derivation and possible applications , along with possible pitfalls and weaknesses does make you proficient , though , and you can ' t learn a lot of those derivations without at least knowing ODEs , for any area . Nothing makes you ' smart ', it merely makes you competent . The people who propagate change and come up with radical theories do so from a place of intuition . Only after understanding the previous theory . You need adequate training in how to make hypotheses and test them for experimentalists , at least , and you need to have a basic grasp of the history of the topic before you can have a good chance at advancing the field . Otherwise , your theories will likely violate some basic tenet in physics , or you ' ll end up reinventing the wheel . You need to understand possible statistical pitfalls , and how to write a research paper . That ' s what a PhD is for .