Why do you say it as bullshit?

One important thing in higher education for math and physics is to be able to perform detail technical computations or modeling for phenomenons. In common high school and undergraduate physics class, it only requires students to be able to come up models with intuitions. But in graduate schools, you are trained to examine each step to make sure nothing is left out or based on assumptions that are wrong in your mind.

Therefore a lot of time you are not sure what something is until you re-examine all postulates that you learn when you are young.