A college physics professor was explaining a particularly complicated concept to his class when a pre-med student interrupted him.

"Why do we have to learn this stuff?" The young man blurted out.

"To save lives," the professor responded before continuing the lecture.

A few minutes later the student spoke up again. "So how does difficult physics save lives professor?"

Without missing a beat, the professor said to the student "Difficult physics saves lives, because it keeps the idiots out of medical school."